Interwoven diamond grid-structured flexible strain sensor constructed with carbon nanotube-embedded PDMS

Abstract Real-time monitoring of human joint motion is crucial for assessing joint health, diagnosing motor dysfunction, and enhancing motor performance. However, conventional strain sensors often suffer from significant limitations, such as reduced sensitivity and nonlinear response, when exposed to complex dynamic deformations or large strain ranges (>50%). To address these challenges, this study presents a flexible strain sensor with an interwoven diamond grid architecture, fabricated from a polydimethylsiloxane/carbon nanotube composite substrate. The proposed sensor was systematically optimized using an orthogonal experimental approach by tuning the material composition and grid parameters. Experimental results revealed that the optimized sensor exhibited both improved sensitivity and linearity, with a gauge factor of 1.67 and a high coefficient of determination ( R 2 = 0.9979) across a broad strain range of 0%–60%. Moreover, the sensor demonstrated a rapid response time of 200 ms and exceptional cyclic stability, maintaining a relative resistance variation of less than 3% (Δ R /R 0 < 3%) after 1000 loading cycles. Multi-joint motion monitoring tests involving the wrist, elbow, finger, neck, and knee further verified the sensor’s capability to capture strain characteristics during various motion patterns. This work proposes a promising sensing strategy for wearable medical applications and human–machine interaction systems, contributing to the advancement of flexible electronics and personalized healthcare monitoring.