ORP Salinity Sensor - Science Olympiad Gold Medal

Project Dates: Jan - Apr 2024

Description

• An Oxidation-Reduction Potential salinity sensor that measures the NaCl concentration of a solution and displays it on the Arduino Serial Monitor
• The probe consists of a Cu/CuSO₄ half-cell and an Ag wire which generate a voltage when dipped in solution
• Three LEDs indicate the solution’s concentration range
• The device won Gold at the 2024 CT Science Olympiad

Materials & Tools

Mechanical:

• Glass tube
• Rubber stopper
• String
• Bottle cap

Electrical:

• Arduino UNO
• Breadboard
• Resistors (330Ω, 1KΩ, 100KΩ)
• Red, Green, and Blue LEDs
• Male-to-male Jumper wires
• Hookup Wire
• Operational Amplifier
• 60/40 Solder
• 9V Battery

Chemical:

• 0.1M Copper Sulfate Solution
• Silver Wire
• Copper Wire

Tools:

• Arduino IDE
• Ruler
• Wire cutter/stripper
• Soldering iron
• X-Acto knife

Methodology

• Designed a non-inverting Op Amp circuit to amplify the half-cell's signal which is fed into the Arduino
• Experimentally determined a linear relationship between NaCl ppm and voltage with R² = 0.988
• Constructed the half-cell with a glass tube containing 0.1M CuSO₄, a Cu wire, and a thin string as a semi-permeable membrane