Self-assembly method of glucose oxidase in a fully packaged microfluidic glucose biosensor

In this work, a self-assembly approach is proposed to bio-functionalize the fully packaged microfluidic biosensors for catalyzing glucose based on the designed and fabricated microfluidic chip with suspending structure by micro-electro-mechanical system technology. Glucose oxidase is successfully immobilized on the surface of microelectrodes to build composite layers by the proposed self-assembly approach, with cysteamine applied as a functional linker. The biological activity and stability of glucose oxidase is optimized by the electrodeposition of chitosan membrane. Experiments results suggest that the fully packaged microfluidic biosensor integrated with self-assembled glucose oxidase can effectively detect the existence of glucose in sample solution. The detection range of glucose concentration is 0–10 mM. With SNR of 3, the detection limit is 51.2 μM and sensitivity is 23.47 ± 1.36 μA·cm⁻²·mM⁻¹ within low concentration range of 0–0.1 mM, while the detection limit is 497 μM and the sensitivity is 10.63 ± 1.28 μA·cm⁻²·mM⁻¹ among high concentration range of 0.1–10 mM. The proposed study provides a straightforward method to construct a microfluidic biosensor, which is promising in miniaturized clinical medical device.