Electronic implants are used inside the body for everything from keeping a person's heart beating regularly to the slow and measured release of a drug. And now scientists are working on an alternative to these implants that's far less invasive: non-toxic, easily digestible 'smart pills'. 

One of the main challenges in developing a smart pill is in figuring out how to provide enough power in the absence of an electronic battery, but researchers have found that the naturally occuring melanin pigments in our hair and eyes could be used as electrode materials to keep these ingested pills running.

"We're interested in converting the world of implantable medical devices into ingestible medical devices," one of the researchers behind the smart pill, biopolymer researcher Chris Bettinger from Carnegie Mellon University in the US, told Emiko Jozuka at Motherboard. "So we're taking all the sophisticated electronics that are used in things like pacemakers and drug delivery systems and converting them into ingestible formats… we want to create smart devices that don't just release drugs arbitrarily, but that release specific dosages at specific times - as and when your body needs it."

The opportunity to release drugs on a schedule is just one potential advantage of a smart pill. Unlike electronic implants, they don't require invasive surgery, and there's a much lower chance of the body rejecting them. Implants also carry the risk of bacterial infection and persistent inflammation; what's more, the total cost of smart pills is likely to be much lower in the long run.

"We're interested in answering this question: what would an ingestible medical device need to have in terms of a material profile? What will the power supply be? If we're designing, batteries what will they be made of?" says Bettinger. Smart pill testing has been going on since the 1970s, but scientists have struggled to find materials and electronics that don't harm the body or get stuck anywhere they shouldn't.

Biodegradable materials are a promising option, and Bettinger says a polymer network called an elastomer (both semi-fluid and stretchable) could be the answer: it would be able to bend, stretch, and degrade without getting stuck, and the pill would just dissolve naturally once its job was done. As electronics grow ever more miniature in size and natural in composition, the idea of smart pills is moving closer to becoming a reality - though there's still plenty of work to do yet.

"There are many rapid advances in materials, inventions, and discoveries that can be brought to bear on medical problems," says Bettinger. "If we can engineer devices that get the most mileage out of existing drugs, then that is a very attractive value proposition. I believe these devices can be tested in patients within the next five to 10 years."