A wireless wearable surface functional electrical stimulator

• Published in: International journal of electronics 2017-09, Vol.104 (9), p.1514-1526
• Main Authors: Wang, Hai-Peng, Guo, Ai-Wen, Zhou, Yu-Xuan, Xia, Yang, Huang, Jia, Xu, Chong-Yao, Huang, Zong-Hao, Lü, Xiao-Ying, Wang, Zhi-Gong
• Format: Article
• Language: English
• Subjects: Algorithms; charge-balanced biphasic stimulation; Circuit design; Conversion; Electric charge; Electric potential; Functional electrical stimulation (FES); Impedance; Patients; Real time; Smartphones; Stimulation; stimulation circuit; time division multiplexing; wearable device; Wearable technology; Wrist
• ISSN: 0020-7217; 1362-3060
• DOI: 10.1080/00207217.2017.1312708

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 cm 3 . 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.