A Soft Somesthetic Robotic Finger Based on Conductive Working Liquid and an Origami Structure

The tactile and proprioceptive sensation increases human manipulability, and soft tissue compliance stabilizes the grasping function. However, it is challenging to transpose this system to the small confined space of soft robotic fingers due to the material properties and complex wiring entailed. Furthermore, soft robotic fingers also incorporate actuating components, making such a system more difficult to bring to fruition. Therefore, optimizing soft robotic finger structure for greater functionality and manufacturability would be a desirable innovation. In this study, we developed a soft somesthetic robotic finger based on the conductive working liquid and an origami structure. The proposed design comprises an origami structure, porous scaffolds, and a silicone-coated fabric outer layer. The robotic finger was filled with conductive liquid used for both somesthetic sensing and bending actuation simultaneously. The origami structure was fabricated by connecting printed circuit boards (PCBs) and a polyimide film, with electrodes embedded on each PCB to enable somesthetic sensing. The electrodes were used to inject currents and measure voltage, with the measured data then used to reconstruct the deformation map and hinge angle by means of electrical resistance tomography (ERT). The experimental results confirm that the robotic finger could acquire tactile and proprioceptive information in real-time.