Multimodal soft sensor integrated with hydrogel-optoelectronic for wrist motion monitoring

Developing a multimodal flexible sensor capable of incorporating multiple sensing mechanisms in a restricted space remains difficult. In this study, we propose a unique multimodal soft sensor that utilizes a rectangular transparent conductive hydrogel as both strain resistance and optoelectronic propagation channel to achieve the integration of both resistive and optoelectronic sensing mechanisms in a single geometrical unit, which further enables the detection of multiple mechanical deformation modes. This sensor exhibits excellent sensitivity (1.92 for stretching, 4.43 rad−1 for width-bending, 1.78 rad−1 for height-bending), a large measurement range (0-90° for bidirectional bending, 0–100 % for stretching), and high stability (drift 3.0 % for stretching, 2.9 % for width-bending, 1.9 % for height-bending). And a Bidirectional Long Short-Term Memory Network (BiLSTM) is created to address the strong coupling issue in multimodal sensing, to achieve decoupling of different deformation signals, and to further realize accurate monitoring of complex wrist motion states.