Xiaoying Lv

A novel functional electrical stimulation-control system for restoring motor function of post-stroke hemiplegic patients

Hemiparesis is one of the most common consequences of stroke. Advanced rehabilitation techniques are essential for restoring motor function in hemiplegic patients. Functional electrical stimulation applied to the affected limb based on myoelectric signal from the unaffected limb is a promising therapy for hemiplegia. In this study, we developed a prototype system for evaluating this novel functional electrical stimulation-control strategy. Based on surface electromyography and a vector machine model, a self-administered, multi-movement, force-modulation functional electrical stimulation-prototype system for hemiplegia was implemented. This paper discusses the hardware design, the algorithm of the system, and key points of the self-oscillation-prone system. The experimental results demonstrate the feasibility of the prototype system for further clinical trials, which is being conducted to evaluate the efficacy of the proposed rehabilitation technique.

Effects of Microelectrode Array Configuration and Position on the Threshold in Electrical Extracellular Stimulation of Single Nerve Fiber：a Modeling Study

A transient flnite-element model has been presented to simulate extracellular potential stimulating in a neural tissue by a nonplanar microelectrode array (MEA). This model allows simulating the extracellular potential and transmembrane voltage by means of a single transient computation performed within single flnite element (FE) software. The difierential efiects of the conflguration and position of MEA in electrical extracellular stimulation are analyzed theoretically. 3-D models of single nerve flber and difierent MEA are used for the computation of the stimulation induced fleld potential, whereas a cable model of a nerve flbre is used for the calculation of the transmembrane voltage of the nerve flber. The position of MEA and the spacing of the microelectrodes are varied while mono-, bi-, tri-, and penta-polar MEAs are applied. The model predicts that the lowest stimulation voltage threshold is obtained in the stimulation with penta-polar MEA. Moreover, the relationships, which exist between the thresholds of the electrical extracellular stimulation and the parameters including position of the electrode array and the spacing of the microelectrodes in array, are studied and obtained.

Design and Experiments of Transmitter for Transcutaneous Energy Transmission

The design of the RF transmitter for transcutaneous energy transmission is analyzed and experimentally tested. The transmitter consists of a crystal oscillator, a class-E power amplifier, a supply voltage regulator, and a transmitting coil. The transmitting coils made of enameled wire and the receiving coils made on Printed Circuit Board (PCB) were designed simultaneously. In this paper, the compensated methods of transmitting coils and receiving coils are discussed. The topology and working principle of the transmitter are analyzed, the design parameters of the transmitter are calculated. Driven by a crystal oscillator, the class-E power amplifier operates at 13.56 MHz (ISM frequency band). In the conditions of a distance of 10 mm between two coils and 5-9 V DC supply, the voltage measured across the transmitting coil is from 90 V to 130 V, while the voltage across the receiving coil can reach 28 V. The experimental results are in good agreement with the simulating ones. With a distance of 35 mm and a slice of skin between the coils, the receiving voltage reaches still up to 4 V at least, which meets the need of implanted integrated circuits.

Real-time and wearable functional electrical stimulation system for volitional hand motor function control using the electromyography bridge method

Voluntary participation of hemiplegic patients is crucial for functional electrical stimulation therapy. A wearable functional electrical stimulation system has been proposed for real-time volitional hand motor function control using the electromyography bridge method. Through a series of novel design concepts, including the integration of a detecting circuit and an analog-to-digital converter, a miniaturized functional electrical stimulation circuit technique, a low-power super-regeneration chip for wireless receiving, and two wearable armbands, a prototype system has been established with reduced size, power, and overall cost. Based on wrist joint torque reproduction and classification experiments performed on six healthy subjects, the optimized surface electromyography thresholds and trained logistic regression classifier parameters were statistically chosen to establish wrist and hand motion control with high accuracy. Test results showed that wrist flexion/extension, hand grasp, and finger extension could be reproduced with high accuracy and low latency. This system can build a bridge of information transmission between healthy limbs and paralyzed limbs, effectively improve voluntary participation of hemiplegic patients, and elevate efficiency of rehabilitation training.

Microelectronic neural bridging of toad nerves to restore leg function

The present study used a microelectronic neural bridge comprised of electrode arrays for neural signal detection, functional electrical stimulation, and a microelectronic circuit including signal amplifying, processing, and functional electrical stimulation to bridge two separate nerves, and to restore the lost function of one nerve. The left leg of one spinal toad was subjected to external mechanical stimulation and functional electrical stimulation driving. The function of the left leg of one spinal toad was regenerated to the corresponding leg of another spinal toad using a microelectronic neural bridge. Oscilloscope tracings showed that the electromyographic signals from controlled spinal toads were generated by neural signals that controlled the spinal toad, and there was a delay between signals. This study demonstrates that microelectronic neural bridging can be used to restore neural function between different injured nerves.

Design of motor function restoration system based on myoelectric signals recognition

In this paper, a system aiming at motor function restoration based on myoelectric signals recognition has been presented. This system contains four main components: analog front, AD converter, digital signal processor, and functional electrical stimulator. Functions and designing consideration of each component, and a myoelectric signals recognition algorithm with low computational complexity have been introduced. Finally, the testing results of the system will be presented and the qualified performance for the further animal experiment is demonstrated.