Smart Pills Can Tell Your Doctor That You’ve Taken Them

The mechanism of action is ingenious. A tiny CMOS circuit is placed in the pill, along with a primitive battery cell. The battery cell is made up of magnesium and copper chloride. It is activated and releases its energy when the pill is in the presence of stomach acid, powering the CMOS circuit which sends a low-power modulated signal at a frequency of between 10 and 30 KHz, at a rate of approximately two packets per second. The signal is then picked up by a patch worn on the body, which sends a ping to a paired smartphone or tablet over standard Bluetooth. The components that make up the sensor are either harmlessly processed by the body or passed out as waste, with the sensor itself roughly the size of a grain of sand.