Hai-Peng Wang

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.

A frequency and pulse-width co-modulation strategy for transcutaneous neuromuscular electrical stimulation based on sEMG time-domain features.

OBJECTIVE Surface electromyography (sEMG) is often used as a control signal in neuromuscular electrical stimulation (NMES) systems to enhance the voluntary control and proprioceptive sensory feedback of paralyzed patients. Most sEMG-controlled NMES systems use the envelope of the sEMG signal to modulate the stimulation intensity (current amplitude or pulse width) with a constant frequency. The aims of this study were to develop a strategy that co-modulates frequency and pulse width based on features of the sEMG signal and to investigate the torque-reproduction performance and the level of fatigue resistance achieved with our strategy. APPROACH We examined the relationships between wrist torque and two stimulation parameters (frequency and pulse width) and between wrist torque and two sEMG time-domain features (mean absolute value (MAV) and number of slope sign changes (NSS)) in eight healthy volunteers. By using wrist torque as an intermediate variable, customized and generalized transfer functions were constructed to convert the two features of the sEMG signal into the two stimulation parameters, thereby establishing a MAV/NSS dual-coding (MNDC) algorithm. Wrist torque reproduction performance was assessed by comparing the torque generated by the algorithms with that originally recorded during voluntary contractions. Muscle fatigue was assessed by measuring the decline percentage of the peak torque and by comparing the torque time integral of the response to test stimulation trains before and after fatigue sessions. MAIN RESULTS The MNDC approach could produce a wrist torque that closely matched the voluntary wrist torque. In addition, a smaller decay in the wrist torque was observed after the MNDC-coded fatigue stimulation was applied than after stimulation using pulse-width modulation alone. SIGNIFICANCE Compared with pulse-width modulation stimulation strategies that are based on sEMG detection, the MNDC strategy is more effective for both voluntary muscle force reproduction and muscle fatigue reduction.

A wireless wearable surface functional electrical stimulator

ABSTRACT In this paper, a wireless wearable functional electrical stimulator controlled by Android phone with real-time-varying stimulation parameters for multichannel surface functional electrical stimulation application has been developed. It can help post-stroke patients using more conveniently. This study focuses on the prototype design, including the specific wristband concept, circuits and stimulation pulse-generation algorithm. A novel stimulator circuit with a driving stage using a complementary current source technique is proposed to achieve a high-voltage compliance, a large output impedance and an accurate linear voltage-to-current conversion. The size of the prototype has been significantly decreased to 17 × 7.5 × 1 cm3. The performance of the prototype has been tested with a loaded resistor and wrist extension/flexion movement of three hemiplegic patients. According to the experiments, the stimulator can generate four-channel charge-balanced biphasic stimulation with a voltage amplitude up to 60 V, and the pulse frequency and width can be adjusted in real time with a range of 100–600 μs and 20–80 Hz, respectively.

Design of a Pulse-Triggered Four-Channel Functional Electrical Stimulator Using Complementary Current Source and Time Division Multiplexing Output Method

In this paper, a four-channel pulse-triggered functional electrical stimulator using complementary current source and time division output method is proposed for the research and application of functional electrical stimulation (FES). The high-voltage compliance and output impedance is increased by adopting the complementary current source, which can also realize the linear voltage-to-current conversion and high channel isolation. A high-voltage analog switch chip MAX14803, combined with a FIFO queue algorithm in the microprocessor, is used to setup the H-bridge and multiplexers for the four-channel time division multiplexing output. With this method, the size and cost of the key components are reduced greatly. The stimulating core circuit area is 30×50 mm2. According to the experiments, the stimulator can achieve the four-channel charge-balanced biphasic stimulation with a current range between 0 and 60 mA and a single-phase pulse amplitude up to 60 V.

A novel distributed functional electrical stimulation and assessment system for hand movements using wearable technology

In this paper, a novel distributed functional electrical stimulation (FES) and assessment system for hand movement using wearable technology is proposed. It consists of an FES of wireless EMG-bridge (EMGB) type, a sensor glove and a smartphone-based application software for displaying the virtual 3D hand environment. Combined with the FES therapy and the sensor glove, the proposed system provides a way to evaluate individual responses to rehabilitation among the stroke patients. The smartphone-based application software for displaying the virtual 3D hand environment has been applied to enhance the engagement and motivation needed to drive neuroplastic changes. The prototype system has been validated by performing wrist and finger extension on one healthy subject.

An alternating controlled functional electrical stimulation strategy based on sample entropy for rehabilitation of lower extremity hemiplegia

In this study, we present an alternating controlled functional electrical stimulation (FES) strategy for rehabilitation of lower extremity motor function of hemiplegia after stroke. The muscle activity onset time, determined by using sample entropy (SampEn) analysis of an electromyographic (EMG) signal, is used as a trigger for FES to manage stimulations. The EMG-bridge (EMGB) type FES is a novel motor functional rehabilitation idea that it exploits sEMG signal from a healthy limb to regulate the stimulus parameters of stimulations applied to the paralyzed limb, so as to achieve synchronous movement of bilateral or different limbs. The alternating controlled FES strategy was realized on the basis of combing muscle activity onset time with EMGB-type FES system. Using this FES control strategy, experiments on a healthy subject have been carried out successfully to realize alternating stimulation to plantar flexor (PF) and dorsiflexor (DF) muscles of lower limb in sitting position.

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.

EMG-signal regeneration and motor function rebuilding of paralyzed/anergic limbs based on communication principles and with RF-wireless technology

This work presents motor function rebuilding of paralyzed limbs of hemiplegic patients after stroke and anergic limbs of senile people. The biomedical methods and the traditional physical methods for rehabilitation of the paralyses are reviewed. The core part is to discuss EMG-signal regeneration and the limb function rebuilding based on communication principles and functional electrical stimulation-a novel concept developed by the speakers. For the EMG-signal transmission, different radio-frequency (RF) transmission systems are utilized. The construction of the whole bio-electronic system and the preliminary experiments on healthy patients are demonstrated.

Electromyography signal bridge and motor function rebuilding of paralyzed limbs based on principles of communication of body-sensor network

In this presentation the motor function rebuilding of paralyzed limbs of hemiplegic patients after stroke and paraplegic patients due to spinal cord injury is concerned. Novel biomedical methods and traditional physical methods for the rehabilitation of two kinds of paralyses are reviewed. The core part is to discuss the electromyography signal bridge and the rebuilding of limb functions based on principles of communication of body sensor network and functional electrical stimulation. For the communication part, a ZigBee system and a super-regenerative system are incorporated. The construction of the whole bio-electronic system, the animal experiments, and the preliminary experiments on healthy subjects and paralyzed patients will be demonstrated.

Neural signal regeneration and motor function rebuilding of paralyzed limbs based on principles of communication incorporated with microwave transmission system

In this presentation the motor function rebuilding of paralyzed limbs of the paraplegic patients caused by spinal cord injury and the hemiplegic patients after stroke and SCI is concerned. The biomedical methods and the traditional physical methods for the rehabilitation of two kinds of paralyses are reviewed. The core part is to discuss the neural and muscular signal regeneration and the limb function rebuilding based on the principles of communication and functional electrical stimulation - a novel concept developed by the speakers. For the communication, a microwave transmission system is incorporated. The construction of the whole bio-electronic system, the animal experiments, and the elementary experiments on healthy and paralyzed patients will be demonstrated.