Results

Proof of Concept

UV-Vis-NIR Spectrophotometry Trials

To calibrate our device, we needed to show lactic acid detection by absorbance using an IR spectrophotometer. Attempts to detect varied concentrations in water and research-grade acetone are seen in figures 1.

Fig. 1: NIR spectra of lactate absorbance in various media A) Lactate in water, baseline-adjusted B) Lactate in water, baseline-adjusted, with water absorbance overlayed C) Lactate in acetone, baseline-adjusted, with acetone absorbance overlayed — Fig. 1: NIR spectra of lactate absorbance in various media
A) Lactate in water, baseline-adjusted
B) Lactate in water, baseline-adjusted, with water absorbance overlayed
C) Lactate in acetone, baseline-adjusted, with acetone absorbance overlayed

Device Verification

To prove that the LED-photoconductor circuit worked as designed, the two circuits were put close together (<1cm) and the photoconductor output was recorded. A Fourier transform of the output showed strong signal at the LED pulse frequency as seen in figure 2.

Fig. 4: Fourier Transform of our device output signal — Fig. 2: Fourier Transform of our output signal

Conclusion

In the given time frame, a construct of a novel circuit for detection of lactate was developed. We were able to come to the following conclusions:

Our device can detect changes in absorbance, as seen in figure 4.
Further optimization needs to be done to finetune the spectroscopy for various concentrations of lactate.
The lactate signal was virtually undetectable relative to water and other hydrogenated solvents (i.e., low signal-to-noise ratio [SNR]).
Use a deuterated solvent to acquire a better signal and improve SNR.