S Outline S Project Background S Design Specifications S Components - - PowerPoint PPT Presentation

S Not-a-Drop Spectrophotometer Project Update

Michael Shang 12.05.2016

Outline

S Project Background S Design Specifications S Components of a Spectrophotometer S Pugh Analysis S Budget Proposal

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Project Background

Current Market and Need

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Market: Low-volume spectrophotometers for measuring concentration of proteins and nucleic acids

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Need: Low-cost instruments for basic analysis of biological samples while preserving sample volume and minimizing contaminants

Nanodrop 2000 Orion AQ8000

The Nucleotube

S Designed by Spectrum Perception S Total Volume: 1.5 mL

Optical Region Volume: 6 μL

Body Legs Optical Region

Project Scope

S Design and prototype a low-cost spectrophotometer that

is compatible with the Nucleotube and measures concentration and purity of nucleic acid samples.

S No changes to scope, team responsibilities, or design

schedule

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Design Specifications

Product Specifications

Absorbance Accuracy +/- 5.0% of known standard across entire range (10% for prototype) Absorbance Range Linear from 0.1 – 300 Repeatability +/- 2.0% between measurements Detection Limit 2.0 ng/µL Measurement Time < 10.0 s Number of Samples Measured at Once 1

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Includes LED display that reports:

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Absorbance – at 260nm and 280nm wavelengths

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Percent transmittance

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Purity - A260/A280 ratio for DNA/RNA applications

Design Considerations

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Cost

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Accuracy

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Ease of Implementation

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Portable (size, power required)

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Reliability

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Sensitivity

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Modularity

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Components of a Spectrophotometer

Components: Light Source

S Produces UV light that passes through sample to

detector

S Major influence on all design considerations

Deep UV LED Halogen/Deuterium Lamp UV Laser

Components: Optical Guides

S Define the path in which light travels through the device S Influences sensitivity and ease of implementation

Mirrors/Lens Fiber Optics

Components: Light Detector

S Silicon Photodiode

S Semiconductor devices that convert light into current S Sensitive in the UV range (190nm-340nm)

S Influences sensitivity, cost, modularity

Adafruit GUVA-S12SD Detector response curve

Microprocessor and User Interface

S Microprocessor – stores, processes, and transfers data S User Interface – touchscreen display that reports

absorbance/transmittance, concentration, and purity

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Pugh Analysis

Spectrophotometer Layout

Halogen/Deuterium Lamp with Monochromator

Advantages Disadvantages Broad-spectrum lamp with wavelength selector can generate full chromatograph Overly complex for intended applications Very expensive Requires stepper motor

Halogen Lamp with Polychromator

Advantages Disadvantages Faster measurements No moving parts More complex than monochromator

Linear Design w/ UV-LED

Advantages Disadvantages Very simple design No monochromator needed Low power required Not modular Reduced accuracy from additional wavelengths in LED

Modular Design w/ Reflective Lens

Advantages Disadvantages Modular design allows device to run other assays (BCA, Bradford, etc.) Decreased sensitivity due to increased scattering

Modular Design w/ Fiber Optic Light Guides

Advantages Disadvantages Easier to implement than reflective mirrors Increased sensitivity No additional

Spectrophotometer Layout: Pugh Chart

Microcontroller: Pugh Chart

User Interface: Pugh Chart

Chosen Solution and Budget

Component Chosen Solution Cost Light Source 260/280nm Deep UV LED $274+$186 Optical Guides 1/16” Fiber Optics $82.50 Detector Silicon Photodiode UV Detector $100 Microcontroller Adafruit Feather M0 Bluefruit LE $29.95 Display TFT Featherwing $29.95 3D Printing PLA Filament $20.00 Total Budget Requested: $722.40

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Questions?

Thank you for listening

Works Cited

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Deep UV LED - http://www.roithner-laser.com/deepuv_cross.html

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Mirror - https://store.schoolspecialty.com/OA_HTML/ibeCCtpItmDspRte.jsp?minisite=10029&item=36815&gclid=CjwKEAiA94nCBRDxi smumrL83icSJAAeeETQMnNtg6JQ8MmBPOOmxRaVUid2QCgNScOwrx6NzWfkgRoC7q7w_wcB

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Photodiode spectrum - http://www.gano-uv.com/admin1234/kindeditor/attached/file/20160106/20160106143281108110.pdf

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Monochromator figure – http://chem.libretexts.org/Core/Physical_and_Theoretical_Chemistry/Kinetics/Reaction_Rates/Experimental_Determination_of_ Kinetcs/Spectrophotometry

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Adafruit GUVA - https://www.adafruit.com/product/1918

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UV Laser - http://www.crystalaser.com/laser/uv-laser.html

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Fiber Optic light guides - https://www.warneronline.com/product_info.cfm?id=1455&name=Flexi..

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Polychromator figure - http://www.hwe.oita-u.ac.jp/kiki/ronnbunn/paper_choi.pdf