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1.
IEEE Trans Biomed Eng ; PP2021 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-33497323

RESUMO

Ankle plantarflexion plays an important role in forward propulsion and anterior-posterior balance during locomotion. This component of gait is often critically impacted by neurotraumas and neurological diseases. We hypothesized that augmenting plantar cutaneous feedback, via closed-loop distal-tibial nerve stimulation, could increase ankle plantarflexion during walking. To test the hypothesis, one intact rat walked on a motorized treadmill with implanted electronic device and electrodes for closed-loop neural recording and stimulation. Constant-current biphasic electrical pulse train was applied to distal-tibial nerve, based on electromyogram recorded from the medial gastrocnemius muscle, to be timed with the stance phase. The stimulation current threshold to evoke plantar cutaneous feedback was set at 30 A (1T), based on compound action potential evoked by stimulation. The maximum ankle joint angle at plantarflexion, during the application of stimulation currents of 3.3T and 6.6T, respectively, was increased from 149.4 (baseline) to 165.4 and 161.6. The minimum ankle joint angle at dorsiflexion was decreased from 59.4 (baseline) to 53.1, during the application of stimulation currents of 3.3T, but not changed by 6.6T. Plantar cutaneous augmentation also changed other gait kinematic parameters. Stance duty factor was increased from 51.9% (baseline) to 65.7% and 64.0%, respectively, by 3.3T and 6.6T, primarily due to a decrease in swing duration. Cycle duration was consistently decreased by the stimulation. In the control trial after two stimulation trials, a strong after-effect was detected in overall gait kinematics as well as ankle plantarflexion, suggesting that this stimulation has the potential for producing long-term changes in gait kinematics.

2.
Mil Med ; 186(Suppl 1): 688-695, 2021 01 25.
Artigo em Inglês | MEDLINE | ID: mdl-33499499

RESUMO

INTRODUCTION: The three major unresolved problems in bone-anchored limb prosthetics are stable, infection-free integration of skin with a percutaneous bone implant, robust skeletal fixation between the implant and host bone, and a secure interface of sensory nerves and muscles with a prosthesis for the intuitive bidirectional prosthetic control. Here we review results of our completed work and report on recent progress. MATERIALS AND METHODS: Eight female adult cats received skin- and bone-integrated pylon (SBIP) and eight male adult cats received SBIP-peripheral neural interface (PNI) pylon into the right distal tibia. The latter pylons provided PNI for connection between a powered sensing transtibial prosthesis and electrodes in residual soleus muscle and on residual distal tibial nerve. If signs of infection were absent 28-70 days after implantation, cats started wearing a passive prosthesis. We recorded and analyzed full-body mechanics of level and slope locomotion in five cats with passive prostheses and in one cat with a powered sensing prosthesis. We also performed histological analyses of tissue integration with the implants in nine cats.Four pigs received SBIPs into the left hindlimb and two pigs-into the left forelimb. We recorded vertical ground reaction forces before amputation and following osseointegration. We also conducted pullout postmortem tests on the implanted pylons. One pig received in dorsum the modified SBIPs with and without silver coating. RESULTS: Six cats from the SBIP groups had implant for 70 days. One cat developed infection and did not receive prosthesis. Five cats had pylon for 148 to 183 days, showed substantial loading of the prosthesis during locomotion (40.4% below presurgery control), and demonstrated deep ingrowth of skin and bone tissue into SBIP (over 60%). Seven of eight cats from the SBIP-PNI group demonstrated poor pylon integration without clinical signs of infection. One cat had prosthesis for 824 days (27 months). The use of the bidirectionally controlled prosthesis by this animal during level walking demonstrated increased vertical loading to nearly normal values, although the propulsion force was significantly reduced.From the study on pigs, it was found that symmetry in loading between the intact and prosthetic limbs during locomotion was 80 ± 5.5%. Skin-implant interface was infection-free, but developed a stoma, probably because of the high mobility of the skin and soft tissues in the pig's thigh. Dorsal implantation resulted in the infection-free deep ingrowth of skin into the SBIP implants. CONCLUSIONS: Cats with SBIP (n = 5) and SBIP-PNI (n = 1) pylons developed a sound interface with the residuum skin and bone and demonstrated substantial loading of prosthetic limb during locomotion. One animal with SBIP developed infection and seven cats with SBIP-PNI demonstrated poor bone integration without signs of infection. Future studies of the SBIP-PNI should focus on reliability of integration with the residuum. Ongoing study with pigs requires decreasing the extra mobility of skin and soft tissues until the skin seal is developed within the SBIP implant.

3.
Artigo em Inglês | MEDLINE | ID: mdl-33170781

RESUMO

Although it seems intuitive to address the issue of reduced plantar cutaneous feedback by augmenting it, many approaches have adopted compensatory sensory cues, such as tactile input from another part of the body, for multiple reasons including easiness and accessibility. The efficacy of the compensatory approaches might be limited due to the cognitive involvement to interpret such compensatory sensory cues. The objective of this study is to test the hypothesis that the plantar cutaneous augmentation is more effective than providing compensatory sensory cues on improving postural regulation, when plantar cutaneous feedback is reduced. In our experiments, six healthy human subjects were asked to maintain their balance on a lateral balance board for as long as possible, until the balance board contacted the ground, for 240 trials with five interventions. During these experiments, subjects were instructed to close their eyes to increase dependency on plantar cutaneous feedback for balancing. Foam pad was also added on the board to emulate the condition of reduced plantar cutaneous feedback. The effects of tactile augmentation from the foot sole or the palm on standing balance were tested by applying transcutaneous electrical stimulation on calcaneal or ulnar nerve during the balance board tests, with and without a cognitively-challenging counting task. Experimental results indicate that the plantar cutaneous augmentation was effective on improving balance only with cognitive load, while the palmar cutaneous augmentation was effective only without cognitive load. This result suggests that the location of sensory augmentation should be carefully determined according to the attentional demands.

4.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 3751-3754, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018817

RESUMO

The aging process, as well as neurological disorders, causes a decline in sensorimotor functions, which can often bring degraded motor output. As a means of compensation for such sensorimotor deficiencies, sensorimotor augmentation has been actively investigated. Consequently, exoskeleton devices or functional electrical stimulation could augment the muscle activity, while textured surfaces or electrical nerve stimulations could augment the sensory feedback. However, it is not easy to precisely anticipate the effects of specific augmentation because sensory feedback and motor output interact with each other as a closed-loop operation via the central and peripheral nervous systems. A computational internal model can play a crucial role in anticipating such an effect of augmentation therapy on the motor outcome. Still, no existing internal sensorimotor loop model has been represented in a complete computational form facilitating the anticipation. This paper presents such a computational internal model, including numerical values representing the effect of sensorimotor augmentation. With the existing experimental results, the model performance was evaluated indirectly. The change of sensory gain affects motor output inversely, while the change of motor gain did not change or minimally affects the motor output.Clinical Relevance- The presented computational internal model will provide a simple and easy tool for clinicians to design therapeutic intervention using sensorimotor augmentation.


Assuntos
Retroalimentação Sensorial , Sensação , Estimulação Elétrica
5.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 4306-4309, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018948

RESUMO

There is an increasing demand for real-time neural signal monitoring from a large number of electrode contacts to provide adequate spatial and temporal resolution for brain mapping and high-resolution neural interface. This paper proposes a novel multi-channel neural recording system that records neural signals from a large number of electrodes with a smaller number of recording channels. The system utilizes an adaptive electrode selection technique to automatically scan the electrode arrays and record from selected electrodes where neural spikes are detected. The proposed neural recording IC was fabricated in CMOS 180 nm process and tested with in vitro environments. Experiment results with pre-recorded neural data indicate that neural spikes can be separated and amplified with the proposed system and counted in real-time.


Assuntos
Mapeamento Encefálico , Registros , Eletrodos
6.
J Clin Med ; 9(2)2020 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-32102421

RESUMO

Reduced balance function has been observed during balance challenging conditions in the chronic obstructive pulmonary disease (COPD) population and is associated with an increased risk of falls. This study aimed to examine postural balance during quiet standing with eyes open and functional balance in a heterogeneous group of COPD and non-COPD (control) subjects, and to identify risk factors underlying balance impairment using a large panel of methods. In COPD and control subjects, who were mostly overweight and sedentary, postural and functional balance were assessed using center-of-pressure displacement in anterior-posterior (AP) and medio-lateral (ML) directions, and the Berg Balance Scale (BBS), respectively. COPD showed 23% greater AP sway velocity (p = 0.049). The presence of oxygen therapy, fat mass, reduced neurocognitive function, and the presence of (pre)diabetes explained 71% of the variation in postural balance in COPD. Transcutaneous oxygen saturation, a history of exacerbation, and gait speed explained 83% of the variation in functional balance in COPD. Neurocognitive dysfunction was the main risk factor for postural balance impairment in the control group. This suggests that specific phenotypes of COPD patients can be identified based on their type of balance impairment.

7.
Sci Rep ; 10(1): 163, 2020 01 13.
Artigo em Inglês | MEDLINE | ID: mdl-31932709

RESUMO

For teleoperation tasks requiring high control accuracy, it is essential to provide teleoperators with information on the interaction between the end effector and the remote environment. Real-time imaging devices have been widely adopted, but it delivers limited information, especially when the end effectors approach the target following the line-of-sight. In such situations, teleoperators rely on the perspective at the screen and can apply high force unintentionally at the initial contact. This research proposes to deliver the distance information at teleoperation to the fingertips of teleoperators, i.e., proximity sensation. Transcutaneous electrical stimulation was applied onto the fingertips of teleoperators, with the pulsing frequency inversely proportional to the distance. The efficacy of the proximity sensation was evaluated by the initial contact force during telerobotic pinch in three sensory conditions: vision only, vision + visual assistance (distance on the screen), and vision + proximity sensation. The experiments were repeated at two viewing angles: 30-60° and line-of-sight, for eleven healthy human subjects. For both cases, the initial contact force could be significantly reduced by either visual assistance (20-30%) or the proximity sensation (60-70%), without additional processing time. The proximity sensation is two-to-three times more effective than visual assistance regarding the amount of force reduction.

8.
J Exp Biol ; 222(Pt 14)2019 07 26.
Artigo em Inglês | MEDLINE | ID: mdl-31308054

RESUMO

Cutaneous sensory feedback from the paw pads plays an important role in regulating body balance, especially in challenging environments like ladder or slope walking. Here, we investigated the contribution of cutaneous sensory feedback from the paw pads to balance control in cats stepping on a split-belt treadmill. Forepaws and hindpaws were anesthetized unilaterally using lidocaine injections. We evaluated body balance in intact and compromised cutaneous feedback conditions during split-belt locomotion with belt-speed ratios of 0.5, 1.0, 1.5 and 2.0. Measures of body balance included step width, relative duration of limb support phases, lateral bias of center of mass (CoM) and margins of static and dynamic stability. In the intact condition, static and dynamic balance declined with increasing belt-speed ratio as a result of a lateral shift of the CoM toward the borders of support on the slower moving belt. Anesthesia of the ipsilateral paws improved locomotor balance with increasing belt-speed ratios by reversing the CoM shift, decreasing the relative duration of the two-limb support phase, increasing the duration of four- or three-limb support phases, and increasing the hindlimb step width and static stability. We observed no changes in most balance measures in anesthetized conditions during tied-belt locomotion at 0.4 m s-1 CoM lateral displacements closely resembled those of the inverted pendulum and of human walking. We propose that unilaterally compromised cutaneous feedback from the paw pads is compensated for by improving lateral balance and by shifting the body toward the anesthetized paws to increase tactile sensation during the stance phase.


Assuntos
Gatos/fisiologia , Retroalimentação Sensorial , Locomoção , Equilíbrio Postural , Animais , Feminino
9.
Front Neurosci ; 12: 471, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30057524

RESUMO

We developed a prototype of a neural, powered, transtibial prosthesis for the use in a feline model of prosthetic gait. The prosthesis was designed for attachment to a percutaneous porous titanium implant integrated with bone, skin, and residual nerves and muscles. In the benchtop testing, the prosthesis was fixed in a testing rig and subjected to rhythmic vertical displacements and interactions with the ground at a cadence corresponding to cat walking. Several prosthesis functions were evaluated. They included sensing ground contact, control of transitions between the finite states of prosthesis loading, and a closed-loop modulation of the linear actuator gain in each loading cycle. The prosthetic design parameters (prosthesis length = 55 mm, mass = 63 g, peak extension moment = 1 Nm) corresponded closely to those of the cat foot-ankle with distal shank and the peak ankle extension moment during level walking. The linear actuator operated the prosthetic ankle joint using inputs emulating myoelectric activity of residual muscles. The linear actuator gain was modulated in each cycle to minimize the difference between the peak of ground reaction forces (GRF) recorded by a ground force sensor and a target force value. The benchtop test results demonstrated a close agreement between the GRF peaks and patterns produced by the prosthesis and by cats during level walking.

10.
IEEE Trans Neural Syst Rehabil Eng ; 24(1): 68-78, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25730827

RESUMO

Tongue-Drive System (TDS) is a wireless and wearable assistive technology that enables people with severe disabilities to control their computers, wheelchairs, and smartphones using voluntary tongue motion. To evaluate the efficacy of the TDS, several experiments were conducted, in which the performance of nine able-bodied (AB) participants using a mouse, a keypad, and the TDS, as well as a cohort of 11 participants with tetraplegia (TP) using the TDS, were observed and compared. Experiments included the Fitts' law tapping, wheelchair driving, phone-dialing, and weight-shifting tasks over five to six consecutive sessions. All participants received a tongue piercing, wore a magnetic tongue stud, and completed the trials as evaluable participants. Although AB participants were already familiar with the keypad, throughputs of their tapping tasks using the keypad were only 1.4 times better than those using the TDS. The completion times of wheelchair driving task using the TDS for AB and TP participants were between 157 s and 180 s with three different control strategies. Participants with TP completed phone-dialing and weight-shifting tasks in 81.9 s and 71.5 s, respectively, using tongue motions. Results showed statistically significant improvement or trending to improvement in performance status over the sessions. Most of the learning occurred between the first and second sessions, but trends did suggest that more practice would lead to increased improvement in performance using the TDS.


Assuntos
Aplicativos Móveis , Quadriplegia/reabilitação , Smartphone/instrumentação , Língua/fisiopatologia , Interface Usuário-Computador , Cadeiras de Rodas , Adolescente , Adulto , Desenho de Equipamento , Análise de Falha de Equipamento , Feminino , Humanos , Masculino , Sistemas Homem-Máquina , Sistemas Microeletromecânicos/instrumentação , Pessoa de Meia-Idade , Movimento , Quadriplegia/fisiopatologia , Tecnologia sem Fio/instrumentação , Adulto Jovem
11.
Sensors (Basel) ; 14(11): 21565-87, 2014 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-25405513

RESUMO

We present a new arch-shaped intraoral Tongue Drive System (iTDS) designed to occupy the buccal shelf in the user's mouth. The new arch-shaped iTDS, which will be referred to as the iTDS-2, incorporates a system-on-a-chip (SoC) that amplifies and digitizes the raw magnetic sensor data and sends it wirelessly to an external TDS universal interface (TDS-UI) via an inductive coil or a planar inverted-F antenna. A built-in transmitter (Tx) employs a dual-band radio that operates at either 27 MHz or 432 MHz band, according to the wireless link quality. A built-in super-regenerative receiver (SR-Rx) monitors the wireless link quality and switches the band if the link quality is below a predetermined threshold. An accompanying ultra-low power FPGA generates data packets for the Tx and handles digital control functions. The custom-designed TDS-UI receives raw magnetic sensor data from the iTDS-2, recognizes the intended user commands by the sensor signal processing (SSP) algorithm running in a smartphone, and delivers the classified commands to the target devices, such as a personal computer or a powered wheelchair. We evaluated the iTDS-2 prototype using center-out and maze navigation tasks on two human subjects, which proved its functionality. The subjects' performance with the iTDS-2 was improved by 22% over its predecessor, reported in our earlier publication.


Assuntos
Magnetismo/instrumentação , Imãs , Equipamentos de Autoajuda , Língua/fisiologia , Transdutores , Interface Usuário-Computador , Tecnologia sem Fio/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento , Humanos , Sistemas Homem-Máquina , Postura/fisiologia , Processamento de Sinais Assistido por Computador/instrumentação , Integração de Sistemas
12.
J Rehabil Res Dev ; 51(3): 451-65, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25019667

RESUMO

The Tongue Drive System (TDS) is a minimally invasive, wireless, and wearable assistive technology (AT) that enables people with severe disabilities to control their environments using tongue motion. TDS translates specific tongue gestures into commands by sensing the magnetic field created by a small magnetic tracer applied to the user's tongue. We have previously quantitatively evaluated the TDS for accessing computers and powered wheelchairs, demonstrating its usability. In this study, we focused on its qualitative evaluation by people with high-level spinal cord injury who each received a magnetic tongue piercing and used the TDS for 6 wk. We used two questionnaires, an after-scenario and a poststudy, designed to evaluate the tongue-piercing experience and the TDS usability compared with that of the sip-and-puff and the users' current ATs. After study completion, 73% of the participants were positive about keeping the magnetic tongue-barbell in order to use the TDS. All were satisfied with the TDS performance and most said that they were able to do more things using TDS than their current ATs (4.22/5).


Assuntos
Pessoas com Deficiência/psicologia , Satisfação do Paciente , Quadriplegia/reabilitação , Equipamentos de Autoajuda , Traumatismos da Medula Espinal/reabilitação , Língua , Adulto , Piercing Corporal/efeitos adversos , Vértebras Cervicais , Feminino , Gestos , Humanos , Imãs , Masculino , Pessoa de Meia-Idade , Dor/etiologia , Quadriplegia/etiologia , Pesquisa Qualitativa , Traumatismos da Medula Espinal/complicações , Inquéritos e Questionários
13.
IEEE Trans Microw Theory Tech ; 62(12): 3205-3215, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26236039

RESUMO

This paper explores communication methods and frequencies for wireless intraoral electronic devices, by using an intraoral tongue drive system (iTDS) as a practical example. Because intraoral devices do not meet the operating conditions of the body channel communication, we chose radio frequency communication. We evaluated and compared three frequencies in industrial, scientific, and medical bands (27 MHz, 433.9 MHz, and 2.48 GHz) in terms of their data link performance based on path loss and radiation patterns over horizontal and vertical planes. To do so, we dynamically minimize the impedance mismatch caused by the varying oral environment by applying the adaptive impedance matching technique to 433.9 MHz and 2.48 GHz bands. Experimental results showed that 27 MHz has the smallest path loss in the near-field up to 39 cm separation between transmitter and receiver antennas. However, 433.9 MHz shows the best performance beyond 39 cm and offers a maximum operating distance of 123 cm with 0 dBm transmitter output power. These distances were obtained by a bit error rate test and verified by a link budget analysis and full functionality test of the iTDS with computer access.

14.
Sci Transl Med ; 5(213): 213ra166, 2013 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-24285485

RESUMO

The Tongue Drive System (TDS) is a wireless and wearable assistive technology, designed to allow individuals with severe motor impairments such as tetraplegia to access their environment using voluntary tongue motion. Previous TDS trials used a magnetic tracer temporarily attached to the top surface of the tongue with tissue adhesive. We investigated TDS efficacy for controlling a computer and driving a powered wheelchair in two groups of able-bodied subjects and a group of volunteers with spinal cord injury (SCI) at C6 or above. All participants received a magnetic tongue barbell and used the TDS for five to six consecutive sessions. The performance of the group was compared for TDS versus keypad and TDS versus a sip-and-puff device (SnP) using accepted measures of speed and accuracy. All performance measures improved over the course of the trial. The gap between keypad and TDS performance narrowed for able-bodied subjects. Despite participants with SCI already having familiarity with the SnP, their performance measures were up to three times better with the TDS than with the SnP and continued to improve. TDS flexibility and the inherent characteristics of the human tongue enabled individuals with high-level motor impairments to access computers and drive wheelchairs at speeds that were faster than traditional assistive technologies but with comparable accuracy.


Assuntos
Computadores , Traumatismos da Medula Espinal , Língua , Cadeiras de Rodas , Adolescente , Adulto , Feminino , Humanos , Masculino , Adulto Jovem
15.
Analog Integr Circuits Signal Process ; 75(3): 459-465, 2013 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-23682207

RESUMO

We present a new noise shaping method and a dual polarity calibration technique suited for successive approximation register type analog to digital converters (SAR-ADC). Noise is pushed to higher frequencies with the noise shaping by adding a switched capacitor. The SAR capacitor array mismatch has been compensated by the dual-polarity digital calibration with minimum circuit overhead. A proof-of-concept prototype SAR-ADC using the proposed techniques has been fabricated in a 0.5-µm standard CMOS technology. It achieves 67.7 dB SNDR at 62.5 kHz sampling frequency, while consuming 38.3µW power with 1.8 V supply.

16.
IEEE Trans Neural Syst Rehabil Eng ; 21(6): 979-91, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23475380

RESUMO

We are presenting a new wireless and wearable human computer interface called the dual-mode Tongue Drive System (dTDS), which is designed to allow people with severe disabilities to use computers more effectively with increased speed, flexibility, usability, and independence through their tongue motion and speech. The dTDS detects users' tongue motion using a magnetic tracer and an array of magnetic sensors embedded in a compact and ergonomic wireless headset. It also captures the users' voice wirelessly using a small microphone embedded in the same headset. Preliminary evaluation results based on 14 able-bodied subjects and three individuals with high level spinal cord injuries at level C3-C5 indicated that the dTDS headset, combined with a commercially available speech recognition (SR) software, can provide end users with significantly higher performance than either unimodal forms based on the tongue motion or speech alone, particularly in completing tasks that require both pointing and text entry.


Assuntos
Medida da Produção da Fala/instrumentação , Traumatismos da Medula Espinal/fisiopatologia , Traumatismos da Medula Espinal/reabilitação , Terapia Assistida por Computador/instrumentação , Língua/fisiopatologia , Interface Usuário-Computador , Tecnologia sem Fio/instrumentação , Adulto , Vértebras Cervicais/lesões , Vértebras Cervicais/fisiopatologia , Desenho de Equipamento , Análise de Falha de Equipamento , Feminino , Humanos , Masculino , Miniaturização , Movimento , Valores de Referência , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Interface para o Reconhecimento da Fala , Análise e Desempenho de Tarefas , Processamento de Texto/instrumentação , Adulto Jovem
17.
IEEE J Solid-State Circuits ; 48(9): 2203-2216, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24678126

RESUMO

A power-efficient wireless stimulating system for a head-mounted deep brain stimulator (DBS) is presented. A new adaptive rectifier generates a variable DC supply voltage from a constant AC power carrier utilizing phase control feedback, while achieving high AC-DC power conversion efficiency (PCE) through active synchronous switching. A current-controlled stimulator adopts closed-loop supply control to automatically adjust the stimulation compliance voltage by detecting stimulation site potentials through a voltage readout channel, and improve the stimulation efficiency. The stimulator also utilizes closed-loop active charge balancing to maintain the residual charge at each site within a safe limit, while receiving the stimulation parameters wirelessly from the amplitude-shift-keyed power carrier. A 4-ch wireless stimulating system prototype was fabricated in a 0.5-µm 3M2P standard CMOS process, occupying 2.25 mm². With 5 V peak AC input at 2 MHz, the adaptive rectifier provides an adjustable DC output between 2.5 V and 4.6 V at 2.8 mA loading, resulting in measured PCE of 72 ~ 87%. The adaptive supply control increases the stimulation efficiency up to 30% higher than a fixed supply voltage to 58 ~ 68%. The prototype wireless stimulating system was verified in vitro.

18.
IEEE Trans Biomed Circuits Syst ; 6(6): 571-85, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23853258

RESUMO

Tongue drive system (TDS) is a tongue-operated, minimally invasive, unobtrusive, and wireless assistive technology (AT) that infers users' intentions by detecting their voluntary tongue motion and translating them into user-defined commands. Here we present the new intraoral version of the TDS (iTDS), which has been implemented in the form of a dental retainer. The iTDS system-on-a-chip (SoC) features a configurable analog front-end (AFE) that reads the magnetic field variations inside the mouth from four 3-axial magnetoresistive sensors located at four corners of the iTDS printed circuit board (PCB). A dual-band transmitter (Tx) on the same chip operates at 27 and 432 MHz in the Industrial/Scientific/Medical (ISM) band to allow users to switch in the presence of external interference. The Tx streams the digitized samples to a custom-designed TDS universal interface, built from commercial off-the-shelf (COTS) components, which delivers the iTDS data to other devices such as smartphones, personal computers (PC), and powered wheelchairs (PWC). Another key block on the iTDS SoC is the power management integrated circuit (PMIC), which provides individually regulated and duty-cycled 1.8 V supplies for sensors, AFE, Tx, and digital control blocks. The PMIC also charges a 50 mAh Li-ion battery with constant current up to 4.2 V, and recovers data and clock to update its configuration register through a 13.56 MHz inductive link. The iTDS SoC has been implemented in a 0.5-µm standard CMOS process and consumes 3.7 mW on average.


Assuntos
Equipamentos de Autoajuda , Língua/fisiologia , Interface Usuário-Computador , Engenharia Biomédica/instrumentação , Desenho de Equipamento , Humanos , Fenômenos Magnéticos , Traumatismos da Medula Espinal/fisiopatologia , Traumatismos da Medula Espinal/reabilitação , Telemetria/instrumentação , Tecnologia sem Fio/instrumentação
19.
Artigo em Inglês | MEDLINE | ID: mdl-23366102

RESUMO

Tongue Drive System (TDS) is a wireless tongue-operated assistive technology (AT), developed for people with severe physical impediments to control their environments using their tongue motion. We have developed a new intraoral TDS (iTDS) in a form of a dental retainer, which can tightly clasp onto the upper teeth, completely hidden inside the mouth, using commercial off-the-shelf components (COTS). The iTDS retainer was tested by two healthy subjects and their performance was compared with that of an external TDS (eTDS) implemented in the form of a headset. The iTDS retainer showed comparable performance with the eTDS headset. The iTDS is expected to improve the stability and robustness of the TDS, while giving users a certain degree of privacy.


Assuntos
Língua , Interface Usuário-Computador , Tecnologia sem Fio/instrumentação , Feminino , Humanos , Masculino
20.
Artigo em Inglês | MEDLINE | ID: mdl-23366818

RESUMO

Tongue Drive System (TDS) is a wireless and wearable assistive technology (AT) that enables people with severe disabilities to control their computers, wheelchairs, and electronic gadgets using their tongue motion. We developed the TDS to control smartphone's (iPhone/iPod Touch) built-in and downloadable apps with a customized Bluetooth mouse module by emulating finger taps on the touchscreen. The TDS-iPhone Bluetooth mouse interface was evaluated by four able-bodied subjects to complete a scenario consisting of seven tasks, which were randomly ordered by using touch on the iPhone screen with index finger, a computer mouse on iPhone, and TDS-iPhone Bluetooth mouse interface with tongue motion. Preliminary results show that the average completion times of a scenario with touch, mouse, and TDS are 165.6 ± 14.50 s, 186.1 ± 15.37 s, and 651.6 ± 113.4 s, respectively, showing that the TDS is 84.37% and 81.16% slower than touch and mouse for speed of typing with negligible errors. Overall, considering the limited number of commands and unfamiliarity of the subjects with the TDS, we achieved acceptable results for hands-free functionality.


Assuntos
Telefone Celular , Redes de Comunicação de Computadores/instrumentação , Computadores de Mão , Equipamentos de Autoajuda , Língua/fisiologia , Tato , Interface Usuário-Computador , Desenho de Equipamento , Análise de Falha de Equipamento , Humanos , Telemetria/instrumentação
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