March 4, 2019
Society of Photo-Optical Instrumentation Engineers

Development of a low cost SWIR spectrometer for low resource settings (conference presentation)

Matthew D. Keller, James W. Stafford, Wenbo Wang, Ryan Calderon, Benjamin K. Wilson

Optical spectroscopic devices have historically been too expensive or not portable enough to take full advantage of their abilities to offer real-time, on-site, objective results, especially in the developing world. Recent advancements toward smaller and cheaper hardware, especially in the visible and near infrared (NIR) ranges, could enable widespread use in low resource settings, down to a rural health clinic or at the individual farm level. We recently designed and tested a spectroscopic device with these goals in mind. It is based on an initial commercial version of a low cost MEMS spectral detection chip operating in the NIR, or more properly short wave infrared (SWIR) region. Custom optics, electronics, and mechanical designs were created to produce a complete handheld system capable of operation in the lab or in the field. Initial lab testing indicated excellent reproducibility both within and between five different devices. We have verified desired performance (e.g. acceptable signal to noise for target integration times, spectral features equivalent to lab-grade devices, etc.) for applications including pharmaceutical analysis and for analyzing multiple agricultural materials, including soils, plants, fertilizers, and manures. We have also developed a custom mobile app to accompany the devices in upcoming field testing, which will validate their performance in realistic settings in sub-Saharan Africa.

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