msd1 senior design project- oxygen gas sensor
DESCRIPTION
MSD1 Senior Design Project- Oxygen Gas Sensor. P09051 Samuel Shin Jeremy Goodman Sponsor: RIT uE & EE department Project Guide: Professor Slack. Agenda. Project description High Level Customer Needs/ Eng Specs Concept Description & Rationale System Architecture High Risk Assessment - PowerPoint PPT PresentationTRANSCRIPT
MSD1 Senior Design Project- Oxygen Gas SensorP09051Samuel ShinJeremy GoodmanSponsor: RIT uE & EE departmentProject Guide: Professor Slack
AgendaProject descriptionHigh Level Customer Needs/ Eng
SpecsConcept Description & RationaleSystem ArchitectureHigh Risk AssessmentDetailed Assembly
◦ Emitter and Receiver Circuit◦ Photodiode Fabrication
Testing ResultsFuture Plans
Project DescriptionOxygen 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
High Level Customer Needs / Eng SpecsProvide 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.
Concept Description/ RationaleIncorporate the
entire system inside a light-tight box
Inject fixed amounts of nitrogen and oxygen to exhibit an environment with fixed %Oxygen
System ArchitectureInput 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)
High Risk AssessmentStill a proof of concept
◦ Design will have to be modified to match needs Unclear Parameters will exist
Where noise is coming from, etcMaterials
◦ 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
Final Results- LED Emitter CircuitCircuit assembled
to exhibit a steady source of LED light, in a set fixed pulse.◦Used a power
PMOSFETCompleted
assembly using vectoboard and soldering components.
V 1
TD = 0
TF = 5 nP W = 1 mP E R = 1 0 m
V 1 = 5
TR = 5 n
V 2 = 1
M 1
M b re a k P
V 25 v d c
0
R 12 . 6
0
D 1D 1 N 4 1 4 9
0
V
I
V
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.
Photodiode PlanningTwo 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
Photodiode Design
N-Type Wafer P+ Implant
N+ Implant
Finger Contacts
LATERAL PHOTODIODE
N-Type Wafer
P-Well Implant
Contact Ring
PLANAR PHOTODIODE
Photodiode Fabrication Process
Photodiode Fabrication Process
Photodiode Fabrication Process
Photodiode Results - Responsivity
Planar responsivity >2x greater than Lateral!
400 500 600 700 800 900 1000 11000
0.1
0.2
0.3
0.4
0.5
Wavelength (nm)
Pow
er (
A/W
)
PlanarLateral
PLANAR
LATERAL
>2xDifferenc
e
Wavelength
Resp
onsiv
ity (A
/W)
↑ Active AreaTuned Junction↑ Responsivity
GREATER SIGNAL!
BUT↑ DARK CURRENT!
Photodiode Results - CapacitancePlanar capacitance much higher than
Lateral
-20 -18 -16 -14 -12 -10 -8 -6 -4 -2 00
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2x 104
Voltage (V)
Capa
cita
nce
per u
nit A
rea
(pF/
cm2)
PlanarLateral
PLANAR
LATERAL
↑ Surface Area↑ Capacitance↑ Response Time
SLOWER DIODE!
Photodiode ConclusionPlanar diode had increased
responsivity◦Higher Signal from Fluorescence
Signal◦Higher Dark Current
Lateral diode had low capacitance◦Fast Response TimePlanar likely candidate for Fluorescence
Spec.
Testing ResultsPlan 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.
Strong / Weak Points of Design/ Room for future research & improvementStrong 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
ConclusionProject descriptionHigh Level Customer Needs/ Eng SpecsConcept Description & RationaleSystem ArchitectureHigh Risk AssessmentDetailed Assembly
◦ Emitter and Receiver Circuit◦ Photodiode Fabrication
Testing ResultsStrengths & weakness of design, plans for
future research