Phototriggerable, Fully Transient Electronics: Component and Device Fabrication

Electronic devices that can physically or functionally disintegrate on-demand have applications as remote sensors, bioelectronics for diagnostics, and other multifunctional devices with temporal functional profiles. This emerging field requires materials, devices, and systems which effectively disappear, (i.e. vaporize), with little or no traceable remains. Prior efforts have achieved transience with devices either submerged in an aqueous solution, which degrades the materials over time, or by triggering an inundation of the materials with a liquid solution. Neither scenario allow for both control of the life cycle of the system and assurance that transience would be complete. Metastable polymers, which can be induced to depolymerize rapidly through a specific trigger, offers a more versatile approach to selecting materials and allows for more control over the device's lifetime. A triggerable, transient material which vaporizes on command was prepared by the addition of a photo-acid generator (PAG) to an acid-sensitive metastable polymer, where the rate of degradation can be controlled by the concentration of the PAG and the intensity of light irradiance. In this work, a transient electronic component, a multilayer interconnect board was fabricated using a PAG-loaded, cyclic poly(phthalaldehyde) substrate. The p(PHA) material used to fabricate the dielectric acts as the support substrate for the metal routing layers, where the conductive 'wiring' was composed of a silver nanoparticle-filled p(PHA) formulation. Elastic modulus, resistivity, connectivity, and conductor sheet resistance of the individual components were evaluated and transience was demonstrated.