Obesity remains a major global health problem, with almost 40% of adults and 18.5% of children in the U.S. alone considered obese in 2015 to 2016, the most recent period for which U.S. Centers for Disease Control Operation principle of the VNS system schematically showing the pathway for biphasic electric signal generation and VNS. Source: University of Wisconsin-MadisonOperation principle of the VNS system schematically showing the pathway for biphasic electric signal generation and VNS. Source: University of Wisconsin-MadisonNational Health and Nutrition Examination Survey data are available.

Surgical procedures to treat severe obesity, such as gastric bypass, are generally effective but invasive, causing a range of side effects. An emerging remedial option relies on vagus nerve stimulation (VNS) to signal the feeling of fullness and suppress appetite.

This mechanism is exploited in a battery-free implant engineered at the University of Wisconsin-Madison. The device, measuring 1 cm across, produces electric pulses in response to peristaltic movements of the stomach and stimulates the vagus nerve to send an “all full” message to the brain. For laboratory trials, the device was built based on a flexible triboelectric nanogenerator that was attached to the stomach wall of rats and could generate biphasic electric pulses when the stomach wall moved. Tests demonstrated a 40% body weight loss in the animal models after 100 days.

The patented system requires no external charging of power sources and can be implanted with a minimally invasive procedure. The research is published in Nature Communications.

To contact the author of this article, email shimmelstein@globalspec.com