The 'pill' was developed with backing from chip maker Texas Instruments and generates enough power to run a temperature sensor and wireless link for several days. This could offer a safer and lower-cost alternative to the traditional batteries, as these can cause burns when swallowed.
The researchers attached zinc and copper electrodes to the surface of their ingestible sensor. The zinc emits ions into the acid in the stomach to power the voltaic circuit, generating enough energy to power a commercial temperature sensor and a 912MHz transmitter.
In tests in pigs, the devices took an average of six days to travel through the digestive tract. While in the stomach, the voltaic cell produced enough energy to power a temperature sensor and to wirelessly transmit the data to a base station located 2 meters away, with a signal sent every 12 seconds.
The current prototype of the device is a cylinder about 40 millimeters long and 12 millimeters in diameter, but the researchers anticipate that they could make the capsule about one-third that size by building a customized ASIC with the energy harvester, transmitter, and a small microprocessor.