Flexible three-unit spatially encoded triboelectric sensor array for discrete bending–twisting decoding and wrist-motion recognition

Abstract

When bending and twisting occur simultaneously, triboelectric responses from a single sensing position can become coupled, making the two deformation components difficult to distinguish. Here, we develop a flexible three-unit triboelectric sensor array that converts position-dependent response differences into usable spatial information for discrete bending‒twisting decoding. Three spatially separated units with the same material system and basic triboelectric configuration provide complementary position-dependent responses. Unit-level waveform features are extracted from each position, and explicit spatial-relation features are further constructed to represent inter-position relationships. Separate classifiers identify discrete bending and twisting states within the measured state space, while multi-cycle probability fusion improves prediction stability. Across 24 mechanical states, bending, twisting, and joint-state recognition accuracies reached 97.40%, 99.69%, and 97.19%, respectively. On-body tests further demonstrated multi-position responses from wrist, elbow, knee, and finger motions. For four badminton wrist-motion classes, a conditional dual-task model achieved 95.59% classification accuracy. These results demonstrate a compact spatial-encoding strategy that enriches the information available from a simple flexible sensor and supports recognition of coupled deformation and complex human motion.

Graphical abstract

Keywords

triboelectric sensor / flexible sensor array / spatial encoding / bending–twisting decoding / human motion recognition

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