Non-invasively determining which microbes make up a person's "gut microbiome," however, can be difficult – which is why a new 3D-printed capsule was developed.

Created by a team at Massachusetts' Tufts University, the capsule is designed to be orally ingested, collecting various species of bacteria as it passes through the gastrointestinal tract. Once it's excreted in the feces, the capsule can be retrieved and its contents analyzed.

It incorporates two interior chambers that are separated by a semi-permeable membrane. One of these chambers contains helical (helix-shaped) microfluidic channels, in which bacteria gathered from different stages of the GI tract are stored. The other contains calcium salt which produces an osmotic flow across the membrane, pulling bacteria from outside of the capsule into the channels in the first chamber.