Microdegree polarimetry using a diode laser for glucose detection

Goetz, M.J.; Fox, M.D.; Northrop, Robert B.

doi:10.1109/nebc.1992.285971

Cited by 11 publications

(9 citation statements)

References 5 publications

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“…15 Following their work, Goetz reported a closed-loop feedback system with less than a millidegree standard deviation using a faraday rotator for signal modulation and feedback. 16 In order to be able measure other optically active compounds, King et al…”

Section: Introductionmentioning

confidence: 99%

Dual-wavelength polarimetry for monitoring glucose in the presence of varying birefringence

2005

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In a continuing effort to develop a noninvasive means of monitoring glucose levels using the aqueous humor of the eye, a dual wavelength system has been developed in order to show that varying birefringence, similar to what is seen with a moving cornea, can be compensated. In this paper a dual wavelength, closed-loop, system was designed and a model was developed to extract the glucose concentration information. The system and model were tested using various concentrations of glucose in a birefringent test cell subject to motion artifact. The results show that for a static, non-moving sample, glucose can be predicted to within 10 mg/dl for the entire physiologic range (0-600mg/dl) for either laser wavelength (523nm or 635nm). In the presence of moving birefringence, each individual wavelength produced standard errors on the order of a few thousand mg/dL. However, when the two wavelengths are combined into the developed model, this error is less than 20mg/dL. The approach shows that multiple wavelengths can be used to drastically reduce the error in the presence of a moving birefringent sample. This research also shows promising preliminary results that the error is less than 25mg/dl in presence of a motion induced cornea birefringence artifact in NZW rabbits' eyes.

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Section: Introductionmentioning

confidence: 99%

Dual-wavelength polarimetry for monitoring glucose in the presence of varying birefringence

2005

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“…The equation for the electric field at the detector can be derived using the Jones vector calculus. 25 For a given wavelength, the optical system can be modeled as a linear polarizer, followed by two Faraday rotators (compensator and modulator), the eye model, and finally the analyzer. When the initial polarizer is aligned with either the fast or the slow axis, the resulting system matrix representation is where V system is the system-equivalent Jones matrix; ϕ g and ϕ f represent changes in optical rotation due to glucose and optical rotation from the Faraday compensator, respectively; δ 1 ðtÞ and δ 2 ðtÞ are the amount of retardation from entering and exiting the cornea as a function of time; ΔδðtÞ ¼ δ 1 ðtÞ − δ 2 ðtÞ is the difference between them; θ m is the modulation depth for the Faraday modulator; and ω m is the modulation frequency.…”

Section: Optical Systemmentioning

confidence: 99%

Dual-wavelength polarimetric glucose sensing in the presence of birefringence and motion artifact using anterior chamber of the eye phantoms

2013

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Abstract. Noninvasive glucose monitoring is being investigated as a tool for effectively managing diabetes mellitus. Optical polarimetry has emerged as one such method, which can potentially be used to ascertain blood glucose levels by measuring the aqueous humor glucose levels in the anterior chamber of the eye. The key limitation for realizing this technique is the presence of sample noise due to corneal birefringence, which in the presence of motion artifact can confound the glucose signature in the aqueous humor of the eye. We present the development and characterization of a real-time, closed-loop, dual-wavelength polarimetric system for glucose monitoring using both a custom-built plastic eye phantom (in vitro) and isolated rabbit corneas (ex vivo) mounted in an artificial anterior chamber. The results show that the system can account for these noise sources and can monitor physiologic glucose levels accurately for a limited range of motion-induced birefringence. Using the dual-wavelength system in vitro and ex vivo, standard errors were 14.5 mg∕dL and 22.4 mg∕dL, respectively, in the presence of birefringence with motion. The results indicate that although dual-wavelength polarimetry has a limited range of compensation for motion-induced birefringence, when aligned correctly, it can minimize the effect of time-varying corneal birefringence for a range of motion larger than what has been reported in vivo.

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“…Goetz et al investigated a polarimetric system that used an integrator as the feedback element, and they were able to measure incremental rotation in a precision rotational mount with microdegree sensitivity. 8 King et al reported a multispectral polarimetric system in order to account for other optically active components in the aqueous humor, which was based on modulation and compensation via a Pockels cell. 9 Cameron and Coté reported a system similar to Rabinovitch, with a digital closed-loop controller that significantly enhanced the stability and repeatability of the system.…”

Section: 23mentioning

confidence: 99%

“…Several optical modalities have been employed as means to ascertain glucose levels noninvasively. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] These include, but are not limited to, optical coherence tomography ͑OCT͒, 2-4 optical polarimetry, [5][6][7][8][9][10][11][12] and spectroscopic techniques such as Raman, 13,14 mid-infrared ͑MIR͒, 15 near-infrared ͑NIR͒, 16,17 and fluorescence spectroscopy. [18][19][20][21] The focus in this paper is in addressing the critical issue of corneal birefringence in the presence of eye motion for glucose monitoring using optical polarimetry.…”

Section: Introductionmentioning

confidence: 99%

Real-time, closed-loop dual-wavelength optical polarimetry for glucose monitoring

Malik

Coté

2010

J. Biomed. Opt.

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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 dualwavelength 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 openloop 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 dualwavelength 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.

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Microdegree polarimetry using a diode laser for glucose detection

Cited by 11 publications

References 5 publications

Dual-wavelength polarimetry for monitoring glucose in the presence of varying birefringence

Dual-wavelength polarimetry for monitoring glucose in the presence of varying birefringence

Dual-wavelength polarimetric glucose sensing in the presence of birefringence and motion artifact using anterior chamber of the eye phantoms

Real-time, closed-loop dual-wavelength optical polarimetry for glucose monitoring

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