Dispersed, Porous Nanoislands Landing on Stretchable Nanocrack Gold Films: Maintenance of Stretchability and Controllable Impedance

Stretchable electronic devices have great potential for serving as bioelectrical interfaces due to their better deformability and modulus match with biological organs. However, surface modification, which is usually applied to enhance the capability of sensing and stimulating, as well as biocompatibility, may cause problems since their stretchability highly depends on the surface structure. In this work, stretchable nanocrack gold (SNCG) electrodes were fabricated, which can be stretched by a maximum 120% uniaxial strain while maintaining their electrical conductivity. We found that the electrodes lost their stretchability after surface modification of an additional continuous platinum layer, which was found to selectively weld or fully cover the nanocracks, consequently eliminating its crack structure. To address this issue, we designed a complex structure of dispersed, porous nanoislands landing on the SNCG film, which was further demonstrated as capable of maintaining the stretchability of electrodes while allowing the reshaping of cracks. Moreover, stretchable microelectrode arrays were then developed with this complex structure. Animal experiments demonstrated their capability of conformally wrapping on a rat brain cortex and effectively monitoring an intracranial electroencephalogram under deformation. In addition, their impedance can be precisely controlled by modulating the dispersity, diameter, and aspect ratio of individual nanoislands. This complex structure has great potential for developing highly stretchable, multiplexing sensors, allowing stiff materials to land on a stretchable conducting surface with maintenance of stretchability and controllable functional area.