A disposable on-line microsystem for continuous sampling and monitoring of glucose

A copolymerized gel composed of poly(N-isopropylacrylamide) and acrylic acid was used to construct a mechanism that withdrew sample solution slowly. A gel of 11 mm×11 mm×4 mm was used and a volume change was caused by changing the temperature, changing the temperature and pH, and using a pH change caused by the enzymatic reaction of glucose oxidase. With the enzyme-loaded gel, the gel shrank most slowly spanning nearly 10 h. The volume change of the gel could be converted into a pressure change in a flow channel with the help of a silicone rubber diaphragm. As a result, the mechanism could withdraw an external solution into the flow channel. The sampling mechanism was incorporated in a system that imitates a mosquito. An external glucose standard solution could be introduced into the system autonomously and the glucose concentration could be monitored continuously using an on-chip micro glucose sensor.