Highly Stretchable and Self-Powered Triboelectric Sensor for Smart Detection of Materials

In Industry 4.0, soft robots are creating a profound impact on human life in various applications, from industrial floor management to medical and healthcare systems. However, the soft robots cannot differentiate the type of contact materials and their environmental surface conditions. Recently, triboelectric nanogenerators (TENGs) based sensors are attracted to provide signals from mechanical actions such as motion, vibration, rubbing, and touching without needing any power pack. However, the inclusion of such a TENG sensor which is composed of a dielectric layer and conductive current collector on a soft robotic body body is difficult due to the incompatibility of materials between TENG components and a soft robotic body, and their additional circuit to integrate on the soft robot. In this research, a highly stretchable triboelectric sensor is developed and attached to a cotton glove for wearing on a prosthetic soft robotic hand. The dielectric layer of the triboelectric sensor is fabricated employing 2D MXene (V₂CT_x, T= −OF, −F) and Ecoflex-based composite film. The conductive V₂CT_x with fluoride surface termination enhances the triboelectric properties of the triboelectric sensor. The amount of MXene/Ecoflex weight ratio is optimized to obtain the highest signal output. The triboelectric sensors are assembled on the cotton glove to work as single-electrode mode TENG, and the triboelectric output signals are recorded wirelessly by integrating a microprocessor (ESP32) with the glove. The contact signals from the different household materials made of plastic (PET bottle), metal (soft-drinks can), and ceramic (tea mug) are recorded wirelessly and programmed to identify the type of contact material. Additionally, the contact signals are recorded in the wet condition of the materials. Thus, the triboelectric sensor-integrated glove can differentiate materials like metal, polymer, or ceramic and their surface condition (wettability). The smart gloves can be worn on a prosthetic soft-robotic hand for such sensing actions. In future, this research will pave the way for developing intelligent triboelectric sensors and smart gloves for the identification of any unknown materials from the family of metals, polymers and ceramics.