MIT researchers have fabricated tiny batteries—7.5 mm discs and 24 mm bars—that generate 1.84 V using magnesium anodes, molybdenum trioxide cathodes, and an ionic‑liquid gel electrolyte. The entire stack is bioresorbable, meaning it can dissolve in the gastrointestinal (GI) tract.
When immersed in a highly acidic solution mimicking gastric juice, the batteries operate normally for about three days, then gradually lose performance and fully degrade within a few weeks. The rectangular version was integrated into a degradable capsule that delivers a low‑level electric current to the stomach lining, stimulating endocrine cells to release the hunger hormone ghrelin. In animal tests, a 20‑minute stimulation raised ghrelin levels by roughly 50%.
The same battery powered a bioresorbable RFID capsule designed to improve medication adherence. The RFID tag, made from molybdenum and cellulose, combined with a disc‑shaped battery achieved continuous transmission up to 1.5 m, far exceeding the range of previous passive tags.
Compared with conventional lithium or silver‑oxide coin cells, these magnesium‑molybdenum batteries offer superior safety and reduced environmental impact. Apart from a printed circuit board, the entire device can be absorbed by the body or excreted, minimizing risks to patients and sewage systems.
The work was funded by Novo Nordisk, MIT’s Mechanical Engineering Department, Brigham and Women’s Hospital, and the U.S. ARPA‑H. The team aims to start a clinical trial of the SAFARI system within the next two years.
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