A Geometrically Transient Platform for Bioelectronic Implants.

The outstanding barrier properties of skin make it difficult to obtain reliable physiological information (especially chemical) without the use of implantable bioelectronic sensing devices to directly access the internal biology. The clinical utility of bioelectronic implants, however, hinges on a key geometrical optimization problem: devices must scale down in size to reduce surgical invasiveness while also creating enough space to integrate electronics for wireless power delivery, data exchange, and electrical/electrochemical monitoring. Here, we present a minimally invasive bioelectronic implant with a transient geometry that can be inserted subcutaneously and measures important markers, such as pH, temperature, cardiac and respiratory activity, and lithium dynamics, an important element for medical applications. To produce this new class of minimally invasive and foldable implantable sensors, we developed a fabrication method that works with highly flexible substrates to enable multiple-fold miniaturization during implantation. After implantation, the implant autonomously unfolds back to its planar form for continuous wireless operation. We demonstrate proof-of-concept for the key concepts concerning implantation, operation, and removal through extensive in vitro, ex vivo, and in vivo animal experiments. Ultimately, our approach could provide multiplexed monitoring using quick and suture-free insertion procedures, which may provide a unique advantage in the transition toward personalized healthcare.