Physically transient electronic materials and devices

Transient electronics, which can be tuned to be completely or partially dissoluble, degradable, and disintegrable, create new opportunities in the upcoming ubiquitous electronics era that are inaccessible with conventional permanent electronics. This emerging field offers unique electronic applications in environmentally degradable eco-devices with minimal or zero waste, biodegradable medical implants not requiring secondary removal surgery, and hardware-based security devices with self-destructing circuits. Nanoscale thin-film processing that exploits Si in single-crystalline form and related techniques allow construction of transient electronics with high performance and versatile characteristics, including nearly all types of active electronic components, integrated circuits, sensors and other integrated wireless medical devices. Here we review recently developed transient electronics and materials, mainly illustrating representative inorganic and Si electronic materials technologies. Dissolution chemistry and reaction kinetics of semiconductors, dielectric and metal conductors are described to explain the dependence on environmental conditions such as temperature, pH, ion species and materials microstructure, density, crystallinity, composition. Materials and approaches that define the functional lifetime of transient electronic are introduced in two aspects: using passive encapsulation layers to control water-vapor diffusion and using on-demand active triggerable systems of stimulus-responsive materials. Transfer-printing approaches and solution printing processes offer strategies to integrate high-performance inorganic electronic materials with soft and flexible biodegradable organic substrates. Various examples of biodegradable medical electronics for clinically relevant diseases and symptoms support effective practical applications.