Biomaterials for Ingestible Electronics
The materials for transient electronics are being chosen based on their inherent characteristics, such as permeability, degradation rates, morphology, hydrophobicity or hydrophilicity, chemical properties, and mechanical properties of the polymer. In a study on bioresorbable silicon electronic sensors, devices were fabricated on silicon nanomembranes, thin SiO2 layers, and magnesium foils and molybdenum interconnects that can dissolve or disintegrate in a time-controlled manner. Another study demonstrated a range of functional transient devices fabricated on polyanhydride substrates (~124 μm thick) where transience was triggered by moisture and time-controlled by the polymeric chemistry. The anhydride groups in the polymeric substrate absorbed the surrounding moisture to cause its hydrolysis and eventually degrade into a viscous liquid. Various transient electronic devices were fabricated from metals (e.g., copper, nickel, and aluminum), semiconductors (e.g., indium gallium zinc oxide (IGZO)), and dielectrics (e.g., magnesium oxide).
