MIT Technology Review is reporting on Proteus Biomedical, a Redwood City, California company, which is working on electronic pills, and accompanying sensors, that can virtually guarantee prescription regiment compliance and provide basic information about the body’s condition before and after ingestion.
In the Raisin system, each pill contains an “ingestible event marker” (IEM). The IEM consists of a sand-grain-size microchip with a thin-film battery that is activated on ingestion, as it is exposed to water. The battery, Proteus says, is nontoxic because it is made from materials similar to those in a vitamin pill. Once swallowed, the IEM sends through the body’s tissues a high-frequency electrical current that’s modulated in such a way that it provides a unique marker of the pill. It’s not an RFID technology: it uses the conductive tissues of the body to conduct the signal, rather than a radio, and the signal is confined within the body. Mark Zdeblick, the company’s CTO, says that the IEMs could cost less than a penny each when manufactured in volume.
The electrical current is picked up and logged by a receiver on a patch placed on the patient’s chest or abdomen, or placed underneath the skin as a subcutaneous insert. The receiver also contains sensors that monitor physiological parameters such as heart rate, respiration, and bodily movement. Heart rate is monitored by detecting the electrical activity of the heart; respiration is monitored by detecting changes in the impedance of the electrodes as the chest expands and contracts; activity is monitored with a miniature accelerometer, similar to the ones in iPhones. Combining the parameters can reveal behavioral measures such as sleep patterns.