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MSD1 Senior Design Project- Oxygen Gas Sensor

MSD1 Senior Design Project- Oxygen Gas Sensor

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MSD1 Senior Design Project- Oxygen Gas Sensor

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  1. MSD1 Senior Design Project- Oxygen Gas Sensor P09051 Samuel Shin Jeremy Goodman Sponsor: RIT uE & EE department Project Guide: Professor Slack

  2. Agenda • Project description • High Level Customer Needs/ Eng Specs • Concept Description & Rationale • System Architecture • High Risk Assessment • Detailed Assembly • Emitter and Receiver Circuit • Photodiode Fabrication • Testing Results • Future Plans

  3. Project Description • Oxygen gas detection via fluorescence quenching. • Based on Tris-Ruthenium[II](dichloride) material incorporated in an oxygen-permeable polymer • Responds to gaseous %Oxygen which changes fluorescent intensity and lifetime • Higher O2 conc = decreased intensity and lifetime • Method has been researched and is widely used • Expensive • Equipment not readily available to everyday user • Plan is to design a complete cost & size- efficient sensor system for the measurement of % Oxygen

  4. High Level Customer Needs / Eng Specs • Provide consistent measurement results • LED pulse width at 100ms • Entering wavelength at 455nm • Cost and size-effective • Commercially available LED source • Standard electronic components for signal conditioning • Low-cost, high performance optical filters • RIT SMFL designed/built photodetector • Ru(dpp) polymer created in RIT Chem dept.

  5. Concept Description/ Rationale • Incorporate the entire system inside a light-tight box • Inject fixed amounts of nitrogen and oxygen to exhibit an environment with fixed %Oxygen

  6. System Architecture Input Signal (100ms pulse width from function generator) LED Pulsing Circuit (455nm) Ru(dpp) Thin Film (fluorescent material) – emitting wavelength of 613nm Optical & Signal Conditioning Amplified Signal in Oscilloscope (I or V vs. Time)

  7. High Risk Assessment • Still a proof of concept • Design will have to be modified to match needs • Unclear Parameters will exist • Where noise is coming from, etc • Materials • Creating Ru(dpp) polymer has to be done with help from a faculty member • Funding • Assembly of chamber, gas canisters needed. • Difficult to obtain funds

  8. Final Results- LED Emitter Circuit • Circuit assembled to exhibit a steady source of LED light, in a set fixed pulse. • Used a power PMOSFET • Completed assembly using vectoboard and soldering components.

  9. Final Results- Receiver Circuit • Circuit assembled to receive the light source and transfer it into voltage output. • Used photovoltaic amplifier circuit configuration. • Completed assembly using vectoboard and soldering components. • Completed circuit demonstration in lab, and also with complete light-tight box. • Used commercial photodiode for test.

  10. Photodiode Planning • Two Architectures – 4” n-type silicon • Lateral (Finger) Diode • Small Active Area • Fast Response Time • Planar Diode • Large Active Area • Slow Response Time • Tunable Junction Depth (Wavelength Selectable) • Fabricated in the RIT SMFL

  11. Photodiode Design PLANAR PHOTODIODE P-Well Implant Finger Contacts N+ Implant Contact Ring N-Type Wafer N-Type Wafer P+ Implant LATERAL PHOTODIODE

  12. Photodiode Fabrication Process

  13. Photodiode Fabrication Process

  14. Photodiode Fabrication Process

  15. Photodiode Results - Responsivity ↑ Active Area Tuned Junction ↑ Responsivity GREATER SIGNAL! BUT ↑ DARK CURRENT! PLANAR >2x Difference Responsivity (A/W) LATERAL Wavelength Planar responsivity >2x greater than Lateral!

  16. Photodiode Results - Capacitance ↑ Surface Area ↑ Capacitance ↑ Response Time SLOWER DIODE! PLANAR LATERAL Planar capacitance much higher than Lateral

  17. Photodiode Conclusion Planar likely candidate for Fluorescence Spec. • Planar diode had increased responsivity • Higher Signal from Fluorescence Signal • Higher Dark Current • Lateral diode had low capacitance • Fast Response Time

  18. Testing Results Plan was to assemble a tight flow chamber with valves with oxygen and nitrogen flowing in. Emitter and receiver circuit showed proper required behavior as outlined in specifications and customer needs. Limited testing environment available, but still showed a change in intensity, as specified.

  19. Strong / Weak Points of Design/ Room for future research & improvement • Strong points of final design • Was able to exhibit a possible, more affordable alternative. • Introduced cost effective fabrication method of photodiode. • Weak points & places for improvements • Actual testing of chamber incomplete • Abnormal behavior in emitter circuit • Needed more people in respective fields • Needed more funding

  20. Conclusion • Project description • High Level Customer Needs/ Eng Specs • Concept Description & Rationale • System Architecture • High Risk Assessment • Detailed Assembly • Emitter and Receiver Circuit • Photodiode Fabrication • Testing Results • Strengths & weakness of design, plans for future research