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MicroPIV

MicroPIV. Particle Image Velocimetry System for Micron Resolution Flow Measurements. Key Aspects. Non-invasive global flow measurement technique Systems provide accurate measurement of fluid flow in micro fluidic environments Utilizes special concepts in

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MicroPIV

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  1. MicroPIV Particle Image Velocimetry System for Micron Resolution Flow Measurements

  2. Key Aspects • Non-invasive global flow measurement technique • Systems provide accurate measurement of fluid flow in micro fluidic environments • Utilizes special concepts in • illumination, scattered light collection, seed particle concentration, optical design and data analysis to offer the most powerful and versatile system • Worked with pioneers in MicroPIV to incorporate unique ideas into the system (Meinhart, Adrian, Wereley, Santiago)

  3. Bio-MEMS applications Lab-on-a-chip, Caliper Caltech • Chemical and biological analysis • “lab-on-a-chip” for medical and defense applications • Microfabricated needles for drug delivery • Flow sorter (Caltech)

  4. Aero-MEMS applications 500 mm Microfabricated supersonic nozzle (MIT) MEMS-controlled remote aircraft (Caltech) • Micron scale supersonic nozzles (MIT) • Remote surveillance aircraft (UCLA, Caltech) • Micro Air Vehicle (MAV): • flapping-wing vehicle < 15 cm in all directions (UCLA) • Micro-jet engine (Epstein et al., MIT)

  5. Micro PIV Issues • Reduce flare from walls by using fluorescent particles and • filter the illuminating wavelength • Particles must be very small to fit in small measurement volume • Small particles have significant Brownian motion • Volume illumination instead of light sheet. • Creates unwanted images from out-of-focus particles • Reduce background glow • Implies shallow channels or low concentrations of particles • Short times between pulses and short pulses, even in slow flows • Need pulsed lasers

  6. Details on Microflow Measurement Flow Model Focal Plane Flood Illumination Glass Plate Microscope Objective Laser beam Flow In Flow Out

  7. System for Microflow Measurements System for microflow measurements utilizes many of the same components as the standard PIV system Main components: • Dual Nd:YAG laser at energy level of 15 mJ to 50 mJ • POWERVIEW Plus and PIVCAM series of cameras • INSIGHT 3G software for Data capture and analysis, with enhanced capabilities for microflow measurements • Microscope optics

  8. Laser illumination system for Microflow Measurements • Nd:YAG laser • 15 mJ to 50 mJ energy level • Laser light attenuator • used with the laser to provide more precise control of the intensity of illumination • Diffusion optics • employed in the Model 660000 microscope to ensure uniform light intensity to the flow model • Option to use laser light guide • to deliver the light to the microscope

  9. Cameras for MicroFlow Measurements • Powerview Plus and PIVCAM family of cameras are applicable for microflows measurements • Powerview Plus 2MP, 4MP, 11MP, HS-200 • with high pixel resolution and 12-bit dynamic range • PIVCAM 14-10 • with 1360 by 1024 pixel resolution. 12-bit dynamics range

  10. INSIGHT 3G software for MicroFlow Measurements • Image capture • With full pixel resolution or Area of Interest capture • Image analysis schemes • including FFT, Hart correlation and Direct correlation as Plug-ins • Image enhancement algorithms for microflows measurements including • the averaging of correlation functions, image averaging and image subtraction • Different filter schemes • to improve signal-to noise level of correlation function

  11. Removing the background Image with background Background

  12. Image with background removed Flow around a bubble

  13. Average Correlation Algorithm Peak Search CorrelationRAB Image Sequence Image A(t = t0 ) Image B(t = t0+Dt ) B1 1 RA1B1 A1 2 RA2B2 A2 B2 3 B3 RA3B3 A3 AN BN RAN BN N < RA B > (Ensemble Ave.) Courtesy: C. Meinhart

  14. Arithmetic Average Correlation RA2B2 RA3B3 RA1B1 <RAB> RANBN Courtesy: C. Meinhart

  15. Key Aspects • Configuration based on unique ideas developed by • Carl Meinhart, Juan Santiago, Steve Wereley and Ron Adrian • Special concepts in illumination, image capture, seeding and data analysis (Patented) • PowerView cameras – cameras with mask designed for PIV • INSIGHT – unique tools designed in for PIV • Background removal, averaging, correlation averaging • Plug-ins (make the package always the most advanced) • Plug-in library

  16. Optical Systems for Microflow Measurements Two types of Optical systems are available to make measurements in microchannels of different dimensions • System with the Model 660000 Microscope • Offers a complete microscope and is used to measure flows in channels with width down to even less than 100 µm! • System using the Model 610048 special optics assembly • provides flexibility in system arrangement and is suitable for measuring flows in channels with width greater than 1000 µm

  17. Model 610048 Special Optics Assembly • Components of the assembly include • a relay lens, microscope traverse body, a long working distance microscopic objective, fluorescent filter and fluorescent particles • The assembly offers • high flexibility in flow model arrangements. • It can be positioned either vertically or horizontally to accommodate the model configuration. • This is especially attractive if the model is part of a larger assembly from which the model could not be separated • Designed to make flow measurements for • Channel width larger than 1000 µm

  18. Model 610048 Special Optics Assembly

  19. Model 610048 Special Optics Assembly POWERVIEW 4MP Camera with Model 610048 Optics Assembly

  20. Stereoscopic MicroPIV System

  21. System using the Model 660000 Microscope • Model 660000 microscope is • an inverted microscope with all the accessories to be used as a stand-alone unit. • epi-fluorescent attachment, a double lamp housing with halogen lamp and a 10X microscope objective are part of the microscope • Components to be used with the Microscope for PIV • Model 660004 laser light attenuator assembly • Model 660006 laser light guide assembly • Camera relay lens

  22. System using Model 660000 Microscope

  23. Microscope with epi-fluorescent optics Fluorescent Particles Focal Plane Sample Cover Microscope Objective Exciter 532 nm Filter Cube Laser Beam Expander Emitter 12 bit CCD Camera (2048 x 2048 pixels) Computer (Post processing) Vector Plot • Pulsed green laser (532 nm) illuminates flow volume and excites particles. • Particles fluoresce, emitting light of a different wavelength • Emitted light image is captured by digital camera. • Images are processed to produce vector flow plots.

  24. Microscope-based System SystemCapabilities • Microscope with all the accessories to be operated as a stand-alone unit • Inverted microscope configuration and side-mounted camera arrangement • offer the utmost stability for microflows measurements • Upright Microscope configuration can also be used • Epi-Fluorsecent attachment with filter cube • uses the same optical train for the illumination and particle emission collection • Collection of fluorescent emission from particles • so that only the particle images are captured and not reflected light from the model

  25. MicroPIV Systemusing Upright Microscope

  26. Microscope-based System SystemCapabilities • Diffusion optics provide • sufficient and uniform laser intensity to the flow model • Various microscope objective lenses • (from 4X to 40X) to allow imaging of flow in different model sizes • Combination of the camera relay lenses and microscope objective lenses • provides the best illumination quality for various imaging areas • Attachment for laser light guide • provides flexibility of laser light delivery from the laser

  27. Microscope-based System SystemCapabilities • Can Switch between laser illumination and white light illumination • Facilitates alignment and focusing of the model • Laser safety optics included in the system • Prevents viewing laser light by the operator • Flow model holder • Accommodate models of varies sizes and shapes • System is capable of measuring microflows in a wide range of channels (or channel widths) • Even within channels with width less than 100 µm

  28. Micro PIV example Hele-Shaw flow around a red blood cell. (Santiago, et al. 1998)

  29. Application of micro-PIV • Inkjet meniscus visualization and micro-PIV results (courtesy of Meinhart et al., 1999)

  30. Examples of MicroFlow Measurements • Flow in a diverging micro-channel Image field Vector field

  31. Examples of Microflow

  32. Microchannel flow 500 mm 150 mm

  33. Microchannel measurements Kobayashi, Taniguchi Oshima Lab University of Tokyo

  34. Microflow Channels

  35. Flow around an obstacle

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