Peningkatan Kinerja Kolorimetri Multi Spektra Berbasis Arduino melalui Optimasi Ketebalan Diffuser dan Sudut Lensa Fokus

Abstract

Azo group dyes, such as Congo Red (CR), Procion Red (PR), and Remazol Red (RR), have the potential to pose a risk to human health, being reported as carcinogenic, mutagenic, and toxic, so an accurate and efficient analysis method is needed to detect them. This study developed an RGB–Arduino Uno R3-based multispectral colorimeter, optimized through diffuser thickness and focusing lens angle, to evaluate its potential as an alternative to commercial visible spectrophotometers, with the advantages including a simpler analysis process, a smaller instrument size, and flexibility for use in various field conditions. The device is designed by integrating an RGB LED light source, a BH1750 light sensor as a detector, an Arduino Uno R3 microcontroller, a diffuser film, and a focusing lens, all housed in a black casing to minimize external light interference. Testing was conducted using 36 combinations of LED light colors across a wavelength range of 380–730 nm, optimized with diffuser thicknesses of 0, 1, and 2 layers and lens angles of 15°, 30°, 45°, 60°, and 90°. The results showed that a 2-layer diffuser produced full homogeneity across all 36 light color combinations, while a 30° lens angle provided the best balance between light homogeneity and increased intensity. Spectrum scanning results showed a broader absorbance response compared to the visible spectrophotometer, with a shift in maximum wavelength for each dye (CR: 460 nm vs 496 nm; PR: 511 nm vs 538 nm; RR: 511 nm vs 540 nm). Performance comparison indicated high linearity (R² = 0.9608–0.9975), strong Pearson correlation coefficients (r = 0.976–0.998), and acceptable LOD, LOQ, and precision values, though still lower than the commercial spectrophotometer. These findings demonstrate that the developed multispectral colorimeter is suitable for simple quantitative analysis of azo dyes, with Remazol Red showing the best measurement performance, and overall performance approaching that of commercial spectrophotometers.