A newly approved pill design lets doctors know the patient is taking the medication on schedule. It’s designed to pick up patterns rather than cover critical situations.

The Food and Drug Administration approved the technology in Abilify MyCite, a drug used to treat schizophrenia and some bipolar disorder episodes. It’s also used as an “add-on” treatment for depression.

The pills contain a sensor that’s similar in size to a grain of salt and has coatings of copper and magnesium. When the pill dissolves, stomach juices complete an electrical circuit between these coatings, with the resulting tiny electrical charge sending a signal to a patch worn by the patient. This patch in turn relays a message to a smartphone app that passes on the data to the relevant medical professionals.

The theory is that this will help doctors know when a patient isn’t taking the pills. That’s relevant to the mental health conditions in this case where a patient who misses a scheduled pill might become less able or willing to remember to take the next one, creating a vicious circle. In the long term, the technology could be extended to cover other drugs, such as those for elderly patients who may forget their medication schedule.

Although the FDA has approved the inclusion of the sensor as being potentially useful (and not presenting any significant risks), it did note that it’s not yet proven that it does “improve patient compliance with their treatment regimen.”