Encapsulation method of glucose oxidase solution with ionic liquid solvent and direct parylene deposition

We developed new encapsulation method of glucose oxidase solution with ionic liquid solvent and direct Parylene deposition for the application to MEMS glucose sensors. Glucose oxidase has been immobilized in gel or polymer on MEMS sensors, but its weak mechanical property has been remained to be solved. Then, its encapsulation has been demanded, but high-temperature MEMS bonding process (>150*deg;C) for packaging the solution is destructive to glucose oxidase which is denatured over 50 °C. To solve these problems, we encapsulated the glucose oxidase-ionic liquid solution with room-temperature packaging (25 °C) of direct Parylene deposition process. The glucose oxidase solution array with the area of 1 ×3) mm² (approximately 1 μl) was patterned on the hydrophilic-hydrophobic surface modification on the MEMS electrochemical electrodes in the use of the wetting phenomenon of the solution and, then, packaged by the chemical vapor deposition of 1.5 μm Parylene. Parylene packages could be opened by pushing when used. The opened glucose oxidase solution reacted to 150 mM glucose solution, revealing the electrochemical potential of 150 mV. The sensitivity of our sensor ranged from 1 to 100 mM, which is the glucose concentration in the blood of the diabetic patients. Therefore, proposed encapsulation method exhibits the potential application to glucose sensor packages for diabetic patients.