This work presents two novel devices with a microcontroller and two different light sensors, namely, Light Dependent Resistor (LDR) and Ambient Light Sensor (ALS), which can provide a quantitative output from the colorimetric variations of citrate capped borohydride reduced silver nanoparticles (AgNPs) and citrate capped gold nanoparticles (AuNPs) upon addition of melamine adulterated milk. The limit of detection (LOD) of the LDR setup with AgNPs and AuNPs was found to be 1.24 ppm and 1.68 ppm, respectively, and the corresponding recovery rates were 92.86% and 88.57%, respectively. The device fabricated with the ALS with AgNPs displayed a recovery rate of 97.14% with a LOD value of 0.64 ppm.