Medication non-adherence is one of the most significant global challenges in healthcare. In the United States alone, it contributes to approximately 125,000 preventable deaths annually and results in more than $100 billion in additional healthcare costs. Nearly half of patients with chronic diseases do not take their medications as prescribed, leading to poor disease control, increased complications, and higher hospitalization rates. Â
Current methods for assessing medication adherence, such as patient self-reporting, pharmacy refill records, and smart pill bottles, are often inaccurate, difficult to scale, or dependent on active patient participation. Although ingestible electronic sensors can directly verify pill ingestion, most existing designs rely on non-degradable electronic components that are not excreted from the gastrointestinal tract, raising concerns regarding long-term safety and electronic waste.
Researchers developed Smart Adherence via Faraday cage and Resorbable Ingestible (SAFARI), a fully bioresorbable, passive, RFID-tagged capsule, designed to verify medication intake while minimizing safety and environmental risks. The SAFARI system incorporates a zinc-based RFID antenna, a commercial RFID chip, and a 000-size gelatine or hydroxypropyl methylcellulose (HPMC) capsule containing the medication payload. A key innovation is the electromagnetic interference (EMI) shielding layer, composed of hydroxyethyl cellulose embedded with bioresorbable metal particles, mostly molybdenum. Â
This shielding layer functions as a Faraday cage, blocking radiofrequency signals prior to ingestion. Upon ingestion, the acidic gastric environment dissolves the shielding coating, switching the RFID tag from an OFF to an ON state. The activated tag is then wirelessly detected by an external RFID reader operating at 915 MHz, thereby confirming ingestion. The system is entirely battery-free and does not require device retrieval after use.
The bioresorbable RFID tag demonstrated reliable wireless performance, with a received signal strength indicator (RSSI) of 50–65 dBm measured in air, within capsules, and in an ex vivo stomach. The zinc-based antenna resonated at 915 MHz and remained functional even when bent to fit within a size 000 capsule. The shielding coating provided effective RF attenuation, achieving approximately 25 dB of shielding at 915 MHz using molybdenum particles measuring 1-5 µm in diameter. When exposed to gastric fluid, the coating dissolved within 10-20 minutes, enabling signal activation.
The zinc antenna and shielding components degraded within 24 hours, while the cellulose-based substrate decomposed over several weeks. In vivo studies on swine proved the accurate detection of ingestion events. RFID readings were similar across the 900-925 MHz range, and free movement of the device within the stomach. Â
Metal dissolution analyses showed peak concentration of 7ppm zinc and 3ppm molybdenum in simulated gastric fluid on Day III. Notably, the blood serum analysis revealed no significant post-ingestion increases in the levels of zinc and molybdenum, and exposure remained well below established dietary intake limits (2,000 ppm/day for zinc and 1 ppm/day for molybdenum).
Overall, this study demonstrates the feasibility of a fully bioresorbable battery-free RFID pill for monitoring medication adherence. Environmental safety, robust gastrointestinal safety, and elimination of permanent electronic waste combine with reliable ingestion verification, which makes SAFARI an excellent choice. The materials used, such as zinc, molybdenum, cellulose, gelatine, and HPMC, are biocompatible, biodegradable, and widely used in medical or dietary applications. SAFARI holds promise for high-impact clinical settings such as HIV, tuberculosis, transplant medicine, and cardiovascular disease, where adherence is critical. By enabling passive, digital, and scalable verification of medication ingestion, SAFARI offers a foundation for next-generation sustainable electronics and improved therapeutic outcomes.
Reference:Â Say MG, You SS, Cai Y, et al. Bioresorbable RFID capsule for assessing medication adherence. Nat Commun. 2026;17:52. doi:10.1038/s41467-025-67551-5
