The objective is to measure blood sugar levels in diabetic patients with a near infrared non-invasive glucometer.

 

Team Members

Michael DeCasper | Adam Cary | Alastair Knott | Ronen Adany |

Project Poster

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Project Summary

 

Overview

As a diabetic, measuring blood sugar level tends to be painful, time consuming, and costly. The current method (invasive) requires gaining access to blood, collecting a sample with a one-time use enzyme strip, and then correcting blood-sugar levels pharmaceutically with an injection. With the proposed non-invasive method, blood-sugar levels can be measured with an external device attached to the finger.

Objectives

The goal of the non-invasive glucometer is to measure blood sugar levels of the user. Once a design was finalized, the circuit components were simulated and prototyped. Several electrical tests and an anatomical test were conducted to ensure that the glucometer was operating as designed.

Approach

  • The group started by exploring the available scientific research on NIR spectroscopy.
    • Specifically, the molar absorptivity of glucose and other biological molecules as a function of wavelength
  • Once a suitable wavelength was decided, the designs were completed and simulated
  • Design Outputs
    • Constant current circuit for maintaining an output light intensity from the LED
    • Photosensor and current to voltage circuit for measuring the transmitted light
    • Band Pass filter for isolating the oscillation in the transmitted light due to the movement of blood
      • High pass filter with a -3 dB point of 0.1 Hz
      • 4th order Low pass filter with a -3 dB point of 10 Hz
    • Software for reading and displaying the output voltage

Outcomes

The implemented circuits and software work as expected. However, when measuring light absorption by vials with varying concentrations of glucose solutions, an inverse in the Beer-Lambert Law was observed.

  • These results suggest that water absorbs more light than glucose at the selected wavelength (940 nm).
  • Adjusting the wavelength to a suitable harmonic where glucose is more optically active.

The spectral analysis of the signal did not provide any definitive data when the device was attached to a patient.

  • This could be explained in part due to the inverse in the Beer-Lambert observed.