%A NIM.: 21106020014 Nurul Dwi Hastuti %O Frida Agung Rakhmadi, S.Si., M.Sc. dan Bagus Haryadi, S.Si., M.T., Ph.D. %T RANCANG BANGUN ALAT UKUR KADAR ALKOHOL MENGGUNAKAN SENSOR OPTIK BERBASIS HUKUM BEER-LAMBERT %X This research aims to design and develop an alcohol concentration measuring device based on optical sensors using the principle of the Beer-Lambert law. The problems found in conventional alcohol measurement methods which tend to be time-consuming, costly, and require specialized expertise form the basis for conducting this study. The Beer-Lambert law states that light absorbance is directly proportional to the concentration of a substance in a solution, which can be utilized as the fundamental principle for designing an alcohol concentration measuring instrument. The developed device consists of five main subsystems: an input subsystem using a UV LED as the light source, a sensor subsystem using a photodiode to detect light intensity, a microcontroller subsystem using Arduino Nano for reading and Arduino IDE for data processing, a data display subsystem using an I2C LCD, and a data processing subsystem based on Microsoft Excel. The method used in absorbance data processing is based on the Beer-Lambert law, with a linear regression approach between absorbance values and alcohol concentration. The design results show that the system is capable of detecting changes in light intensity linearly with respect to the alcohol concentration in the sample. The resulting standard curve produces the regression equation: % alcohol concentration = 0.0333A + 0.01, where A is the absorbance, and it indicates that the device has a high sensitivity to variations in alcohol levels. Instrument testing showed very satisfactory results, with a linearity value of 0.9741, an accuracy of 99.50%, and a repeatability precision of 99.96%, which exceed the minimum thresholds set by the SNI ISO 17025:2017 standard. This proves that the developed alcohol concentration measuring device is not only accurate and precise but also stable and feasible to be used as an alternative measurement tool in scientific and industrial applications. Overall, this research demonstrates that an approach based on the Beer-Lambert law and optical sensor technology can be used to design an alcohol concentration measuring device that is effective, efficient, and user-friendly. %K Sensor Optik, Kadar Alkohol, Hukum Beer-Lambert, Arduino Nano, Absorbansi, Regresi Linear %D 2025 %I UIN SUNAN KALIJAGA YOGYAKARTA %L digilib71322