MIT develops dissolvable paper battery that operated for three days inside a living stomach
Swallowing a battery is a medical emergency. Unless, apparently, that’s exactly what the doctor ordered.
MIT scientists have developed a pill-sized battery made from paper that can travel through the gastrointestinal tract, quietly powering sensors and stimulators along the way — then dissolve on its own, leaving nothing behind that needs to be retrieved. What’s harder to picture is how something as thin and ordinary as paper could generate real electricity inside a living body in the first place.
A battery built to be swallowed
This paper battery comes from the lab of MIT professor Giovanni Traverso and colleagues, with findings published in Nature Chemical Engineering on September 21. At its core, the design replaces the bulky adhesives used in earlier biodegradable battery attempts with cellulose nanofibrils — which is, essentially, paper. Those fibrils bind the electrode materials together while keeping the overall structure thin, porous, and capable of breaking down inside the body.
Traverso described encapsulation as “critical” to making the system work reliably inside a living body, following a report from IEEE Spectrum.
The electrodes are made from magnesium and molybdenum trioxide, both previously explored for biodegradable applications. The key difference is form. Earlier approaches loaded large particles of these materials into thick electrodes that degraded slowly, but the nanofiber structure keeps everything compact and porous enough to dissolve on a reasonable timeline.
Then there’s the electrolyte — the substance that shuttles electric charges between electrodes. Conventional battery electrolytes are often toxic. This one uses a biodegradable ionic liquid gel made from choline chloride and lactic acid, a combination that outperformed several other biodegradable electrolyte candidates in stability, according to Traverso.
Why powering smart pills has always been so hard
The appeal of ingestible electronics is obvious. A device that monitors temperature, detects disease markers, or delivers a drug payload from inside the gut could transform how doctors diagnose and treat conditions in real time. Power, though, has always been the problem.
Standard alkaline and lithium-ion batteries are genuinely dangerous if their casings crack or leak inside the body. That’s not a theoretical risk — it’s exactly why swallowing a battery sends you to the emergency room. Researchers have tried harvesting energy from body movement or chemical gradients, but those methods tend to produce output that’s low and inconsistent. Biodegradable batteries have also been explored, and most earlier designs could only store limited amounts of energy — not enough to run a sensor or stimulator for any meaningful stretch of time.
The MIT design is notable because it doesn’t just solve one of these problems. Safety, power output, and biodegradability are addressed together.
Tuning the battery to survive — then dissolve
Getting a battery to power a device for days and then disappear requires precise engineering. Traverso described encapsulation as “critical” to making the system work reliably inside a living body, following a report from IEEE Spectrum.
The challenge is timing. Gastric fluid reaching the battery too quickly causes capacity to drop before the device has done its job; hold the outer layer too long, and the battery won’t degrade as intended. The team solved this with natural wax coatings that slow fluid penetration, letting engineers dial in exactly how long the battery stays active. In accelerated lab tests, the electrode material had almost completely dissolved after 90 days — suggesting the battery doesn’t just break down in theory, but actually disappears under conditions designed to simulate extended use.
What happened when pigs swallowed it
Animal trials moved the research from controlled lab conditions into something closer to reality. In live pig experiments, the batteries reached a peak voltage of 1.84 volts and remained operational inside the stomach for up to three days.
That was enough to do real work. A battery-powered RFID tag, once swallowed, maintained stable wireless communication with a receiver 1.5 meters away — enough to send a signal through the body to a nearby device, which is exactly what a medication-adherence monitor would need. A separate test used the battery to power electrical stimulation of the stomach for 20 minutes. Gastric electrical stimulation is an established technique for treating nausea, impaired digestion, and loss of appetite. No notable tissue damage was observed. The RFID tag and circuit board used in these tests weren’t biodegradable, but the animals excreted them naturally.
From pig trials to human clinics
The range of potential applications is broad. Traverso points to sensors for temperature, pH, pressure, motility, and biochemical signals; controlled drug-delivery systems; temporary electrophysiological recording; and gastric or intestinal electroceutical devices. For any device meant to stay in the stomach for several days, a power source that dissolves on its own removes the need for surgical retrieval — a significant practical advantage.
The team is currently prototyping devices that pair the new battery with biodegradable antennas and RFID systems, working toward a fully dissolvable package. The next major milestone is a human clinical trial focused on monitoring medication adherence, which Traverso says the team aims to begin within approximately two years.
If that trial goes well, the gap between swallowing a battery as an emergency and swallowing one as a treatment could close faster than most people expect.
Daniel García is an Editor-in-Chief with strong expertise in structural work and engineering principles. He combines this technical foundation with deep knowledge of energy, spatial design, and emerging technologies, bringing a forward-thinking and analytical approach to editorial leadership.
