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MZI Based Biosensing. Joe Novak. Outline. What Is An MZI? How Does It Work? Application In Biosensing Device Production Thoughts on Research. What Is An MZI?. Mach-Zehnder Interferometer Light based detection via interference. How Does It Work?. Power split into two equal beams
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MZI Based Biosensing Joe Novak
Outline What Is An MZI? How Does It Work? Application In Biosensing Device Production Thoughts on Research
What Is An MZI? • Mach-Zehnder Interferometer • Light based detection via interference
How Does It Work? • Power split into two equal beams • Reference beam • Sample Beam • Interference produces power at detector one(constructive) and no power at detector two(destructive) • Introduction of sample causes change in phase of sample beam, resulting in power differences at outputs
Modifications Bio-sensing arm s Powersplitter Power combiner L Phase shift reference arm Output reduced to a single detector Light paths of same length Medium consisting of waveguide materials
Waveguide Structure W = 3 μm H = 250 nm H = 20 nm W Si H h SiO2 • Several factors determine structure size • Device Functionality • Mode Selection • Sensitivity • Ease of Production • Lithography • Deposition/Etching
Biosensing Application EvanescentWave SurfaceFunctionalization Waveguide • Selected materials attach to biological handles • Presence of material changes effective refractive index of sample arm • Phase shift occurs in sample beam
Biosensing Application Recombination of sample beam with reference beam reduces power based on amount of phase shift Observed output capable of inferring the presence of minute amounts of material
Pros and Cons of MZI Sensor • Pros • Detection by output power rather than fringe patterns • Simple production, no moving parts • High theoretical sensitivity • Cons • Coupling misalignment introduces error • Larger waveguide structure increases sensing area but introduces higher order modes
Device Production Sensors created on SOI(Silicon On Insulator) wafers Various Etching, Photolithography, and Deposition steps Processes utilizing Silicon and Silicon Dioxide have been researched for decades
Waveguide Construction (5) silicon dioxide deposition (1) PR application silicon PR Silicon dioxide (2) development (6) PR application and development (3) silicon etching (7) silicon dioxide etch (4) strip PR
Thoughts on Research • Multidisciplinary benefits • Insights and different viewpoints are invaluable • Research Process • Simulation and research during design can save months • Determination and endurance • Nothing is perfect, setbacks provide experience