Bionic octopus-like flexible three-dimensional force sensor for meticulous handwriting recognition in human-computer interactions

With the advantages of high flexibility, multifunctional integration, and wearing comfort, flexible tactile sensors hold great potential for application in the field of intelligent sensing system and human-computer interaction. However, the high sensitivity acquisition and the issue of decoupling of complex tactile signals, and improving compatibility of flexible tactile sensors in human-computer interfaces are still serious challenges in current research. In this study, drawing inspiration from the body structure of an octopus, we developed a flexible three-dimensional (3D) force sensor in which a CNT/Ecoflex conductive elastomer as the body of the bionic octopus-like sensor could capture the normal component of 3D spatial force, meanwhile a laser-induced graphene sensing film transferred to Ecoflex (LIG/Ecoflex) as the tactile wrists of the bionic octopus sensor could discern the magnitude and direction of the tangential component of the 3D spatial force. The bionic sensor offered excellent sensing and wearable characteristics, including fast and efficient response, cyclic stability, and flexible skin-fit performance. The unique structural design of the sensor enabled spatial force sensing capability and precise decoupling and output of 3D forces through the use of a multilayer perceptron (MLP) for mapping and calibration. The octopus-inspired flexible 3D force sensors were further attached to the fingertips of human fingers for successful extraction of handwriting minutia of wearer, showcasing their promising potential in areas such as smart wearables, handwriting recognition, and interactive human-computer interfaces.