title: Glucose-sensitive membrane and infrared absorption spectroscopy for potential use as an implantable glucose sensor.
abstract: The applicability of using infrared absorption spectroscopy for an implantable glucose sensor was tested by measuring absorbance at 9.66 microns for glucose in aqueous solution at known concentrations. A commercial Fourier transform infrared spectrometer was used with an attenuated total reflection technique (ATR). Absorbance measurements were reproducible and linearity was excellent (coefficient of correlation: 0.996), in spite of pH and temperature changes over values that span the human physiologic ranges (pH 6.8-7.8, temperature, 32-43 degrees C) and 18-34% decreases in incident infrared energy. The minimum detectable concentration of glucose, however, was 31 mmol/L (560 mg/d) and, to use infrared sources and detectors compatible with an implantable device, an absorbance peak between 1 and 3 microns must be used. To solve the detection sensitivity and wavelength problems, the ATR prism was coated with a hydrophobic liquid membrane. The absorbance of water varied at 2.95 microns in inverse linear proportion to glucose concentration between 2-31 mmol/L (35-560 mg/dL, r = -0.992). Estimated incident infrared energy at 2.95 microns (0.2 micron bandwidth) was low enough to theoretically allow the use of a lithium battery small enough for implantation. These findings support the concept of using infrared absorption spectroscopy for an implantable glucose sensor.
authors.affiliation: Department of Internal Medicine, Kettering Medical Center, Ohio.
authors.forename: R J
authors.initials: RJ
authors.lastname: Robinson
authors.forename: S D
authors.initials: SD
authors.lastname: McDonald
mesh_terms: D015374:Biosensing Techniques; D001774:Blood Chemical Analysis / Q000295:instrumentation / Q000706:statistics & numerical data; D001786:Blood Glucose / Q000032:analysis; D005069:Evaluation Studies as Topic; D005947:Glucose / Q000032:analysis*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008567:Membranes, Artificial; D019736:Prostheses and Implants; D012680:Sensitivity and Specificity; D013055:Spectrophotometry, Infrared; D013696:Temperature
chemical_list: D001786:Blood Glucose; D008567:Membranes, Artificial; D005947:Glucose