Forearm Dual-Triboelectric Sensor (FDTS) for assistive Human-Machine-Interfaces (HMIs) and robotic control with potential uses in prosthetic devices

This work describes a new sensitive non-intrusive forearm device with two triboelectric sensors (TS) integrated into one flexible PCB (FPCB) that indirectly differentiates finger and hand movements based on the forearm muscles and tendons' combined responses. The new Forearm Dual Triboelectric Sensor (FDTS) intends to demonstrate triboelectric nanogenerators (TENGs) as an affordable and flexible alternative to expensive and bulky EMG devices used in prosthetic limbs by amputated patients. The proposed concept can successfully recognize up to 10 different input signals from the bending or tapping of the middle and little fingers and hand opening-closing action used as input commands for a Human-Computer-Interface (HCI) for computer navigation. In the experiments, we can successfully control horizontal, vertical and diagonal movements, left and right click of the cursor on the screen, and scroll up/down options. The FDTS was also implemented in robotic hand remote control, where different index and small finger bending amplitudes were translated to different mechanical finger rotation degrees and overall robot hand movement. Additionally, the robotic hand was able to perform right and left clicks controlled by fast finger bending. More experiments demonstrate the FDTS response to other wrist movements, such as pronation and supination. This proves the potential benefits of TS in cost-effective prosthetic devices, with limited but better functionality than standard body-powered prostheses. In the future, FDTS-like devices can be modularly integrated with artificial limbs to allow amputated patients to control computers and external devices. Additionally, this solution can positively impact the integration of online spaces like the Metaverse with healthcare technologies for rehabilitation and social inclusion.