Electrically Conductive Liquid Metal Composite Adhesives for Reversible Bonding of Soft Electronics

Conductive adhesives are required for the integration of dissimilar material components to create soft electronic and robotic systems. Here, a heterogeneous liquid metal-based conductive adhesive is developed that reversibly attaches to diverse surfaces with high stretchability (>100% strain), low modulus (<100 kPa), and strain-invariant electrical conductivity. This SofT integrated composite with tacK through liquid metal (STICK-LM) adhesive consists of a heterogeneous graded film with a liquid metal-rich side that is embossed at prescribed locations for electrical conductivity and an electrically insulating adhesive side for integration. Adhesion behavior is tuned for adhesion energies > 70 Jm(-)(2) (& AP; 25x enhancement over unmodified composites) and described with a viscoelastic analysis, providing design guidelines for controllable yet reversible adhesion in electrically conductive systems. The architecture of STICK-LM adhesives provides anisotropic and heterogeneous electrical conductivity and enables direct integration into soft functional systems. This is demonstrated with deformable fuses for robotic joints, repositionable electronics that rapidly attach on curvilinear surfaces, and stretchable adhesive conductors with nearly constant electrical resistance. This study provides a methodology for electrically conductive, reversible adhesives for electrical and mechanical integration of multicomponent systems in emerging technologies.