Elastic Metal Microtube for Flexible Ultralow-Hysteresis Tactile Sensor

Low-hysteresis and fast-response tactile sensors that mimic the human sense of touch can empower robotic systems to manipulate diverse objects rapidly and accurately. However, current tactile sensors, which mostly rely on viscoelastic polymers as functional materials, suffer from high hysteresis and slow response time, limiting their applicability in intelligent robotics. Here, we introduce an elastic metal microtube enhanced (EMME) tactile sensor with ultralow hysteresis and fast response. The microtube structure is achieved by utilizing the inner stress of thermally evaporated metal films after dissolving a sacrificial layer. The superior elasticity of the metal microtubes minimizes energy dissipation during deformation under external mechanical stimuli, contributing to ultralow hysteresis and fast response of EMME tactile sensor. Furthermore, the positive correlation between hysteresis and energy dissipation is theoretically and experimentally established in capacitive tactile sensors based on parallel plate structure. Our flexible EMME tactile sensor possesses ultralow hysteresis (~0.8%), fast response time (<1 ms), high endurance (10000 cycles), and the ability to keep up with high-frequency vibration. Upon integration with the robotic hand, accurate and autonomous manipulation of shape-changing objects with a feedback loop is achieved, mimicking air pressure monitoring via balloon volume change in chemical experiments, exhibiting its potential in future intelligent and autonomous laboratory robotic systems.