| 1. |
- Sandberg, David, 1980, et al.
(författare)
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Detecting driver sleeepiness using optimized non-linear combinations of sleepiness indicators
- 2011
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Ingår i: IEEE Transactions on Intelligent Transportation Systems. - 1524-9050 .- 1558-0016. ; 12:1, s. 97-108
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Tidskriftsartikel (refereegranskat)abstract
- This paper addresses the problem of detecting sleepiness in car drivers. First, a variety of sleepiness indicators (based on driving behavior) proposed in the literature were evaluated. These indicators were then subjected to parametric optimization using stochastic optimization methods. To improve performance, the functional form of some of the indicators was generalized before optimization. Next, using a neural network, the best performing sleepiness indicators were combined with a mathematical model of sleepiness, i.e., the sleep/wake predictor (SWP). The analyses were based on data obtained from a study that involved 12 test subjects at the moving-base driving simulator at the Swedish National Road and Transportation Research Institute (VTI), Linkping, Sweden. The data were derived from 12 1-h driving sessions for each test subject, with varying degrees of sleepiness. The performance measure (range [0,1]) for indicators was taken as the average of sensitivity and specificity. Starting with indicators proposed in the literature, the best such indicator, i.e., the standard deviation of the yaw angle, reached a performance score of 0.72 on previously unseen test data. It was found that indicators based on a given signal gave essentially equal performance after parametric optimization, but in no case was it better than 0.72. The best generalized indicator (the generic variability indicator) obtained a performance score of 0.74. SWP achieved a score of 0.78. However, by nonlinearly combining SWP with the generic variability indicator, a score of 0.83 was obtained. Thus, the results imply that a nonlinear combination of a measure based on driving behavior with a model of sleepiness significantly improves driver sleepiness detection.
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| 2. |
- Enrico, Alessandro, et al.
(författare)
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Cleanroom-Free Direct Laser Micropatterning of Polymers for Organic Electrochemical Transistors in Logic Circuits and Glucose Biosensors
- 2024
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Ingår i: Advanced Science. - : Wiley. - 2198-3844.
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Tidskriftsartikel (refereegranskat)abstract
- Organic electrochemical transistors (OECTs) are promising devices for bioelectronics, such as biosensors. However, current cleanroom-based microfabrication of OECTs hinders fast prototyping and widespread adoption of this technology for low-volume, low-cost applications. To address this limitation, a versatile and scalable approach for ultrafast laser microfabrication of OECTs is herein reported, where a femtosecond laser to pattern insulating polymers (such as parylene C or polyimide) is first used, exposing the underlying metal electrodes serving as transistor terminals (source, drain, or gate). After the first patterning step, conducting polymers, such as poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), or semiconducting polymers, are spin-coated on the device surface. Another femtosecond laser patterning step subsequently defines the active polymer area contributing to the OECT performance by disconnecting the channel and gate from the surrounding spin-coated film. The effective OECT width can be defined with high resolution (down to 2 mu m) in less than a second of exposure. Micropatterning the OECT channel area significantly improved the transistor switching performance in the case of PEDOT:PSS-based transistors, speeding up the devices by two orders of magnitude. The utility of this OECT manufacturing approach is demonstrated by fabricating complementary logic (inverters) and glucose biosensors, thereby showing its potential to accelerate OECT research. Ultrafast focused femtosecond laser has been introduced for the direct micropatterning of organic electrochemical transistors (OECTs), providing high resolution (2 mu m), selective cleanroom-free patterning of insulating and conjugated polymer layers while preserving device operation, and high flexibility in device design. The approach has been validated in the fabrication of complementary inverters and glucose biosensors.image
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| 3. |
- Zhou, Bo, et al.
(författare)
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Textile Pressure Mapping Sensor for Emotional Touch Detection in Human-Robot Interaction
- 2017
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Ingår i: Sensors. - : MDPI, Multidisciplinary Digital Publishing Institute. - 1424-8220. ; 17:11
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we developed a fully textile sensing fabric for tactile touch sensing as the robot skin to detect human-robot interactions. The sensor covers a 20-by-20 cm2 area with 400 sensitive points and samples at 50 Hz per point. We defined seven gestures which are inspired by the social and emotional interactions of typical people to people or pet scenarios. We conducted two groups of mutually blinded experiments, involving 29 participants in total. The data processing algorithm first reduces the spatial complexity to frame descriptors, and temporal features are calculated through basic statistical representations and wavelet analysis. Various classifiers are evaluated and the feature calculation algorithms are analyzed in details to determine each stage and segments’ contribution. The best performing feature-classifier combination can recognize the gestures with a 93.3% accuracy from a known group of participants, and 89.1% from strangers.
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| 4. |
- Hedberg, Yolanda S., et al.
(författare)
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Can Cobalt(II) and Chromium(III) ions released from joint prostheses influence the friction coefficient?
- 2015
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Ingår i: ACS Biomaterial Science and Engineering. - : American Chemical Society (ACS). - 2373-9878. ; 1:8, s. 617-620
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Tidskriftsartikel (refereegranskat)abstract
- Cobalt chromium molybdenum alloys (CoCrMo) are commonly used as articulating components in joint prostheses. In this tribocorrosive environment, wear debris and metal ionic species are released and interact with proteins, possibly resulting in protein aggregation. This study aimed to investigate whether this could have an effect on the friction coefficient in a typical material couple, namely CoCrMo-on-polyethylene. It was confirmed that both Co(II) and Cr(III) ions, and their combination, at concentrations relevant for the metal release situation, resulted in protein aggregation and its concomitant precipitation, which increased the friction coefficient. Future studies should identify the clinical importance of these findings.
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| 5. |
- Marquez, Juan Carlos, 1976-, et al.
(författare)
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Textile electrode straps for wrist-to-ankle bioimpedance measurements for Body Composition Analysis : Initial validation & experimental results
- 2010
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Ingår i: 2010 ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC). - : IEEE Engineering in Medicine and Biology Society. - 9781424441235 ; 2010, s. 6385-8
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Konferensbidrag (refereegranskat)abstract
- Electrical Bioimpedance (EBI) is one of the non-invasive monitoring technologies that could benefit from the emerging textile based measurement systems. If reliable and reproducible EBI measurements could be done with textile electrodes, that would facilitate the utilization of EBI-based personalized healthcare monitoring applications. In this work the performance of a custom-made dry-textile electrode prototype is tested. Four-electrodes ankle-to-wrist EBI measurements have been taken on healthy subjects with the Impedimed spectrometer SFB7 in the frequency range 5 kHz to 1 MHz. The EBI spectroscopy measurements taken with dry electrodes were analyzed via the Cole and Body Composition Analysis (BCA) parameters, which were compared with EBI measurements obtained with standard electrolytic electrodes. The analysis of the obtained results indicate that even when dry textile electrodes may be used for EBI spectroscopy measurements, the measurements present remarkable differences that influence in the Cole parameter estimation process and in the final production of the BCA parameters. These initial results indicate that more research work must be done to in order to obtain a textile-based electrode that ensures reliable and reproducible EBI spectroscopy measurements.
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| 6. |
- Seoane, Fernando, 1976-, et al.
(författare)
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Textile-Friendly Interconnection between Wearable Measurement Instrumentation and Sensorized Garments-Initial Performance Evaluation for Electrocardiogram Recordings.
- 2019
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Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 19:20
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Tidskriftsartikel (refereegranskat)abstract
- The interconnection between hard electronics and soft textiles remains a noteworthy challenge in regard to the mass production of textile-electronic integrated products such as sensorized garments. The current solutions for this challenge usually have problems with size, flexibility, cost, or complexity of assembly. In this paper, we present a solution with a stretchable and conductive carbon nanotube (CNT)-based paste for screen printing on a textile substrate to produce interconnectors between electronic instrumentation and a sensorized garment. The prototype connectors were evaluated via electrocardiogram (ECG) recordings using a sensorized textile with integrated textile electrodes. The ECG recordings obtained using the connectors were evaluated for signal quality and heart rate detection performance in comparison to ECG recordings obtained with standard pre-gelled Ag/AgCl electrodes and direct cable connection to the ECG amplifier. The results suggest that the ECG recordings obtained with the CNT paste connector are of equivalent quality to those recorded using a silver paste connector or a direct cable and are suitable for the purpose of heart rate detection.
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| 7. |
- Pfeiffer, Christoph, 1989, et al.
(författare)
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Localizing on-scalp MEG sensors using an array of magnetic dipole coils
- 2018
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 13:5
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Tidskriftsartikel (refereegranskat)abstract
- Accurate estimation of the neural activity underlying magnetoencephalography (MEG) signals requires co-registration i.e., determination of the position and orientation of the sensors with respect to the head. In modern MEG systems, an array of hundreds of low- T c SQUID sensors is used to localize a set of small, magnetic dipole-like (head-position indicator, HPI) coils that are attached to the subject's head. With accurate prior knowledge of the positions and orientations of the sensors with respect to one another, the HPI coils can be localized with high precision, and thereby the positions of the sensors in relation to the head. With advances in magnetic field sensing technologies, e.g., high-T-c SQUIDs and optically pumped magnetometers (OPM), that require less extreme operating temperatures than low- T-c SQUID sensors, on-scalp MEG is on the horizon. To utilize the full potential of on-scalp MEG, flexible sensor arrays are preferable. Conventional co-registration is impractical for such systems as the relative positions and orientations of the sensors to each other are subject-specific and hence not known a priori. Herein, we present a method for co-registration of on-scalp MEG sensors. We propose to invert the conventional co-registration approach and localize the sensors relative to an array of HPI coils on the subject's head. We show that given accurate prior knowledge of the positions of the HPI coils with respect to one another, the sensors can be localized with high precision. We simulated our method with realistic parameters and layouts for sensor and coil arrays. Results indicate co-registration is possible with sub-millimeter accuracy, but the performance strongly depends upon a number of factors. Accurate calibration of the coils and precise determination of the positions and orientations of the coils with respect to one another are crucial. Finally, we propose methods to tackle practical challenges to further improve the method.
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| 8. |
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| 9. |
- Buendia, Ruben, 1982, et al.
(författare)
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Estimation of body fluids with bioimpedance spectroscopy: state of the art methods and proposal of novel methods
- 2015
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Ingår i: Physiological Measurement. - : IOP Publishing. - 0967-3334 .- 1361-6579. ; 36:10
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Tidskriftsartikel (refereegranskat)abstract
- Determination of body fluids is a useful common practice in determination of disease mechanisms and treatments. Bioimpedance spectroscopy (BIS) methods are non-invasive, inexpensive and rapid alternatives to reference methods such as tracer dilution. However, they are indirect and their robustness and validity are unclear. In this article, state of the art methods are reviewed, their drawbacks identified and new methods are proposed. All methods were tested on a clinical database of patients receiving growth hormone replacement therapy. Results indicated that most BIS methods are similarly accurate (e.g. < 0.5 +/- 3.0% mean percentage difference for total body water) for estimation of body fluids. A new model for calculation is proposed that performs equally well for all fluid compartments (total body water, extra-and intracellular water). It is suggested that the main source of error in extracellular water estimation is due to anisotropy, in total body water estimation to the uncertainty associated with intracellular resistivity and in determination of intracellular water a combination of both.
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| 10. |
- Hafid, Abdelakram, et al.
(författare)
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Full Impedance Cardiography Measurement Device Using Raspberry PI3 and System-on-Chip Biomedical Instrumentation Solutions
- 2018
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Ingår i: IEEE journal of biomedical and health informatics. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2168-2194 .- 2168-2208. ; 22:6, s. 1883-1894
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Tidskriftsartikel (refereegranskat)abstract
- Impedance cardiography (ICG) is a noninvasive method for monitoring cardiac dynamics using electrical bioimpedance (EBI) measurements. Since its appearance more than 40 years ago, ICG has been used for assessing hemodynamic parameters. This paper presents a measurement system based on two System on Chip (SoC) solutions and Raspberry PI, implementing both a full three-lead ECG recorder and an impedance cardiographer, for educational and research development purposes. Raspberry PI is a platform supporting Do-I t-Yourself project and education applications across the world. The development is part of Biosignal PI, an open hardware platform focusing in quick prototyping of physiological measurement instrumentation. The SoC used for sensing cardiac biopotential is the ADAS1000, and for the EBI measurement is the AD5933. The recordings were wirelessly transmitted through Bluetooth to a PC, where the waveforms were displayed, and hemodynamic parameters such as heart rate, stroke volume, ejection time and cardiac output were extracted from the ICG and ECG recordings. These results show how Raspberry PI can be used for quick prototyping using relatively widely available and affordable components, for supporting developers in research and engineering education. The design and development documents will be available on www.BiosignalPl.com, for open access under a Non Commercial-Share A like 4.0 International License.
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