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1.	Ortiz Catalan, Max Jair, 1982, et al. (author) Patterned Stimulation of Peripheral Nerves Produces Natural Sensations With Regards to Location but Not Quality 2019 In: IEEE Transactions on Medical Robotics and Bionics. - 2576-3202. ; 1:3, s. 199-203 Journal article (peer-reviewed)abstract Sensory feedback is crucial for dexterous manipulation and sense of ownership. Electrical stimulation of severed afferent fibers due to an amputation elicits referred sensations in the missing limb. However, these sensations are commonly reported with a concurrent “electric” or “tingling” character (paresthesia). In this paper, we examined the effect of modulating different pulse parameters on the quality of perceived sensations. Three subjects with above-elbow amputation were implanted with cuff electrodes and stimulated with a train of pulses modulated in either amplitude, width, or frequency (“patterned stimulation”). Pulses were shaped using a slower carrier wave or via quasi-random generation. Subjects were asked to evaluate the natural quality of the resulting sensations using a numeric rating scale. We found that the location of the percepts was distally referred and somatotopically congruent, but their quality remained largely perceived as artificial despite employing patterned modulation. Sensations perceived as arising from the missing limb are intuitive and natural with respect to their location and, therefore, useful for functional restoration. However, our results indicate that sensory transformation from paresthesia to natural qualia seems to require more than patterned stimulation.
2.	Rezaei Aghdam, Sina, 1989, et al. (author) Reducing Motion Artifacts in Microwave-Based Hemorrhagic Stroke Detection 2019 In: 13th European Conference on Antennas and Propagation, EuCAP 2019. Conference paper (peer-reviewed)abstract The use of microwave technology for brain stroke detection opens up the opportunity for developing low-cost transportable devices which can be employed for rapid and prehospital detection of bleeding in patients with traumatic brain injury. Since the detection relies on changes in the scattering parameters of the tissues during pathological conditions, the movements in head or the antennas can deteriorate the detection accuracy. As a countermeasure to this problem, we introduce a technique for reducing the sensitivity of the detection system to motion artifacts. Via analyzing the scattering from an anatomically accurate model of human brain, we evidence that the channels between different pairs of antennas exhibit significantly different levels of sensitivity to the movement. Using this as a ground truth, we develop a generalized singular value decomposition (GSVD)-based approach for assigning appropriate weights to the channels between different antennas such that the probability of correct bleeding detection is maximized.
3.	Rowa, Per, et al. (author) Automated Malaria Parasite Detection 1977 Reports (other academic/artistic)abstract A system for malaria parasite detection in thin blood-smears is presented. Sample slides prepared with standard methods are accepted. A low-cost TV-camera mounted on an ordinary microscope with a computer controlled stage is used as a picture sensor. Frames, digitized in windows of 64 x 64 pixels are fed into a special purpose picture processor at normal frame rate (25 frames/sec). In the picture processor measurements are made on the images at high speed. The classification problem is split into different levels each having different characteristics such as different sampling density. Four classes, three of which are different types of malaria parasites, are recognized. As a whole the classification is best labelled as a sequential pattern recognition procedure.In its preliminary version the system has been run at a speed comparable to that of a human operator, that is l 500 cells per minute. A test on 80 000 cells gave 25 false negatives out of 283 parasites (9%) and 41 false positives (0.05%).
4.	Tomasic, Ivan, et al. (author) Comparison of publicly available beat detection algorithms performances on the ECGs obtained by a patch ECG device 2019 In: 2019 42nd International Convention on Information and Communication Technology, Electronics and Microelectronics, MIPRO 2019 - Proceedings. - : Institute of Electrical and Electronics Engineers Inc.. - 9789532330984 ; , s. 275-278 Conference paper (peer-reviewed)abstract Eight ECG beat detection algorithms, from the PhysioNet's WFDB and Cardiovascular Signal toolboxes, were tested on twenty measurements, obtained by the Savvy patch ECG device, for their accuracy in beat detection. On each subject, one measurement is obtained while sitting and one while running. Each measurement lasted from thirty seconds to one minute. The measurements obtained while running were more challenging for all the algorithms, as most of them almost perfectly detected all the beats on the measurements obtained in sitting position. However, when applied on the measurements obtained while running, all the algorithms have performed with decreased accuracy. Considering overall percentage of the faulty detected peaks, the four best algorithms were jqrs, from the Cardiovascular Signal Toolbox, and ecgpuwave, gqrs, and wqrs, from the WFDB Toolbox, with percentages of faulty detected beats 1.7, 2.3, 2.9, and 3, respectively.
5.	Zanoli, Massimiliano, 1989 (author) Ultra wideband microwave hyperthermia for brain cancer treatment 2022 Doctoral thesis (other academic/artistic)abstract Despite numerous clinical trials demonstrating that microwave hyperthermia is a powerful adjuvant modality in the treatment of cancers, there have been few instances where this method has been applied to brain tumors. The reason is a combination of anatomical and physiological factors in this site that require an extra degree of accuracy and precision in the thermal dose delivery. Current clinical applicators are not able to provide such control, partly because they are designed to operate at a single fixed frequency. In terms of treatment planning, the use of a single frequency is limiting as the size of the focal spot cannot be modified to accommodate the specific tumor volume and location. The introduction of ultra wide-band (UWB) systems opens up an opportunity to overcome these limitations, as they convey the possibility of adapting the focal spot and obtaining different power deposition patterns to reduce the heating of healthy tissues. In this thesis, we explore whether the current SAR-based treatment planning methods can be meaningfully translated to the UWB setting and propose new solutions for deep UWB microwave hyperthermia. We analyze the most commonly used cost functions for treatment planning optimization and discuss their suitability for use with UWB systems. Then, we propose a novel SAR-based cost function (HCQ) for UWB optimization that exhibits a high correlation with the resulting tumor temperature. To solve for the HCQ, we describe a novel, time-reversal-based, iterative scheme for a rapid and efficient optimization of UWB treatment plans. Next, we investigate the design possibilities of UWB brain applicators and introduce a fast E-field approximation scheme to quickly explore a large number of array configurations. The method determines the best antenna arrangement around the head with respect to the multiple objectives and requirements of clinical hyperthermia. Together, the proposed solutions manage to achieve the level of tumor coverage and hot-spot suppression that is necessary for a successful treatment. Finally, we investigate the benefit of integrating hyperthermia delivered by an optimized UWB applicator into the radiation therapy plan for a pediatric medulloblastoma patient. The results suggest that UWB microwave hyperthermia for brain cancer treatment is feasible and motivate efforts for further development of UWB applicators and systems.
6.	Zeng, Xuezhi, 1980, et al. (author) Investigation of an ultra wideband noise sensor for health monitoring 2020 In: Sensors. - : MDPI AG. - 1424-8220. ; 20:4 Journal article (peer-reviewed)abstract Quick on-scene assessment and early intervention is the key to reduce the mortality of stroke and trauma patients, and it is highly desirable to develop ambulance-based diagnostic and monitoring devices in order to provide additional support to the medical personnel. We developed a compact and low cost ultra wideband noise sensor for medical diagnostics and vital sign monitoring in pre-hospital settings. In this work, we demonstrated the functionality of the sensor for respiration and heartbeat monitoring. In the test, metronome was used to manipulate the breathing pattern and the heartbeat rate reference was obtained with a commercial electrocardiogram (ECG) device. With seventeen tests performed for respiration rate detection, sixteen of them were successfully detected. The results also show that it is possible to detect the heartbeat rate accurately with the developed sensor.
7.	Khodadad, Davood, 1985-, et al. (author) Optimized breath detection algorithm in electrical impedance tomography 2018 In: Physiological Measurement. - : IOP Publishing. - 0967-3334 .- 1361-6579. ; 39:9 Journal article (peer-reviewed)abstract Objective: This paper defines a method for optimizing the breath delineation algorithms used in electrical impedance tomography (EIT). In lung EIT the identification of the breath phases is central for generating tidal impedance variation images, subsequent data analysis and clinical evaluation. The optimisation of these algorithms is particularly important in neonatal care since the existing breath detectors developed for adults may give insufficient reliability in neonates due to their very irregular breathing pattern.Approach: Our approach is generic in the sense that it relies on the definition of a gold standard and the associated definition of detector sensitivity and specificity, an optimisation criterion and a set of detector parameters to be investigated. The gold standard has been defined by 11 clinicians with previous experience with EIT and the performance of our approach is described and validated using a neonatal EIT dataset acquired within the EU-funded CRADL project.Main results: Three different algorithms are proposed that improve the breath detector performance by adding conditions on (1) maximum tidal breath rate obtained from zero-crossings of the EIT breathing signal, (2) minimum tidal impedance amplitude and (3) minimum tidal breath rate obtained from time-frequency analysis. As a baseline a zero-crossing algorithm has been used with some default parameters based on the Swisstom EIT device.Significance: Based on the gold standard, the most crucial parameters of the proposed algorithms are optimised by using a simple exhaustive search and a weighted metric defined in connection with the receiver operating characterics. This provides a practical way to achieve any desirable trade-off between the sensitivity and the specificity of the detectors.
8.	Boyraz Baykas, Pinar, 1981, et al. (author) Design of a Low-cost Tactile Robotic Sleeve for Autonomous Endoscopes and Catheters 2020 In: Measurement and Control. - : SAGE Publications. - 0020-2940. ; 53:3-4, s. 613-626 Journal article (peer-reviewed)abstract Recent developments in medical robotics have been significant, supporting the minimally invasive operation requirements, such as smaller devices and more feedback available to surgeons. Nevertheless, the tactile feedback from a catheter or endoscopic type robotic device has been restricted mostly on the tip of the device and was not aimed to support the autonomous movement of the medical device during operation. In this work, we design a robotic sheath/sleeve with a novel and more comprehensive approach, which can function for whole-body or segment-based feedback control as well as diagnostic purposes. The robotic sleeve has several types of piezo-resistive pressure and extension sensors, which are embedded at several latitudes and depths of the silicone substrate. The sleeve takes the human skin as a biological model for its structure. It has a better tactile sensation of the inner tissues in the torturous narrow channels such as cardiovascular or endo-luminal tracts in human body thus can be used to diagnose abnormalities. In addition to this capability, using the stretch sensors distributed alongside its body, the robotic sheath/sleeve can perceive the ego-motion of the robotic backbone of the catheter and can act as a position feedback device. Because of the silicone substrate, the sleeve contributes toward safety of the medical device passively by providing a compliant interface. As an active safety measure, the robotic sheath can sense blood-clots or sudden turns inside a channel and by modifying the local trajectory, and can prevent embolisms or tissue rupture. In the future, advanced manufacturing techniques will increase the capabilities of the tactile robotic sleeve.
9.	Böhler, Christian, et al. (author) Multilayer Arrays for Neurotechnology Applications (MANTA): Chronically Stable Thin-Film Intracortical Implants 2023 In: Advanced Science. - : John Wiley & Sons. - 2198-3844. ; 10:14 Journal article (peer-reviewed)abstract Flexible implantable neurointerfaces show great promise in addressing one of the major challenges of implantable neurotechnology, namely the loss of signal connected to unfavorable probe tissue interaction. The authors here show how multilayer polyimide probes allow high-density intracortical recordings to be combined with a reliable long-term stable tissue interface, thereby progressing toward chronic stability of implantable neurotechnology. The probes could record 10–60 single units over 5 months with a consistent peak-to-peak voltage at dimensions that ensure robust handling and insulation longevity. Probes that remain in intimate contact with the signaling tissue over months to years are a game changer for neuroscience and, importantly, open up for broader clinical translation of systems relying on neurotechnology to interface the human brain.
10.	Cubo, Rubén, et al. (author) Electric field modeling and spatial control in Deep Brain Stimulation 2015 In: Proc. 54th Conference on Decision and Control. - Piscataway, NJ : IEEE. - 9781479978847 - 9781479978861 ; , s. 3846-3851 Conference paper (peer-reviewed)abstract Deep Brain Stimulation (DBS) is an established treatment, in e.g. Parkinson's Disease, whose underlying biological mechanisms are unknown. In DBS, electrical stimulation is delivered through electrodes surgically implanted into certain regions of the brain of the patient. Mathematical models aiming at a better understanding of DBS and optimization of its therapeutical effect through the simulation of the electrical field propagating in the brain tissue have been developed in the past decade. The contribution of the present study is twofold: First, an analytical approximation of the electric field produced by an emitting contact is suggested and compared to the numerical solution given by a Finite Element Method (FEM) solver. Second, the optimal stimulation settings are evaluated by fitting the field distribution to a target one to control the spread of the stimulation. Optimization results are compared to those of a geometric approach, maximizing the intersection between the target and the activated volume in the brain tissue and reducing the stimulated area beyond said target. Both methods exhibit similar performance with respect to the optimal stimuli, with the electric field control approach being faster and more versatile.
11.	Davidsson, Johan, 1967, et al. (author) A Model for Research on Penetrating Traumatic Brain Injuries 2019 In: Neuromethods. - New York, NY : Springer New York. - 1940-6045 .- 0893-2336. ; 149, s. 47-59 Book chapter (other academic/artistic)abstract The animal model presented here produces high-speed penetrating traumatic brain injuries (pen-TBI) to simulate a form of neurotrauma that is severe and is the prevailing TBI in warzones and in areas with high incidence of violence. Commonly, these neurotraumas involve laceration of brain tissue, accompanying hemorrhage, edema, and inflammation. This also occurs in the pen-TBI model designed for rats that is presented here. During trauma, a probe, constructed in one single unit in aluminum and guided by a probe holder, is propelled by a lead bullet and penetrates at high speed into the brain parenchyma of the anesthetized animal. The animal’s head is held in position in a purposely built stereotactic frame. This frame can be adjusted in position relative the tip of the probe so that the tip of the probe is positioned on the exposed dura, using three orthogonally arranged horizontal slides. This procedure will facilitate high similarity in probe penetration location. By adjusting the air pressure in the air-driven accelerator used to accelerate the lead bullet, a large range of probe velocities can be achieved; 110 m/s probe velocity is commonly used. Several probe tip shapes are available for use in the pen-TBI model; pointy, blunt, and flat. The distance the probe penetrates the brain can be controlled. A typical distance is 5.5 mm, and this distance has been found to be almost independent of probe velocity and probe tip shape. After the probe has penetrated the animal, the pen-TBI device facilitates removal of the probe without causing additional brain damage. To do so, the animal is removed using the horizontal slider on the device that moves the animal’s head away from the probe in the direction of probe travel. The pen-TBI device is easy to operate and requires limited pre-trauma and post-trauma surgery. The device induces a small cavity, primary injury in a greater volume of the brain than the cavity and secondary injuries in an even greater volume that is several times that of the primary injury volume. The model appears to produce identical injuries in terms of appearance and dimensions in-between animals of same sex and body mass. The device also produces substantial but short-lived intracranial brain pressure changes, some 8-bar overpressure in the contralateral ventricle has been recorded, with high repeatability.
12.	Fredén Jansson, Karl-Johan, 1988, et al. (author) Robustness and lifetime of the bone conduction implant - a pilot study 2019 In: Medical Devices: Evidence and Research. - 1179-1470. ; 12, s. 89-100 Journal article (peer-reviewed)abstract Objectives: The objective of this study was to develop methods for evaluating the mechanical robustness and estimating the lifetime of the novel bone conduction implant (BCI) that is used in a clinical study. The methods are intended to be applicable to any similar device. Materials and methods: The robustness was evaluated using tests originally developed for cochlear implants comprising a random vibration test, a shock test, a pendulum test, and an impact test. Furthermore, magnetically induced torque and demagnetization during magnetic resonance imaging at 1.5 T were investigated using a dipole electromagnet. To estimate the lifetime of the implant, a long-term age-accelerated test was performed. Results: Out of all the tests, the pendulum and the impact tests had the largest effect on the electro-acoustic performance of the BCI implant, even if the change in performance was within acceptable limits (< 20%). In comparison with baseline data, the lower and higher resonance peaks shifted down in frequency by 13% and 18%, respectively, and with a loss in magnitude of 1.1 and 2.0 dB, respectively, in these tests. Conclusion: A complete series of tests were developed, and the BCI passed all the tests; its lifetime was estimated to be at least 26 years for patients who are using the implant for 12 hours on a daily basis.
13.	Håkansson, Bo, 1953, et al. (author) VEMP using a new low-frequency bone conduction transducer 2018 In: Medical Devices: Evidence and Research. - 1179-1470. ; 11, s. 301-312 Journal article (peer-reviewed)abstract Objective: A new prototype bone conduction (BC) transducer B250, with an emphasized low-frequency response, is evaluated in vestibular evoked myogenic potential (VEMP) investigations. The aim was to compare cervical (cVEMP) and ocular (oVEMP) responses using tone bursts at 250 and 500 Hz with BC stimulation using the B250 and the conventional B81 transducer and by using air conduction (AC) stimulation. Methods: Three normal subjects were investigated in a pilot study. BC stimulation was applied to the mastoids in cVEMP, and both mastoid and forehead in oVEMP investigations. Results: BC stimulation was found to reach VEMP thresholds at considerably lower hearing levels than in AC stimulation (30-40 dB lower oVEMP threshold at 250 Hz). Three or more cVEMP and oVEMP responses at consecutive 5 dB increasing mastoid stimulation levels were only obtained in all subjects using the B250 transducer at 250 Hz. Similar BC thresholds were obtained for both ipsilateral and contralateral mastoid stimulation. Forehead stimulation, if needed, may require a more powerful vibration output. Conclusion: Viable VEMP responses can be obtained at a considerably lower hearing level with BC stimulation than by AC stimulation. The cVEMP and oVEMP responses were similar when measured on one side and with the B250 attached to both ipsilateral and contralateral mastoids.
14.	Lindau, Björn, 1961, et al. (author) Virtual fixturing: Inspection of a non-rigid detail resting on 3-points to estimate free state and over-constrained shapes 2020 In: ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE). ; 2B-2020 Conference paper (peer-reviewed)abstract When the geometry of a non-rigid part or pre-assembly is measured fully clamped (over-constrained) in a measurement fixture, the spring-back information and influence from gravity forces are usually lost in the collected data. From the 3D-measurement data, it is hard to understand built in tensions, and the detail's tendency to bend, twist and warp after release from the measurement fixture. These effects are however important to consider when analyzing each part´s contribution to geometrical deviations after assembly. In this paper a method is presented, describing how free state shape and over-constrained shape of a measured detail can be virtually estimated starting from acquired data when the part or the preassembly is resting on only 3-points. The objective is to minimize the information loss, to spare measurement resources and to allow for a wider use of the collected data, describing the geometry. Part stiffnesses, part to part contacts and gravity effects are considered in the proposed method. The method is based on 3D-scanning techniques to acquire the shape of the measured object. Necessary compensations for part stiffnesses and gravity effects are based upon Finite Element Analysis (FEA) and the Method of Influence Coefficients (MIC). The presented method is applied to an industrial case to demonstrate its potential. The results show that estimated over-constrained shapes show good resemblance with measurements acquired when part is over-constrained in its measurement fixture.
15.	Persson, Ann-Charlotte, 1970, et al. (author) A novel method for objective in-situ measurement of audibility in bone conduction hearing devices - a pilot study using a skin drive BCD 2023 In: International Journal of Audiology. - : Informa UK Limited. - 1499-2027 .- 1708-8186. ; 62:4, s. 357-361 Journal article (peer-reviewed)abstract Objective Objective measurement of audibility (verification) using bone conduction devices (BCDs) has long remained an elusive problem for BCDs. For air conduction hearing aids there are well-defined and often used objective methods, and the aim of this study is to develop an objective method for BCDs. Design In a novel setup for audibility measurements of bone-anchored hearing aid (BAHA) attached via a soft band, we used a skin microphone (SM) on the forehead measuring in-situ sound field thresholds, maximum power output (MPO) and international speech test signal (ISTS) responses. Study sample Five normal-hearing persons. Result Using the electrical output of SM it was possible to objectively measure the audibility of a skin drive BCD, presented as an eSPL-o-gram showing thresholds, MPO and ISTS response. Normalised eSPL-o-gram was verified against corresponding FL-o-grams (corresponding force levels from skull simulator and artificial mastoid (AM)). Conclusion The proposed method with the SM can be used for objective measurements of the audibility of any BCDs based on thresholds, MPO and speech response allowing for direct comparisons of hearing and BCD output on the same graph using an eSPL-o-gram. After normalisation to hearing thresholds, the audibility can be assessed without the need for complicated calibration procedures.
16.	Rems, Lea, et al. (author) Cell electrofusion using nanosecond electric pulses 2013 In: Scientific Reports. - : Macmillan Publishers Ltd.. - 2045-2322. ; 3 Journal article (peer-reviewed)abstract Electrofusion is an efficient method for fusing cells using short-duration high-voltage electric pulses. However, electrofusion yields are very low when fusion partner cells differ considerably in their size, since the extent of electroporation (consequently membrane fusogenic state) with conventionally used microsecond pulses depends proportionally on the cell radius. We here propose a new and innovative approach to fuse cells with shorter, nanosecond (ns) pulses. Using numerical calculations we demonstrate that ns pulses can induce selective electroporation of the contact areas between cells (i.e. the target areas), regardless of the cell size. We then confirm experimentally on B16-F1 and CHO cell lines that electrofusion of cells with either equal or different size by using ns pulses is indeed feasible. Based on our results we expect that ns pulses can improve fusion yields in electrofusion of cells with different size, such as myeloma cells and B lymphocytes in hybridoma technology.
17.	Fredén Jansson, Karl-Johan, 1988 (author) The Balanced Electromagnetic Separation Transducer for Bone Conduction Audiometry and Hearing Rehabilitation 2017 Doctoral thesis (other academic/artistic)abstract Hearing via air conduction (AC) and bone conduction (BC) are attributed to bethe natural ways of conducting sound to the cochlea. With AC hearing, air pressurevariations are transmitted to the cochlea via the ear canal, whereas with BChearing, sound vibrations are transmitted through the skull bone to the cochlea.Patients with a hearing loss in the cochlea or auditory nerve are commonly rehabilitatedwith conventional AC hearing aids in the ear canal, but also using cochlearimplants. If the pathway for AC sound to reach the cochlea is obstructed, patientscan often benet from bone conduction devices (BCDs). In order to determinethe type and degree of hearing loss, the BC hearing thresholds are measured usinga bone conduction vibrator, and then analyzed together with the AC hearingthresholds for the diagnosis and to suggest an appropriate rehabilitation alternative.The motor unit in conventional BCDs and bone vibrators are known togenerate high amount of distortion at low frequencies where the Balanced ElectromagneticSeparation Transducer (BEST) principle may oer a new era in BChearing rehabilitation and audiometry.This thesis combines two BC hearing related topics, where the rst topic is anevaluation of a new audiometric bone vibrator, Radioear B81, which is assumedto oer more accurate BC hearing threshold measurements. The second topic isrelated to a new type of active transcutaneous BCD, called the Bone ConductionImplant (BCI), which leaves the skin intact by using a wireless solution thatdoes not require a permanent skin penetration. Even though the applications aredierent, both devices use the BEST principle as motor unit in their design.The audiometric bone vibrator Radioear B81 was found to have an improvedperformance at low frequencies where it can produce higher output levels with lessharmonic distortion than the conventional Radioear B71. In a clinical study of therst six patients, the BCI was found as ecient as already commercially availableBCDs, and with the advantage of not needing a skin penetration. In a technicalevaluation of the BCI, it was shown to be a mechanically robust design and totolerate magnetic resonance imaging at 1.5 Tesla.
18.	Grishenkov, Dmitry, 1983-, et al. (author) In search of the optimal ultrasound heart perfusion imaging platform 2015 In: Journal of ultrasound in medicine. - : Wiley. - 0278-4297 .- 1550-9613. ; 34:9, s. 1599-1605 Journal article (peer-reviewed)abstract ObjectiveQuantification of the myocardial perfusion by contrast echocardiography (CEC) remains a challenge. Existing imaging phantoms used to evaluate the performance of ultrasound scanners do not comply with perfusion basics in the myocardium, where perfusion and motion are inherently coupled.MethodsTo contribute towards an improvement, we developed a CEC perfusion imaging platform based on isolated rat heart coupled to the ultrasound scanner. Perfusion was assessed using three different types of contrast agent: dextran-based Promiten®, phospholipid-shelled SonoVue®, and polymer-shelled MB-pH5-RT. The myocardial video-intensity was monitored over time from contrast administration to peak and two characteristic constants were calculated using exponential fit (A representing capillary volume and b representing inflow velocity).ResultsAcquired experimental evidence demonstrates that the application of all three types of contrast agent allow ultrasonic estimation of myocardial perfusion in the isolated rat heart. Video-intensity maps show that an increase in contrast concentration increases the late plateau values, A, mimicking increased capillary volume. Estimated values of the flow, proportional to Axb, increase when the pressure of the perfusate column increases from 80 to 110 cm of water. This finding is in agreement with the true values of the coronary flow increase measured by the flowmeter attached to the aortic cannula.ConclusionsThe described CEC perfusion imaging platform holds promise for standardized evaluation and optimization of ultrasound contrast perfusion imaging where real time inflow curves at low acoustic power semi-quantitatively reflect coronary flow.
19.	Khodadad, Davood, 1985-, et al. (author) The Value of Phase Angle in Electrical Impedance Tomography Breath Detection 2018 In: 2018 Progress in Electromagnetics Research Symposium (PIERS-Toyama). - : Electromagnetics Academy. - 9784885523168 - 9781538654552 ; , s. 1040-1043 Conference paper (peer-reviewed)abstract The objective of this paper is to report our investigation demonstrating that the phase angle information of complex impedance could be a simple indicator of a breath cycle in chest Electrical Impedance Tomography (EIT). The study used clinical neonatal EIT data. The results show that measurement of the phase angle from complex EIT data can be used as a complementary information for improving the conventional breath detection algorithms.
20.	Kothapalli, Veera Venkata Satya Naray, 1985-, et al. (author) Unique pumping-out fracturing mechanism of a polymer-shelled contrast agent : An acoustic characterization and optical visualization 2014 In: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. - 0885-3010 .- 1525-8955. ; 62:3, s. 451-462 Journal article (peer-reviewed)abstract This work describes the fracturing mechanism of air-filled microbubbles (MBs) encapsulated by a cross-linked poly(vinyl alcohol) (PVA) shell. The radial oscillation and fracturing events following the ultrasound exposure were visualized with an ultrahigh-speed camera, and backscattered timedomain signals were acquired with the acoustic setup specific for harmonic detection. No evidence of gas emerging from defects in the shell with the arrival of the first insonation burst was found. In optical recordings, more than one shell defect was noted, and the gas core was drained without any sign of air extrusion when several consecutive bursts of 1 MPa amplitude were applied. In acoustic tests, the backscattered peak-to-peak voltage gradually reached its maximum and exponentially decreased when the PVA-based MB suspension was exposed to approximately 20 consecutive bursts arriving at pulse repetition frequencies of 100 and 500 Hz. Taking into account that the PVA shell is porous and possibly contains large air pockets between the cross-linked PVA chains, the aforementioned acoustic behavior might be attributed to pumping gas from these pockets in combination with gas release from the core through shell defects. We refer to this fracturing mechanism as pumping-out behavior, and this behavior could have potential use for the local delivery of therapeutic gases, such as nitric oxide.
21.	Eeg-Olofsson, Måns, 1967, et al. (author) Transmission of bone conducted sound – Correlation between hearing perception and cochlear vibration 2013 In: Hearing Research. - : Elsevier. - 0378-5955 .- 1878-5891. ; 306, s. 11-20 Journal article (peer-reviewed)abstract The vibration velocity of the lateral semicircular canal and the cochlear promontory was measured on 16 subjects with a unilateral middle ear common cavity, using a laser Doppler vibrometer, when the stimulation was by bone conduction (BC). Four stimulation positions were used: three ipsilateral positions and one contralateral position. Masked BC pure tone thresholds were measured with the stimulation at the same four positions. Valid vibration data were obtained at frequencies between 0.3 and 5.0 kHz. Large intersubject variation of the results was found with both methods. The difference in cochlear velocity with BC stimulation at the four positions varied as a function of frequency while the tone thresholds showed a tendency of lower thresholds with stimulation at positions close to the cochlea. The correlation between the vibration velocities of the two measuring sites of the otic capsule was high. Also, relative median data showed similar trends for both vibration and threshold measurements. However, due to the high variability for both vibration and perceptual data, low correlation between the two methods was found at the individual level. The results from this study indicated that human hearing perception from BC sound can be estimated from the measure of cochlear vibrations of the otic capsule. It also showed that vibration measurements of the cochlea in cadaver heads are similar to that measured in live humans.
22.	Iacobaeus, Christian, et al. (author) A novel portal imaging device for advanced radiation therapy 2001 In: Nuclear Science, IEEE Transactions on. - Nuclear Science, IEEE Transactions on : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9499 .- 1558-1578. ; 48:4, Part 2, s. 1496-1502 Journal article (peer-reviewed)
23.	Rohlén, Robin, et al. (author) Estimating the neural spike train from an unfused tetanic signal of low-threshold motor units using convolutive blind source separation 2023 In: Biomedical engineering online. - : BioMed Central (BMC). - 1475-925X. ; 22 Journal article (peer-reviewed)abstract Background: Individual motor units have been imaged using ultrafast ultrasound based on separating ultrasound images into motor unit twitches (unfused tetanus) evoked by the motoneuronal spike train. Currently, the spike train is estimated from the unfused tetanic signal using a Haar wavelet method (HWM). Although this ultrasound technique has great potential to provide comprehensive access to the neural drive to muscles for a large population of motor units simultaneously, the method has a limited identification rate of the active motor units. The estimation of spikes partly explains the limitation. Since the HWM may be sensitive to noise and unfused tetanic signals often are noisy, we must consider alternative methods with at least similar performance and robust against noise, among other factors.Results: This study aimed to estimate spike trains from simulated and experimental unfused tetani using a convolutive blind source separation (CBSS) algorithm and compare it against HWM. We evaluated the parameters of CBSS using simulations and compared the performance of CBSS against the HWM using simulated and experimental unfused tetanic signals from voluntary contractions of humans and evoked contraction of rats. We found that CBSS had a higher performance than HWM with respect to the simulated firings than HWM (97.5 ± 2.7 vs 96.9 ± 3.3, p < 0.001). In addition, we found that the estimated spike trains from CBSS and HWM highly agreed with the experimental spike trains (98.0% and 96.4%).Conclusions: This result implies that CBSS can be used to estimate the spike train of an unfused tetanic signal and can be used directly within the current ultrasound-based motor unit identification pipeline. Extending this approach to decomposing ultrasound images into spike trains directly is promising. However, it remains to be investigated in future studies where spatial information is inevitable as a discriminating factor.
24.	Sepehri, Sobhan, 1986, et al. (author) Volume-amplified magnetic bioassay integrated with microfluidic sample handling and high-Tc SQUID magnetic readout 2018 In: APL Bioengineering. - : AIP Publishing. - 2473-2877. ; 2:1 Journal article (peer-reviewed)abstract A bioassay based on a high-Tc superconducting quantum interference device (SQUID) reading out functionalized magnetic nanoparticles (fMNPs) in a prototype microfluidic platform is presented. The target molecule recognition is based on volume amplification using padlock-probe-ligation followed by rolling circle amplification (RCA). The MNPs are functionalized with single-stranded oligonucleotides, which give a specific binding of the MNPs to the large RCA coil product, resulting in a large change in the amplitude of the imaginary part of the ac magnetic susceptibility. The RCA products from amplification of synthetic Vibrio cholera target DNA were investigated using our SQUID ac susceptibility system in microfluidic channel with an equivalent sample volume of 3 μl. From extrapolation of the linear dependence of the SQUID signal versus concentration of the RCA coils, it is found that the projected limit of detection for our system is about 1.0 e5 RCA coils (0.2e−18 mol), which is equivalent to 66 fM in the 3 μl sample volume. This ultra-high magnetic sensitivity and integration with microfluidic sample handling are critical steps towards magnetic bioassays for rapid detection of DNA and RNA targets at the point of care.
25.	Taghavi, Hamidreza, 1981 (author) The Bone Conduction Implant (BCI) - Preclinical Studies, Technical Design and a Clinical Evaluation 2014 Doctoral thesis (other academic/artistic)abstract The Bone Conduction Implant (BCI) system has been developed as an alternative to the percutaneous bone anchored hearing aid (BAHA) with the advantage that the skin is kept intact. The transducer is permanently implanted and attached to the skull via a flat surface contact to the temporal bone. By applying amplitude modulation, the sound signal is transmitted to the implanted transducer through the intact skin via an efficient wireless inductive link. The external audio processor includes digital and analog signal processing units, and an Application Specific Integrated Circuit driving the inductive link. Its retention is provided by permanent magnets.Preclinical investigations of the BCI system have been performed on a skull simulator, a dry skull, cadaver heads and in an animal model study. In an extensive technical evaluation using a skull simulator, it was found that the power output from the BCI system was very robust for skin flap thicknesses from 2 to 8 mm with variability of less than 1.5 dB. Moreover, the peak of the maximum power output was 107 dB relative to 1 μN at transducer resonance frequency and at 5 mm skin flap thickness. This means that the highest output forces were produced in the "normal" skin thickness range, which in fact was one important design goal. The BCI system drains approximately 7.5 mA of battery current at 1 kHz and at 65 dB input sound pressure level, which corresponds to a battery lifetime of 5-7 days under normal use. It was found that significantly higher gain setting can be used without feedback problems for the BCI as compared to the BAHA. In an animal model (sheep), it was found that the implant-to-bone attachment became firmer over time and that the vibration transmission was stable over this period of eight months.Finally, in a clinical study, the results of the first patient were reported at one month follow up. The surgical procedure for installing the implant was found to be easy and safe, and the BCI gave a significant improvement in hearing over the unaided condition. The functional power output of the BCI was similar to most powerful ear level BAHA devices on headband at lower frequencies and superior at higher frequencies. In summary, it was found that the new BCI system can be an attractive alternative to the present percutaneous BAHA system.
26.	Takook, Pegah, 1982, et al. (author) Performance evaluation of helmet-like hyperthermia applicators for brain tumors 2017 In: 31st annual meeting of the European Society for Hyperthermic Oncology (ESHO 2017), Athens, Greece. Conference paper (peer-reviewed)
27.	Haj-Hosseini, Neda, 1980-, et al. (author) Early Detection of Oral Potentially Malignant Disorders: A Review on Prospective Screening Methods with Regard to Global Challenges 2024 In: Journal of Maxillofacial & Oral Surgery. - New Delhi, India : Springer Science and Business Media LLC. - 0972-8279 .- 0974-942X. ; 23:1, s. 23-32 Journal article (peer-reviewed)abstract Oral cancer is a cancer type that is widely prevalent in low-and middle-income countries with a high mortality rate, and poor quality of life for patients after treatment. Early treatment of cancer increases patient survival, improves quality of life and results in less morbidity and a better prognosis. To reach this goal, early detection of malignancies using technologies that can be used in remote and low resource areas is desirable. Such technologies should be affordable, accurate, and easy to use and interpret. This review surveys different technologies that have the potentials of implementation in primary health and general dental practice, considering global perspectives and with a focus on the population in India, where oral cancer is highly prevalent. The technologies reviewed include both sample-based methods, such as saliva and blood analysis and brush biopsy, and more direct screening of the oral cavity including fluorescence, Raman techniques, and optical coherence tomography. Digitalisation, followed by automated artificial intelligence based analysis, are key elements in facilitating wide access to these technologies, to non-specialist personnel and in rural areas, increasing quality and objectivity of the analysis while simultaneously reducing the labour and need for highly trained specialists.
28.	Hirsch, Jan-Michaél, et al. (author) Icke-invasiv kontroll av cellförändringar i munslemhinnan 2021 In: Tandläkartidningen. - Stockholm, Sweden : Sveriges Tandläkarförbund. - 0039-6982. ; :9, s. 48-55 Research review (peer-reviewed)
29.	Peskov, Vladimir, et al. (author) Fundamentals of gas micropattern detectors 2001 In: arXiv preprint physics/0106016. - Cornell University Library. Journal article (peer-reviewed)
30.	Waterton, John C., et al. (author) Repeatability and reproducibility of longitudinal relaxation rate in 12 small-animal MRI systems 2019 In: Magnetic Resonance Imaging. - : Elsevier BV. - 1873-5894 .- 0730-725X. ; 59, s. 121-129 Journal article (peer-reviewed)abstract Background: Many translational MR biomarkers derive from measurements of the water proton longitudinal relaxation rate R 1 , but evidence for between-site reproducibility of R 1 in small-animal MRI is lacking. Objective: To assess R 1 repeatability and multi-site reproducibility in phantoms for preclinical MRI. Methods: R 1 was measured by saturation recovery in 2% agarose phantoms with five nickel chloride concentrations in 12 magnets at 5 field strengths in 11 centres on two different occasions within 1–13 days. R 1 was analysed in three different regions of interest, giving 360 measurements in total. Root-mean-square repeatability and reproducibility coefficients of variation (CoV) were calculated. Propagation of reproducibility errors into 21 translational MR measurements and biomarkers was estimated. Relaxivities were calculated. Dynamic signal stability was also measured. Results: CoV for day-to-day repeatability (N = 180 regions of interest) was 2.34% and for between-centre reproducibility (N = 9 centres) was 1.43%. Mostly, these do not propagate to biologically significant between-centre error, although a few R 1 -based MR biomarkers were found to be quite sensitive even to such small errors in R 1 , notably in myocardial fibrosis, in white matter, and in oxygen-enhanced MRI. The relaxivity of aqueous Ni 2+ in 2% agarose varied between 0.66 s −1 mM −1 at 3 T and 0.94 s −1 mM −1 at 11.7T. Interpretation: While several factors affect the reproducibility of R 1 -based MR biomarkers measured preclinically, between-centre propagation of errors arising from intrinsic equipment irreproducibility should in most cases be small. However, in a few specific cases exceptional efforts might be required to ensure R 1 -reproducibility.
31.	Clemente, Francesco, et al. (author) Non-Invasive, Temporally Discrete Feedback of Object Contact and Release Improves Grasp Control of Closed-Loop Myoelectric Transradial Prostheses 2016 In: IEEE transactions on neural systems and rehabilitation engineering. - 1534-4320 .- 1558-0210. ; 24:12, s. 1314-1322 Journal article (peer-reviewed)abstract Human grasping and manipulation control critically depends on tactile feedback. Without this feedback, the ability for fine control of a prosthesis is limited in upper limb amputees. Although various approaches have been investigated in the past, at present there is no commercially available device able to restore tactile feedback in upper limb amputees. Based on the Discrete Event-driven Sensory feedback Control (DESC) policy we present a device able to deliver short-lasting vibrotactile feedback to transradial amputees using commercially available myoelectric hands. The device (DESC-glove) comprises sensorized thimbles to be placed on the prosthesis digits, a battery-powered electronic board, and vibrating units embedded in an arm-cuff being transiently activated when the prosthesis makes and breaks contact with objects. The consequences of using the DESC-glove were evaluated in a longitudinal study. Five transradial amputees were equipped with the device for onemonth at home. Through a simple test proposed here for the first time-the virtual eggs test-we demonstrate the effectiveness of the device for prosthetic control in daily life conditions. In the future the device could be easily exploited as an add-on to complement myoelectric prostheses or even embedded in prosthetic sockets to enhance their control by upper limb amputees.
32.	Fröberg, Asa, et al. (author) High variability in strain estimation errors when using a commercial ultrasound speckle tracking algorithm on tendon tissue 2016 In: Acta Radiologica. - : Sage Publications. - 0284-1851 .- 1600-0455. ; 57:10, s. 1223-1229 Journal article (peer-reviewed)abstract Background: Ultrasound speckle tracking offers a non-invasive way of studying strain in the free Achilles tendon where no anatomical landmarks are available for tracking. This provides new possibilities for studying injury mechanisms during sport activity and the effects of shoes, orthotic devices, and rehabilitation protocols on tendon biomechanics. Purpose: To investigate the feasibility of using a commercial ultrasound speckle tracking algorithm for assessing strain in tendon tissue. Material and Methods: A polyvinyl alcohol (PVA) phantom, three porcine tendons, and a human Achilles tendon were mounted in a materials testing machine and loaded to 4% peak strain. Ultrasound long-axis cine-loops of the samples were recorded. Speckle tracking analysis of axial strain was performed using a commercial speckle tracking software. Estimated strain was then compared to reference strain known from the materials testing machine. Two frame rates and two region of interest (ROI) sizes were evaluated. Results: Best agreement between estimated strain and reference strain was found in the PVA phantom (absolute error in peak strain: 0.21 +/- 0.08%). The absolute error in peak strain varied between 0.72 +/- 0.65% and 10.64 +/- 3.40% in the different tendon samples. Strain determined with a frame rate of 39.4Hz had lower errors than 78.6Hz as was the case with a 22mm compared to an 11mm ROI. Conclusion: Errors in peak strain estimation showed high variability between tendon samples and were large in relation to strain levels previously described in the Achilles tendon.
33.	Grishenkov, Dmitry, 1983-, et al. (author) Ultrasound contrast agent loaded with nitric oxide as a theranostic microdevice : Theranostic contrast agent loaded with nitric oxide 2015 In: Drug Design, Development and Therapy. - 1177-8881. ; 9, s. 2409-2419 Journal article (peer-reviewed)abstract The current study describes novel multifunctional polymer-shelled microbubbles (MBs) loaded with nitric oxide (NO) for integrated therapeutic and diagnostic applications, i.e. theranostics, of myocardial ischemia. We used gas filled MBs with an average diameter of 4 µm stabilized by a biocompatible shell of poly(vinyl)alcohol. In vitro acoustic tests showed a sufficient enhancement of the backscattered power (20 dB) acquired from the MBs suspension. The values of attenuation coefficient (0.8 dB/cm MHz) and phase velocities (1517 m/s) were comparable to those reported for the soft tissue. Moreover, polymer MBs demonstrate increased stability compared to clinically approved contrast agents with fracture threshold of about 900 kPa. In vitro chemiluminescence measurements demonstrated that dry powder of NO-loaded MBs releases its gas content in about 2 hours following an exponential decay profile with an exponential time constant equal 36 min. The application of high power ultrasound pulse (MI=1.2) on the MBs resuspended in saline decreases the exponential time constant from 55 to 4 min in air saturated solution and from 17 to 10 min in degased solution. Thus, ultrasound-triggered release of NO is achieved. Cytotoxicity tests indicate that phagocytosis of the MBs by macrophages starts within 6 to 8 hours. This is suitable time for initial diagnostics, treatment and monitoring of the therapeutic effect using single injection of the proposed multifunctional MBs.
34.	Hamid Muhammed, Hamed, 1967-, et al. (author) Optomyografi (OMG) : Ny teknik för muskelaktivitets mätning 2015 In: Abstract Proceedings of Medicinteknik dagarna 2015. Conference paper (other academic/artistic)abstract Introduktion / MålDen nya tekniken är effektivare och har inte de brister som de existerande teknikerna (elektromyografi EMG och mekanomyografi MMG) lider av, exempelvis, lågt signal till brus förhållande (SNR), interferens med andra biosignaler, interferens med externa signaler från omgivningen, påverkas av hudegenskaperna, komplicerad installation och kalibrering, kan inte användas vid extrema förhållanden, kan inte användas i rymden eller under vatten. Den nya tekniken används av:Idrottare: för att optimera träningen.Patienter och handikappade personer som lider av rörelsestörningar, svaga händer, amputerade händer, rygg eller nackskador.*Astronauter: för människa-dator interaktion och robotstyrning.MetodDen nya tekniken använder fotoelektriska sensorer som mäter reflekterade närainfraröda strålar från hudytan. Den reflekterade signalen varierar då topografiska förändringar, på landskapet som formas av hudytan, sker. Nästan inga bio- eller omgivande signaler interfererar med närainfraröda strålar. Hudens kemiska och fysiska egenskaper påverkar inte heller mätsignalernas kvalitet. Därför registreras signaler av hög SNR. Ytterligare fördelar med den nya tekniken är att den är kostnadseffektiv, mobil, användarvänlig, icke-invasiv och riskfri. Ett armband med två sensorer används för att mäta kontinuerliga tidssignaler när försökspersonen utför ett antal handrörelser.ResultatOlika handrörelser producerar olika signaler som mäts med hjälp av ett oscilloskop. Varje rörelse ger två signaler eller ett signalpar som skiljer sig från de signalpar som produceras av andra handrörelser.SammanfattningFotoelektriska sensorer används för att mäta reflekterade närainfraröda strålar från huden. Olika muskelaktiviteter och rörelser förändrar topografin av landskapet som formas av hudytan. Miniatyr lysdiod-sensor par byggs in i kläder för att mäta och analysera muskelaktivitet och rörelse. Mätvärdena skickas trådlöst till mobilen för att analyseras och ge återkoppling i realtid för att varna och optimera tränings eller rehabiliterings aktiviteterna.
35.	Hamid Muhammed, Hamed, 1967-, et al. (author) Optomyography (OMG) : A Novel Technique for the Detection of Muscle Surface Displacement Using Photoelectric Sensors 2015 In: Measurements - Proceedings of the 10th International Conference on Bioelectromagnetism. - International Society for Bioelectromagnetism. Conference paper (peer-reviewed)abstract Several techniques have been introduced for detecting, measuring, processing and analyzing the signals generated during muscular activities. With the development of more advanced technical solutions, the measurement and analysis of these signals help not only to understand the medical abnormalities and characterization of muscle activities but also to develop human machine interfaces of higher efficiency. In this work, a novel technique to detect and measure the displacement caused on the surface of the skin due to muscle activities was introduced and developed using near-infrared photoelectric sensors. The new technique was coined as OptoMyoGraphy (OMG). In order to evaluate the new technique, real-time pairs of signals were registered using two photoelectric sensors measuring near-infrared rays reflected on the forearm while moving the hand to make a number of different gestures. Different pairs of signals, changing over time and showing repeated patterns while repeating the same hand gesture, were measured for different hand gesture. The signal to noise ratio (SNR) of these signals was good enough to be able to differentiate among the pairs of signals which correspond to different hand gestures using visual inspection.
36.	Hammarström, Thomas, 1974 (author) Partial discharge characteristics at ultra-short voltage risetimes 2018 In: IEEE Transactions on Dielectrics and Electrical Insulation. - 1558-4135 .- 1070-9878. ; 25:6, s. 2241-2249 Journal article (peer-reviewed)abstract This paper describes continuation of author's works on the impact of PWM waveforms characterized by ultra-short rise times on PD characteristics in high voltage insulation systems. The implications of this kind of voltage exposure is becoming increasingly important as with rapid development of silicon carbide (SiC) and gallium nitride (GaN) based power electronic components the rise times used in machine control circuits keep getting shorter and the carrier frequencies higher. There is an imminent need to further develop diagnostic methods for PD detection at such extreme conditions. A PD measurement circuit based on capacitive decoupling and suitable for ultra-short rise times is presented here. Functionality of the circuit is demonstrated for a twisted pair test object insulated by enamel containing chromium oxide (Cr2O3) filler for rise times between 15 and 800 ns. The impact of voltage steepness on the PD extinction voltages (PDEV) and on other measurable parameters is reported. Specifically, the total number of PDs and their amplitude per modulated cycle are shown. The PD magnitude keeps increasing with the gradually decreased rise time, while the PDEV decreases. However, when compensating for voltage overshoot, less difference is noted. It is also demonstrated that the used PD detector allow for measurements at carrier frequencies well exceeding 1 kHz and rise times well below 100 ns as well as how the PD characteristics changes due to voltage overshoots inflicted by reflections.
37.	Jing, Yujia, 1985 (author) Hyperthermia-responsive liposomal systems 2015 Doctoral thesis (other academic/artistic)abstract Abstract Sophisticated liposomal systems are emerging at an increasing rate to meet the demands for multifunctional drug carriers in chemotherapies in combined with hyperthermia. For example, liposomal drug carriers for temperature-controlled drug release under hyperthermic conditions have recently been tested in clinical trials. More advanced designs of liposomes are expected to release encapsulated contents and activate hidden surface-functions in response to heat stimulus. Towards this aim, the present thesis is focused on formulating asymmetric lipid systems that can preserve functional moieties, and reactivate the targeted function as well as release the encapsulated compounds upon local heating. The design of the asymmetric liposomal systems utilizes the heat-activated transmembrane lipid diffusion during gel to liquid-crystalline phase transitions of the lipid membranes.Rational design of advanced liposomal drug-delivery systems will require understanding of the physicochemical properties of lipid membranes under, e.g., hyperthermic conditions. Here, supported lipid membranes on planar solid surfaces were used for model studies of lipid composition yielding a gel to liquid crystalline phase-transition temperature in the range 40 – 45 °C. It was found that the liposome-to-membrane formation process is not only size-dependent but also governed by temperature. Two methods of preparing supported asymmetric lipid membranes were investigated. As a proof-of-concept, the upper leaflets were either replaced or chemically transformed by enzymatic hydrolysis. The processes were monitored using surface sensitive techniques such as quartz crystal microbalance with dissipation (QCM-D) and dual polarization interferometry (DPI). The asymmetric structures were stable at a room temperature, while lipid flip-flop was induced upon increasing of the temperature. Transmembrane lipid exchange in the asymmetric structure under hyperthermic conditions was demonstrated by detecting, through streptavidin binding, biotinylated lipids appearing at the top leaflet which were first located in the lower leaflet. The protocols developed for the supported lipid systems were adapted for the preparation of asymmetric liposomes. Biotinylated asymmetric liposomes were used as a model system to demonstrate the principle of heat-activated targeting of asymmetric liposomes to streptavidin-coated surfaces. More biologically relevant interaction was utilized to replace the biotin-streptavidin function, where asymmetric cationic liposomes were binding to anionic supported membrane immobilized surfaces upon heating. The described strategies for assembly of asymmetric supported membranes provide a guide to the development of multifunctional drug carriers. The protocols used in experiments with supported membranes were readily adapted to the preparation of asymmetric liposomes. The ongoing study tests the asymmetric liposomes in vitro, which is designed to demonstrate hyperthermia treatment can enhance accumulation of liposomes in FaDu cells, and at the same time activate release of the encapsulated components. The results of in vitro tests can be used to analyze the feasibility of utilizing the asymmetric liposomes as a platform in vivo to explore further improvement in their functions upon microwave hyperthermia.
38.	Lui, Hoi-Shun, 1980, et al. (author) Microwave and Antenna Systems in Medical Applications 2024 In: Sensors. - 1424-8220. ; 24:4 Journal article (other academic/artistic)
39.	Lui, Hoi-Shun, 1980, et al. (author) On the matching medium for microwave-based medical diagnosis 2018 In: Biomedical Physics and Engineering Express. - : IOP Publishing. - 2057-1976. ; 4:3 Journal article (peer-reviewed)abstract In microwave-based medical diagnosis, reflections of electromagnetic waves from the air-skin interface can be reduced with a proper choice of matching medium such that electromagnetic radiation can be effectively penetrated into and through human bodies. Due to the heterogeneous and lossy nature of tissue and the fact that the electromagnetic problem varies as a function of matching medium, frequency, incident angles and polarization, it is not trivial to analyze the entire propagation phenomena. In this study, transmission of electromagnetic wave through a multi-layer planar human tissue model with different matching medium is considered. The reflected, absorbed and transmitted power components are computed to quantify the transmission performance of the matching medium. Our results show that although reflection can be minimized through a proper choice of matching medium, it does not necessary result in an optimal transmission as the transmitted signal is severely attenuated inside the tissue. Our results also show that the oblique incidence plane wave components, which in general correspond to the non-zero spatial frequency components of a near field distribution, can better penetrate through the tissue when a low-permittivity matching medium is used. These findings suggest that a better signal integrity can be obtained when a low-permittivity matching medium (ϵr between 5 and 30) is used.
40.	Marques, Filipe, et al. (author) Absorbable cyst brushes 2023 In: Biomedical microdevices (Print). - : Springer Nature. - 1387-2176 .- 1572-8781. ; 25:3 Journal article (peer-reviewed)abstract Cytobrushes are used for low-invasive sample collection and screening in multiple diseases, with a significant impact on early detection, prevention, and diagnosis. This study focuses on improving the safety of cell brushing in hard-to-reach locations by exploring brush construction from absorbable materials. We investigated the efficacy of loop brushes made of absorbable suture wires of Chirlac, Chirasorb, Monocryl, PDS II, Vicryl Rapid, Glycolon, and Catgut during their operation in conjunction with fine-needle aspiration in an artificial cyst model. PDS II brushes demonstrated the highest efficiency, while Monocryl and Catgut also provided a significant brushing effect. Efficient brushes portrayed higher flexural rigidity than their counterparts, and their efficiency was inversely proportional to their plastic deformation by the needle. Our results open avenues for safer cell biopsies in hard-to-reach locations by utilizing brushes composed of absorbable materials.
41.	Marquez Ruiz, Juan Carlos (author) Sensor-Based Garments that Enable the Use of Bioimpedance Technology : Towards PersonalizedHealthcare Monitoring. 2013 Doctoral thesis (other academic/artistic)abstract Functional garments for physiological sensing purposes have been utilized in several disciplinesi.e. sports, firefighting, military and medical. In most of the cases textile electrodes (Textrodes)embedded in the garment are employed to monitor vital signs and other physiologicalmeasurements. Electrical Bioimpedance (EBI) is a non-invasive and effective technology that canbe used for detection and supervision of different health conditions. In some specific applicationssuch as body composition assessment EBIS has shown encouraging results proving good degreeof effectiveness and reliability. In a similar way Impedance Cardiography (ICG) is anothermodality of EBI primarily concerned with the determination of Stroke Volume SV, indices ofcontractility, and other aspects of hemodynamics.EBI technology in the previously mentioned modalities can benefit from a integration with agarment; however, a successful implementation of EBI technology depends on the goodperformance of textile electrodes. The main weakness of Textrodes is a deficient skin-electrodeinterface which produces a high degree of sensitivity to signal disturbances. This sensitivity canbe reduced with a suitable selection of the electrode material and an intelligent and ergonomicgarment design that ensures an effective skin-electrode contact area.This research work studies the performance of textile electrodes and garments for EBIspectroscopy for Total Body Assessment and Transthoracic Electrical Bioimpedance (TEB) forcardio monitoring. Their performance is analyzed based on impedance spectra, estimation ofparameters, influence of electrode polarization impedance Zep and quality of the signals using asreference Ag/AgCl electrodes. The study includes the analysis of some characteristics of thetextile electrodes such as conductive material, skin-electrode contact area size and fabricconstruction.The results obtained in this research work present evidence that textile garments with a dry skinelectrodeinterface like the ones used in research produce reliable EBI measurements in bothmodalities: BIS for Total Body Assessment and TEB for Impedance Cardiography. Textiletechnology, if successfully integrated, may enable the utilization of EBI in both modalities andconsequently implementing wearable applications for home and personal health monitoring.
42.	Morin, Maxim, et al. (author) Skin hydration dynamics investigated by electrical impedance techniques in vivo and in vitro 2020 In: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10:1, s. 17218- Journal article (peer-reviewed)abstract Skin is easily accessible for transdermal drug delivery and also attractive for biomarker sampling. These applications are strongly influenced by hydration where elevated hydration generally leads to increased skin permeability. Thus, favorable transdermal delivery and extraction conditions can be easily obtained by exploiting elevated skin hydration. Here, we provide a detailed in vivo and in vitro investigation of the skin hydration dynamics using three techniques based on electrical impedance spectroscopy. Good correlation between in vivo and in vitro results is demonstrated, which implies that simple but realistic in vitro models can be used for further studies related to skin hydration (e.g., cosmetic testing). Importantly, the results show that hydration proceeds in two stages. Firstly, hydration between 5 and 10 min results in a drastic skin impedance change, which is interpreted as filling of superficial voids in skin with conducting electrolyte solution. Secondly, a subtle impedance change is observed over time, which is interpreted as leveling of the water gradient across skin leading to structural relaxation/changes of the macromolecular skin barrier components. With respect to transdermal drug delivery and extraction of biomarkers; 1 h of hydration is suggested to result in beneficial and stable conditions in terms of high skin permeability and extraction efficiency.
43.	Mårtensson, Mattias, et al. (author) Assessment of left ventricular volumes using simplified 3-D echocardiography and computed tomography - a phantom and clinical study 2008 In: Cardiovascular Ultrasound. - : Springer Science and Business Media LLC. - 1476-7120. ; 6 Journal article (peer-reviewed)abstract Objectives: To compare the accuracy of simplified 3-dimensional (3-D) echocardiography vs. multi-slice computed tomography (MSCT) software for the quantification of left ventricular (LV) volumes. Design: Three-D echocardiography (3-planes approach) and MSCT-CardIQ software were calibrated by measuring known volumes of 10 phantoms designed to closely mimic blood-endocardium interface. Subsequently, LV volumes were measured with both the methods in 9 patients referred routinely for coronary angiography and the agreement between the measurements was evaluated. Results: Simplified 3D-echocardiography provided higher degree of agreement between the measured and true phantom volumes (mean difference 0 +/- 1 ml, variation range + 4 to -4 ml) than MSCT software (mean difference 6 +/- 5 ml; variation range + 22 to -10 ml). The agreement between LV measurements in the patients was considerably poorer, with significantly larger volumes produced by MSCT (mean difference - 23 +/- 40 ml, variation between + 93 and -138 ml). Conclusion: Simplified 3-D echocardiography provides more accurate assessment of phantom volumes than MSCT-CardIQ software. The discrepancy between the results of LV measurements with the two methods is even greater and does not warrant their interchangeable diagnostic use.
44.	Mårtensson, Mattias, et al. (author) Evaluation of tissue Doppler-based velocity and deformation imaging : a phantom study of ultrasound systems. 2011 In: European Journal of Echocardiography. - : OXFORD UNIV PRESS. - 1525-2167 .- 1532-2114. ; 12:6, s. 467-476 Journal article (peer-reviewed)abstract AIMS: The objective of this study was to test the accuracy and diagnostic interchangeability of tissue Doppler-based displacement, velocity, strain, and strain rate measurements in commercially used ultrasound (US) systems. METHODS AND RESULTS: Using an in-house made phantom, four different US scanner models were evaluated. Two different scanners of the same model were tested, and one scanner acquisition was tested twice with two generations of the same workstation giving six test results in total. The scanners were in active clinical use and are subject to regular maintenance checks. There were three displacement and four velocity results that stood out from the rest and could be regarded as accurate and interchangeable. Among the deformation measurements, three acceptable strain results were found while there were no acceptable strain rate results. Furthermore, the study showed that measurements from scanners of the same model, same acquisition post-processed on different workstations and repeated measurements from the same scanner, can yield disparate results. CONCLUSION: Measurements that are accurate and of interchangeable use can be found for displacement and velocity measurements, but are less likely to be found for strain and strain rate measurements. It is strongly recommended that the ability of each individual US scanner to measure displacement, velocity, strain, and strain rate is evaluated before it is introduced into clinical practice, and it must always be evaluated together with the workstation the scanner is intended to be used in conjunction with.
45.	Nilebäck, Erik, 1984, et al. (author) QCM-D - a useful tool for cell studies? 2012 In: eCM Journal. ; 23:Supplement 5, s. 52- Conference paper (other academic/artistic)
46.	Paulides, M. M., et al. (author) ESHO benchmarks for computational modeling and optimization in hyperthermia therapy 2021 In: International Journal of Hyperthermia. - : Informa UK Limited. - 0265-6736 .- 1464-5157. ; 38:1, s. 1425-1442 Journal article (peer-reviewed)abstract Background: The success of cancer hyperthermia (HT) treatments is strongly dependent on the temperatures achieved in the tumor and healthy tissues as it correlates with treatment efficacy and safety, respectively. Hyperthermia treatment planning (HTP) simulations have become pivotal for treatment optimization due to the possibility for pretreatment planning, optimization and decision making, as well as real-time treatment guidance. Materials and methods: The same computational methods deployed in HTP are also used for in silico studies. These are of great relevance for the development of new HT devices and treatment approaches. To aid this work, 3 D patient models have been recently developed and made available for the HT community. Unfortunately, there is no consensus regarding tissue properties, simulation settings, and benchmark applicators, which significantly influence the clinical relevance of computational outcomes. Results and discussion: Herein, we propose a comprehensive set of applicator benchmarks, efficacy and safety optimization algorithms, simulation settings and clinical parameters, to establish benchmarks for method comparison and code verification, to provide guidance, and in view of the 2021 ESHO Grand Challenge (Details on the ESHO grand challenge on HTP will be provided at https://www.esho.info/). Conclusion: We aim to establish guidelines to promote standardization within the hyperthermia community such that novel approaches can quickly prove their benefit as quickly as possible in clinically relevant simulation scenarios. This paper is primarily focused on radiofrequency and microwave hyperthermia but, since 3 D simulation studies on heating with ultrasound are now a reality, guidance as well as a benchmark for ultrasound-based hyperthermia are also included.
47.	Pigot, Henry, et al. (author) A novel nonlinear afterload for ex vivo heart evaluation: Porcine experimental results 2022 In: Artificial Organs. - : Wiley. - 0160-564X .- 1525-1594. ; 46:9, s. 1794-1803 Journal article (peer-reviewed)abstract Background: Existing working heart models for ex vivo functional evaluation of donor hearts often use cardiac afterloads made up of discrete resistive and compliant elements. This approach limits the practicality of independently controlling systolic and diastolic aortic pressure to safely test the heart under multiple loading conditions. We present and investigate a novel afterload concept designed to enable such control. Methods: Six ∼70 kg pig hearts were evaluated in vivo, then ex vivo in left-ventricular working mode using the presented afterload. Both in vivo and ex vivo, the hearts were evaluated at two exertion levels: at rest and following a 20 μg adrenaline bolus, while measuring aortic pressure and flow, left ventricular pressure and volume, and left atrial pressure. Results: The afterload gave aortic pressure waveforms that matched the general shape of the in vivo measurements. A wide range of physiological systolic pressures (93 to 160 mm Hg) and diastolic pressures (73 to 113 mm Hg) were generated by the afterload. Conclusions: With the presented afterload concept, multiple physiological loading conditions could be tested ex vivo, and compared with the corresponding in vivo data. An additional control loop from the set pressure limits to the measured systolic and diastolic aortic pressure is proposed to address discrepancies observed between the set limits and the measured pressures.
48.	Seoane, Fernando, 1976-, et al. (author) Electrical Bioimpedance Spectroscopy on Acute Unilateral Stroke Patients : Initial Observations regarding Differences between Sides 2015 In: BioMed Research International. - : Hindawi Publishing Corporation. - 2314-6133 .- 2314-6141. ; 2015 Journal article (peer-reviewed)abstract Purpose. Electrical Bioimpedance Cerebral Monitoring is assessment in real time of health of brain tissue through study of passive dielectric properties of brain. During the last two decades theory and technology have been developed in parallel with animal experiments aiming to confirm feasibility of using bioimpedance-based technology for prompt detection of brain damage. Here, for the first time, we show that electrical bioimpedance measurements for left and right hemispheres are significantly different in acute cases of unilateral stroke within 24 hours from onset. Methods. Electrical BIS measurements have been taken in healthy volunteers and patients suffering from acute stroke within 24 hours of onset. BIS measurements have been obtained using SFB7 bioimpedance spectrometer manufactured by Impedimed ltd. and 4-electrode method. Measurement electrodes, current, and voltage have been placed according to 10–20 EEG system obtaining mutual BIS measurements from 4 different channels situated in pairs symmetrically from the midsagittal line. Obtained BIS data has been analyzed, assessing for symmetries and differences regarding healthy control data.Results. 7 out of 10 patients for Side-2-Side comparisons and 8 out 10 for central/lateral comparison presented values outside the range defined by healthy control group. When combined only 1 of 10 patients exhibited values within the healthy range. Conclusions. If these initial observations are confirmed with more patients, we can foresee emerging of noninvasive monitoring technology for brain damage with the potential to lead to paradigm shift in treatment of brain stroke and traumatic brain damage.
49.	Sturm, Dennis (author) Wireless Multi-Sensor Feedback Systems for SportsPerformance Monitoring : Design and Development 2012 Doctoral thesis (other academic/artistic)abstract Wireless applications have become a common part of daily life. Whether it is mobile phones, the Wi-Fi router at home, the keycard which has replaced the car key, a radio frequency identification access system to a building or a Bluetooth headset for your computer or phone, the means of modern wireless data exchange is an omnipresent technology. In sports, the market is in its infancy for wireless, technical applications or gadgets. Only heart rate monitors and GPS watches are currently used by recreational athletes. Even though most of the larger sports equipment companies regularly launch new products related to sports performance monitoring and mobile phone technology, product innovation leaps are rare.In this work the design of a wireless sports performance measurement platform is presented. Using the example of kayaking, this platform is configured as a paddle performance measuring system, the Kayak XL System, which can monitor propulsive paddle force, paddle kinematics and boat velocity, interalia. A common mobile phone platform has been chosen as the user interface for this system. The design approach focussing on user requests, demands and expectations in combination with the process of iterative technical development are unveiled in this thesis. An evaluation of the system is presented and the work is finalised with an overview of further systems which have been designed based on the developed measurement platform. The Kayak XL System is a flexible system designed to be mounted onto any standard kayak paddle and installed in any competition kayak. Versatility, unobtrusiveness and usability were major design concerns. The developed system consists of four modules plus a software which has been designed for Android mobile phones. The phone communicates with each of the four modules trough Bluetooth radio. These four modules are also referred to as nodes and have specific measurement purposes. Two nodes have been designed to measure paddle force and kinematics, one node has the purpose to measure foot stretcher force and boat motion data, and the fourth node enables a more convenient method of calibrating paddle force measurement. The fourth node is therefore only needed prior to performance data acquisition. Results show that paddle and foot stretcher force can be measured with a resolution below 1N after calibration. Installing the paddle nodes on a previously configured paddle without repeated calibration is facilitated with the compromise of a doubled error margin. The default sampling frequency is set to 100 Hz and can, like all system parameters, be configured on the mobile phone. Real-time computation of complex performance parameters is only limited by the phone CPU. The system adds twice 109 g to the paddle and approximately 850 g to the kayak, excluding the mass of the mobile phone
50.	Wang, Yuanmo, 1986, et al. (author) Counting the Number of Glutamate Molecules in Single Synaptic Vesicles 2019 In: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 141:44, s. 17507-17511 Journal article (peer-reviewed)abstract Analytical tools for quantitative measurements of glutamate, the principal excitatory neurotransmitter in the brain, are lacking. Here, we introduce a new enzyme-based amperometric sensor technique for the counting of glutamate molecules stored inside single synaptic vesicles. In this method, an ultra-fast enzyme-based glutamate sensor is placed into a solution of isolated synaptic vesicles, which stochastically rupture at the sensor surface in a potential-dependent manner at a constant negative potential. The continuous amperometric signals are sampled at high speed (10 kHz) to record sub-millisecond spikes, which represent glutamate release from single vesicles that burst open. Glutamate quantification is achieved by a calibration curve that is based on measurements of glutamate release from vesicles pre-filled with various glutamate concentrations. Our measurements show that an isolated single synaptic vesicle encapsulates about 8000 glutamate molecules and is comparable to the measured exocytotic quantal glutamate release in amperometric glutamate sensing in the nucleus accumbens of mouse brain tissue. Hence, this new methodology introduces the means to quantify ultra-small amounts of glutamate and to study synaptic vesicle physiology, pathogenesis, and drug treatments for neuronal disorders where glutamate is involved.

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