Portable and low-cost LED based Spectrophotometer for the Detection of Nitrite in simulated-Urine

This paper describes a portable and inexpensive spectrophotometer for the detection of nitrite in simulated urine, indicating the presence of a bacterial infection in the urinary tract. It is based on a single ultraviolet light-emitting-diode (LED) of peak emission at 370 nm. A silicon pin photodiode was used as a detector to measure the intensity of light passing though a simulated urine sample made in de-ionized water. The electrical current generated by the photodiode was converted to a voltage signal and analysed by a microcontroller. The detection of nitrite was performed by measuring the absorbance of light by the nitrite molecules in the sample using the Beer-Lambert law. The proposed spectrophotometer components are inexpensive and readily available in market. By being portable and controlled by a microcontroller, it provides real-time result to a user. The results obtained by the spectrophotometer were compared with those of a dipstick test. The positive aspect of obtained results would encourage the authors to perform the experimental trials on actual urine samples in future prospects.