Long-life miniature oxygen sensor avoids metal leakage, degradation of sensor performance

The blood gas analyzer is a testing device that analyzes the partial pressure of oxygen and carbon dioxide in the blood and pH. The results are used to learn about the patient’s condition and determine treatment methods. It plays a particularly important role as an emergency testing device that can determine the pathology of critically ill patients, such as those with respiratory failure, and is used in emergency rooms and operating rooms.

Its use is limited in highly urgent medical settings however, because it is difficult to perform accurate blood analysis using simple methods such as commonly used pulse oximeters. Currently, medium- to large-sized devices that can be used continuously are the mainstream, and their market size is expected to reach 240 billion yen in 2020 and 350 billion yen in 2027.

In this context, the effectiveness of blood gas analysis, especially in children and neonates, requires a reduction in the size of equipment and the volume of specimens (blood sampling volume). For this reason, the development of compact oxygen sensors is being actively pursued.

Conventional compact oxygen sensors have a problem—silver eluted from the Ag/AgCl reference electrode precipitates on the working electrode, making accurate analysis impossible in a short time, which is an obstacle to miniaturization. There is therefore a need to develop a long-life, compact blood oxygen sensor that uses a reference electrode that prevents degradation of sensor performance and that is capable of continuous measurement.

Researchers at AIST, Techno Medica Co., Ltd, Tohoku University, Fuji Silysia Chemical Ltd. and University of Tsukuba have successfully developed such a miniature oxygen sensor. This achievement was made possible by the development of a reference electrode that does not cause silver contamination of the working electrode. The results are published in ACS Applied Materials & Interfaces.

By using highly crystalline graphene-coated porous silica spheres (PB/G/PSS) with highly dispersed Prussian blue as the reference electrode, the team succeeded in developing a compact oxygen sensor that can be used continuously for a long period without ion elution. This achievement can be applied to blood oxygen analysis in the medical field, and could improve the quality of life for patients.