| 1. |
- Taghavi, Hamidreza, 1981, et al.
(författare)
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Technical design of a new bone conduction implant (BCI) system
- 2015
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Ingår i: International Journal of Audiology. - : Informa UK Limited. - 1499-2027 .- 1708-8186. ; 54:10, s. 736-744
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The objective of this study is to describe the technical design and verify the technical performance of a new bone conduction implant (BCI) system. Design: The BCI consists of an external audio processor and an implanted unit called the bridging bone conductor. These two units use an inductive link to communicate with each other through the intact skin in order to drive an implanted transducer. Study sample: In this study, the design of the full BCI system has been described and verified on a skull simulator and on real patients. Results: It was found that the maximum output force (peak 107 dB re 1 N) of the BCI is robust for skin thickness range of 2-8 mm and that the total harmonic distortion is below 8% in the speech frequency range for 70 dB input sound pressure level. The current consumption is 7.5 mA, which corresponds to 5-7 days use with a single battery. Conclusions: This study shows that the BCI is a robust design that gives a sufficiently high output and an excellent sound quality for the hearing rehabilitation of indicated patients.
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| 2. |
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| 3. |
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| 4. |
- Bengtsson, Bo, et al.
(författare)
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Residential Mobility and Housing Policy : Continuity and Change in the Swedish Housing Regime
- 2019
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Ingår i: Investigating Spatial Inequalities: Mobility, Housing and Employment in Scandinavia and South-East Europe. - : Emerald Group Publishing Limited. - 9781789739428 ; , s. 139-158
-
Bokkapitel (refereegranskat)abstract
- Transaction costs, responsive housing supply, rent controls, tenant protection, and access to credit affect residential mobility these different parts of housing policy are included in what has been defined as housing regimes, which embrace regulations, laws, norms, and ideology as well as economic factors. In this chapter, we investigate how these regimes change by using institutional theories of path dependence. We use Sweden as an example and study three Swedish housing market reforms during the past decades that may have affected residential mobility, each related to one of the main institutional pillars of housing provision: tenure legislation, taxation, and finance. More precisely, we study the development of the rental regulation since the late 1960s, the tax reform in 1991, and the new reforms on mortgages since 2010. What caused these reforms? What were the main mechanisms behind them, and why did they occur at the time they did? We argue, besides affecting residential mobility, these reforms have the common feature of including interesting elements of path dependence and forming critical junctures that have led the development on to a new path. Institutions of tenure legislation, housing finance, and taxation are often claimed to have effects on residential mobility. Although they are seldom designed with the explicit aim of supporting (or counteracting) residential mobility, they may sometimes do so as more or less unintended consequences.
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| 5. |
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| 6. |
- Clemente, Francesco, et al.
(författare)
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Touch and Hearing Mediate Osseoperception
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Osseoperception is the sensation arising from the mechanical stimulation of a bone-anchored prosthesis. Here we show that not only touch, but also hearing is involved in this phenomenon. Using mechanical vibrations ranging from 0.1 to 6 kHz, we performed four psychophysical measures (perception threshold, sensation discrimination, frequency discrimination and reaction time) on 12 upper and lower limb amputees and found that subjects: consistently reported perceiving a sound when the stimulus was delivered at frequencies equal to or above 400 Hz; were able to discriminate frequency differences between stimuli delivered at high stimulation frequencies (similar to 1500 Hz); improved their reaction time for bimodal stimuli (i.e. when both vibration and sound were perceived). Our results demonstrate that osseoperception is a multisensory perception, which can explain the improved environment perception of bone-anchored prosthesis users. This phenomenon might be exploited in novel prosthetic devices to enhance their control, thus ultimately improving the amputees' quality of life.
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| 7. |
- Fredén Jansson, Karl-Johan, 1988, et al.
(författare)
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Electro-acoustic performance of the new bone vibrator Radioear B81: A comparison with the conventional Radioear B71
- 2015
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Ingår i: International Journal of Audiology. - : Informa UK Limited. - 1499-2027 .- 1708-8186. ; 54:5, s. 334-340
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The objective is to evaluate the electro-acoustic performance of a new audiometric bone vibrator, the B81 from Radioear Corporation, USA. Comparison will be made with the widely used B71 which has well-known limitations at low frequencies. Design: The B81 is based on the balanced electromagnetic separation transducer (BEST) principle where static forces are counterbalanced so that nonlinear distortion forces are reduced and maximum hearing levels can be increased. Study sample: Maximum hearing level, total harmonic distortion (THD), frequency response, and electrical impedance were measured for six devices of each bone vibrator type on an artificial mastoid. Results: It was found that B81 reaches 10.7-22.0 dB higher maximum (@ THD. 6% or V-in. 6 V-RMS) hearing levels than B71 for frequencies below 1500 Hz, and had significantly lower THD up to 1000 Hz. There was no statistically significant difference between their frequency response, except a deviation at the mid frequencies (alpha = 0.01) where B81 was more efficient and the electrical impedances were practically the same. Conclusions: In general, B81 had an improved electro-acoustic performance compared to B71 and is compatible with same audiometers. In particular, B81 allows for sensorineural hearing loss to be measured at considerably higher hearing levels than with B71 below 1500 Hz.
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| 8. |
- Fredén Jansson, Karl-Johan, 1988, et al.
(författare)
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Magnetic resonance imaging investigation of the bone conduction implant - a pilot study at 1.5 Tesla.
- 2015
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Ingår i: Medical devices (Auckland, N.Z.). - 1179-1470. ; 8, s. 413-23
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this pilot study was to investigate if an active bone conduction implant (BCI) used in an ongoing clinical study withstands magnetic resonance imaging (MRI) of 1.5 Tesla. In particular, the MRI effects on maximum power output (MPO), total harmonic distortion (THD), and demagnetization were investigated. Implant activation and image artifacts were also evaluated.
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| 9. |
- Fredén Jansson, Karl-Johan, 1988, et al.
(författare)
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Robustness and lifetime of the bone conduction implant - a pilot study
- 2019
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Ingår i: Medical Devices: Evidence and Research. - 1179-1470. ; 12, s. 89-100
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Tidskriftsartikel (refereegranskat)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.
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| 10. |
- Fredén Jansson, Karl-Johan, 1988, et al.
(författare)
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Vibrotactile Thresholds on the Mastoid and Forehead Position of Deaf Patients Using Radioear B71 and B81
- 2017
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Ingår i: Ear and Hearing. - 1538-4667 .- 0196-0202. ; 38:6, s. 714-723
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The main objective of this study was to measure the vibrotactile thresholds on the mastoid process and forehead positions using patients with bilateral deafness and to compare the results from the two bone conduction vibrators Radioear B71 and B81. Design: There is a possibility that the vibrotactile sensation on the skin makes it difficult to discriminate between sound and vibration. The risk is highest for patients who have bone conduction hearing thresholds in proximity to or worse than their vibrotactile thresholds. All measurements were performed similar to regular bone conduction threshold testing using an audiometer-driven bone conduction vibrator and pulsed warble tones, but the patients were instructed to respond only when feeling vibrations of the bone conduction vibrator instead of when hearing sound. Both the posterior forehead position and the mastoid process position on the temporal bone were tested for comparative reasons. In total, 16 patients participated in the study, 31% females and 69% males of age 29 to 77 years. All subjects were cochlear implant recipients, either uni-or bilaterally implanted. They were selected based on their audiogram data showing unmeasurable unaided hearing. Results: The force level at which the vibrotactile thresholds were reached, increased with frequency from 125 up to 500 Hz, but remained constant for higher frequencies up to 2 kHz. A statistically significant difference was found between the 2 devices at 125 Hz at both the mastoid process and forehead position, where the vibrotactile threshold seem to be more sensitive for B71, possibly due to contribution of distortion components. There was no statistically significant difference in vibrotactile thresholds between the mastoid process and forehead position in absolute values (force level in dB re 1 mu N), but in terms of hearing levels (dB HL) there was an average difference of 10 and 9 dB for B71 and B81, respectively. Conclusions: The results indicate that the vibrotactile thresholds can be confounded with bone conduction hearing thresholds measurements up to 500 Hz when using a standard audiometer and in particular when measuring on the forehead position.
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| 11. |
- Håkansson, Bo, 1953, et al.
(författare)
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The bone conduction implant - a review and 1-year follow-up
- 2019
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Ingår i: International Journal of Audiology. - : Informa UK Limited. - 1499-2027 .- 1708-8186. ; 58:12, s. 945-955
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The objective of this study is to evaluate its safety and effectiveness of the bone conduction implant (BCI) having an implanted transducer and to review similar bone conduction devices. Design: This is a consecutive prospective case series study where the patients were evaluated after 1, 3, 6 and 12 months. Outcome measures were focussed on intraoperative and postoperative safety, the effectiveness of the device in terms of audiological performance and patient's experience. Study sample: Sixteen patients with average age of 40.2 (range 18-74) years have been included. Thirteen patients were operated in Gothenburg and three in Stockholm. Results: It was found that the procedure for installing the BCI is safe and the transmission condition was stable over the follow-up time. No serious adverse events or severe adverse device effects occurred. The hearing sensitivity, speech in noise and the self-assessment as compared with the unaided condition improved significantly with the BCI. These patients also performed similar or better than with a conventional bone conduction reference device on a softband. Conclusions: In summary, it was found that the BCI can provide a safe and effective hearing rehabilitation alternative for patients with mild-to-moderate conductive or mixed hearing impairments.
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| 12. |
- Håkansson, Bo, 1953, et al.
(författare)
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VEMP using a new low-frequency bone conduction transducer
- 2018
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Ingår i: Medical Devices: Evidence and Research. - 1179-1470. ; 11, s. 301-312
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Tidskriftsartikel (refereegranskat)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.
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| 13. |
- Håkansson, Nina, et al.
(författare)
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Improvement of animal welfare by strategic analysis and logistic optimisation of animal slaughter transportation
- 2016
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Ingår i: Animal Welfare. - : Universities Federation for Animal Welfare. - 0962-7286 .- 2054-1538. ; 25:2, s. 255-263
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Tidskriftsartikel (refereegranskat)abstract
- The transportation of animals to slaughterhouses is a major welfare concern. The number of slaughterhouses has decreased over time in Europe due to centralisation. This is expected to increase transport time for animals and as a consequence negatively affect animal welfare. We propose an optimisation model based on a facility location model to perform strategic analysis to improve transportation logistics. The model is tested on the Swedish slaughter transport system. We show that, by strategic planning and redirection of transports while keeping the slaughterhouse capacities as of the originaldata, the potential exists to reduce transport distance by 25% for pigs and 40% for cattle. Furthermore, we demonstrated that approximately 50% of Swedish slaughterhouses can be shut down with a minimal effect on total transport distances. This implies that in terms of the overall welfare picture, the decision of which animals to send where plays a for more significant role than the number of slaughterhouses. In addition, by changing relative weights on distances in the optimisation function the amount of individualtransports with longjourney times can be decreased. We also show results from altered slaughterhouse capacity and geographical location of slaughterhouses. This is the first time an entire country has been analysed in great detail with respect to the location, capacity and number of slaughterhouses. The focus is mainly on the analysis of unique and detailed information of actual animal transports in Sweden and a demonstration of the potential impact redirection of the transports and/ or altering of slaughterhouses can have on animal welfare.
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| 14. |
- Håkansson, Stellan, et al.
(författare)
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Reduced incidence of neonatal early-onset group B streptococcal infection after promulgation of guidelines for risk-based intrapartum antibiotic prophylaxis in Sweden : analysis of a national population-based cohort
- 2017
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Ingår i: Acta Obstetricia et Gynecologica Scandinavica. - : WILEY. - 0001-6349 .- 1600-0412. ; 96:12, s. 1475-1483
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Tidskriftsartikel (refereegranskat)abstract
- IntroductionThis study aimed to investigate the incidence of neonatal early-onset group B streptococcal (GBS) infection in Sweden after promulgation of guidelines (2008) for risk factor-based intrapartum antibiotic prophylaxis, and evaluate the presence of risk factors and obstetric management in mothers. Material and methodsNational registers were searched for infants with early-onset GBS infection during 2006-2011. Medical records of cases and case mothers were abstracted. Verified cases of sepsis/meningitis and cases with clinical sepsis/pneumonia were documented, as well as risk factors in case mothers and timeliness of intrapartum antibiotic prophylaxis administration. ResultsThere were 227 cases with verified infection, with an incidence of 0.34 of live births during the whole period. There was a significant decrease after promulgation of guidelines, from 0.40 to 0.30 parts per thousand [odds ratio (OR) 0.75, 95% confidence interval (CI) 0.57-0.99]. A significant decrease in the number of cases with clinical GBS sepsis/pneumonia was also observed. In parturients with one or more risk factors, the incidence of any GBS infection was reduced by approximately 50% (OR 0.47, 95% CI 0.35-0.64), although there were many cases where the opportunity for timely administration of intrapartum antibiotic prophylaxis was missed. In infants of mothers without risk factor(s) there was no reduction in early-onset GBS morbidity. The mortality in verified cases was 4.8% (95% CI 2.1-7.6). ConclusionsThe introduction of national guidelines for risk-based intrapartum antibiotic prophylaxis coincided with a significant 50% risk reduction of neonatal early-onset GBS infection in infants of parturients presenting with one or more risk factors. A stricter adherence to guidelines could probably have reduced the infant morbidity further.
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| 15. |
- Jacobsson, Bo, et al.
(författare)
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Förtidsbörd största perinatala problemet: 5,7 procent av graviditeter i Sverige slutar för tidigt, inte klarlagt varför – kostar miljardbelopp varje år : [Preterm delivery: an overview on epidemiology, pathophysiology and consequences for the individual and the society]
- 2019
-
Ingår i: Läkartidningen. - : Läkartidningen förlag. - 0023-7205 .- 1652-7518. ; 116
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Tidskriftsartikel (refereegranskat)abstract
- Preterm delivery in Sweden constitutes 5.7 % of all deliveries, which is among the lowest rates in the world. There has not been any increase in the proportion of iatrogenic preterm deliveries during the last decades.The main hypothesis concerning the causality of preterm delivery is still that of the ascending infection from the vagina to the uterus and inflammation resulting in contractions, rupture of membranes and delivery. The mechanisms behind parturition at term are still elusive and this is also true for preterm delivery. The genetic contribution to preterm delivery is about 25-30 %. The first genes that are associated with preterm delivery and gestational duration have recently been published. Huge progress has been made in care of preterm born infants. Sweden has among the lowest rates of mortality and morbidity in the world, especially in the lowest gestational weeks. New modes of care, family-centered care and hospital-assisted home care, have empowered the parents and reduced the cost for care.
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| 16. |
- Jacobsson, Bo, et al.
(författare)
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Förtidsbörd största perinatala problemet [Preterm delivery an overview on epidemiology, pathophysiology and consequences for the individual and the society]
- 2019
-
Ingår i: Läkartidningen. - : Läkartidningen Förlag AB. - 0023-7205 .- 1652-7518. ; 116
-
Forskningsöversikt (refereegranskat)abstract
- Preterm delivery in Sweden constitutes 5.7 % of all deliveries, which is among the lowest rates in the world. There has not been any increase in the proportion of iatrogenic preterm deliveries during the last decades.The main hypothesis concerning the causality of preterm delivery is still that of the ascending infection from the vagina to the uterus and inflammation resulting in contractions, rupture of membranes and delivery. The mechanisms behind parturition at term are still elusive and this is also true for preterm delivery. The genetic contribution to preterm delivery is about 25-30 %. The first genes that are associated with preterm delivery and gestational duration have recently been published. Huge progress has been made in care of preterm born infants. Sweden has among the lowest rates of mortality and morbidity in the world, especially in the lowest gestational weeks. New modes of care, family-centered care and hospital-assisted home care, have empowered the parents and reduced the cost for care.
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| 17. |
- Jacobsson, Bo, 1960, et al.
(författare)
-
Preterm delivery: an overview on epidemiology, pathophysiology and consequences for the individual and the society : Förtidsbörd största perinatala problemet - 5,7 procent av graviditeter i Sverige slutar för tidigt, inte klarlagt varför – kostar miljardbelopp varje år.
- 2019
-
Ingår i: Läkartidningen. - 1652-7518. ; 116
-
Tidskriftsartikel (refereegranskat)abstract
- Preterm delivery in Sweden constitutes 5.7 % of all deliveries, which is among the lowest rates in the world. There has not been any increase in the proportion of iatrogenic preterm deliveries during the last decades.The main hypothesis concerning the causality of preterm delivery is still that of the ascending infection from the vagina to the uterus and inflammation resulting in contractions, rupture of membranes and delivery. The mechanisms behind parturition at term are still elusive and this is also true for preterm delivery. The genetic contribution to preterm delivery is about 25-30 %. The first genes that are associated with preterm delivery and gestational duration have recently been published. Huge progress has been made in care of preterm born infants. Sweden has among the lowest rates of mortality and morbidity in the world, especially in the lowest gestational weeks. New modes of care, family-centered care and hospital-assisted home care, have empowered the parents and reduced the cost for care.
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| 18. |
- Lendaro, Eva, 1989, et al.
(författare)
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Real-time classification of non-weight bearing lower-limb movements using EMG to facilitate phantom motor execution: Engineering and case study application on phantom limb pain
- 2017
-
Ingår i: Frontiers in Neurology. - : Frontiers Media SA. - 1664-2295. ; 8:SEP, s. Article number 470-
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Tidskriftsartikel (refereegranskat)abstract
- Phantom motor execution (PME), facilitated by myoelectric pattern recognition (MPR) and virtual reality (VR), is positioned to be a viable option to treat phantom limb pain (PLP). A recent clinical trial using PME on upper-limb amputees with chronic intractable PLP yielded promising results. However, further work in the area of signal acquisition is needed if such technology is to be used on subjects with lower-limb amputation. We propose two alternative electrode configurations to conventional, bipolar, targeted recordings for acquiring surface electromyography. We evaluated their performance in a real-time MPR task for non-weight-bearing, lower-limb movements. We found that monopolar recordings using a circumferential electrode of conductive fabric, performed similarly to classical bipolar recordings, but were easier to use in a clinical setting. In addition, we present the first case study of a lower-limb amputee with chronic, intractable PLP treated with PME. The patient's Pain Rating Index dropped by 22 points (from 32 to 10, 68%) after 23 PME sessions. These results represent a methodological advancement and a positive proof-of-concept of PME in lower limbs. Further work remains to be conducted for a high-evidence level clinical validation of PME as a treatment of PLP in lower-limb amputees.
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| 19. |
- Mastinu, Enzo, 1987, et al.
(författare)
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An Alternative Myoelectric Pattern Recognition Approach for the Control of Hand Prostheses : A Case Study of Use in Daily Life by a Dysmelia Subject
- 2018
-
Ingår i: IEEE Journal of Translational Engineering in Health and Medicine. - : Institute of Electrical and Electronics Engineers (IEEE). - 2168-2372. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- The functionality of upper limb prostheses can be improved by intuitive control strategies that use bioelectric signals measured at the stump level. One such strategy is the decoding of motor volition via myoelectric pattern recognition (MPR), which has shown promising results in controlled environments and more recently in clinical practice. Moreover, not much has been reported about daily life implementation and real-time accuracy of these decoding algorithms. This paper introduces an alternative approach in which MPR allows intuitive control of four different grips and open/close in a multifunctional prosthetic hand. We conducted a clinical proof-of-concept in activities of daily life by constructing a self-contained, MPR-controlled, transradial prosthetic system provided with a novel user interface meant to log errors during real-time operation. The system was used for five days by a unilateral dysmelia subject whose hand had never developed, and who nevertheless learned to generate patterns of myoelectric activity, reported as intuitive, for multi-functional prosthetic control. The subject was instructed to manually log errors when they occurred via the user interface mounted on the prosthesis. This allowed the collection of information about prosthesis usage and real-time classification accuracy. The assessment of capacity for myoelectric control test was used to compare the proposed approach to the conventional prosthetic control approach, direct control. Regarding the MPR approach, the subject reported a more intuitive control when selecting the different grips, but also a higher uncertainty during proportional continuous movements. This paper represents an alternative to the conventional use of MPR, and this alternative may be particularly suitable for a certain type of amputee patients. Moreover, it represents a further validation of MPR with dysmelia cases.
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| 20. |
- Mastinu, Enzo, 1987, et al.
(författare)
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Analog Front-Ends comparison: on the way to a portable, lowpower and low-cost EMG controller based on Pattern Recognition
- 2015
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Ingår i: Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS. - 1557-170X. - 9781424492718 ; 2015-November, s. 2111-2114
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Konferensbidrag (refereegranskat)abstract
- Compact and low-noise Analog Front-Ends (AFEs)are becoming increasingly important for the acquisition ofbioelectric signals in portable system. In this work, we comparetwo popular AFEs available on the market, namely theADS1299 (Texas Instruments) and the RHA2216 (IntanTechnologies). This work develops towards the identification ofsuitable acquisition modules to design an affordable, reliableand portable device for electromyography (EMG) acquisitionand prosthetic control. Device features such as Common ModeRejection (CMR), Input Referred Noise (IRN) and Signal toNoise Ratio (SNR) were evaluated, as well as the resultingaccuracy in myoelectric pattern recognition (MPR) for thedecoding of motion intention. Results reported better noiseperformances and higher MPR accuracy for the ADS1299 andsimilar SNR values for both devices.
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| 21. |
- Mastinu, Enzo, 1987, et al.
(författare)
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Digital Controller for Artificial Limbs fed by Implanted Neuromuscular Interfaces via Osseointegration
- 2016
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Ingår i: 38th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC). ; , s. 1-
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Konferensbidrag (refereegranskat)abstract
- Despite the technological progress in robotics, mechatronic limbs still lack functionality, reliability and comfort. This work builds upon osseointegration and implanted neuromuscular interfaces for the realization of an embedded system for artificial upper limb control. The controller allows for bioelectric signals acquisition, processing, decoding and prosthetic control. It includes a neurostimulator to provide direct neural feedback aimed for restoration of tactile sensations. It was designed to be reliably used in activities of daily living, as well as a research platform to monitor prosthesis usage and training, machine learning based control techniques and neural stimulation paradigms. The system has passed bench tests and its functionality was proven in a first pilot patient.
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| 22. |
- Mastinu, Enzo, 1987, et al.
(författare)
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Digital Controller for Artificial Limbs fed by Implanted Neuromuscular Interfaces via Osseointegration
- 2016
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Ingår i: Trent International Prosthetic Symposium 2016.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Although the development of bioelectrically controlled upper limb prosthesis started in the 1970’s, the majority of amputees do not use this technology due to its poor functionality, reliability and comfort. This study is based on the previous work conducted by Ortiz-Catalan, Håkansson, and Brånemark, who developed a permanent bidirectional interface into the human body, namely the Osseointegrated Human-Machine Gateway (OHMG).The aim of this study was to develop an Artificial Limb Controller (ALC) that decodes motor volition and provides sensory feedback using the OHMG.
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| 23. |
- Mastinu, Enzo, 1987, et al.
(författare)
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Embedded System for Prosthetic Control Using Implanted Neuromuscular Interfaces Accessed Via an Osseointegrated Implant
- 2017
-
Ingår i: IEEE Transactions on Biomedical Circuits and Systems. - 1940-9990 .- 1932-4545. ; 11:4, s. 867-877
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Tidskriftsartikel (refereegranskat)abstract
- Despite the technological progress in robotics achieved in the last decades, prosthetic limbs still lack functionality, reliability, and comfort. Recently, an implanted neuromusculoskeletal interface built upon osseointegration was developed and tested in humans, namely the Osseointegrated Human-Machine Gateway. Here, we present an embedded system to exploit the advantages of this technology. Our artificial limb controller allows for bioelectric signals acquisition, processing, decoding of motor intent, prosthetic control, and sensory feedback. It includes a neurostimulator to provide direct neural feedback based on sensory information. The system was validated using real-time tasks characterization, power consumption evaluation, and myoelectric pattern recognition performance. Functionality was proven in a first pilot patient from whom results of daily usage were obtained. The system was designed to be reliably used in activities of daily living, as well as a research platform to monitor prosthesis usage and training, machine-learning-based control algorithms, and neural stimulation paradigms.
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| 24. |
- Mastinu, Enzo, 1987, et al.
(författare)
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Grip control and motor coordination with implanted and surface electrodes while grasping with an osseointegrated prosthetic hand
- 2019
-
Ingår i: Journal of Neuroengineering and Rehabilitation. - : Springer Science and Business Media LLC. - 1743-0003. ; 16:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Replacement of a lost limb by an artificial substitute is not yet ideal. Resolution and coordination of motor control approximating that of a biological limb could dramatically improve the functionality of prosthetic devices, and thus reduce the gap towards a suitable limb replacement. Methods: In this study, we investigated the control resolution and coordination exhibited by subjects with transhumeral amputation who were implanted with epimysial electrodes and an osseointegrated interface that provides bidirectional communication in addition to skeletal attachment (e-OPRA Implant System). We assessed control resolution and coordination in the context of routine and delicate grasping using the Pick and Lift and the Virtual Eggs Tests. Performance when utilizing implanted electrodes was compared with the standard-of-care technology for myoelectric prostheses, namely surface electrodes. Results: Results showed that implanted electrodes provide superior controllability over the prosthetic terminal device compared to conventional surface electrodes. Significant improvements were found in the control of the grip force and its reliability during object transfer. However, these improvements failed to increase motor coordination, and surprisingly decreased the temporal correlation between grip and load forces observed with surface electrodes. We found that despite being more functional and reliable, prosthetic control via implanted electrodes still depended highly on visual feedback. Conclusions: Our findings indicate that incidental sensory feedback (visual, auditory, and osseoperceptive in this case) is insufficient for restoring natural grasp behavior in amputees, and support the idea that supplemental tactile sensory feedback is needed to learn and maintain the motor tasks internal model, which could ultimately restore natural grasp behavior in subjects using prosthetic hands. © 2019 The Author(s).
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| 25. |
- Mastinu, Enzo, 1987, et al.
(författare)
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Low-cost, open source bioelectric signal acquisition system
- 2017
-
Ingår i: 14th International Conference on Wearable and Implantable Body Sensor Networks. - 9781509062447 ; , s. 19-22
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Konferensbidrag (refereegranskat)abstract
- Bioelectric potentials provide an intuitive source of control in human-machine interfaces. In this work, a low-cost system for bioelectric signals acquisition and processing was developed and made available as open source. A single module based on the ADS1299 (Texas Instruments, USA) can acquire up to 8 differential or single-ended channels with a resolution of 24 bits and programmable gain up to 24 V/V. Several modules can be daisy-chained together to increase the number of input channels. Opto-isolated USB communication was included in the design to interface safely with a personal computer. The system was designed to be compatible with a low-cost and widely available microcontroller development platform, namely the Tiva LaunchPad (Texas Instruments, USA) featuring an ARM Cortex-M4 core. We made the source files for the PCB, firmware, and high-level software available online (GitHub: ADS_BP). Digital processing was used for float conversion and filtering. The high-level software for control and acquisition was integrated into an already existent open source platform for advanced myoelectric control, namely BioPatRec. This integration provide a complete system for intuitive myoelectric control where signal processing, machine learning, and control algorithms are used for the prediction of motor volition and control of robotic and virtual devices.
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| 26. |
- Nilsson, Niclas, et al.
(författare)
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Classification complexity in myoelectric pattern recognition
- 2017
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Ingår i: Journal of NeuroEngineering and Rehabilitation. - : Springer Science and Business Media LLC. - 1743-0003. ; 14:1, s. Article no. 68 -
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Limb prosthetics, exoskeletons, and neurorehabilitation devices can be intuitively controlled using myoelectric pattern recognition (MPR) to decode the subject's intended movement. In conventional MPR, descriptive electromyography (EMG) features representing the intended movement are fed into a classification algorithm. The separability of the different movements in the feature space significantly affects the classification complexity. Classification complexity estimating algorithms (CCEAs) were studied in this work in order to improve feature selection, predict MPR performance, and inform on faulty data acquisition. Methods: CCEAs such as nearest neighbor separability (NNS), purity, repeatability index (RI), and separability index (SI) were evaluated based on their correlation with classification accuracy, as well as on their suitability to produce highly performing EMG feature sets. SI was evaluated using Mahalanobis distance, Bhattacharyya distance, Hellinger distance, Kullback-Leibler divergence, and a modified version of Mahalanobis distance. Three commonly used classifiers in MPR were used to compute classification accuracy (linear discriminant analysis (LDA), multi-layer perceptron (MLP), and support vector machine (SVM)). The algorithms and analytic graphical user interfaces produced in this work are freely available in BioPatRec. Results: NNS and SI were found to be highly correlated with classification accuracy (correlations up to 0.98 for both algorithms) and capable of yielding highly descriptive feature sets. Additionally, the experiments revealed how the level of correlation between the inputs of the classifiers influences classification accuracy, and emphasizes the classifiers' sensitivity to such redundancy. Conclusions: This study deepens the understanding of the classification complexity in prediction of motor volition based on myoelectric information. It also provides researchers with tools to analyze myoelectric recordings in order to improve classification performance.
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| 27. |
- Ortiz Catalan, Max Jair, 1982, et al.
(författare)
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Offline Accuracy: A Potentially Misleading Metric in Myoelectric Pattern Recognition for Prosthetic Control.
- 2015
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Ingår i: Proceedings of the 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Milan, Italy, 15-19 August 2015. - 1557-170X. - 9781424492718 ; , s. 1140-1143
-
Konferensbidrag (refereegranskat)abstract
- Offline accuracy has been the preferred performance measure in myoelectric pattern recognition (MPR) for the prediction of motion volition. In this study, different metrics relating the fundamental binary prediction outcomes were analyzed. Our results indicate that global accuracy is biased by 1) the unbalanced number of possible true positive and negative outcomes, and 2) the almost perfect specificity and negative predicted value, which were consistently found across algorithms, topologies, and movements (individual and simultaneous). Therefore, class-specific accuracy is advisable instead. Additionally, we propose the use of precision (positive predictive value) and sensitivity (recall) as a complement to accuracy to better describe the discrimination capabilities of MPR algorithms, as these consider the effect of false predictions. However, all the studied offline metrics failed to predict real-time decoding, and therefore real-time testing continue to be necessary to truly evaluate the clinical usability of MPR.
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| 28. |
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| 29. |
- Reinfeldt, Sabine, 1978, et al.
(författare)
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Nasal sound pressure as objective verification of implant in active transcutaneous bone conduction devices
- 2019
-
Ingår i: Medical Devices: Evidence and Research. - 1179-1470. ; 12, s. 193-202
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Active transcutaneous bone conduction devices consist of an external audio processor and an internal implant under intact skin. During the surgical procedure, it is important to verify the functionality of the implant before the surgical wound is closed. In a clinical study with the new bone conduction implant (BCI), the functionality of the implant was tested with an electric transmission test, where the output was the nasal sound pressure (NSP) recorded in the ipsilateral nostril. The same measurement was performed in all follow-up visits to monitor the implant's functionality and transmission to bone over time. The objective of this study was to investigate the validity of the NSP method as a tool to objectively verify the implant's performance intraoperatively, as well as to follow-up the implant's performance over time. Design: Thirteen patients with the BCI were included, and the NSP measurement was part of the clinical study protocol. The implant was electrically stimulated with an amplitude-modulated signal generator using a swept sine 0.1-10 kHz. The NSP was measured with a probe tube microphone in the ipsilateral nostril. Results: The NSP during surgery was above the noise floor for most patients within the frequency interval 0.4-5 kHz, showing NSP values for expected normal transmission of a functioning implant. Inter-subject comparison showed large variability, but follow-up results showed only minor variability within each subject. Further investigation showed that the NSP was stable over time. Conclusion: The NSP method is considered applicable to verify the implant's functionality during and after surgery. Such a method is important for implantable devices, but should be simplified and clinically adapted. Large variations between subjects were found, as well as smaller variability in intra-subject comparisons. As the NSP was found to not change significantly over time, stable transmission to bone, and implant functionality, were indicated.
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| 30. |
- Reinfeldt, Sabine, 1978, et al.
(författare)
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New developments in bone-conduction hearing implants: a review
- 2015
-
Ingår i: Medical Devices: Evidence and Research. - 1179-1470. ; 8, s. 79-93
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Tidskriftsartikel (refereegranskat)abstract
- The different kinds of bone-conduction devices (BCDs) available for hearing rehabilitation are growing. In this paper, all BCDs currently available or in clinical trials will be described in categories according to their principles. BCDs that vibrate the bone via the skin are referred to as skin-drive devices, and are divided into conventional devices, which are attached with softbands, for example, and passive transcutaneous devices, which have implanted magnets. BCDs that directly stimulate the bone are referred to as direct-drive devices, and are further divided into percutaneous and active transcutaneous devices; the latter have implanted transducers directly stimulating the bone under intact skin. The percutaneous direct-drive device is known as a bone-anchored hearing aid, which is the BCD that has the largest part of the market today. Because of some issues associated with the percutaneous implant, and to some extent because of esthetics, more transcutaneous solutions with intact skin are being developed today, both in the skin-drive and in the direct-drive category. Challenges in developing transcutaneous BCDs are mostly to do with power, attachment, invasiveness, and magnetic resonance imaging compatibility. In the future, the authors assume that the existing percutaneous direct-drive BCD will be retained as an important rehabilitation alternative, while the transcutaneous solutions will increase their part of the market, especially for patients with bone-conduction thresholds better than 35 dB HL (hearing level). Furthermore, the active transcutaneous direct-drive BCDs appear to be the most promising systems, but to establish more detailed inclusion criteria, and potential benefits and drawbacks, more extensive clinical studies are needed.
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| 31. |
- Reinfeldt, Sabine, 1978, et al.
(författare)
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Study of the Feasible Size of a Bone Conduction Implant Transducer in the Temporal Bone
- 2015
-
Ingår i: Otology and Neurotology. - 1531-7129 .- 1537-4505. ; 36:4, s. 631-637
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Tidskriftsartikel (refereegranskat)abstract
- Hypothesis: The aim was to assess the temporal bone volume to determine the suitable size and position of a bone conduction implant (BCI) transducer. Background: A BCI transducer needs to be sufficiently small to fit in the mastoid portion of the temporal bone for a majority of patients. The anatomical geometry limits both the dimension of an implanted transducer and its positions in the temporal bone to provide a safe and simple surgery. Methods: Computed tomography (CT) scans of temporal bones from 22 subjects were virtually reconstructed. With an algorithm in MATLAB, the maximum transducer diameter as function of the maximum transducer depth in the temporal bone, and the most suitable position were calculated in all subjects. Results: An implanted transducer diameter of 16 mm inserted at a depth of 4 mm statistically fitted 95% of the subjects. If changing the transducer diameter to 12 mm, a depth of 6 mm would fit in 95% of the subjects. The most suitable position was found to be around 20 mm behind the ear canal. Conclusion: The present BCI transducer casing, used in ongoing clinical trials, was designed from the results in this study, demonstrating that the present BCI transducer casing (largest diameter [diagonal]: 15.5 mm, height: 6.4 mm) will statistically fit more than 95% of the subjects. Hence, the present BCI transducer is concluded to be sufficiently small to fit most normal-sized temporal bones and should be placed approximately 20 mm behind the ear canal.
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| 32. |
- Reinfeldt, Sabine, 1978, et al.
(författare)
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The bone conduction implant: Clinical results of the first six patients.
- 2015
-
Ingår i: International journal of audiology. - : Informa UK Limited. - 1708-8186 .- 1499-2027. ; 54:6, s. 408-416
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To investigate audiological and quality of life outcomes for a new active transcutaneous device, called the bone conduction implant (BCI), where the transducer is implanted under intact skin. Design: A clinical study with sound field audiometry and questionnaires at six-month follow-up was conducted with a bone-anchored hearing aid on a softband as reference device. Study sample: Six patients (age 18-67 years) with mild-to-moderate conductive or mixed hearing loss. Results: The surgical procedure was found uneventful with no adverse events. The first hypothesis that BCI had a statistically significant improvement over the unaided condition was proven by a pure-tone-average improvement of 31.0 dB, a speech recognition threshold improvement in quiet (27.0 dB), and a speech recognition score improvement in noise (51.2 %). At speech levels, the signal-to-noise ratio threshold for BCI was - 5.5 dB. All BCI results were better than, or similar to the reference device results, and the APHAB and GBI questionnaires scores showed statistically significant improvements versus the unaided situation, supporting the second and third hypotheses. Conclusions: The BCI provides significant hearing rehabilitation for patients with mild-to-moderate conductive or mixed hearing impairments, and can be easily and safely implanted under intact skin.
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| 33. |
- Rigato, Cristina, 1989, et al.
(författare)
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Audiometric comparison between Bone Anchored Hearing Aid and Bone Conduction Implant
- 2016
-
Ingår i: AudiologyNOW!2016.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Patients suffering from conductive or mixed hearing losses can often be successfully rehabilitated using bone conduction devices (BCDs). Percutaneous BCDs are widely used today, but the trend is to develop transcutaneous solutions able to providing equally good rehabilitation and less complications. Here, the transcutaneous Bone Conduction Implant was compared with percutaneous BCDs under the hypothesis that they are equally effective. Tone and speech audiometry and questionnaires were utilized to assess the overall performance. The outcome confirmed the initial hypothesis.
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| 34. |
- Rigato, Cristina, 1989, et al.
(författare)
-
Audiometric Comparison Between the First Patients With the Transcutaneous Bone Conduction Implant and Matched Percutaneous Bone Anchored Hearing Device Users
- 2016
-
Ingår i: Otology & Neurotology. - : Ovid Technologies (Wolters Kluwer Health). - 1531-7129 .- 1537-4505. ; 37:9, s. 1381-1387
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Tidskriftsartikel (refereegranskat)abstract
- Hypothesis:The transcutaneous bone conduction implant (BCI) is compared with bone-anchored hearing aids (BAHAs) under the hypothesis that the BCI can give similar rehabilitation from an audiological as well as patient-related point of view.Background:Patients suffering from conductive and mixed hearing losses can often benefit more from rehabilitation using bone conduction devices (BCDs) rather than conventional air conduction devices. The most widely used BCD is the percutaneous BAHA, with a permanent skin-penetrating abutment. To overcome issues related to percutaneous BCDs, the trend today is to develop transcutaneous devices, with intact skin. The BCI is an active transcutaneous device currently in a clinical trial phase. A potential limitation of active transcutaneous devices is the loss of power in the induction link over the skin. To address this issue, countermeasures are taken in the design of the BCI, which is therefore expected to be as effective as percutaneous BCDs.Methods:An early observational study with a matched-pair design was performed to compare BCI and BAHA groups of patients over several audiometric measurements, including speech audiometry and warble tones thresholds with and without the device. Additionally, questionnaires were used to assess the general health condition, benefit, and satisfaction level of patients.Results:No statistically significant difference was detected in any of the audiological measurements. The outcome of patient-related measurements was slightly superior for BCI in all subscales.Conclusion:Results confirm the initial hypothesis of the study: the BCI seems to be capable of providing as good rehabilitation as percutaneous devices for indicated patients.
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| 35. |
- Rigato, Cristina, 1989, et al.
(författare)
-
Audiometric comparison in BCI and BAHA matched patients
- 2015
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Purpose: Patients that are suffering from outer or middle ear hearing impairment can often benefit more from rehabilitation using bone conduction devices (BCDs) rather than conventional air conduction devices. The most widely used BCD is the percutaneous Bone Anchored Hearing Aid (BAHA), which gives excellent sound, but can cause side effects from the skin penetration abutment. There is a growing interest in the development of transcutaneous BCDs such as the Bone Conduction Implant (BCI), comprising an externally worn audio processor wirelessly driving a transducer implanted in the temporal bone. In an ongoing clinical study, the device is used in six patients and the objective with this study is to compare their audiometric results with patients using the BAHA.Methods & Materials: Audiometric measurements are currently carried out on patients using a BAHA (Ponto Pro Power, Oticon Medical) that are matched one by one according to age- and hearing loss-based criteria with the six first patients treated with the BCI. In particular, warble tone thresholds, speech recognition score (SRS) in noise, speech recognition threshold (SRT) and signal-to-noise ratio (SNR) threshold are compared in a sound field. The patients’ general health status and personal satisfaction is also evaluated using Glasgow Benefit Inventory and Abbreviated Profile of Hearing Aid Benefit questionnaires. Furthermore, maximum power output and total harmonic distortion are measured for each device on a skullsimulator.Results: The study is on-going and detailed results will be presented. Preliminary results from two patients tested with the BAHA indicate that they generally perform the same or slightly worse than matched patients with BCI regarding warble tone thresholds, SRS, SRT and SNR threshold. The self-reported questionnaires show in general similar outcome for both devices, but slightly better results for BCI compared with the BAHA concerning physical benefit and avoidance of negative reactions to unpleasant sounds.Conclusion: Preliminary results from audiometric measurements show a clear improvement over the unaided condition for both devices, and indicate that the BCI is equal or slightly better
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| 36. |
- Rigato, Cristina, 1989, et al.
(författare)
-
Audiometric results of the Bone Conduction Implant: a comparative study with the Bone Anchored Hearing Aid
- 2015
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background:Patients suffering from conductive-, sensorineural- or mixed hearing loss that are unable to use conventional air conduction hearing aids, can often be rehabilitated with bone conduction devices (BCDs) . The most widely used BCD is the percutaneous Bone Anchored Hearing Aid (BAHA), which gives excellent sound but has some known complications related to the side effects from the skin penetration. In order to overcome such issues, the development of transcutaneous BCDs has increased. Among them, the Bone Conduction Implant (BCI) is an active BCD developed in Gothenburg, Sweden. It comprises an externally worn audio processor unit which is magnetically attached to an implanted unit to wirelessly drive a transducer in the temporal bone. The device is currently implanted in six patients in the clinical trial phase and the objective with this study is to compare the BCI and BAHA devices.Methods:Audiometric measurements are currently carried out on BCI and BAHA patients matched one by one according to age- and hearing loss-based criteria. In particular, pure tones hearing thresholds, speech recognition threshold (SRT) in quiet and speech recognition score (SRS) in noise are compared as well as signal to noise ratio (SNR). In addition, maximum power output (MPO) and total harmonic distortion (THD) are measured for each device on a skullsimulator in an anechoic chamber. The patients’ satisfaction and general health condition are also evaluated by means of questionnaires. Results:Results from three patients tested with the BAHA indicate that they generally perform as or slightly worse than matched patients with BCI in all tested audiometric measurements. The self-reported questionnaires show in general similar outcome for both devices, with slightly better results for BCI compared with the BAHA concerning physical benefit and avoidance of negative reactions to unpleasant sounds.Conclusions:Results from audiometric measurements show a clear improvement over the unaided condition for both devices, and indicate that the BCI is equal or slightly better than the BAHA. As this is a pilot study currently ongoing, the results may change when all six BCI patients have been matched with a BAHA patient.
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| 37. |
- Rigato, Cristina, 1989, et al.
(författare)
-
Direct bone conduction stimulation: effect of different transducer attachments
- 2017
-
Ingår i: Osseo 2017, Nijmegen, The Netherlands.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Objective(s): When choosing a method to implant a transducer for direct bone conduction stimulation, several options are available with the trade-off being, among other aspects, between achieving a robust contact to the bone and keeping an open possibility for potential future explantation. The aim of this study is to compare how different attachment methods for direct bone conduction stimulation can affect the vibrations transmission to the cochleae. The ultimate goal is to gain more insights on the dynamical properties of the skull to apply them to the design and optimization of bone conduction devices for hearing rehabilitation.Study design:Experimental.Patients:Measurements were performed on four human heads. The tympanic membrane, the malleus and the incus were removed to expose the cochlear promontory on both sides of each subject. The subjects have not undergone any previous surgery as verified by visual inspection.Methods:Three different attachments are tested on eight sides: (A) flat small-sized surface, (B) flat wide surface and (C) two separated screws. The different typologies of contact to bone are established by three dummy implants and an adapter to attach the transducer giving a swept sine stimulus from 0.1 to 10 kHz. The response is evaluated in terms of cochlear promontory acceleration and ear canal sound pressure level (ECSP). The measurement setup consists of the following parts: human head, transducer with adaptor (to apply the stimulus), signal generator and analyzer (to drive the transducer and receive the recorded data), Laser Doppler Vibrometer (LDV, measuring the cochlear promontory acceleration), video to USB converter (to couple the built-in camera of LDV with the computer), microphones (to measure ECSP) and laptop (to save data).Results:Average results show slightly higher ECSP level and cochlear promontory acceleration for attachment A compared to attachment B especially at frequencies above 1 kHz. An improvement in transmission is achieved with attachment C compared to B in the frequency range 5–7 kHz, where the levels differ by nearly 10 dB both ipsi- and contralaterally. In the same frequency range, the transmission from attachment C appears to be slightly higher relative to attachment A as well, however no statistical significance is found. The comparison between attachment A and C is not straightforward due to high variability over frequencies and sometimes contradictory results between LDV and ECSP measurements.Conclusion:On an average level, the screw stimulation technique seems to improve the transmission at frequencies above 5 kHz. However,, when considering the whole frequency range, average results from the different attachment techniques are comparable. Still, conclusions for single subjects should be drawn with care as measurements show a very high inter-subject variability.
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| 38. |
- Rigato, Cristina, 1989, et al.
(författare)
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Direct bone conduction stimulation: Ipsilateral effect of different transducer attachments in active transcutaneous devices
- 2018
-
Ingår i: Hearing Research. - : Elsevier BV. - 0378-5955 .- 1878-5891. ; 361, s. 103-112
-
Tidskriftsartikel (refereegranskat)abstract
- Active transcutaneous bone conduction devices, where the transducer is implanted, are used for rehabilitation of hearing impaired patients by directly stimulating the skull bone. The transducer and the way it is attached to the bone play a central role in the design of such devices. The actual effect of varying the contact to bone has not been addressed yet. The aim of this study is therefore to compare how different attachment methods of the transducer to the bone for direct stimulation affect the ear canal sound pressure and vibration transmission to the ipsilateral cochlea. Three different attachments to the bone were tested: (A) via a flat small-sized surface, (B) via a flat wide surface and (C) via two separated screws. Measurements were done on four human heads on both sides. The attachments were compared in terms of induced cochlear promontory velocity, measured by a laser Doppler vibrometer, and ear canal sound pressure, measured by a low noise microphone. A swept sine stimulus was used in the frequency range 0.1-10 kHz. On an average level, the attachment method seems to affect the transmission mainly at frequencies above 5 kHz. Furthermore, the results suggest that a smaller contact surface might perform better in terms of transmission of vibrations at mid and high frequencies. However, when considering the whole frequency range, average results from the different attachment techniques are comparable. (C) 2018 The Authors. Published by Elsevier B.V.
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| 39. |
- Rigato, Cristina, 1989, et al.
(författare)
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Effect of transducer attachment on vibration transmission and transcranial attenuation for direct drive bone conduction stimulation
- 2019
-
Ingår i: Hearing Research. - : Elsevier BV. - 0378-5955 .- 1878-5891. ; 381
-
Tidskriftsartikel (refereegranskat)abstract
- Direct drive bone conduction devices (BCDs) are used to rehabilitate patients with conductive or mixed hearing loss by stimulating the skull bone directly, either with an implanted transducer (active trans cutaneous BCDs), or through a skin penetrating abutment rigidly coupled to an external vibrating transducer (percutaneous BCDs). Active transcutaneous BCDs have been under development to overcome limitations of the percutaneous bone anchored hearing aid (BAHA), mainly related to the skin penetration. The attachment of a direct drive BCD to the skull bone can differ significantly between devices, and possibly influence the vibrations' transmission to the cochleae. In this study, four different attachments are considered: (A) small-sized flat surface, (B) extended flat surface, (C) bar with a screw at both ends, and (D) standard bone anchored hearing aid screw. A, B, and C represent three active transcutaneous options, while D is for percutaneous applications. The primary aim of this study was to investigate how the different transcutaneous attachments (A, B, and C) affect the transmission of vibrations to the cochleae to the ipsilateral and the contralateral side. A secondary aim was to evaluate and compare transcranial attenuation (TA, ipsilateral minus contralateral signal level) between transcutaneous (A, B, and C) and percutaneous attachments (D). Measurements were performed on four human heads, measuring cochlear promontory velocity with a LDV (laser Doppler vibrometer) and sound pressure in the ear canal (ECSP) with an inserted microphone. The stimulation signal was a swept sine between 0.1 and 10 kHz. The comparison of ipsilateral transmission between transcutaneous adaptors A, B, and C was in agreement with previous findings, confirming that: (1) Adaptor C seems to give the most effective transmission for frequencies around 6 kHz but somewhat lower in the mid frequency range, and (2) keeping a smaller contact area seems to provide advantages compared to a more extended one. The same trends were seen ipsilaterally and contralaterally. The observed TA was similar for adaptors A, B, and C at the mastoid position, ranging-10-0 dB below 500 Hz, and 10-20 dB above. A lower TA was seen above 500 Hz when using adaptor D at the parietal position. (C) 2019 The Authors. Published by Elsevier B.V.
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| 40. |
- Rigato, Cristina, 1989, et al.
(författare)
-
Rehabilitating Patients with Bone Conduction Hearing Devices: Two Effective Alternatives
- 2017
-
Ingår i: Engineering Health.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Background: Bone conduction devices (BCDs) are today widely used to rehabilitate patients suffering from specific types of hearing impairment, when the main hearing loss originates in the middle or outer ear. BCDs act by stimulating the skull bone with vibrations that are directly transmitted to the cochlea in the inner ear and result in a hearing sensation, referred to as bone conduction hearing.BCDs are on the market since several decades in various alternative designs, externally worn or partially implanted. In 1977 the first bone anchored hearing aid (BAHA) was implanted in a patient in Gothenburg, and now this technology is one of the most used all over the world. A novel device, the BCI (Bone Conduction Implant), was developed in collaboration between Chalmers and Sahlgrenska in the past few years. The BCI is an alternative to the well-established BAHA that aims at overcoming some of its limitations mainly related to the skin-penetrating abutment. Objectives: In this study, the well-established BAHA and the novel BCI are compared in terms of rehabilitation effect on hearing impaired patients. The purpose of comparing the BCI with an established device available on the market is to find out if the BCI can be a valuable rehabilitation alternative for indicated patients.Methods: Audiometric measurements and user self-reported questionnaires were performed on two groups of patients, one fitted with the BCI and one fitted with BAHAs.Six BCI users were included in the study as part of the clinical trial for the device, and six BAHA users were selected in order to match them one by one in terms of hearing ability, gender and age.Results: The overall results from the performed measurements show a clear improvement over the unaided condition for both devices. Outcomes from the audiometric tests as well as from the patient-related measurements were comparable in the two groups. Conclusions: The two devices seem to give an equally satisfactory rehabilitation for indicated patients. The novel BCI is shown to be a successful example of translational science, where the collaboration between Chalmers and Sahlgrenska provided solid bases to integrate technical and medical requirements.
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| 41. |
- Thesleff, Alexander, 1986, et al.
(författare)
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Biomechanical Characterisation of Bone-anchored Implant Systems for Amputation Limb Prostheses: A Systematic Review
- 2018
-
Ingår i: Annals of Biomedical Engineering. - : Springer Science and Business Media LLC. - 0090-6964 .- 1573-9686. ; 46:3, s. 377-391
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Tidskriftsartikel (refereegranskat)abstract
- Bone-anchored limb prostheses allow for the direct transfer of external loads from the prosthesis to the skeleton, eliminating the need for a socket and the associated problems of poor fit, discomfort, and limited range of movement. A percutaneous implant system for direct skeletal attachment of an external limb must provide a long-term, mechanically stable interface to the bone, along with an infection barrier to the external environment. In addition, the mechanical integrity of the implant system and bone must be preserved despite constant stresses induced by the limb prosthesis. Three different percutaneous implant systems for direct skeletal attachment of external limb prostheses are currently clinically available and a few others are under investigation in human subjects. These systems employ different strategies and have undergone design changes with a view to fulfilling the aforementioned requirements. This review summarises such strategies and design changes, providing an overview of the biomechanical characteristics of current percutaneous implant systems for direct skeletal attachment of amputation limb prostheses.
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| 42. |
- Tjellström, A., et al.
(författare)
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Analysis of the mechanical impedance of bone-anchored hearing aids
- 2018
-
Ingår i: Acta Oto-Laryngologica. - : Informa UK Limited. - 1651-2251 .- 0001-6489. ; 138:3, s. 288-296
-
Tidskriftsartikel (refereegranskat)abstract
- Some patients who need hearing aids are unable to use an apparatus which transmits the sound via the external ear canal and have to use a bone conduction hearing aid. The bone vibration transducer of this aid is applied to the skin over the mastoid process and the sound is transmitted via the soft tissue and bone to the cochlea. The pressure needed to apply the transducer often gives the patient discomfort and the damping effect of the soft tissue gives poor quality of the sound transmitted. Advances in the ability to permanently implant foreign material in the body and perform permanent skin penetration has made it possible to develop a bone-anchored hearing aid. Fourteen patients have been equipped with such hearing aids. To be able to give these patients the best hearing aid, a new transducer has to be constructed to match the new situation. The impedance of the bone-anchored titaniumscrew/skull has been studied and the resistance and reactance of the mechanical impedance have been measured. The influence of a damping soft tissue layer over the bone has been analyzed. The difference between the impedance of the skull and the impedance of the soft tissue + skull was in the order of 10 to 25 dB depending on the frequency.
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| 43. |
- Wagman, Petra, et al.
(författare)
-
Occupational balance in health professionals in Sweden
- 2017
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Ingår i: Scandinavian Journal of Occupational Therapy. - : Taylor & Francis. - 1103-8128 .- 1651-2014. ; 24:1, s. 18-23
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Tidskriftsartikel (refereegranskat)abstract
- Background: Health care employees are often women, a group that has high degrees of sick leave and perhaps problems attaining occupational balance. However, people think differently about their everyday activities and it is therefore important to take their perceptions into account but occupational balance has not yet been measured in health professionals. The aim was to describe occupational balance in three different samples of health professionals in Sweden. A further aim was to investigate whether occupational therapists (OTs) rate their occupational balance differently from other health professionals.Material and method: Four hundred and eighty-two health professionals, employees in public dentistry, mental health care and OTs, aged 21–70 years participated. The participants’ occupational balance was measured using the occupational balance questionnaire (OBQ).Results: The ratings of occupational balance were similar to earlier studies and did not differ significantly between the samples. The OTs’ occupational balance was also similar to that of the other health professionals.Conclusion: The similarities in occupational balance indicate the same difficulties in attaining it.Significance: The result highlights the possibility that working people face similar difficulties in achieving occupational balance. Further research is warranted about how to attain it.
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