Permeation-Driven Flow - Essay Example

Placeholder2)____________________________________________________________________________ Nov 10, Dr. David Bell Abdulmajed Alnahwae Subject: Permeation ______________________________________________________________________________ GRADE Data analysis: 28 Other technical content: 33 Technical writing: 22 TOTAL 83 SUMMARY Permeation is necessary on a microfluidic scale, since it creates an incoming flow at the walls of the microchannel, where the flow occurs between both ends of the microchannel. This experiment tests how well various liquids permeate through PDMS device. The aim of this experiment is to prove that various liquids permeate to different range over a given time. This experiment proved the hypothesis that for different liquids permeation rate range over a given period of time. Since different liquids permeate at different rates, the permeation rates can be plotted against the time-radius series and the flux can be calculated from these plots. Our experiment dealt with taking PDMS devices and also focused on the study of how water with rhodium-B, ethanol with rhodium-B, isopropanol with rhodium-B (control experiment), and mineral oil with Sudan red react during permeation. However, we were only able to get results from two liquids, water and mineral oil. We observed mineral permeating more than water. We therefore concluded that the study of micro fluids can tell us a lot about making better gasoline, cleaning liquids and other everyday liquids by making sure that liquids whose permeation rates are low are used in such industries. For instance, the battery acid is unlikely to corrode your vehicle if the permeation rate of the liquid used is low and thus the liquid won’t leak from the battery. In the lab, we had to replace ocular lenses with the iPhone since we had no good setting for the use of optical microscope. The more reasons we could only manage to get results for two liquids. BACKGROUND AND METHODS The materials used to complete this experiment are test tubes, aluminum foil,30G syringe, Tygon tubes, Deionized no cap water ,pipet, Rhodium-B, Mineral Oil, Sudan red Dye, Ruler no cap, PDMS, Curing no cap solution, Scalpel no cap, cover slides Empty 20G Syringe no cap, Ethanol no cap, Timer no cap and Plasma Tray no cap. The Devices no cap needed are Vortex Machine no cap , Vacuum filter no cap, Sonicator no cap, Vacuum no cap chamber, Camera no cap, Microscope no cap and air tank. In figure1 below showing the PDMS device connected with pipet from one side and empty 20G Syringe in another side Permeation is necessary in the context of understanding the flow characteristics of fluids at the microchannel level, since it has been observed that a steady converging flow tends to attain a terminal equilibrium (also called steady-state value) of the permeation constant. Thus, the study of permeation characteristics has been acknowledged as a powerful way to quantify chemical interactions at the center of the channel, where the reaction of the fluid stream would take place. Figure1: PDMS Device connected with pipet from one side and empty 20G Syringe in another side PROCEDURE Making the test Samples Three test tubes were collected and labeled sample 1, 2 and 3. Wrap sample tubes. Tube 1 and tube 2 were wrapped in aluminum foil because Rhodium reacts with UV rays. 1 mL pipet used to get 1.98 mL of deionized water and put it in test tube 1. Then 200 micrometer pipet used to get 0.02 mL of Rhodium B and injected that to test tube 1. This process also were repeated but ethanol were used instead of deionized water. Contents were located in the tube label sample 2. For the sample 3, 2 mL of mineral oil in test tube were acquired using a pipet. Then 0.1g of Sudan Red Dye were measured by using the electronic scale and also by using a funnel add it to the mineral oil. Test tube were pushed down on the center of vortex to start the machine and hold the tube there for 30 seconds to mix the dye properly. After the dye was mixing, a filter with test tube attached to it, to filter the excess particulate. Extra fluid was stored in test tube labeled sample 3. Experiment Prep 1. We made the microscope and camera ready for use. 2. We then cut 6, 6.5’’ stands of Tygon tubing placed the tubing into the outlets of device and tapped the ends of the Tygon tubes, to a centrifuge tubes to gather used fluid. Three 30G syringes were attained and attached the left over tubes to the needles by pulling the tube halfway down the needle. 3. Next, we labeled Syringes as S1, S2 and S3 and wrapped them in a foil to block rhodamine reacting with UV rays. 4. We used sample 1 syringe to separate sample 1 fluid. This was repeated for other two samples. Sample 1 syringe were inserted with tube to inlet of device. Then we moved the systems under microscope and focused them on the cannel sp used. 5. We finally pumped the fluid to the channel slowly and once fluid reached the end, the timer was started and pictures were taken every 10 minutes for 1 hour. This also was repeated for the other two samples by using different channels each time so the results unaltered. Data analysis Program Image J used to analyze data by doing the following steps: 1- Upload the photo in the image j program 2- Then Draw a vertical line through the picture ( the line has to be perpendicular to the channel) 3- Click into analyze then plot profile Figure2: shows vertical line through the channel was drawn to collect data of the distance of permeation Figure3: the graph appear after drawing the perpendicular line to the channel Equation Used Equation used to calculate the permeation rate is CITATION Ran05 \l 2057 (Randall & Doyle, 2005) Where J= permeation flux D=diffusion coefficient = Saturation Concentration of fluid in PDMS T= time W= width of microchannel Results and Discussion A Plot of permeation vs. distance from the channel end for ethanol is showing below (figure 1). In this graph it shows the relationship of the distance and the permeation rate of the ethanol. Figure 1: Permeation vs. distance for ethanol Line colored blue (series 1) represents curve for ethanol 50, 255 for 50 min. Line colored dark red (series 2) represents curve for ethanol 50, 255 for 40 min. Line colored gray (series 3) represents curve for ethanol 60, 255 for 60 min. Line colored yellow (series 4) represents curve for ethanol 255 at start point. Line colored purple (series 5) represents curve for ethanol 10, 255 for 10 min. Line colored green (series 6) represents curve for ethanol 10, 254 for 30 min. Line colored light blue (series 7) represents curve for ethanol 10, 255 for 20 min. In this plot, it has been observed that the shape of the graph is the form of a plateau, with a peak in the middle, which is where steady-state flow occurs within the channel. In (figure 2) below A Plot of permeation vs. distance from the channel end for water. In this graph it shows the relationship of the distance and the permeation rate of the water. Figure 2: Permeation vs. distance for water Line colored blue (series 1) represents curve for water 60 for 50 min. Line colored red (series 2) represents curve for water 36 for 60 min. Line colored gray (series 3) represents curve for water 56 at start point. Line colored yellow (series 4) represents curve for water 62 for 10 min. Line colored purple (series 5) represents curve for water 50 for 30 min. Line colored green (series 6) represents curve for water 59 for 20 min. It is observed that the shape of the plot is similar as with the case of ethanol, but the peaks are not sharply defined. The reason for this is that water has a lower degree of viscosity than ethanol. Microfluidic flow in a microchannel driven by the permeation of a solvent into a PDMS wall has been shown to be described by the lubrication approximation and radial diffusion (two approximations which were made use of in this experiment), and it seeks to explains the dependence of the flow on the distance from either end of the microchannel. A Plot of steady state permeation vs. distance from the channel end for ethanol is showing below (figure 3) . In this graph it shows the relationship of the distance and the permeation rate of the ethanol in a steady state status. Figure 3: Steady-state permeation plot for ethanol Taking point (209, 5.1 E-08) = 4098 seconds which is equivalent to 68.3 minutes waiting. A Plot no cap of steady state permeation vs. distance from the channel end for ethanol is showing below (figure 4). In this graph it shows the relationship of the distance and the permeation rate of the water in a steady state status. Figure 4: Steady-state permeation plot for water. Taking point (250, 1.18 E-08) = 21186.44 seconds which is equivalent to 5.885 hours waiting. References 1. Randall, G. C., & Doyle, P. S. (2005, August 2). Permeation-driven flow in poly (dimethylsiloxane) microfluidic devices. (D. D. Joseph, Ed.) MIT, 102, 1-8. Retrieved from www.pnas.org/cgi/doi/10.1073/pnas.0503287102 Read More