Noninvasive glucose sensing utilizing a digital closed-loop polarimetric approach

Cameron, Brent D.; Coté, Gerard L.

doi:10.1109/10.649993

Cited by 111 publications

(76 citation statements)

References 9 publications

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“…To further improve repeatability and stability while preserving accuracy, Cameron et al developed a faraday-based system that demonstrated the potential to compensate for rotation due to the presence of other optically active components using a digital closed-loop feedback technique with sub-millidegree sensitivity in vitro. 18,19 This same group showed that the time lag between blood and aqueous humor glucose levels is on average less than 5 min in New Zealand rabbits, thus validating the ability of this sensing sight to correlate with blood glucose levels. 20 An eye coupling device was developed to couple the input laser beam through the anterior chamber of the eye for an in vivo system.…”

Section: Introductionmentioning

confidence: 84%

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: 84%

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

2005

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“…1 Several research groups have demonstrated the application of optical polarimetry to glucose sensing in vitro with acceptable repeatability of less than 15-mg/ dl standard error. [2][3][4][5] In contrast, the in vivo performance of this technique has been limited primarily by the inherent time-varying birefringence of cornea due to motion artifact, which makes it difficult to discern the rotation due to glucose. 6 The cornea changes the state of polarization of the transmitted beam due to the structure of corneal stroma, which mainly consists of collagen lamellae.…”

Section: Introductionmentioning

confidence: 99%

Modeling the corneal birefringence of the eye toward the development of a polarimetric glucose sensor

Malik

Coté

2010

J. Biomed. Opt.

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Abstract. Optical polarimetry for monitoring glucose concentration in the aqueous humor of the eye as a potential noninvasive means of assessing blood glucose has promise, but the realization of such an approach has been limited by noise from time-varying corneal birefringence due to motion artifact. Modeling the corneal birefringence of the eye is critically important toward understanding the overall effect of this noise source compared to other changes in the signal, and can aid in design of the polarimetric system. To this end, an eye model is introduced in this work that includes spatially varying birefringence properties of the cornea. The degree of birefringence and the fast axis orientation is calculated as a function of beam position on the anterior chamber. It is shown that the minimum change in polarization vector orientation occurs for beam position near the midpoint between the corneal apex and limbus. In addition, the relative wavelength independence of motion artifact is shown in the same region. The direct consequence of these findings are that a multiwavelength polarimetric system can potentially be utilized to eliminate the effect of time-varying corneal birefringence, and that eye coupling is optimal at the midpoint between the apex and limbus.

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“…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. 10 Chou et al investigated an amplitude-based optical heterodyne approach that employed a Zeeman laser. 11 In a subsequent work by Coté et al, a dual-wavelength system was utilized to minimize the effect of optical confounders in aqueous humor, and potentially, corneal birefringence coupled with motion artifact.…”

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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Noninvasive glucose sensing utilizing a digital closed-loop polarimetric approach

Cited by 111 publications

References 9 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

Modeling the corneal birefringence of the eye toward the development of a polarimetric glucose sensor

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

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