Electronic Capsules Developed to Sense Gases in the Gut

An electronic capsule which, when taken orally, can sense the gases oxygen, hydrogen and carbon dioxide in the digestive tract has been developed. The capsule has the potential to be used to guide dietary changes or as a diagnostic tool for digestive tract disorders. A pilot study carried out on the capsule was published in Nature Electronics. The electronic capsule is 26 mm length and 9.8 mm in diameter with a non-transparent shell and contains sensors for carbon dioxide, hydrogen and oxygen, membranes with embedded nanomaterials (to allow the fast diffusion of dissolved gases, and at the same time block out liquid) beside a temperature sensor to measure the core body temperature (when the temperature falls below 35°C, it indicates that the capsule has been excreted out of the body), a microcontroller, a transmission system, button-size silver oxide batteries. The information obtained by the capsule is transmitted to a small receiver that the patient can carry in his/her pocket, and is displayed on a mobile phone screen every 5 minutes through Bluetooth communication. The scientists conducted a small pilot study on the capsule in seven individuals on a normal fiber, low fiber and an extremely high-fiber diet.

The gases in the digestive tract are due to swallowing of air, chemical and enzymatic changes, and the action of the intestinal bacteria on the undigested foods.

The measurement of the gases gives the following information:

• Since different parts of the digestive tract vary in the oxygen content, the measurement of the oxygen levels can indicate the position of the capsule in the digestive tract. This was confirmed through ultrasound done every 20 minutes during the study to locate the capsule.
• Since the hydrogen levels are altered by the microbial activity in the colon, the measurement of the hydrogen levels gives an indication of the health of the microbiota in the individual. The carbon dioxide levels are also indicative of the fermentation in the gut, though they may be altered by the carbon dioxide produce by respiration.

The electronic capsule appears to have several advantages:

• The test done with the capsule is simple, non-invasive and easy to perform, and continuous monitoring of the gas profiles is possible. Earlier methods to measure gases in the digestive tract that include flatus analysis, tube insertion, whole body calorimetry and breath test are inconvenient for the patient and are often unreliable.
• Though an occasional loss of data transmission occurred, the capsules did not fail during the trials. They were easy to swallow and were not damaged during their passage through the gut.
• The intake of the capsule was not associated with any adverse effect. Abdominal discomfort following a very high fiber diet and mild constipation following a low fiber diet were noted, which were more likely to be due to the diet than the capsule itself.
• In the pilot study, changes in the fiber content of the diet caused changes in small intestinal and colonic transit time and gut fermentation. For example:
• A very high fiber rich diet was associated with lack of fermentation, bacterial microbiota associated with poor gut heath, and a failure of the colon to become anerobic. This could be due to the inability of the microbiota to ferment whole fiber possibly because of the trapping of oxygen in the fiber and affecting the activity of anerobic bacteria. The diet was also associated with discomfort, which could be due to the oxidative stress in the colon.
• A low fiber diet was associated with reduced frequency of bowel movements. This was followed by increased fermentation after introduction of fiber.

The findings of the digestive tract revealed by the capsule are specific for a particular individual can help to individualize dietary changes

In their study, the scientists also found that the stomach may be releasing oxidizing chemicals to fight foreign bodies, and the colon may also contain oxygen under certain situations.

The capsules can thus help to study the function of the intestine, the bacterial flora and the changes with diet. The scientists feel that the capsule has the potential to study disorders of the digestive tract varying from malabsorption to colon cancer They hope to see the capsule in the market in the near future.

Reference:

1. Kalantar-Zadeh K et al. A human pilot trial of ingestible electronic capsules capable of sensing different gases in the gut. Nature Electronics 1, 79–87 (2018).Doi:10.1038/s41928-017-0004-x

Source-Medindia