In Situ Grown Strain Sensors on 3D Curved Surface for Stretchable Human–Machine Interfaces

Abstract Stretchable strain sensors play a vital role in monitoring human body movements and have been widely applied in human–machine interface (HMI) systems. Conventional planarfabricated sensors attached to curved surfaces often suffer from low fabrication efficiency and reduced measurement accuracy due to poor conformability. This study presents a laser direct writing–based approach for the direct fabrication of double‐layer strain sensor arrays, interconnects and electrodes on complex curved, stretchable substrates. The resulting strain sensor exhibits a high gauge factor of 10⁶ at 80% strain and a minimum detectable strain as low as 0.1%, enabling precise monitoring of joint motion across a bending range of 0° to 90°. Additionally, tuning the material composition and structural design enables precise control over the sensor's electromechanical responses to suit various HMI applications. As a demonstration, an HMI with integrated strain sensors and interconnect arrays is directly fabricated onto the 3D surfaces of a glove. This system enables the robotic hand to accurately mimic multiple human gestures, highlighting its potential for advanced human–machine interaction.