A new fiber probe developed by researchers at The University of Texas at Austin delivers two major innovations in health monitoring to help both patients around the world and the clinicians who care for them.
The probe can track three key biomarkers simultaneously, enabling faster, minimally invasive patient monitoring. All that in a tiny package–the probe is the smallest of its kind with a diameter of only 1.1 millimeters.
"Real-time monitoring of biomarkers like glucose, lactate and ethanol is essential for understanding metabolic health and guiding treatment decisions in critical care settings," said Tanya Hutter, professor in the Cockrell School of Engineering's Walker Department of Mechanical Engineering and lead author on new research published in Nature Communications. "Our compact fiber probe offers a unique solution to measure these compounds simultaneously, providing a more complete picture of the metabolic state."
Why it matters
Glucose monitoring is crucial for diabetes management, while lactate levels can indicate sepsis or tissue hypoxia. Ethanol monitoring is essential in cases of alcohol intoxication, addiction treatment, and alcohol-related liver or brain injuries.
These three molecules are also important for general health, fitness and metabolic assessment. Their concentrations provide insight into energy utilization, physical performance and overall physiological stress. Continuous or point‑of‑care tracking of glucose, lactate and ethanol can therefore support early diagnosis, guide clinical interventions and enable personalized wellness monitoring in both medical and everyday settings.
Traditionally, these biomarkers are measured separately using different devices, which can be time-consuming, invasive and costly. Compared to microdialysis, a common method for in vivo measurement of small molecules that requires collecting fluid samples for analysis, the fiber probe tracks biomarkers directly in the tissue, offering real-time results continuously.
In the case of a patient suffering from a severe traumatic brain injury, a microdialysis probe is inserted into the brain to monitor chemical changes that guide clinical management. However, this method is highly labor‑intensive and only provides delayed information, as samples must be collected, processed and analyzed offline. This delay limits clinicians' ability to respond rapidly to evolving metabolic crises, underscoring the need for continuous, real‑time sensing technologies that can offer immediate insight into cerebral chemistry. "In an intensive care unit where every second counts; they need this information rapidly," Hutter said.
How it works
The mid-infrared fiber probe is designed with two silver halide optical fibers housed in a durable polyetheretherketone (PEEK) tube, surrounded by a semi-permeable membrane. One fiber has an angled tip for delivering and collecting light, while the other is coated with gold to act as a mirror.
The membrane prevents direct contact between the sensing region and tissue, enhancing biocompatibility and reducing interference from large compounds like proteins.
The probe is connected to a quantum cascade laser (QCL) for providing mid-infrared light, which interacts with molecules in the tissue.
Each molecule absorbs light at specific wavelengths, creating a unique spectral signature, and the extent of light absorption is proportional to its concentration, enabling quantification. The probe does not react or alter the molecules; it simply measures their response to light.
"Unlike microdialysis, it doesn't disturb the local tissue environment, so it is more representative of what's actually happening inside the tissue," said Tse-Ang Lee, a Ph.D. student in Hutter's lab and a co-author on the new paper.
What else
This particular project, funded by the National Institute on Alcohol Abuse and Alcoholism (NIAAA), focused on developing the technology for measuring alcohol continuously in vivo, but it goes back more than a decade in Hutter's career. When she was studying for her Ph.D. at the University of Cambridge in the United Kingdom, she was approached by clinicians seeking to improve care for traumatic brain injury. Her goal in this research is to speed up measurement of important biomarkers and also make it less invasive for the body as a whole.
The device is intended for use by clinicians in hospitals and other medical settings, but the technology also has the potential to be adapted into a wearable consumer device for wellness monitoring. The University has filed a patent application, which can be licensed to an appropriate industry partner.
