Several years ago they collaborated to create a star-shaped structure that could be folded up inside a capsule and then released when the capsule dissolved in the stomach.
There's also a pyloric sphincter, or valve, at the end of the stomach which closes while eating, keeping food inside for the stomach to churn over and over again.
He watched the gobbits of food dissolve over time, which is partly how he discovered the stomach's role in digestion was as much chemical as mechanical.
In the stomach and small intestine, for example, fiber helps slow down food processing and absorption in ways that promote fullness and mellow the body's insulin response.