Coral-inspired pill offers a new window into the hidden world of the gut

In the depths of the ocean, marine corals have evolved intricate, porous structures that shelter diverse microbial communities.

Now, researchers have borrowed this biological blueprint to create an ingestible pill that can sample bacteria from one of the most inaccessible regions of the human body: the small intestine.

The CORAL (Cellularly Organized Repeating Lattice) capsule, developed by Khalil Ramadi – assistant professor of bioengineering at NYU Tandon School of Engineering and NYU Abu Dhabi (NYUAD) – and NYUAD collaborators, promises the first passive, non-invasive way to collect microbes from the upper digestive tract. Once swallowed, the device physically traps bacteria as it travels naturally through the digestive system before exiting the body.

In a study published in Device, the team demonstrated that their coral-inspired device provides a more comprehensive picture of the small intestine's bacterial landscape than traditional stool samples, the current gold standard for microbiome research.

"Fecal samples, though easy to collect, do not accurately represent the microbial communities in distinct regions of the gut," said Ramadi, who directs the Laboratory for Advanced Neuroengineering and Translational Medicine at NYUAD.

While the gut microbiome has been linked to everything from immune disorders to mental health, most stool-sample studies primarily reflect bacteria from the large intestine and miss the unique microbial communities of the small intestine. This matters because the small intestine is where much of the critical action occurs. As the body's largest mucosal surface, it hosts a high density of receptors, immune cells, and neurons, making it a crucial site for host-microbiome interactions.

Recent research suggests that various diseases — including immune disorders, metabolic diseases, and endocrine diseases — may actually originate in the gut, with distinct microbial populations in the small intestine playing essential roles in metabolism and immunity that differ significantly from those in the colon.

"The CORAL capsule captures bacteria that are otherwise not accessible, addressing a significant blind spot in microbiome science," said Aashish Jha, Assistant Professor of Biology at NYUAD and the paper’s co-senior author. "Understanding these upstream microbial communities could be key to early disease detection and developing more targeted therapeutic interventions."

The capsule's design mimics marine corals using mathematically defined structures called Triply Periodic Minimal Surfaces (TPMS). These create a maze-like network of channels with pore sizes optimized to trap bacteria while allowing safe passage through the digestive tract.

Unlike existing microbiome sampling devices that rely on magnets, mechanical actuators, or electronic components, CORAL operates entirely passively. The capsule is fabricated in a single 3D printing step and contains no moving parts, making it potentially scalable for widespread use. A special coating ensures the device only begins sampling once it reaches the small intestine, avoiding contamination from stomach acid.

"We designed CORAL to be as simple as possible, no batteries or electronics, just a mathematically precise structure that uses the gut's natural movement to sample bacteria," said Hanan Mohammed, lead author of the study and Research Associate at NYUAD. "It gives us access to bacterial communities that have been invisible to researchers until now."

In animal studies, CORAL successfully captured distinct bacterial populations from the small intestine that differed significantly from fecal samples. The capsule samples collected higher levels of beneficial bacteria like Lactobacillus, which thrives in the upper gut's lower pH environment, while intentionally missing bacteria typically found in the large intestine.

This work represents part of Ramadi's broader mission to change how we can diagnose and treat diseases through the gut. His work involves developing "electroceuticals" — ingestible electricals rather than pharmaceutical interventions — that can diagnose and treat conditions from immune disorders to metabolic diseases by leveraging the body's natural neural pathways.

The team envisions translating CORAL to eventual human use by scaling the capsule from its current tiny dimensions to standard pill size. Before human trials could begin, researchers would need to develop reliable retrieval methods (potentially using magnetic detection or other identification techniques) and conduct extensive safety testing to ensure the device poses no risk to patients. The team is continuing this work in the lab and actively working to commercialize this technology through the HealthX program at StartAD and the Abu Dhabi Department of Health.

In addition to Ramadi, Jha, and Mohammed, the paper's co-authors are Sadaf Usmani, Brij Bhushan, Anique Ahmad, Oraib Al-Ketan, Ahmed A. Shibl, Maylis Boitet, and Heba Naser, all at NYU Abu Dhabi, and Devjoy Dev at both NYU Abu Dhabi and NYU Tandon.