Vorschau

PDF, Englisch Download (11MB) | Nutzungsbedingungen

Abstract

The continuous surveillance of the body’s glucose concentration is pivotal for the prevention of short- and long-term health complications for people with diabetes. In this thesis, mid-infrared absorption spectroscopy is investigated as an alternative to conventional enzyme-based glucose monitors. To this end, a quantum cascade laser-based sensor system is designed and implemented with the goal to serve as an optical port for continuous, real-time spectroscopy in vivo. This transflection sensor shows high sensitivity in vitro with a glucose error of prediction as low as 4mg/dL in pure glucose solutions, 10mg=dL in the presence of proteins and 21mg=dL in the presence of other carbohydrates. The impact of the temperature on the optical signal is investigated both theoretically and experimentally. Even under temperature variations up to 15C a glucose prediction error as low as 18:5mg/dL can be achieved. Adding a porous membrane hinders the diffusion of large molecules into the sensor while enabling glucose diffusion on the targeted time scale (<5 minutes). Finally, a stable glucose permeation and concentration prediction over more than 1 month demonstrates the potential of a quantum cascade laser-based transflection technology for application in a long-term implant for continuous glucose sensing.