Ingestible Electronics for Diagnostics and Therapy

Abstract

The gastrointestinal (GI) tract offers the opportunity to detect physiological and pathophysiological signals from the human body. Ingestible electronics can gain close proximity to major organs through the GI tract and therefore, can serve as clinical tools for diagnostics and therapy. In this Review, we summarize physiologic and anatomic characteristics of the GI tract, which present both challenges and opportunities for the development of ingestible devices. We describe recent breakthroughs in material science, electrical engineering, and data science that have permitted exploration of technologies for both sensing and therapy via the GI tract. Novel sensing opportunities include electrochemical, electromagnetic, optical, and acoustic protocols, with capacity to sense luminal or extra-luminal analytes in the GI tract. We review novel therapeutic interventions such as anatomic targeting of drug delivery, enhanced drug delivery including the delivery of macromolecules and potentially the delivery of electrical signals as the therapy. Finally, we investigate major challenges associated with ingestible electronics, including safety, communication, powering, steering and tissue interactions. Ingestible electronics are an exciting arena of scientific innovation and they may pave the way for a novel area in medicine, enabling patients to receive remote, electronically-assisted health care.

Figure 1.. Timeline of ingestible electronic devices.

Figure 2.. Gastrointestinal anatomy, physiology and pathophysiology.

The main organs of the gastrointestinal (GI) tract and vicinal organs are described to demonstrate the potential of ingestible electronics to monitor signals in the GI and extra- GI signals.

Figure 3.. Clinically applied ingestible electronics.

a) An ingestible video capsule endoscope can be applied to record images of the gastrointestinal (GI) tract. The four images taken by the video capsule show potential readouts. b) Digital compliance measurement using an ingestible radio-frequency identification (RFID) chip. Ingestion is registered by a wearable patch, which gives healthcare providers the possibility to adapt the therapy based on an unbiased dataset (with permission or modified from^,).

Figure 4.. Technologies for ingestible electronics.

a) Gas sensing capsule. b) Optical coherence tomography. c) X-ray scanning capsule. d) Intellicap for drug delivery. Modified from ^,,,.

Figure 5.. Communication concepts for ingestible electronics.

Many capsule endoscopes possess wire antennas to address specific stipulations of radiofrequency (RF) communication within the gastrointestinal (GI) tract (for example, omnidirectional radiation pattern or path-loss). Alternatively, antennas can be integrated antennas into the device design i.e. by printing antennas onto components. Conformal design serves to further refine antenna characteristics. Electric field propagation can be applied to address challenges of RF-communication.

Figure 6.. Major challenges for ingestible electronics.

Main challenges for powering, sensing, communication, safety and tissue interactions are illustrated using a standard ingestible capsule design.

Figure 7.. Material design for ingestible electronics.

Material design concepts are shown for structural components, sensors, power supply and communication elements. Soft, degradable or erodible materials or electronics could help to address obstruction risk that is typically associated with non-deformable ingestible electronics: They could help refine functional components such as antennas as well as structural components such as the housing. Soft robotics could be used to manipulate tissue or manoeuvre devices through the gastrointestinal (GI) tract. Novel communication technologies for example the use of small capacitive micromachined ultrasonic transducers (CMUT) could address challenges of radiofrequency (RF) communication in deep tissue (with permission or modified from^,,,,,,,–).