A micromachined glucose monitoring sensor with diffusion control

Considering the long-term, flexible blood glucose monitoring demand, a sensor monitoring system for interstitial fluid (ISF) ultrafiltration sampling and on-line monitoring of blood glucose is presented. In this paper, the glucose sensor chip used in this system will be introduced in detailed. This sensor chip was developed by MEMS technique and it has the advantages of less ISF consumption, smaller structures and easier integration. Otherwise, the silicon glucose sensor chip is provided with diffusion control of the analyte through a porous silicon membrane into a silicon etched cavity containing the agarose immobilised enzyme. First, glucose monitoring principle of this sensor system will be intrudouced briefly. Then, this paper focuses on the design and fabrication of the key component, which is the MEMS sensor chip with diffusion control. Finally, experiments were carried out, and results show that the sensor chip's signal response time at increasing glucose concentrations is about 5s; The linear range is large enough to cover the required broad area of blood glucose (0.2 ~ 20 mmol / L), the sensitivity is 9.76 nA/mmol.L-1, and the correlation coefficient is 0.9954. In addition, experiments results of sensor chip with different pore membrane were compared with each other. We can see that different measuring range and sensitivity can be obtained, which agrees with the theoretical analysis.