title: Real-time, closed-loop dual-wavelength optical polarimetry for glucose monitoring.
abstract: The development of a real-time, dual-wavelength optical polarimetric system to ultimately probe the aqueous humor glucose concentrations as a means of noninvasive diabetic glucose monitoring is the long-term goal of this research. The key impact of the work is the development of an approach for the reduction of the time-variant corneal birefringence due to motion artifact, which is still a limiting factor preventing the realization of such a device. Our dual-wavelength approach utilizes real-time, closed-loop feedback that employs a classical three-term feedback controller and efficiently reduces the effect of motion artifact that appears as a common noise source for both wavelengths. In vitro results are shown for the open-loop system, and although the dual-wavelength system helps to reduce the noise, it is shown that closed-loop control is necessary to bring the noise down to a sufficient level for physiological monitoring. Specifically, in vitro measurement results with the closed-loop dual-wavelength approach demonstrate a sensitivity of 12.8 mg/dl across the physiologic glucose range in the presence of time-variant test cell birefringence. Overall, it is shown that this polarimetric system has the potential to be used as a noninvasive measure of glucose for diabetes.
authors.affiliation: Texas A&M University, Department of Biomedical Engineering, College Station, Texas 77843-3120, USA. malik@tamu.edu
authors.forename: Bilal H
authors.initials: BH
authors.lastname: Malik
authors.forename: Gerard L
authors.initials: GL
authors.lastname: Coté
mesh_terms: D001786:Blood Glucose / Q000032:analysis; D005246:Feedback; D005947:Glucose / Q000032:analysis* / Q000737:chemistry; D016018:Least-Squares Analysis; D016014:Linear Models; D008962:Models, Theoretical; D008991:Monitoring, Physiologic; D009068:Movement; D057109:Scanning Laser Polarimetry / Q000295:instrumentation* / Q000379:methods*
chemical_list: D001786:Blood Glucose; D005947:Glucose