Digital electronic Health Tech devices require a source of power in order to collect data and communicate it to other devices so that it can be put to practical use. When these devices are worn outside the body, it can be a relatively simple matter to change batteries or plug the device in to recharge it. But what about something that you swallow? Many battery technologies rely on potentially toxic components, making them unsafe for ingestible devices.

Researchers at Brigham and Women’s Hospital and the Massachusetts Institute of Technology have come up with a solution. To be more precise, they have a way to tap a chemical solution that already occurs naturally in our bodies: stomach acid. You may have done a science experiment in school where you light a bulb using a lemon and two electrodes. This concept is based on the same principle, replacing the lemon juice with stomach acid. Ingestible devices can be designed to remain active in the body for prolonged periods of time: days or even weeks. One example is a tiny camera that the patient swallows, and it send back images as it passes through the digestive tract.

One important development from this research is the discovery that devices can be powered even in the small intestines, where the acidity is much lower than in the stomach. A prototype device transmitted body temperatures every 12 seconds for a period of six days. The researchers also showed that they could store enough energy to trigger a payload release from an ingestible device, making it possible to deliver a drug dose to a very specific location within the body. By using the body itself to power such devices, we could see a whole new range of “smart pills” take their place in diagnosis and treatment.