[Experiments aimed at developing an implantable and continuously functioning glucose sensors based on polarimetry]

In vitro and in vivo experiments devised with the aim of developing a permanently implantable glucose sensor based on polarimetry are described. It was found that in ultrafiltrated human blood plasma the overall optical rotation was 94% specific for glucose, and that polarisation photometry yielded a sufficiently sensitive signal for in vivo glucose detection. The three types of capillary membrane intended for implantation that we tested, revealed an in vitro response time to glucose concentration of 10 minutes; when implanted, they maintain this over a period of weeks, during which time the same glucose concentrations can be measured daily in ultrafiltrated capillary fluid as in the blood of the animals (guinea pigs). The drop in glucose concentration induced 20 minutes after a single administration of insulin can also be detected in both fluids. The experiments described indicate that the development of an implantable polarimetric glucose sensor is possible.