Wireless Assistive Technology Research Articles

Retracted: Design of LoRa Antenna for Wearable Medical Applications

The intraoral Tongue Drive System (iTDS) is a wireless assistive technology (AT) that may be operated using a variety of user-defined voluntary tongue motions. In this study, we introduce a novel arch-shaped iTDS that takes up the buccal shelf space in the mouth without constricting tongue motions. Damage to the central nervous system that causes upper limb paralysis. For instance, severe spinal cord injuries, certain strokes or multiple amputations of the upper limbs can make it very difficult for a lot of individuals to go about their everyday lives since they cause them to lose function, control, and independence. Because its muscles are strong and dexterous and do not quickly tire when not necessary to exert power, the tongue is an excellent choice for controlling an AT. Additionally, through cranial nerves, which are unaffected by a spinal cord damage, the tongue is directly attached to the brain. Furthermore, since the tongue movements may be totally hidden from view, TDS-based AT safeguard users’ privacy. In order to provide an effective solution, this paper proposed a novel antenna design with dual-band and implantability. The antenna is modelled in single-layer human muscle considering the feasibility and computational time. Then, the performance is evaluated through multi-layered human oral cavity model. A protective layer is established to prevent direct contact between the antenna and human body. Simulation results show that the proposed antenna has better reflection coefficient, impedance, and radiation pattern as compared with existing antennas.

Adaptive Matching Transmitter With Dual-Band Antenna for Intraoral Tongue Drive System

The intraoral Tongue Drive System (iTDS) is a wireless assistive technology that detects users' voluntary tongue gestures, and converts them to user-defined commands, enabling them to access computers and navigate powered wheelchairs. In this paper, we presented a transmitter (Tx) with adaptive matching and three bands (27, 433, and 915MHz) to create a robust wireless link between iTDS and an external receiver (Rx) by addressing the effects of external RF interference and impedance variations of the Tx antenna in the dynamic mouth environment. The upper two Tx bands share a dual-band antenna, while the lower band drives a coil. The Tx antenna is simulated in a simplified human mouth model in HFSS as well as a real human head model. The adaptive triple-band Tx chip was fabricated in a 0.35-μm 4P2M standard CMOS process. The Tx chip and antenna have been characterized in a human subject as part of an iTDS prototype under open-and closed-mouth scenarios, which present the peak gain of -24.4 and -15.63 dBi at 433 and 915MHz, respectively. Two adaptive matching networks for these bands compensate variations of the Tx antenna impedance via a feedback mechanism. The measured S11 tuning range of the proposed network can cover up to 60 and 75 jΩ at 433 and 915MHz, respectively.

Antennas for Intraoral Tongue Drive System at 2.4 GHz: Design, Characterization, and Comparison

The intraoral Tongue Drive System (iTDS), is a tongue-controlled wireless assistive technology, operated by a number of user-defined voluntary tongue gestures to issue control commands. In this paper, we present a new arch-shaped iTDS, occupying the buccal shelf space in the mouth, without limiting the available space for tongue motions. We describe the design, characterization, and comparison between three types of 2.4-GHz antennas for this system: patch, dipole, and planar inverted-F in terms of gain, directivity, bandwidth, and data communication performance to achieve a robust RF link despite mouth motions. The antennas are designed and simulated in a simple human mouth model and measured in the mouth. Based on simulation and measurement results, using an iTDS prototype made of commercial-off-the-shelf components, the patch antenna has the highest gain in both closed- and open-mouth states, at −10.6 and −9 dBi, respectively. We also measured the propagation loss between the iTDS intraoral antenna and out-of-mouth receiver (Rx) in a real user-case scenario and evaluated the link quality by measuring the packet error rate between the transmitter and RX. The presented antennas have larger bandwidth, smaller area, and higher gain compared to prior work on implantable antennas in the literature, resulting in a robust wireless link for the iTDS application.

Simultaneous Multimodal PC Access for People With Disabilities by Integrating Head Tracking, Speech Recognition, and Tongue Motion.

Multimodal Tongue Drive System (mTDS) is a highly integrated wireless assistive technology (AT) in the form of a lightweight wearable headset that utilizes three remaining key control and communication abilities in people with severe physical disabilities, such as tetraplegia, to provide them with effective access to computers: 1) tongue motion for discrete/switch-based control (e.g., clicking), 2) head tracking for proportional control (e.g., mouse pointer movements), and 3) speech recognition for typing, all available simultaneously. The mTDS architecture is presented here with new sensor signal processing algorithm for head tracking. To evaluate the device performance, it was compared against keyboard-and-mouse (KnM) combination, the gold standard in computer input methods, by 15 able-bodied participants, who used both mTDS and KnM to generate and sent an email with randomly selected content, under a 5-minute time constraint. In four repetitions, in the last trial, it took participants only 1.8 times longer to complete the email task, on average, using the mTDS versus KnM at 82.4% typing accuracy. Mean task completion time and typing accuracy improved 24.6% and 18.8% from first to fourth trial using mTDS. Multimodal simultaneous discrete and proportional control input options of mTDS, plus rapid typing, is expected to provide more effective computer access to people with severe physical disabilities.

Assistive technology using integrated flexible sensor and virtual alarm unit for blood leakage detection during dialysis therapy.

Blood leakages and blood loss are both serious complications during dialysis therapies. According to dialysis survey reports, these events are life-threatening issues for nephrology nurses, medical staff, and patients. When venous needle dislodgement occurs, it takes only <2.5 min of reaction time for blood loss in an adult patient, resulting in mortality. As an early-warning design, a wireless assistive technology using an integrated flexible sensor and virtual alarm unit was developed to detect blood leakage during dialysis therapies. The flexible sensor was designed using a screen print technique with printing electronic circuits on a plastic substrate. A self-organising algorithm was used to design a virtual alarm unit, consisting of a virtual direct current grid and a virtual alarm driver. In other words, this warning device was employed to identify the blood leakage levels via wireless fidelity wireless network in cloud computing. The feasibility was verified, and commercialisation designs can also be implemented in an embedded system.

A Wireless Magnetoresistive Sensing System for an Intraoral Tongue-Computer Interface

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.

Evaluation of a Smartphone Platform as a Wireless Interface Between Tongue Drive System and Electric-Powered Wheelchairs

Tongue drive system (TDS) is a new wireless assistive technology (AT) for the mobility impaired population. It provides users with the ability to drive powered wheelchairs (PWC) and access computers using their unconstrained tongue motion. Migration of the TDS processing unit and user interface platform from a bulky personal computer to a smartphone (iPhone) has significantly facilitated its usage by turning it into a true wireless and wearable AT. After implementation of the necessary interfacing hardware and software to allow the smartphone to act as a bridge between the TDS and PWC, the wheelchair navigation performance and associated learning was evaluated in nine able-bodied subjects in five sessions over a 5-week period. Subjects wore magnetic tongue studs over the duration of the study and drove the PWC in an obstacle course with their tongue using three different navigation strategies; namely unlatched, latched, and semiproportional. Qualitative aspects of using the TDS-iPhone-PWC interface were also evaluated via a five-point Likert scale questionnaire. Subjects showed more than 20% improvement in the overall completion time between the first and second sessions, and maintained a modest improvement of ∼9% per session over the following three sessions.

Using Unconstrained Tongue Motion as an Alternative Control Mechanism for Wheeled Mobility

Tongue drive system (TDS) is a tongue-operated, minimally invasive, unobtrusive, noncontact, and wireless assistive technology that infers users' intentions by detecting and classifying their voluntary tongue motions, and translating them to user-defined commands. We have developed customized interface circuitry between an external TDS (eTDS) prototype and a commercial powered wheelchair (PWC) as well as three control strategies to evaluate the tongue motion as an alternative control input for wheeled mobility. We tested the eTDS performance in driving PWCs on 12 able-bodied human subjects, of which 11 were novice. The results showed that all subjects could complete navigation tasks by operating the PWC using their tongue motions. Despite little prior experience, the average time using the eTDS and the tongue was only approximately three times longer than using a joystick and the fingers. Navigation time was strongly dependant on the number of issued commands, which reduced by gaining experience. Particularly, the unintended issued commands (the Midas touch problem) were rare, demonstrating the effectiveness of the tongue tracking and external magnetic field cancellation algorithms as well as the safety of the TDS for wheeled mobility.