Design and Validation of a Wearable and Programmable Functional Electrical Stimulator Based on MCU

The improvement of muscle activity following a stroke is a crucial aspect of a patient’s return to normal function. Functional electrical stimulation technology has been demonstrated to be an effective means of assisting patients in their recovery, enhancing muscle activity, and restoring motor ability. This paper presents the design of a programmable functional electrical stimulation system based on a microcontroller unit (MCU). The system employs an STM32 microcontroller as the primary control chip, a PC817 optocoupler for high- and low-voltage isolation, and an H-bridge conversion circuit for current polarity conversion. Additionally, a NE5532 operational amplifier is utilized for constant current drive, which maintains the stability of the stimulation current and enhances the system’s resilience to interference. Furthermore, this paper employs the system to conduct electrical stimulation experiments on the biceps brachii muscle, with the objective of establishing the relationship between stimulation frequency, pulse width, and the maximum angular velocity of elbow joint movement, as well as the efficacy of different combinations of stimulation intensity in improving muscle activation.