P09051

1. P09051 Low-Cost Oxygen Sensor Via Fluorescence Spectroscopy Professor Slack Samuel H Shin Professor Rommel Jeremy V Goodman Guide: Electrical Engineering Dept. Electrical Engineering Dept. Guide: Microelectronic Engineering Dept. Microelectronic Engineering Dept. • Mission Statement • To design, build, and test a low-cost oxygen sensor by taking advantage of the fluorescent properties of Tris-Ruthenium(II) Dichloride-based compounds. Device uses a custom-made sensing film of Tris(2,2’-bipyridal)Dichlororuthenium(II) as the oxygen indicator with a Philips LumiLED high-power LED as the excitation source and a Hamamatsu PIN Photodiode as a receiver. • Motivation • Most fluorescent spectroscopy systems are accurate, but expensive • Fluorescent oxygen sensors are in demand in industrial, environmental, and biomedical applications • Background • Commercial sensors are available that utilize the fluorescence spectroscopic technique of oxygen measurement. The versatility of the technique enables its use in sensing volumes ranging from micro-scale and larger, all depending on the size of the sensing thin film. • Requirements • Cost-effective method of measuring molecular oxygen concentration in a gaseous environment • Use low-cost electronics and materials which still provide for accurate results • Provide consistent results during life of the sensor Fluorescence Spectroscopy System Outline Customer Needs Customer Specifications Design Process • Main Requirements: • High power LED with an emission wavelength of 455nm (max absorption into sensor thin film) • Large photocurrent response from photodiode to increase Signal-to-Noise Ratio • Fast response time of photodiode will lead to more precise fluorescent lifetime measurements Project included the following design phases: Design and Build Support Electronics for LED and Photodiode Create Oxygen Sensing Thin Film Design and Fabricate Photodiode in the RIT Semiconductor and Microsystems Fabrication Laboratory (SMFL) Assemble Sensor Prototype Test Prototype in Custom-Built Gas Flow Chamber Gather Results to Generate a Stern-Volmer Characteristic Curve Support Electronic Schematic Generation Photodiode – Transimpedance Amplifier with Custom Signal Filtering LED – Pulsing Circuit Assembled Support Electronics Photodiode Assembly (S5973) LED Assembly (455nm LED) Stern-Volmer Kinetic Relationship Long-Pass Optical Filter Integration to Reduce LED to Photodiode Interference Applies to the change in quantum yield of a photochemical reaction in the presence of a quenching element: Φ0/ Φ = Normalized Fluorescence Intensity (Recorded by Photodiode) Φ0 = Measured Intensity in Absence of Oxygen Φ = Measured Intensity in Presence of Oxygen [Q] = Concentration of Elemental Quencher (Oxygen) ksv = Stern-Volmer Constant (Quenching Efficiency of Sensor) Oxygen Quenching Phenomenon Sensor WITHOUT Optical Filter Stray light from LED Sensor WITH Optical Filter No Stray Light Visible Fluorescence Indicator Emits Fluorescence Oxygen Molecule Strikes Indicator Energy Transfer Indicator  Oxygen Indicator Excited by 455nm λ Indicator Ceases to Fluoresce, Decrease in Photonic Signal * Special thanks to JayadevanRadhakrishnan, Dr Robert Pearson, the RIT EE and μE departments, Dr Christopher Collison, Rich Deneen, Hamamatsu Photonics, Philips LumiLEDs, the RIT SMFL