This proposal describes the design and testing of an innovative implantable glucose sensor using pH-sensitive hydrogels and pressure sensing technology. This system is based on pressure transducers and/or piezoelectric transducers in combination with pH-sensitive hydrogels containing glucose oxidase (GOD). The hydrogels swell in response to decreases in pH due to the presence of pH-sensitive pendant groups in the gel. Decreases in pH within the gel occur in response to increases in the surrounding glucose concentration, because gluconic acid is generated by GOD when glucose and oxygen are present. The pH-sensitive hydrogels are swollen by an amount which is proportional to glucose concentration. The swollen hydrogels will give an elevated pressure within the limited chamber which encloses the gel, which can be detected using miniature pressure sensors of well-tested design. Thus glucose concentrations can be continuously monitored using the combination technologies of hydrogels and pressure sensors. The optimal conditions of pH-sensitive gels such as cross-link density, number and type of pendant groups, GOD level, catalase level, gel thickness, etc. will be determined by in vitro measurements of sensor response time, linearity, and oxygen sensitivity, and used to establish the technical merit and feasibility of pressure-based glucose monitoring in Phase I.
Implantable glucose biosensors developed herein could be commercially applied as clinical sensors.
