Caltech researchers have announced the development of PillTrek—a smart ingestible capsule designed to perform advanced electrochemical measurements directly inside the gastrointestinal (GI) tract.
Study: Continuous biochemical profiling of the gastrointestinal tract using an integrated smart capsule. Image Credit: mi_viri/Shutterstock.com
Measuring Biomarkers in Real-Time and In Vivo Could Improve Diagnosis
The GI tract is a complex and dynamic environment rich with chemical and biological markers. These include metabolic indicators such as short-chain fatty acids linked to metabolic syndromes, cytokines tied to inflammation, and neurotransmitters such as serotonin and dopamine that influence mood and neurological health.
Measuring these biomarkers in real time and in vivo could significantly improve how we diagnose and manage a range of conditions, from inflammatory bowel disease and metabolic disorders to neurological illnesses with gut-related symptoms.
Current diagnostic methods, however, fall short. Fecal samples offer only a partial snapshot, and while biopsies are more precise, they’re invasive and sample only limited regions.
The challenge has long been the lack of compact, multi-parameter sensors that can reliably operate in the GI tract’s harsh and ever-changing environment, marked by fluctuating pH levels, constant motion, and a complex mix of biological substances.
Until now, most solutions have been narrow in scope, and the field has lacked a flexible, small-scale, low-power platform that can continuously monitor gut health from within.
PillTrek: A Wireless Capsule for Gut Monitoring
The Caltech team engineered PillTrek, a wireless capsule roughly 7 millimeters (mm) wide and 25 mm long—small enough to be swallowed like a standard endoscopy capsule but packed with much more functionality.
At its core is a reconfigurable electrochemical workstation built onto a microchip. This allows different types of sensors to be added or swapped depending on what needs to be measured.
These sensors can detect pH, temperature, glucose, and neurotransmitters such as serotonin. Thanks to low-power electronics, the capsule can operate for extended periods.
A key innovation is the use of 3D printing to fabricate low-cost, disposable sensors on flexible plastic substrates, making the platform scalable and customizable.
PillTrek also features wireless data transmission, enabling continuous, real-time biomarker monitoring from within the gut.
In initial animal trials, the capsule successfully measured fluctuations in pH, temperature, glucose, and serotonin across different sections of the GI tract, validating its ability to perform continuous, multi-target electrochemical sensing in vivo.
Accurate Tracking of Biochemical and Physical Signals
The preliminary results are promising. PillTrek accurately tracked various biochemical and physical signals in animal models, revealing essential changes in environmental factors such as pH and temperature, as well as biomolecules like glucose and serotonin.
Its reconfigurable sensor array allows it to be tailored for different research or clinical applications, a major advantage for personalized diagnostics.
The capsule’s low-power design supports prolonged use, while its wireless connectivity allows real-time data collection, offering a far more complete view of gut function than traditional methods. It also improves patient comfort and safety, given its non-invasive nature and ability to reach areas of the GI tract that are typically hard to access.
Looking ahead, the team is exploring the integration of additional sensors to detect cytokines and other metabolic markers, further broadening the device’s utility. The modular design supports customization and scalability for research and clinical deployment.
Still, a few challenges remain. Ensuring the capsule is biocompatible and can be safely excreted is essential. Shrinking the device even more would enhance comfort, especially for pediatric use. While electronics are already low-powered, improving energy efficiency and exploring wireless charging options are active areas of development.
The Future of Gut Health Monitoring
The creation of PillTrek represents a major step forward in gut health monitoring. The Caltech team has addressed key limitations of existing diagnostic tools by embedding flexible, low-power electrochemical sensors into a small, wireless capsule.
The technology provides real-time, multi-parameter data inside the GI tract in a comprehensive and minimally invasive technique.
Early animal studies highlight its potential to significantly improve how we diagnose and track gastrointestinal and systemic health conditions. Future work will aim to refine its size, expand its sensing range, enhance power management, and ensure safety for human use.
Journal Reference
Min, J., Ahn, H., Lukas, H. et al. Continuous biochemical profiling of the gastrointestinal tract using an integrated smart capsule. Nat Electron (2025). https://doi.org/10.1038/s41928-025-01407-0