2. Ingestible sensor powered by stomach acidMIT and Brigham and Women’s Hospital researchers have announced an ingestible device innovation: a small voltaic cell that can withstand the acidity of fluids in the stomach and still transmit information to a base station.
The small device can stay in the gastrointestinal tract for long periods of time and can produce enough power to operate small sensors or drug delivery devices. Researchers say that this power is a safer and cheaper alternative to the batteries that are used to power devices now.
Lemon batteries have two electrodes (usually a galvanized nail and a copper penny) stuck into a lemon. The citric acid from the lemon allows a small electrical current to flow between the electrodes. Using this idea, the researchers attached zinc and copper electrodes to the ingestible sensor they created. The stomach acid receives the zinc ions and powers the voltaic current. The current produces enough energy to power a commercial temperature sensor and a 900 mHz transmitter.
Researchers tested these sensors in pigs and found that it took 6 days for the sensor to travel through the digestive tract. During that time, the sensor was able to wirelessly transmit the data to a base station that was 2 meters away and emitted a signal every 12 seconds from within the stomach.
After it moved to the small intestine, the sensor produced 1/100th of the power that it did in the stomach.