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The short version

  • Scientists have created a digestible battery using magnesium, molybdenum, and cellulose that powers internal sensors for several days before breaking down.
  • Tests in pigs demonstrated the device can transmit data externally and stimulate hormone production without causing harm or requiring extraction.
  • The technology aims to replace toxic lithium-ion alternatives and reduce environmental waste from medical implants.

A significant advancement in ingestible medical technology has emerged with the creation of a biodegradable battery designed to power devices inside the human body. Researchers at the Massachusetts Institute of Technology and Brigham and Women’s Hospital have developed a power source that functions for several days before dissolving completely, eliminating the need for surgical removal or the use of potentially toxic materials. The findings were published in Nature Chemical Engineering on September 21, marking a potential shift in how internal health monitoring is conducted.

Current ingestible sensors often rely on standard batteries containing harmful chemicals or external wireless power sources that limit their utility and comfort. The new device addresses these limitations by utilizing materials that are safe for human consumption in small quantities. The electrodes are constructed from magnesium and molybdenum, elements essential for bodily functions, while a biodegradable liquid salt acts as the electrolyte to transfer charge-carrying particles between them.

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The structural integrity of the battery relies on cellulose fibers, which bind the cathode together and give the device its paper-like characteristics. This design was inspired by edible rice-paper wrappings used in confectionery. To prevent premature degradation within the acidic environment of the stomach, the entire assembly is encased in natural waxes. This coating serves as a critical functional component rather than simple packaging, controlling the operational lifespan of the power source.

Testing in simulated gastric fluid revealed that the batteries maintain normal function for approximately three days before their performance begins to decline. Complete degradation occurs within a few months, ensuring that no permanent foreign objects remain in the body. The researchers produced two versions of the battery with varying sizes and voltages to accommodate different medical applications.

To validate the technology, the team integrated the batteries into two distinct devices and tested them in live pigs, chosen for their gastrointestinal similarity to humans. One device was an RFID tag capable of transmitting data from the stomach to an external receiver located five feet away. The other was a capsule designed to generate electrical currents that stimulate the production of ghrelin, a hormone associated with hunger.

The results indicated successful operation in both scenarios. The RFID tag effectively communicated information to the outside reader, demonstrating the viability of internal data transmission. Meanwhile, the stimulation capsule increased ghrelin levels by approximately 50 percent after twenty minutes of activity. These outcomes suggest that such devices could be used for diagnostic monitoring or therapeutic interventions without invasive procedures.

Experts not involved in the study have noted the significance of this development. Micaela Matta, a computational chemist at King’s College London, described the work as a promising step toward improved transient electronic devices. She highlighted that swallowable alternatives represent a major improvement over systems that require surgery for both implantation and removal, reducing patient risk and recovery time.

While other groups are developing similar biodegradable power sources, this study is distinguished by its integration into realistic ingestible systems with multi-day operation in large animals. Yin Lan, a materials scientist at Tsinghua University, noted that the performance aligns with other digestible batteries in development but praised the convincing demonstration of functionality in a biological context.

The implications extend beyond individual patient care to environmental sustainability. Giovanni Traverso, a co-author of the study, emphasized that biodegradable batteries minimize environmental impact because the materials degrade naturally in both the body and the surrounding environment. This contrasts with traditional lithium-ion batteries, which pose toxicity risks if implanted and contribute to electronic waste.

Further studies are required to confirm the safety and efficacy of these devices in humans. If successful, this technology could power a wide range of medical instruments, from diagnostic sensors to therapeutic implants, offering a safer and more sustainable approach to internal medicine.

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Go to the original reporting

  • Smithsonian Magazine↗Scientists Invent a Digestible, Paper-Based Battery That Can Power Swallowed or Implanted Medical Devices