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Microfluidics Lecture
- 3. Other Applications of Microfluidics 3
- 4. Why Microfluidics • Predictable fluid behavior • Accurate spatial control • Reduced sample volume • Lower cost • Parallel processing 4
- 6. Bernoulli’s Equation • Based on energy balance • Quick and easy way to determine stream conditions, given that the fluid flow regime is stable 6
- 7. Bernoulli’s Equation 𝑃1 𝜌𝑔 + 𝑉1 2 2𝑔 + 𝑍1 = 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡 7
- 8. Dimensionless Numbers • Dimensionless numbers characterizes certain properties of flow • It also helps with scaling up or down the process • Reynolds Number Re = 𝜌𝑈𝐿 𝜇 8
- 9. Dimensionless Numbers • Peclet Number 𝑃𝑒 = 𝐿𝑈 𝐷 • Compares the transverse mass transfer rate to the diffusion rate • Want to minimize the effects of diffusion 9
- 10. Dimensionless Numbers • Capillary Number 𝐶𝑎 = 𝜇𝑈 𝛾 • Compares the viscous effect to the surface tension effect 10
- 11. Class Exercise You are asked to design a microfluidic channel of a cylindrical shape to funnel incoming fluids. The fluid flow rate was determined to be 1E-9 m3/s. The channel is 2 micron in diameter. The density and the viscosity of the fluid are 1000 kg/m3 and 1E-3 Pa.s, respectively. Determine the fluid velocity and Reynolds number. 11
- 12. Solution 1. 𝑈 𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦 = 𝑄 𝑓𝑙𝑜𝑤𝑟𝑎𝑡𝑒 𝐴 𝐶𝑟𝑜𝑠𝑠 𝑠𝑒𝑐𝑡𝑖𝑜𝑛𝑎𝑙 𝑎𝑟𝑒𝑎 = 1𝐸−9 𝑚3/𝑠 𝜋 4 (2𝐸−6 𝑚)2 = 318.3 𝑚 𝑠 2. 𝑅𝑒 = 1.3 𝑘𝑔 𝑚3 ∗318.3 𝑚 𝑠 ∗2𝐸−6 𝑚 1.0 𝑚𝑃𝑎.𝑆 = 636 3. Not the behavior you want in a microfluidic device 12
- 13. 13
- 14. Mechanical Application 14 • With sophisticated microfluidic channels, sophisticated controller and actuators are needed • Pumps, valves, etc
- 15. 15 Microfluidic Devices Engineering Microfluidics in Nanoscience
- 16. Diagnostic and Imagining Applications • Lab-on-Chip devices • Glucose meter • Pregnancy test • Organ-on-Chip • Colorimetric assays • pH paper 16
- 17. Microfluidics Paper-based Analytical Devices (μPAD) 17 • μPAD • Inexpensive • Easily Disposed • Independent of lab machines • Biologically Compatible $0.00 $1.00 $2.00 $3.00 $4.00 $5.00 $6.00 $7.00 Paper Towels Technicloth Chromatography Paper Cost of different types of paper Per Unit Area Cost
- 18. Microfluidics based Analytical Devices (μPAD) 18 • Photolithographic technique for patterning paper • Channel width of 186 microns and barrier width of 248 microns • Well defined geometry compared to wax technique
- 19. Microfluidics based Analytical Devices (μPAD) 19
- 20. 20
- 21. 21
- 22. • Microfluidics is a fast and a cost effective method of processing analytes compared to conventional methods • Fundamentals of designing a microfluidic chamber • Evaluated flow velocity and determined the flow regime • Many different applications in imaging and diagnostics and many more to come • What about nanofluidics? • Even smaller in scale, surface charges plays a role in system behavior 22 Use of Microfluidic Devices Engineering Microfluidics in Nanoscience
- 23. Questions? 23
- 24. Reference http://www.custompartnet.com/wu/images/rapid-prototyping/inkjet-printing.png Microfluidic Devices in Nanotechnology. Hoboken, US: Wiley, 2010. ProQuest ebrary. Web. 31 March 2016. Nature Protocols 8, 1459–1474 (2013) doi:10.1038/nprot.2013.082Published online 11 July 2013 Nature Physics 6, 433–437 (2010) doi:10.1038/nphys1637Received 22 September 2009 Accepted 05 March 2010 Published online 18 April 2010 Microfluidics. Somerset, US: Wiley-ISTE, 2013. ProQuest ebrary. Web. 31 March 2016. Martinez, A. W., Phillips, S. T., & Whitesides, G. M. (2009). Diagnostics for the Developing World: Microfluidic Paper-Based Analytical Devices. Analytical Chemistry, 82(1), 3-10. Retrieved April 6, 2016. Jakubek, A. M. (n.d.). Music-Powered Lab-On-A-Chip Promises Easier Health Screening. Retrieved April 06, 2016, from http://www.popsci.com/gear-amp- gadgets/article/2009-07/musical-chip-means-portable-flu-kits-are-just-around-corner 24
Editor's Notes
- Presentation on April 6 By the end of the class student should be able to able to understand why microfluidics works and design a microfluidic chamber, why it is a noteworthy field of exploration not just in nanoscience, and why it plays such a big role in imagine and diagnostics. Background: Interest appeared in the early 1980s The study of fluid transport properties in the micro scale typically from (1-500μm) Gravitation effects diminishes, it exploits capillary surface tension affect
- This will be a continuation of Max’s lecture on microfluidics. In this lecture we will not only step through a few applications of microfluidic devices but also the look at some of the fundamental background of fluids and to provide you a better understanding of how and why microfluidic devices works.
- Inkjet Printers 2 pL microdrops, 15 micro in droplet diameter Reference: http://www.custompartnet.com/wu/images/rapid-prototyping/inkjet-printing.png
- What am I trying to say: microfluidic techniques can offer many advantages compared to conventional techniques. Why: You can do passive pumping, filtering analytes just to provide a few examples. Lower cost – removes unnecessary requirement of cutting edge machines, minimize material use
- Design
- Why: Navier-Stokes is unsolved, we want to characterize fluid flow with ease so we can establish some sort of design 0:05:00
- Conditions: Works given that there’s no friction/heat losses, density stays constant, and that the stream lines does not cross, steady flow Subscript 1: at any given point of the streamline (red dots drawn) P – Pressure Rho – density G – gravity V – fluid velocity Z – height
- Previous discussed in class, keep it SHORT this is just a reminder, Reynolds number is defined as [ ], what does it mean?
- Generally when Ca is less than 1E-5 it’s said to be dominated by capillary forces Ding, M. and Kantzas, A. 2004. Capillary Number Correlations for Gas-Liquid Systems. Paper SPE 2004-062 presented at the Canadian International Petroleum Conference, Calgary, Alberta, Canada, 8–10 June. http://dx.doi.org/10.2118/2004-062.
- Goal is to determine what’s a feasible design, minimize Re, such that no convective mixing occurs Question should take about 2-4 minutes 0:10:00
- Pressurized air is used to siphon and mix the two fluids Read into this Max may have questions. 0:14:00 a) Layout of the microfluidic mixing device. Pressurized air drives the liquids through the center and the two side inlets towards the mixing region. Post arrays prevent collapsing of the PDMS in the large inlets38, and holes are punched into these arrays to allow the solutions to be supplied. Filter post arrays prevent blockage of the device by dust or other particles. Sample molecules leaving the mixing region pass through the wide observation channel before reaching the outlet post array. The observation time extension (serpentine channel) allows observation times up to minutes. (b) Example of a concentration profile from 3D finite-element calculations of the mixing process used for optimization of the chip design. Mixing of buffer (center inlet) with denaturant (side inlets) at a 1:10 ratio is shown. The relative concentration of denaturant is color-coded (see color scale from 0 to 100% denaturant). (c) Electron micrograph of the mixing region. Ticks along the observation channel indicate the distance to the center of the mixing region. (Small ticks are separated by 25 μm.) (d) Observation time extension. (e) Filter post array with six rows of decreasing post separation (20,10,5,4,2,2 μm) connected to the inlet post array to prevent small particles (e.g., dust) from entering the channels and blocking the mixing region. The depth of all features is 10 μm.
- http://www.nature.com/nphys/journal/v6/n6/fig_tab/nphys1637_F1.html
- 0:15:00
- What: Here are some well known examples of current MF applications
- Drawn on board how photolithography works 0:20 Paper is drenched in photo-resistive polymer Prebake Overay patterning mask Exposure to UV Cool and quench with solvent to remove excess/uncured photo-resistive polymer 561 micron Channel 850 microns Barriers
- What is Bovine Serum Albumin, something Albumin or something (protein) Make reference: http://www.ncbi.nlm.nih.gov/pubmed/17211899
- Acoustic controlled MFD, may be a method of propelling fluids. http://www.popsci.com/gear-amp-gadgets/article/2009-07/musical-chip-means-portable-flu-kits-are-just-around-corner