Micropillar-enabled tough adhesion and enhanced sensing

Abstract

Skin-like sensors are key for humanoid robots and wearables. Achieving both robust interfaces and promoted sensing performances in soft sensors may enable their applications in extreme mechanical conditions of high shear. However, strong interfacial adhesion in multilayer sensors often compromise sensing properties. Here, we design hyperbranched polyurethane micropillars with (diameter < length of flaw sensitivity) that serve dual roles as an adhesion layer for exceptional mechanical stability, and adaptive spacer for enhanced sensing properties. We show a strong size effect of the structure to toughen the interface, with ultrahigh interfacial toughness up to 5,095 J m⁻² at a 50-μm pillar diameter. Simultaneously, the micropillars enhance sensitivity and limit of detection by decreasing the stiffness via elastic buckling and enable a rapid response to the acoustic range by reducing energy loss during loading and unloading. The sensors are ideal for the manipulation of heavy objects in humanoid robots and other applications.