Wearable patch with direction-aware sensitivity of in-plane force for self-powered and single communication channel based human-machine interaction

The merging of flexible technologies with human machine interaction (HMI) is now optimizing the way people communicates with electrical terminals. Compared with "press" and "strain", "sliding" is a directional operation which requires the interface to identify the directions of the applied force for accurate interaction. Previous efforts that explore the "directional force" in HMI system are mainly based on sensor array, which brings concern of complex electrode design and multiple communication channels to prevent cross-talk. In view of this, we developed a self-powered and wearable HMI interface that can distinguish the axial directions of in-plane force based on Faraday's law of induction. The interface consists of well-orientated magnetized micropillars, and a conductive coil that collects and transmits the electrical signals during the interaction process. When in-plane sliding force was applied, distinguishable signals were generated to reflect the different axial directions (+X/-X/+Y/-Y) according to the polarity and number of voltage peaks. With this unique behavior, the HMI process can be completed with two electrodes and one communication channel in an interference-free manner. Through the systematic optimization, the intrinsic oscillation from the micropillars results in obviously enhanced signals for a high accuracy and reliability towards real application. The MMPs-based interface was successfully estab-lished for HMI platforms such as intelligent robot control, and Morse code communication, etc. Owing to the robustness, humid resistance, accuracy and reliability, we expect that the interface design can inspire the development of flexible and wearable devices in HMI especially for scenarios that require a high command capacity.