These High-Tech Batteries Are Built To Break Down In Your Digestive System

Typically, swallowing a battery is an emergency, and one that can quickly turn fatal if left untreated. Between their caustic chemicals, damaging electrical current, and choking hazard, your average button battery (or even a AAA) can wreak havoc on the body, if ingested. A swallowed button battery can burn through a child's throat in as little as two hours, which is one reason those loose batteries sitting in a drawer could be a disaster waiting to happen.

However, there are also cutting-edge capsules designed to be swallowed. They can give doctors a thorough look at the gastrointestinal (GI) tract, control exactly when a drug is released, and transmit data to medical professionals from inside the body. However, they require power to work. Until now, these capsules have typically relied on wireless power from an external source or a tiny coin battery. The problem is that wireless power offers limited range, and even though coin batteries are coated for protection, they still pose a risk.

Fortunately, researchers at MIT have developed small batteries that swap out dangerous substances for magnesium and molybdenum trioxide, which the body can safely tolerate in small amounts. The paper-like battery produces 1.84 volts and uses an ionic liquid gel as its electrolyte. The entire battery is bioresorbable, meaning it can be fully broken down and absorbed by the body. It works for about three days before breaking down within weeks. So far, it's been tested on animals rather than humans. And this isn't the only progress being made with regard to powering medical devices, as there are new high-tech batteries that could theoretically last for thousands of years.

One area where this new battery has been tested is treating a symptom that plagues many people with serious diseases. Those diagnosed with cancer, HIV, dementia, or other serious conditions report a loss of appetite, which may also be a side effect of their medication. This can lead to rapid, unhealthy weight loss, along with low levels of essential nutrients. In severe cases, it can contribute to cachexia, a loss of body mass that can occur in patients with cancer or other chronic diseases.

Fortunately, MIT's tests proved promising. The researchers used their bioresorbable battery to power a device that delivers a mild electrical current to the stomach lining, triggering production of ghrelin, the hunger hormone. The battery powered the device for up to three days, and in animal tests, just 20 minutes of stimulation boosted ghrelin levels by about 50%. It's an interesting contrast to another MIT project, since this vibrating capsule could assist in the ways we treat obesity.

Another potential use for the bioresorbable battery is tracking medication. MIT researchers have been building radio frequency identification (RFID) tags into capsules, so medical professionals can confirm whether patients are taking their medication. As project leader Giovanni Traverso told Physics World, "Medication non-adherence remains a major cause of preventable morbidity and cost." The earlier version of this system relied on battery-free tags powered by harvested energy, which limited their range. With the new battery, the tag transmitted continuously from the GI tract at a range of up to nearly 5 feet (1.5 meters) in animal tests.