Abstract
We demonstrate an all-carbon-based, flexible, conformal movement-capturing device capable of precisely monitoring biomechanical movements of both humans and robots. Mechanically robust, metal-free electrodes form a unique component of the device responsible for qualitatively and quantitatively transducing biomechanical movements without any signal artifacts. Importantly, the device withstands and operates in a wide dynamic range for both stretching (25% strain) and bending (140°) actions with minimal cycling hysteresis (2.0), high repeatability (>100 cycles), low creep, and humidity-independent rapid response (∼200 ms). Furthermore, the device qualitatively distinguishes movements such as bending of finger, knuckle, and wrist and also provides quantitative information on the extent of such movements. We establish that single-wall carbon nanotubes (CNTs) embedded in ultralow concentration (0.016 wt %) within an elastomeric matrix undergo three-dimensional conformational changes during biomechanical movements that are subsequently transduced as signals. In addition, such CNT-elastomer strips exhibit enhanced stretchability (>100%) and elasticity (∼77%) in comparison to those of pure elastomers, leading to a wider dynamic working range of the device. Furthermore, seamless integration of a versatile gesture tracker on ubiquitous platforms, such as human skin, kinesiologic tapes, gloves, and robotic arms, is achieved, thereby catering to applications ranging from healthcare monitoring and physiotherapy to robotics and wearable technologies.