Chinese researchers have developed an ingestible optoelectronic capsule that enables two-way communication between humans and engineered gut bacteria, which is a global first. The breakthrough, jointly achieved by teams from Tianjin University and Northwest A&F University, was published on July 28 in the journal Nature Microbiology.

The technology marks a major step forward in biomedical engineering, offering a new tool for real time monitoring of gut health and potential interventions for gastrointestinal diseases, the research team said.

With this system, humans cannot only remotely receive health signals from engineered bacteria but also send precise commands to them, enabling active regulation of gut microbiota.

"This is like creating an optical language between humans and gut microbes," said Wang Hanjie, a professor at Tianjin University, who co-led the project with Professor Liu Duo. "It opens a path for precise diagnosis and dynamic treatment of diseases from within the body."

The human gut hosts billions of microorganisms that influence everything from immunity to emotional well-being. However, due to the gut's complex structure, observing and regulating these microbes in real time has always been challenging.

"Tackling this issue is like trying to detect and control fish in the deep ocean," said Wang. Traditional methods, such as stool analysis, offer only indirect clues.

"It's like picking up shells on a beach. Although it can provide some information about the deep sea, it cannot directly interact with the microorganisms within the gut," added Liu.

The researchers turned to capsule technology, a field under exploration for over two decades, and combined it with genetic engineering. Their solution involved modifying gut bacteria to act as sensors and responders, while an ingestible capsule, equipped with light-based communication tools, serves as a mobile command unit inside the digestive tract.

The capsule uses light signals to communicate, a deliberate choice. "There are no natural light signals in the human gut," explained Zhang Xinyu, a core member of the team. "That makes light a secure, coded language between the device and the bacteria."

He further elaborated, "The electronic capsule acts as an 'interpreter', translating the bacteria's optical language into readable signals for humans."

Engineered bacteria are programmed to emit light upon detecting disease markers such as nitrate, an indicator of inflammation. The capsule's photoelectric sensors convert this light into electrical signals, which are wirelessly transmitted to a mobile phone app via Bluetooth, Zhang said.

Conversely, the capsule also sends out preset light commands using built-in LEDs. The bacteria detect these through light-sensitive proteins and respond by performing specific functions, such as producing anti-inflammatory nanobodies.

To verify the system's stability, researchers ran tests both in vitro and in live pigs.

"Higher bacterial luminescence led to stronger photocurrent signals from the capsule," said the team, confirming the reliability of the signal conversion process.

In tests using a pig model of enteritis, the system proved its practical value. "The engineered bacteria could send early warnings one to two days before traditional stool testing methods," said Liu. The team was also able to issue real time intervention commands remotely through the app, successfully alleviating inflammation.

"The capsule functions like a flexible 'command boat' deep inside the gut," said Liu. "Our next goal is to tailor bacterial sensing to specific clinical needs."

Professor Wang Hanjie added, "In the future, electronic capsules could serve as a digital smart platform, incorporating artificial intelligence and cloud data technologies to intelligently regulate microbial functions, offering new strategies for precise and dynamic disease diagnosis and treatment."

Experts say the study represents a fundamental shift from passive observation of gut flora to active and remote control, offering a foundation for future digital diagnostics and treatment solutions.

Zang Yifan contributed to this story.