A Micro-Organ Based Microfluidic Biosensor for Continuous Glucose Monitoring

Continuous glucose monitoring plays a central role in diabetes management, especially for patients with type 1 diabetes. Current systems typically rely on enzyme-based electrochemical sensors that measure glucose in interstitial fluid. A recent microfluidic study explores a different strategy by using living pancreatic islets as sensing elements to detect glucose fluctuations through their electrical activity.

The researchers proposed a microfluidic biosensing concept that relies on pancreatic islets functioning as biological processors of metabolic signals. Within these microfluidic chip, micro-organs, insulin-producing β-cells respond to glucose by generating electrical signals associated with insulin secretion. Instead of measuring glucose directly through enzymatic reactions, the microfluidic device interprets these electrical responses as an integrated indicator of metabolic state. Because islets naturally process signals from multiple cell types and hormones, they provide a biologically integrated readout that reflects the physiological demand for insulin.

To implement this idea, the team developed a microfluidic microelectrode array chip capable of hosting pancreatic islets and recording their electrical activity. The system was connected to live rats using microdialysis. Interstitial fluid from the animals was continuously sampled through a subcutaneous catheter and transported through microfluidic channels toward the microelectrode array where the islets were located. When glucose levels changed, the electrical signals generated by the islets were recorded and analyzed. These signals included slow potentials, which reflect coordinated activity among β-cells and are linked to insulin secretion dynamics.

The microfluidic device consisted of a PDMS channel aligned over electrodes on a microelectrode array. Approximately forty pancreatic islets were loaded into the channel so that they covered multiple electrodes and could maintain stable electrical recording conditions. Fluid flow through the channel was maintained at low rates compatible with microdialysis sampling, allowing interstitial fluid to interact with the islets without damaging them. Electrical signals were recorded continuously and analyzed to determine both the frequency and amplitude of slow potentials.

Before connecting the device to living animals, the researchers tested the system using human and rat serum containing different glucose concentrations. The electrical responses of the islets changed predictably as glucose levels increased, demonstrating a strong correlation between glucose concentration and slow potential activity. When the biosensor was exposed to serum containing higher glucose levels, both the frequency and amplitude of electrical signals increased, indicating that the islets were responding to metabolic stimulation.

The team then performed in vivo experiments in anesthetized rats. After injecting glucose, blood glucose levels rose rapidly and were followed by a corresponding increase in electrical activity recorded from the islets on the chip. When insulin was later injected, blood glucose levels decreased and the electrical signals from the islets declined accordingly. Statistical analysis revealed strong correlations between glucose levels and the electrical activity of the biosensor across multiple experiments, with correlation coefficients close to 0.9 for several measurements.

One interesting observation was that signal frequency appeared to be a more consistent indicator of glucose levels than signal amplitude. Frequency measurements were less affected by variations in the distance between islets and electrodes, making them more reliable for monitoring changes in metabolic conditions. The system also showed sensitivity to decreases in glucose levels, which may reflect natural physiological feedback mechanisms within pancreatic islets that help prevent hypoglycemia.

Overall, the study demonstrates that micro-organ-based biosensors can be used for continuous monitoring of glucose in living organisms. By using pancreatic islets as biological sensing units, the device captures complex physiological signals that are not accessible to conventional enzyme-based sensors. Although several engineering and biological challenges remain before such systems can be translated into clinical devices, this work provides an important step toward biologically integrated glucose monitoring and the development of more autonomous diabetes management systems.

Figures are reproduced from Puginier, E., Pirog, A., de Gannes, F.P. et al. A micro-organ based microfluidic biosensor for continuous monitoring of glucose levels in vivo. npj Biosensing 3, 12 (2026). https://doi.org/10.1038/s44328-025-00077-4 under a Creative Commons Attribution 4.0 International License.

Read the original article: A micro-organ based microfluidic biosensor for continuous monitoring of glucose levels in vivo

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