Biofuel cell for sensing blood glucose levels using trace amounts of blood developed by the University of Tsukuba

A research group led by Associate Professor Seiya Tsujimura of the Faculty of Pure and Applied Sciences at the University of Tsukuba has developed a sensor capable of displaying blood glucose levels on common devices, such as smart phones, by simply dropping a few microliters of blood. Because the sensor does not rely on dedicated measuring devices, such as conventional electrochemical biosensors, it is expected to serve as an inexpensive sensor system capable of easily and accurately measuring blood glucose levels at home. The results were published in Biosensors and Bioelectronics.

Electrochemical sensors generally measure blood glucose levels using enzymes that selectively detect glucose. However, such electrochemical sensors require special electrodes and devices to control the reactions occurring at the electrodes. This newly developed sensor is a chip version of a biofuel cell.

In this biofuel cell, oxidation of glucose occurs at the negative electrode (anode), whereas reduction of oxygen occurs at the positive electrode (cathode), directly converting the chemical energy of the reaction into electricity. By designing a battery with an output dependent on the sample concentration, continuous measurements of the sample concentration are possible. The research group supplied the counter electrode of the sensor chip with an oxygen reduction catalyst to facilitate the reaction without using special measurement equipment.

This allowed the reaction to proceed similar to that in a biofuel cell. In other words, glucose detection can be realized under the control of the electrode potential, where the reaction proceeds without external energy supply. On the glucose oxidation electrode, glucose dehydrogenase and a redox mediator promoting electron transfer between the enzyme and electrode are immobilized using a cross‐linking agent. The oxygen reduction electrode uses a non‐platinum carbon‐based oxygen reduction catalyst. The electrode was coated using each of these materials, and this was followed by drying to produce the biosensor.

After connecting the two poles, the current was measured by dropping only 5 µL samples of solutions with different glucose concentrations on the sensor. The glucose concentration was proportional over a wide range from 0 to 30 mM, confirming that the sensor could be employed to measure blood glucose levels. Using this principle and changing biorecognition elements based on the biomarkers to be analyzed, disposable sensors capable of detecting various biomarkers are expected to be developed.

Journal Information
Publication: Biosensors and Bioelectronics
Title: A disposable enzymatic biofuel cell for glucose sensing via short‐circuit current
DOI: doi.org/10.1016/j.bios.2023.115272