The tiny sensors, which are ingested and pass harmlessly through the body, are part of the Helius system, developed by Proteus Digital Health in Redwood City, California. Together with a sensor-laden patch worn on the skin, Helius can let patients track personal data like activity levels and body temperature, and share it with their doctors or loved ones.
The system could also help solve a serious problem: half of all medications dispensed in the US are not taken as prescribed, because of factors such as forgetfulness or discomfort with a drug's side effects. This costs healthcare providers between $100 billion and $300 billion in avoidable hospital visits and other expenses, and contributes to as many as 125,000 unnecessary deaths every year.
Several attempts have been made to solve the issue, including cellphone reminders and smart pill caps that record when you pop the bottle open. In the US, the federal Medicare programme recently amended its rules to reward healthcare providers if patients renewed prescriptions on time, and penalise providers if this didn't happen.
But doctors still can't tell for sure whether someone has taken their medication. A device like Helius could change that, and make patients more accountable for their own care.
"It's going to take a little time, but we're at the beginning of a real revolution," says John Kane, a psychiatrist at the Albert Einstein College of Medicine in New York City, who worked with Proteus on early trials of the system.
Proteus declined to comment when contacted by New Scientist, but publicly available information likens their sensor to a potato battery. The millimetre-sized silicon sensor is tacked onto a pill and ingested. It is loaded with magnesium and copper, and when the metals come in contact with stomach acid, they create a small electric charge that triggers transmission of an electrical signal.
That signal is picked up by a skin patch, which can be worn for up to a week, recording each sensor's number and the time it was detected. A suite of sensors in the patch also collect information like the user's skin temperature, activity levels, sleep patterns and heart rate. All that is then relayed via Bluetooth to a computer or smartphone app.
The sensors were approved for use in Europe in 2010 and in the US in 2012. Since then, Proteus has launched a range of trials in patients with different disorders, including those with hypertension, schizophrenia and cystic fibrosis.
In one trial at a tuberculosis clinic in Denver, Colorado, in 2012, a group of 30 patients ingested a total of more than 1000 of the smart pills. Researchers found that an early version of the technology was 95 per cent accurate at tracking the patients' drug regime.
By the end, most of the volunteers were comfortable with the sensors and interested in using them again, says Robert Belknap of the University of Colorado Denver, who led the study. "The technology resonated with people," he said. "If it were available, our clinic would look seriously at using it."
Kane says that, in future, doctors could use such data to tweak prescriptions to better match individual reactions, and to look for telltale signs that an illness is getting worse.
Proteus recently completed a year-long trial with Lloyds Pharmacy in the UK. Interested customers with any kind of ailment could purchase a separate pack of sensor-studded sugar pills to take alongside their usual prescriptions. In addition, Proteus announced plans in March to construct a manufacturing plant in the UK - but it has not said when Helius will be commercially available.
Syndicated content: Aviva Rutkin, New Scientist