Study And Design On Electronic Circuits And Systems For Motor Function Rebilding Of Upper Extremities

The motor function rebuilding of paralyzed limbs is an important medical problem in the field of rehabilitation medicine.The surface electromyography(sEMG)signals extracted from a healthy limb movement can be converted into stimulus signal pulses which can reproduce the same level of muscle contraction force,and can be applied to paralyzed limbs for functional electrical stimulation(FES),so as to rebuild a coordinational motor function of the targeted paralyzed limb.Such a technique is defined "EMG Bridge" or EMGB.In this study,the circuits and systems design related with the EMGB are mainly described for rebuilding the paralyzed upper limbs' motor function.The specific works of this dissertation are as follows:1)Three kinds of stimulators are designed,including a four-channel pulse-triggered constant-current functional electrical stimulator with a complementary current source and a time division multiplexing(CCSTDM)method,a wearable stimulator based on a technique of Internet of Things(IoTs),and a constant-voltage isolated stimulation circuit designed for electroacupuncture stimulation.Three cases of hemiplegia patients wearing the wearable stimulator were conducted in the Southeast University Affiliated Zhongda Hospital to complete the effective wrist extension and flexion.2)On the basis of the previously designed two-channel "EMG Bridge" motor function rebuilding system,the wearable contralaterally EMG controlled FES system is developed.The prototype system structure and the hardware and software design is described in detail,with the use of a super-regenerative receiver of wireless communication technology.In addition,the super-regeneration receiver chip designed by our institute has been accepted complete independent intellectual property rights.3)A multi-pad stimulation electrode with selective stimulating characteristics is designed for its safe and easy to use.Then,combining with the sensor,the communication and the intelligent priority,a wearable and distributed multi-pad selective stimulaitor prototype is illustrated,which can realize fast and intelligent searching of the stimulation electrode sites and form a comfortable stimulation.In addition,an Android application(APP)is also developed for improving the convenience in the clinical and family rehabilitation.Finally,the selective stimulation and anti-fatigue characteristics is verified with a healthy subject.4)Two methods(including blinking and template substraction techniques)used for removing the stimulation-induced artifacts and muscle response waves(M-wave)and extracting spontaneous sEMG signals are firstly studied and analyzed.Then,a rapid prototype for stimulus artifact removal(SAR)based on the Gram-Schmidt prediction error filter(GS-PEF)is introduced with LabVIEW software.The specific novel ideas of this dissertation are listed as follows:1)A four-channel pulse-triggered functional electrical stimulator using a CCSTDM method is proposed.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 30x50 mm2.2)A wireless wearable functional electrical stimulator controlled by Android phone with real-time varying stimulation parameters for multi-channel surface FES application is developed.It can help post-stroke patients to use more conveniently.3)A wearable FES system is proposed for real-time volitional hand motor function control using the EMGB method.Through a series of novel design concepts,the prototype is 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.4)Based on the distributed concept and an android mobile phone as the control terminal,a set of wearable selective FES system is setup and the feasibility of the optimal algorithm for searching stimulation site and muscle fatigue reduction are verified based on the system.This preliminary study is important for solving large number of electrodes attachment and enhancing anti-fatigue ability of stimulation.5)Using a low computational complexity of the adaptive error prediction filter to remove the stimulus artifacts without blanking techniques is proposed.A rapid prototype based on the Lab VIEW has been demonstrated for real-time suppressing the artifacts and M-Wave.This rapid prototyping can be used in the future design for the "EMG Bridge" application in the same limb.