4D printing of shape-adaptive tactile sensor with tunable sensing characteristics

Using 4D printing to fabricate tactile sensors is promising, which will bring exciting functionalities to sensors, such as action self-sensing, environment self-adaptation, and self-healing. Here, we introduce 4D printing technology to fabricate the versatile smart tactile sensor with an adjustable measuring range and sensitivity, and shape adaptation for sensing in unstructured objects, which can sense touch from. The 4D-printed sensors (4DPS) with unique coplanar designs are achieved using a multi-material extrusion process for manufacturing interdigital electrodes composed of nanocarbon black/polylactic acid composites and shape memory polyurethane. The variability in the detection range and sensitivity stems from the changes in the electrode height and spacing caused by the deformation of shape memory polymer (SMP) under heat treatment. By setting printing parameters, not only can the diameter of the interdigital electrodes be precisely regulated, but 3D sensors that adapt to different curved surfaces can also be realized by utilizing thermal stress during the printing process. Moreover, the 4DPS is applicable to non-developable surfaces, such as spherical dome surfaces or saddle surfaces. Therefore, the shape-changing tactile sensor may offer great potential in environment self-adaptation and test range self-adjustment for human-robot cooperation in sensing.