This "sensor pill" can be powered by your stomach acid

Electronic devices are invading every aspect of our lives and, soon, even our own bodies. Pills that contain sensors that transmit data from inside the human body have long been a holy grail for scientists and doctors but they have always been stumped by one critical part of the setup: the power source. Now researchers from MIT might have gotten one step closer by harvesting electricity from the most ubiquitous material inside our stomachs: our own stomach acid.

Willingly ingesting something that looks like a spy movie prop has probably never crossed most people's minds, but for those in the medical and scientific fields, this corner of technology could, in the future, mean the difference between life or death for patients. Such ingestible systems can monitor a person's vital signs or deliver controlled doses of medicine, all without the person having to do anything other than swallow a pill.

But all electronics, in order to function, needs a power supply. In the case of sensors like this, conventional batteries just won't. Either they're too dangerous for the patient or, due to the miniscule size, die out before they can be of much use. The solution is to look for a safe, renewable source of energy. And it just so happens that our stomachs are home to such a source.

The principle used in this research is practically the same one at work in a lemon battery, a once popular science project for kids. In essence, the citric acid inside the lemon carries a small charge between two electrodes, usually a nail and a penny. Substitute zinc and copper electrodes and you pretty much have the same result.

So far, the new type of pill has been testes only on pigs, due to the size of the pill that measures 40x12 mm. The sensor was able to power itself inside the pig's stomach's for six days, sending data to a receiver 2 meters away every 12 seconds. When the pill reached the small intestine, however, the rate was significantly reduced due to less stomach acids around it. The researchers, however, are confident that they would be able to shrink down the pill even further, making it suitable for human ingestion, as well as find ways draw power even side the smaller intestine.