Study on prosthetic hand proprioception feedback based on hybrid vibro-electrotactile stimulation

Objective: Sensory substitution technologies represent a significant advancement in modern prosthetics, with hybrid tactile feedback approaches gaining increasing attention. However, limited studies have examined the role of hybrid tactile feedback in closed-loop prosthetic control, particularly in relation to varying visual conditions. Methods: This study employed a 2-factor mixed design involving 10 able-bodied participants and 3 transradial amputees. Three visual conditions--Optimal Vision, Limited Vision, and Blocked Vision were tested. Participants performed prosthetic wrist and hand position-matching tasks utilizing vibrotactile, electrotactile, and hybrid vibro-electrotactile (HyVE) feedback modes provided by a custom-developed prosthetic position feedback control system. Outcome measures included categorical analysis of task completion outcomes, control precision error (CPE), completion time (CT), and feedback preference. Results: The HyVE feedback mode elevated success rates across all visual conditions, while effectively reducing the incidence of errors and confusion trials. Compared to electrotactile mode, HyVE yielded significantly lower CPE, and compared to vibrotactile mode, it enabled significantly shorter CT. Furthermore, 7 out of 13 participants (>50%) selected HyVE as their preferred feedback mode. Conclusion: The proposed HyVE tactile feedback method effectively combines the advantages of electrotactile and vibrotactile stimulation, mitigating their respective limitations. It enables accurate perception of prosthetic motion without the need for continuous visual monitoring, showing significant potential for enhancing everyday prosthetic functionality.