Introduction

The gastrointestinal (GI) tract plays a crucial role in the human body as a naturally-evolved interface between the body and its environment. Ingestible electronics perform surgical-free screenings and diagnoses within the GI tract and have been proposed since 1957 \cite{WATSON1962,MACKAY1957,JACOBSON1957,FARRAR1957}. Recent advancements have demonstrated the ability to integrate ingestible electronics with sensing, actuation, and drug delivery capabilities, with several examples that have been FDA approved and are in clinical use \cite{Toennies2010,Mandsberg2020,Basar2012,Min2020}. For example, the pill-shaped PillCamâ„¢ provides access to areas of the GI tract which are challenging or infeasible via endoscopic procedures \cite{Min2020}. However, the size of an ingestible device is fundamentally constrained to enable swallowing (e.g., PillCamâ„¢ SB 3 has a diameter of 11.4 mm, and a length of 26.2 mm \cite{medtronic}) and to mitigate the risks of unexpected retention (1.4% for conventional capsule endoscopes)\cite{Li2008} or intestinal obstruction which requires surgical interventions. The limitation in size constrains the possible functionalities that can be integrated into an ingestible system, especially since active components such as microelectronics are rigid and planar parts that have to be assembled into the system. For example, most ingestible electronics do not have the ability to be actively transported towards target regions of interest \cite{Min2020}.