Shape memory polymer adhesives for on-demand, low-force detachment in skin-interfaced devices.

Skin-interfaced biomedical devices require adhesives that provide strong attachment during use while enabling gentle removal with minimized subsurface skin deformation. Conventional medical adhesives lack mechanisms for on-demand adhesion modulation, often causing skin irritation and damage during detachment, particularly in vulnerable populations. Here, we present a thermally triggered shape memory polymer (SMP) adhesive that achieves reversible, high-contrast adhesion switching through programmable pyramidal structure recovery. The adhesive incorporates an array of pyramidal structures that remain flattened in a dormant state to ensure robust skin adhesion, but rapidly recover upon mild heating above the glass transition temperature, significantly reducing effective contact area and enabling low-force detachment. Adhesion switchability performances are supported by quantitative mechanical measurements, including reductions in peel force and adhesion energy after activation, as well as three-dimensional digital image correlation (3D-DIC) analyses demonstrating minimal subsurface skin deformation during detachment. Mechanical testing demonstrates up to ~99% reduction in adhesion energy upon activation, while maintaining stable load-bearing performance during use. 3D-DIC shows that the actuated SMP suppresses stress concentrations and minimizes subsurface skin deformation during detachment, unlike the dormant SMP. A kirigami structural design further enhances conformability on both singly and doubly curved anatomical surfaces while improving water vapor permeability. Finite element analysis and 3D-DIC measurements reveal substantial reductions in effective stiffness and enhanced bending accommodation enabled by the kirigami geometry. Integration with wireless mechano-acoustic sensors confirms reliable physiological signal acquisition in the dormant state and controlled detachment upon activation. This work establishes a thermally switchable SMP adhesive platform for low-force removal of skin-interfaced devices.