An ultimate goal of a conventional silicon-based integrated system is its capability to last forever without any malfunction and physical deformation, in almost any practical uses. Recent works demonstrate a new class of silicon electronics that has the opposite behavior -- it physically dissolves or disappears in water, environment or biofluids, in a controlled fashion, at predefined times or on demand and with programmed rates. This ‘transient’ technology opens up completely new application opportunities for electronic devices in areas, such as implantable medical devices that exist for medically useful timeframes but then dissolve and disappear completely by resorption into the body. This talk summarizes recent work on ‘transient’ technology, ranging from fundamental chemistry of the key materials, to development of various components and systems for biosensors, to in vivo toxicity tests for biocompatibility