Flexible glucose sensor using biocompatible polymers for tear analysis

A flexible amperometric glucose sensor formed on biocompatible polymer was fabricated and tested. The sensor was fabricated by laminating biocompatible polymers and film electrodes. Functional and biocompatible polymers of polydimethyl siloxane (PDMS) and 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymerized with dodecyl methacrylate (DMA) were utilized as the sensor material. Particularly, poly (MPC-co-DMA) (PMD) was not only used as a gas-permeable layer by optimizing the thickness but also used as an enzyme immobilized layer by casting with glucose oxidase (GOD). The sensor measures the glucose concentration as a current change induced by enzyme reaction at the GOD immobilized PMD layer. The advantage of our sensor is its flexibility which enables the sensor to fit a rounded shape of measuring site. The basic characteristics of the biosensor were evaluated using batch measurement system. As a result, output current of the glucose sensor related to the glucose level over a range of 0.100 to 3.00 mmol/l with a correlation coefficient of 0.998. The calibration range includes the reported concentration of tear glucose in normal human subject (0.14 mmol/l). Owing to flexibility and biocompatibility, which are both suitable characteristics for bioinstrumentation, the sensor might be useful for monitoring of glucose concentration in tear fluids. Key-Words: flexible biosensor, tear glucose, rabbit, diabetes, GOD, MEMS, soft contact-lens sensor