After several years of development, swallowable wireless sensors are now ready to begin monitoring the human body. A tiny medical device sold by Buffalo, NY-based SmartPill has received approval by the Food and Drug Administration to be marketed in the United States. The electronic pill is meant to be ingested by a patient; it then gathers information about the digestive system as it travels through it, transmitting the information to a receiver worn by the patient.

The newly approved device, the size and shape of a large vitamin pill, is approved to help clinicians diagnose gastroparesis, a disorder that causes the stomach to empty very slowly. As it journeys through the GI tract, a radio transmitter sends information about the time its journey takes, as well as acidity and pressure levels. The level of acidity helps the physician to determine when the capsule enters and leaves the stomach. A receiver that’s slightly larger than a cell phone collects the data from the device. And the disposable capsule gets excreted from the body after a day or two. The patient then returns the receiver to the doctor, for downloading and analysis. Each capsule will cost $500, and the entire system, including a docking station and software, costs $20,000.

David Barthel, president and CEO of SmartPill, says their device is the first among others they hope to design for addressing motility disorders, which arise when the muscle contractions moving food through the digestive system are abnormal. The most common such disorder is irritable bowel syndrome, which could affect up to 20 percent of Americans.

Gastroenterologists often must use invasive and unpleasant methods for studying the long, winding passage of the digestive tract. So device companies have been trying to develop easier ways to gather this information. Swallowed capsules containing tiny cameras, developed by Israel-based Given Imaging, are currently used to perform endoscopies in the esophagus and small intestine, and the company will soon launch a similar capsule for the large intestine. Chief operating officer Kevin Rubey says such devices help patients avoid endoscope procedures and allow visualization of new areas of the body.

Henry Parkman, a gastroenterologist at Temple University School of Medicine in Philadelphia, who is a member of SmartPill’s scientific advisory board and has tested the device in patients, says it may eventually be used for other disorders of the GI tract.

Gastroparesis, which can cause heartburn, vomiting, and loss of appetite, is most common in patients with diabetes and neurological disorders such as Parkinson’s disease. Currently, the best test for gastroparesis is to have patients eat a meal tagged with a radioisotope, and to monitor them for several hours as the food passes through their digestive system. Clinicians also use long catheters with pressure sensors at the end to measure contractions in the digestive system. Parkman says the new device would be less invasive and inconvenient, and could be used in doctor’s offices, when other techniques are not available.

But the ingestible sensor technology has its skeptics. Nonko Pehlivanov, a gastroenterologist at the University of Texas Medical Branch in Galveston, says that the current methods for diagnosing gastroparesis are invasive and time-consuming. But he says the new device hasn’t yet proven it’s as accurate as them. One of the fundamental problems with ingestible devices is that they’re continuously on the move, which means they can only gather passing snapshots of places. “Sometimes you need prolonged information at a certain point in the GI tract,” Pehlivanov says. And for that, invasive techniques are still needed.