Article

Tunable Laser Diode System for Noninvasive Blood Glucose Measurements

Optical Science and Technology Center and the Department of Chemistry, 100 IATL, University of Iowa, Iowa City, Iowa 52242, USA.
Applied Spectroscopy (Impact Factor: 2.01). 01/2006; 59(12):1480-4. DOI: 10.1366/000370205775142485
Source: PubMed

ABSTRACT Optical sensing of glucose would allow more frequent monitoring and tighter glucose control for people with diabetes. The key to a successful optical noninvasive measurement of glucose is the collection of an optical spectrum with a very high signal-to-noise ratio in a spectral region with significant glucose absorption. Unfortunately, the optical throughput of skin is low due to absorption and scattering. To overcome these difficulties, we have developed a high-brightness tunable laser system for measurements in the 2.0-2.5 microm wavelength range. The system is based on a 2.3 microm wavelength, strained quantum-well laser diode incorporating GaInAsSb wells and AlGaAsSb barrier and cladding layers. Wavelength control is provided by coupling the laser diode to an external cavity that includes an acousto-optic tunable filter. Tuning ranges of greater than 110 nm have been obtained. Because the tunable filter has no moving parts, scans can be completed very quickly, typically in less than 10 ms. We describe the performance of the present laser system and avenues for extending the tuning range beyond 400 nm.

Download full-text

Full-text

Available from: Joachim Wagner, Aug 04, 2015
0 Followers
 · 
195 Views
  • Source
    • "In addition, there are overlapping spectral signatures from other components in blood or interstitial fluid. The broad and highly overlapped characteristics of the near infrared absorption bands dictates the need for a spectrum (or several bands of spectra) rather than performing measurements at one or two discrete wavelengths [28]. Furthermore, glucose spectra have a broad shape with a nonmonotonic increase with glucose concentration as would be expected from normal line-shaped absorption spectra. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Optical methods are one of the painless and promising techniques that can be used for blood glucose predictions for diabetes patients. The use of thermally tunable vertical cavity surface-emitting lasers (VCSELs) as the light source to obtain blood absorption spectra, along with the multivariate technique partial least squares for analysis and glucose estimation, has been demonstrated. With further improvements by using data preprocessing and two VCSELs, we have achieved a clinically acceptable level in the physiological range in buffered solutions. The results of previous experiments conducted using white light showed that increasing the number of wavelength intervals used in the analysis improves the accuracy of prediction. The average prediction error, using absorption spectra from one VCSEL in aqueous solution, is about 1.2 mM. This error is reduced to 0.8 mM using absorption spectra from two VCSELs. This result confirms that increasing the number of VCSELs improves the accuracy of prediction.
    IEEE transactions on bio-medical engineering 09/2009; 57(3):578-85. DOI:10.1109/TBME.2009.2032160 · 2.23 Impact Factor
  • Source
    • "There are overlapping spectral signatures from other components in blood or interstitial fluid. The broad and highly overlapped characteristics of the near infrared absorption bands dictates the need for a spectrum (or several bands of spectra) rather than measurements at one or two discrete wavelengths [9]. Furthermore, due to the correlation of glucose with other physiological conditions and components of body fluid as well as lack of a specific one wavelength point reflecting the glucose concentration, glucose spectra have broad shape with non-monotonic increase with glucose concentration as would be expected from normal lineshape absorption spectra. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Continuous glucose monitoring has been shown to help diabetes mellitus patients stabilize their glucose levels, leading to improved patient health. One promising technique for monitoring blood glucose concentration is to use optical absorption spectroscopy. This letter proposes the use of thermally tunable 2.3-mum vertical-cavity surface-emitting lasers to obtain blood absorption spectra. The partial least squares technique is used to determine the glucose concentration from the spectra obtained in aqueous glucose solutions.
    IEEE Photonics Technology Letters 07/2008; 20(11-20):930 - 932. DOI:10.1109/LPT.2008.922371 · 2.18 Impact Factor
  • Source
    • "Although selection of NIR wavelengths is crucial, the brightness of NIR light source is another factor that affects the signal to noise ratio of non-invasive blood glucose system [2] [3]. In view of this, NIR laser diodes with high light intensity had been proposed as NIR light source for use in non-invasive blood glucose monitoring system [2] [3] [4] [5] [6]. Signal processing plays an important role in determination of blood glucose level from NIR data collected from the noninvasive blood glucose monitoring system. "
    [Show abstract] [Hide abstract]
    ABSTRACT: We used neural network for blood glucose level determination in this study. The data set used in this study was collected using a non-invasive blood glucose monitoring system with six laser diodes, each laser diode operating at distinct near infrared wavelength between 1500nm and 1800nm. The neural network is specifically used to determine blood glucose level of one individual who participated in an oral glucose tolerance test (OGTT) session. Partial least squares regression is also used for blood glucose level determination for the purpose of comparison with the neural network model. The neural network model performs better in the prediction of blood glucose level as compared with the partial least squares model.
    Proceedings of SPIE - The International Society for Optical Engineering 03/2008; DOI:10.1117/12.762529 · 0.20 Impact Factor
Show more