A Review of In-Body Biotelemetry Devices: Implantables, Ingestibles, and Injectables

Objective: We present a review of wireless medical devices that are placed inside the human body to realize many and different sensing and/or stimulating functionalities. Methods: A critical literature review analysis is conducted focusing on three types of in-body medical devices, i.e., 1) devices that are implanted inside the human body (implantables), 2) devices that are ingested like regular pills (ingestibles), and 3) devices that are injected into the human body via needles (injectables). Design considerations, current status, and future directions related to the aforementioned in-body devices are discussed. Results: A number of design challenges are associated with in-body devices, including selection of operation frequency, antenna design, powering, and biocompatibility. Nevertheless, in-body devices are opening up new opportunities for medical prevention, prognosis, and treatment that quickly outweigh any design challenges and/or concerns on their invasive nature. Conclusion: In-body devices are already in use for several medical applications, ranging from pacemakers and capsule endoscopes to injectable microstimulators. As technology continues to evolve, in-body devices are promising several new and hitherto unexplored opportunities in the healthcare. Significance: Unobtrusive in-body devices are envisioned to collect a multitude of physiological data from the early years of each individual. This big-data approach aims to enable a shift from symptom-based medicine to a proactive healthcare model.