3D Printable One-Part Carbon Nanotube Elastomer and Flexible Frequency Tunable Tactors for Sensing-Actuation Platform

Flexible electronics which generate proprioceptive feedback loops are a promising field for those with prosthetic limbs or degenerative nervous system conditions like Parkinson’s disease. A platform which combines the sensing of pressure and stretching in the limbs and sends feedback through an actuator is desirable for those who have difficulty or inability in both sensing and in sending sensory feedback to the brain. To this end, custom mechanical sensors should be designed for facile fabrication, customization for patient specific application, wearability, flexibility, and with consideration for connection to wearable actuators. The connected vibrotactile actuators, similarly, should be designed with high flexibility, custom manufacturing of size, and tunable resonant vibration frequency. First a novel one-part, highly conductive, flexible, stretchable, 3D printable carbon nanotube (CNT)-silicone composite is developed and thoroughly characterized. The one- part ink is an excellent candidate for easily customizable 3D printed sensors since it cures from ambient moisture without mixing, additives, needs no additional post processing, and can be printed at 100 µm resolution. In combination, a novel flexible tactile actuator is fabricated with advanced manufacturing with customizable size (4- and 10-mm diameters demonstrated), high flexibility, customizable vibration resonant frequency, and strong penetrative vibration. A platform which utilizes these 3D printed sensors and actuators are connected mechanically by 3D printed flexible wearable substrates and electrically by 3D printed flexible silver pathing. The event cue feedback loop formed by the mechanical sensing of custom CNT elastomers and the actuation of custom flexible actuators forms advanced e-skin platforms for treatment of freeze of gait, in grip control, prosthetic socket wearability, and beyond towards personalized health monitoring and proprioceptive feedback control for those with limited nervous system function.