A spectrometer based on smartphones and a low-cost kit for transmittance and absorbance measurements in real-time

Abstract

Recently, the use of smartphones has been proposed as a real option for developing measurement instruments in different areas (e.g. bio-sensors, spectroscopy, electro chemical sensor) due to their processing, visualization, connectivity and image capturing capabilities. In this work, we propose the development of a low-cost miniaturized spectrometer that uses the camera of an Android smartphone and processes the images in a self-developed software (spectrometric Android App). It includes a measurement kit with a cuvette holder, an optical fiber with a connecting element, and a high luminous efficiency white LED. The spectrometric Android App allows an initial wavelength calibration and a subsequent calibration for measuring absorbance/transmittance, to obtain spectral curves in real-time. We validated our prototype with a case study in the industrial area, by measuring the concentration of chrome in tanning liquors, and comparing the results with a calibrated conventional spectrophotometer. Thanks to our approach, measurements can be done in-situ and in real-time, thus allowing optimized tanning processes, without requiring expensive measurement equipment.