Dissolution kinetics & lifetime programming

The functional lifetime of a bioresorbable device is set less by the active layers than by the encapsulation that gates water access to them. Because thin conductors and silicon nanomembranes dissolve within hours to days once hydrated, a slowly eroding barrier layer effectively acts as a clock: the device works while the barrier holds, then fails over a defined window as water breaks through. Thermally grown silicon dioxide is a near-ideal water barrier that itself hydrolyses very slowly, letting lifetime be tuned by barrier thickness.

Kinetics depend on temperature, pH, ionic content, and mechanical stress, all of which vary by implant site, so in-body lifetime is more variable than a benchtop buffer measurement suggests. Designing transience means engineering both the dissolution rate of each material and the failure sequence of the whole stack.