Stretchable anisotropic piezoelectric sensors with modulus engineering for monitoring multiaxial joint motion

초록

Real-time tracking of human joint motion is crucial for gesture and posture monitoring, requiring wearable sensors capable of detecting anisotropic signals through form-changing capabilities. Herein, we introduce an anisotropic piezoelectric sensor (APS) developed via modulus engineering of stretchable heterogeneous materials. The APS integrates high-modulus active-line patterns with a low-modulus inactive matrix, utilizing Poisson's effect to generate directional anisotropic outputs based on strain variations in active regions. Singleelectrode APS devices exhibited varied signal polarities in response to bending directions induced by joint movements, thereby enhancing sensing diversity. Remarkably, these devices demonstrated up to a 21-fold variation in output for identical strain across different tensile axis, indicating excellent anisotropic sensitivity. Additionally, an orthogonally stacked APS (s-APS) enabled the detection of eight distinct motion types with a single device, providing consistent feedback during joint deformation and highlighting its potential as a versatile wearable sensor for gesture and posture monitoring across diverse applications.

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