Additive-Manufactured Flexible Triboelectric Sensor Based on Porous PDMS Sponge for Highly Detecting Joint Movements

A hybrid sequential additive manufacturing process combined an extrusion syringe and a fused deposition modeling is developed to fabricate a porous PDMS based triboelectric sensor easily and environmentally. The porosity of the PDMS is controlled by using wet sugar particle sizes, and we fabricate a porous PDMS plate with a pore-to-volume ratio of 46%, which has 11 times larger internal contact area and 52.4% softer mechanical strength compared to a non-porous one. So, two key factors for high performance triboelectric sensor is obtained using the proposed method. A cylinder-shaped triboelectric sensor impregnated carbon black particles on the porous PDMS matrix, which is wearable on a finger, is fabricated for evaluation of its characteristics on detecting finger joint movements. From the experimental results, the sensor shows the ability to help quantitatively analyze finger movements, therefore, the proposed flexible triboelectric sensor can apply to athletes or patients around their knees, wrists, or other joints to analyze their physical behavior. Also, we believe that it can be utilized to measure various physical signals such as contact force, gripping force, and pressure with small values.