Scalable Printing of Self-Healable Triboelectric Pulse Sensors

Triboelectric nanogenerator have been developed to create self-powered devices, either for power generation or for sensing applications. There are many sensor applications for triboelectric nanogenerator in systems where there may be any residual mechanical energy that would have otherwise been unutilized. One such system is the human body and hence a prominent application of triboelectric sensors is in the form of health monitoring sensors. However, due to mechanical nature of these devices, one of the more effective method for these sensors to operate is through direct contact of the device with human skin. Hence there is a need for the development of bio-compatible and skin compliant sensors that, not only are safe as wearable devices, but also are comfortable for the user during regular operation. Through this work we have developed a crosslinked polymeric composite ink that is not only versatile in it’s manufacturability into thin functional triboelectric films, but also it’s ability to form films that have tunable mechanical properties that can yield a more comfortable wearable device. Resulting in the creation of shear thinning viscoelastic ink that can be tuned to have varying rheological properties based on the printing technique used to manufacture the functional triboelectric film for our pulse sensors. We also show that despite the tuning of the polymeric components in the functional film for versatile printability and to enhance mechanical robustness, the triboelectric output of the device isn’t compromised. This ink system also allows for water assisted self-healing of the sensors, making it ideal as a wearable pulse sensor that a user can wear even during more rigorous activities. The facile ink production method, versatility of compatibility of ink with various printing techniques, consistency in triboelectric output and high-resolution pulse signal measurement allow for a wholistic development for a triboelectric pulse sensor that could be manufactured at scale as a consumer product.