DESIGN OF CAMERA-BASED REAL TIME DIGITAL SALINITY MEASUREMENT TOOL FOR SHRIMP FARMING BY UTILIZING SURFACE PLASMON RESONANCE PHENOMENON

• Main Author: Mukharom Darozat, Fajar
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/67334
• Institution: Institut Teknologi Bandung

In shrimp farming, maintaining the water parameter values so that they are always within a certain value range is very necessary so that the cultivation process is optimal. Water salinity is one of these parameters. This study aims to create a camera-based real-time salinity measurement tool that utilizes the phenomenon of surface plasmon resonance (SPR). SPR has several advantages to be used as a method of measuring salinity. The process of making the instrument involves a number of stages, including designing a 3D model, designing an electronic schematic as a control system, making firmware for a control system, creating a 3D model using a 3D printer, and creating an interface application so that the measuring instrument can communicate with the computer. A 650 nm red laser was used as the SPR excitation monochromatic light source. A 28BYJ48 12V stepper motor is used as the laser drive. Two prototype SPR detectors have been built, one visual SPR detector and one digital SPR detector. The visual SPR detector is designed in such a way that the position of the prism with respect to the laser rotating axis can be varied and does not use a light sensor. The digital SPR detector uses an OV2640 camera as a light sensor and an ESP-32 as a controller, while the prism position is fixed. Digital data from the digital detector is sent to the computer wirelessly using HTTP protocol. Experiments using a visual SPR detector have shown that the position of the prism relative to the laser axis of rotation has an effect on whether the SPR can be detected or not. Experiment on the relation between total pixel value and light intensity shows a linear trend with regression gradient 40409 LSB/lux. This is evidence that light intensity information can be replaced with total pixel value information. Experiments using a digital SPR detector were successful in detecting SPR patterns for sample air, demineralized water, 20 ppt NaCl solution, and 50 ppt NaCl solution. The SPR pattern produced by the detector is very similar to the pattern produced by the winspall application, with a difference in the SPR angle at 0.9º for air samples and 0.1º for demineralized water samples. The test results for 20 ppt NaCl and 50 ppt NaCl samples show that the detector is able to distinguish liquids with different salinities. The total normalized pixel values for samples of demineralized water, 20 ppt NaCl solution, and 50 ppt NaCl solution at an angle of incidence of 71.53º are 0.062; 0.258; and 0.463. These results are evidence that the detector can distinguish liquid samples based on their salinity.