When people have a full meal, the stomach sends a signal to the brain, making the body aware that it is time to stop eating. Now, engineers at the Massachusetts Institute of Technology in the United States are using this principle to design edible capsules that can vibrate in the stomach. This vibration activates the same stretching receptors as when sensing gastric dilation, resulting in an illusory feeling of fullness. The study was published in the December 22nd issue of the journal Progress in Science. Researchers have designed a capsule the size of a complex vitamin, which includes a vibrating element. When the capsule, powered by a small silver oxide battery, reaches the stomach, the acidic gastric juice will dissolve the gel membrane covering the capsule and activate the vibration motor. Once the capsule begins to vibrate, it activates the stretching receptors and sends signals to the brain by stimulating the vagus nerve. Researchers tracked hormone levels during device vibration and found that they reflect hormone release patterns after meals. Research has found that taking this capsule 20 minutes before eating can stimulate the release of hormones that produce a feeling of fullness, thereby reducing food intake by about 40%. The current version of the capsule is designed to vibrate for about 30 minutes upon reaching the stomach. Researchers plan to modify it to stay in the stomach for a longer period of time, so that it can be opened and closed wirelessly as needed. In animal studies, these capsules are excreted through the digestive tract within four to five days, and the experimental animals show no signs of obstruction, perforation, or other side effects. (Zhang Jiaxin) (Le Xin She)