Design of a playable spherical grip strength detection system based on a PVDF flexible sensor

Grip strength is a crucial indicator for assessing individual health and muscle function, reflecting the level of upper limb strength development. Current grip strength detection devices, while able to accurately assess the magnitude of grip strength, do not integrate well into daily life and have certain limitations in unobtrusive detection during individual activities. Inspired by elderly individuals playing with walnuts in their hands to improve hand blood circulation, clear meridians, and prevent cardiovascular diseases, this work designs a playable spherical grip strength detection (PSGD) system based on polyvinylidene fluoride (PVDF) flexible sensor. The PVDF sensor has a vertical pressure sensitivity of 3.955 V/N and can respond to vertical pressures in the 0–15 Hz frequency range, maintaining stable output over more than 2000 cycles. The PSGD system consists of a spherical shell, a PVDF flexible sensor, a data collection and transmission module, and a data reception and display module, enabling effective collection, processing, transmission, display, and storage of grip strength signals during playing. The PSGD system can respond excellently to grip strength signals, with the magnitude of the grip strength positively correlating with the output voltage signal. It can also distinguish the grip strength differences between individuals and has excellent output stability. The PSGD system holds broad application prospects in fields such as rehabilitative medicine and elderly health management.