A lightweight ultrasound probe for wearable human-machine interfaces

A novel sensor technology is urgently required to sense the human motion behavior for wearable human-machine interfaces (HMIs) in a wide spectrum of applications, such as rehabilitation. The inherent limitations of surface electromyography signals and the shortages of the existing ultrasound-based sensors constrain the development of wearable devices from actually being applied to improve our life quality. In this paper, a lightweight A-mode probe, consisting of housing and polyvinylidene fluoride (PVDF) membrane, is proposed to enhance the detection of morphological changes of deep-layered muscles in the wearable HMI context. The PVDF-based probe, with 0.75-g weight and 0.6-mm thickness, is designed, simulated, fabricated, and validated in hand gesture recognition. Its classification accuracy achieves 97.64%±1.83%, which is practically accepted for the usage requirements of the existing wearable HMIs. This paper paves the way for feasible wearable HMIs in real-world applications with lightweight ultrasound probes.