Nausea and vomiting aren’t just unpleasant — they can point to numerous gastrointestinal diseases. And in extreme cases, they can lead to malnourishment and dehydration. These woes can be difficult to treat; aside from simply waiting it out, the few options include oral medications, an IV, or feeding tubes.
But a new device might soothe patients' upset stomachs and whet their appetites without the need for drugs or surgeries.
The system, nicknamed FLASH (for fluid-wicking capsule for active stimulation and hormone modulation), is a pill that sends mini pulses of electricity and passes through the stomach in less than an hour.
“They’re the same size as other capsules that you might buy at CVS or Walgreens,” says Giovanni Traverso, a biomedical engineer at the Massachusetts Institute of Technology and co-author of the study, which was published last week in Science Robotics. So far, the electric pulse-generating pills have only been tested in pigs. One day, though, they may offer relief to humans — and pave the way for a new era of electrical stimulation therapy.
It’s electric
Electrical stimulation has a surprisingly long medical history, stretching as far back as ancient Egypt and Greece. There, doctors sometimes prescribed electric fish to hold as a treatment for migraines and joint pain. In more modern contexts, electricity is sometimes used to treat heart conditions like arrhythmia, or even epileptic seizures.
Khalil Ramadi, a bioengineer at New York University Abu Dhabi and co-author of the new research, began studying bioelectricity for its potential to treat neurological diseases, such as Parkinson’s. But he quickly realized that such treatment was extremely invasive — to send tiny shocks to the brain, one typically has to go through the skull. So Ramadi began looking for alternative routes. “That’s where the gut comes in,” he says.
The gut has the body’s highest concentration of neurons outside of the brain. These cells link the central nervous system to the gastrointestinal tract in a two-way signaling pathway called the gut-brain axis. By stimulating neurons in the gut, Ramadi and his co-authors found, it’s possible to send messages to the brain.
The team designed a tiny, battery-powered device that essentially works like a pacemaker and placed it in a dissolvable, edible capsule. Once the capsule melts away and the device comes into contact with a conductive surface — in this case, stomach cells — it delivers small pulses of electricity. These electric pulses induce the release of ghrelin, the body’s so-called “hunger hormone,” which is involved in regulating appetite and alleviating severe nausea and vomiting.
Lizard inspiration
But the stomach isn’t a particularly hospitable environment, so ensuring that the electrical impulses went in the right direction presented an engineering challenge. “It’s actually really messy in there,” says Ramadi. The stomach lining constantly secretes fluid, and the esophagus dumps various other liquids into the organ. “That prevents you from having a good, stable connection.”
The researchers realized they needed a way to channel some of that extra fluid away from their device. “We stumbled on the Australian thorny lizard,” Traverso says.
Australian thorny lizards (Moloch horridus) live in bone-dry regions of the Outback where water is a precious commodity. To survive these parched conditions, they evolved an ingenious water delivery method: Small scaly grooves that run along their bodies. When a drop of water enters one of these grooves, it’s naturally pumped through the lizard’s body due to capillary action — H2O is attracted to the groove’s surface and other water molecules — eventually reaching its mouth.
The new device incorporates similar grooves to channel fluid away from its circuit interface, allowing it to form a connection with stomach cells. When the researchers tested the system on pigs, they were able to successfully stimulate ghrelin release for 20 to 30 minutes before the capsule passed onto the intestinal tract.
Ultimately, the researchers hope this pill could treat eating disorders or gastrointestinal conditions such as gastroenteritis that cause extreme nausea.
Right now, the FLASH system is designed to release electric pulses continuously without any external control. But the researchers say that future iterations might be controlled remotely, giving clinicians more precise control over ghrelin production. And by adjusting the strength and frequency of pulses, they may be able to stimulate the release of other types of hormones without surgery or drugs.
“I think that this is a system that could complement or revolutionize the way we think about healthcare,” Ramadi says. “I’m extremely excited about that.”
