Manufacturing of High-Performance Tactile Sensors by High Resolution 3D Printing and Conformal Polymer Coating

Like human skin, tactile sensors are the e-skin for robotics and personalized medical devices to perceive and interact with the environment. Most existing tactile sensors can detect either hair-like soft objects, or spoon-like stiff ones, but not both. Also, the sensing time ranges from milliseconds to seconds, which is too slow for detecting fast-changing signals, such as vibrational or fast-moving objects. This award supports research that investigates the manufacturing of high-performance tactile sensors that can detect various sizes of objects within microseconds. This project advances the knowledge about high-resolution three-dimensional printing of multi-scale structures and their conformal polymer coating for functionality. The high-performance tactile sensors have the potential to replace those currently employed, such as in touch screen displays, security systems, human-machine interaction, and virtual reality devices. The project addresses manufacturing challenges of forming complex structures and making functional materials. The outcomes can provide a manufacturing tool for many engineering applications requiring novel geometries and materials, such as chemical sensors, photodetectors, batteries, capacitors, and chemical catalysts. The method can also be used to make biological implants with multiscale structures for better cell attachment. This project introduces STEM students, especially, underrepresented minorities to wearable electronics and robotics and stimulates them for careers in engineering. This project enables a new manufacturing capability for hierarchically architected structures with multiple length scales from nanoscale to centimeter scale. This approach is a paradigm shift in manufacturing functional devices, where micron-scale 3D printing fabricates the flexible multiscale substrates while the oxidative chemical-vapor-deposition (oCVD) technique is used to coat with polymers and nanomaterials for functionalities, such as conductivity and sensing. The project advances the fundamental manufacturing knowledge in many ways. It establishes a method to control spatial-temporal exposures for sub-pixel resolutions, which benefits all photo-polymerization processes. By analyzing and engineering the interfacial properties and adhesion characteristics, the project establishes conformal coating strategies which result in a seamless but thin conductive layer to maximize the effect of the multiscale patterns. By a hierarchically architected shape with geometry features across multiple length scales, it determines sensing performance improvements and mechanisms for structure deformation and recovery in microseconds. The project establishes a new benchmark to evaluate the effect of contact angle and object size on the sensing performance for sophisticated activities such as robot object manipulation. A set of guidelines to design sensor shapes and engineer 3D printing and oCVD coating parameters is established and is made available to the research community. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.