Self-Powered Strain Sensing via Ion Physisorption at PVC Ion Gel─Metal Interfaces

Self-powered strain sensors are crucial for wearable technology and low-power applications, where continuous operation with minimal energy is essential. Conventional sensors typically require external power, leading to bulky designs, limited battery life, and frequent maintenance, which hinder seamless integration into wearable devices. This study introduces an ion physisorption-based self-powered strain sensor (IPSS) enabling stable, strain-induced voltage measurements without external power. The IPSS leverages the physical adsorption of [EMIM] cations in a PVC ion gel onto electrode surfaces, generating a measurable voltage difference under strain. Potential of zero charge measurements confirmed selective ion adsorption based on electrode work functions, validating the IPSS's operating mechanism. Notably, the IPSS demonstrated a broad operational range of 0-200% strain with a linear response of 2.3 mV/% in the low-strain range (0-40%), highlighting its precision for wearable applications. Using the IPSS's stable, self-powered signal, a CNN-based gesture recognition model achieved 92% accuracy with just 0.00507 GFLOPs, showing the sensor's potential for low-power, high-accuracy applications in wearable and resource-limited environments.