Glucose concentration monitoring using a small Fabry-Perot etalon.
Accurate measurements of aqueous glucose concentrations have been made in a double-chamber Fabry-Perot etalon that can be miniaturized for subcutaneous implantation to determine the concentration of glucose in interstitial fluid. In general, optical approaches to glucose detection measure light intensity, which in tissue varies due to inherent scattering and absorption. In our measurements, we compare the spectral positions of transmission maximums in two adjunct sections of an etalon in order to determine the refractive index difference between these sections and therefore we can tolerate large changes in intensity. With this approach, we were able to determine aqueous glucose concentrations between 0 mg/dl and 700 mg/dl within the precision of our reference measurement (+/-2.5 mg/dl or 2% of the measurement value). The use of reference cavities eliminates interference due to temperature variations, and we show the temperature independence over a temperature range of 32 degrees C to 42 degrees C. Furthermore, external filters eliminate interference from large molecule contaminants.
Martini
Joerg
J
Palo Alto Research Center, 3333 Coyote Hill Road, Palo Alto, California 94304, USA. joerg.martini@parc.com
Kiesel
Peter
P
Roe
Jeffrey
J
Bruce
Richard H
RH
D015190:Blood Glucose Self-Monitoring / Q000295:instrumentation*; D002138:Calibration; D004867:Equipment Design; D005947:Glucose / Q000032:analysis*; D018670:Monitoring, Ambulatory / Q000295:instrumentation*; D010316:Particle Size; D019736:Prostheses and Implants; D012031:Refractometry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012710:Serum Albumin, Bovine / Q000737:chemistry; D013696:Temperature
D012710:Serum Albumin, Bovine; D005947:Glucose