Nano-fluidic Testing Apparatus

User Manual

By: David Sharp, David West, and Justin Davis

P13373 – Nano-fluidic Characterization

Table Of Contents

  1. Introduction

1.1.System Overview ..……………………………………..…………1

1.2.System Capabilities.………………………………….…...……….1

1.3.Expectations. ……….…………………………..…….……………2

  1. System Set up

2.1.Part breakdown.. …...………………………………..……………2

2.2.System Assembly…………………….…………………….………………3

2.3.FrameAssembly……………….……………...... ……….………………3

2.4.Connecting Sensors

2.4.1.Pressure Transducer to DAQ

2.4.2.Thermocople

  1. Pump Set up

3.1.Syringe Set Up…………………………….………………………4

3.2.Syringe Pump Usage…...………….………………………………4

  1. Software

4.1.Using LabVIEW Program…………………………………………6

4.2.Commands and Error Debugging…..………….…………………7

  1. Experimentation Guide

5.1.Membrane Set-up

5.2.Pump Set-up

5.3.LabVIEW Set-up

5.4.Experimentation

5.5.Data Exportation

  1. System Maintenance

6.1.Cleaning……………………………………………………………11

6.2.Part Handling………………………………………………………12

6.3.System Bleeding…………………………...………………………12

6.4.Safety Considerations…………………...…………………………13

  1. Appendix
  2. Flow Sensor User Guide...…...... …….……………………………X

7.1.1.Specification Guides ...... ….…………………………………X

7.1.2.Operations Guidelines ..….…………………………....……X

7.2.Pressure Transducer User Guide...... ………...…………...……...X

7.2.1.Data Sheets ..………………..………….……………………X

7.2.2.Service Manual ..……...….….………………………………X

7.3.Thermocouple Data Sheet..…….….,………………………………X

7.4.Part Schematics …………………….………………………………X

  1. Introduction

1.1.System Overview

The main objective for this system is to provide fluid flow through various nano-porous membranes so that the characteristics of the flow across these membranes can be measured. Such characteristics include the pressure drop between both sides of the membrane, fluid flow rate through the system, and a measurement of the fluid temperature. The system itself consists of various fittings to ensure the same size diameter piping is used throughout the system, a membrane holder to house and protect the membrane, pressure transducers to observe the pressure difference, a flow sensor, a thermocouple, and a syringe pump to inject the fluid into the piping. The entire system will be kept secured on a ridged frame that will keep all parts connected and in place, preventing them from moving during the procedure. As fluid is injected through the pipe using a syringe pump, data for each of the fluid characteristics will be collected using various sensors. A fitting for secondary fluid injection can also be used for a secondary testing procedure, in which electrolytes and food coloring will be injected into the system during testing. The data collected during the experiment will then be exported onto LabVIEW, where the data can be observed and edited for further analysis.

1.2.System Capabilities

This nano-fluidic flow measurement system consists of three different kinds of sensors, pressure transducers, a flow sensor, and a thermocouple. The sensors themselves are each powered by their own power sources, and are read on the computer through USB. Each of these sensors are calibrated and read on the LabVIEW program provided with the apparatus.

The pressure transducers are located on either side of the membrane, which will be able to measure the pressure values of the fluid before and after the fluid goes through the membrane. The values are then subtracted from eachother to find the pressure difference between both sides of the membrane. The sensors are powered using an external power source and connected to the computer though the DAQ.

The thermocouple has a T type fitting and is connected into a thermocouple reader from LabVIEW. The reader converts the resistive signal into something that it can recognize outputting readings in Fahrenheit, Celsius, and kelvin depending on the desired reading is set on the program.

The flow sensor comes with its own power cable and program that can be used to read the flow values from, however to ensure that the values obtained for the flow match the values for the pressure, the measurements will be taken through LabVIEW using the flow sensor’s driver software. That way, all values obtained can be better compared and correlated to each other correctly since all measurements will be taken at the same time.

The LabVIEW program will be used to monitor the flow process during experimentation. The program itself will be used to control the rate of data collection as well as the duration of the experiment. It will also be designed to output any data found during the procedure onto a separate file for analysis.

1.3.Expectations

All values obtained are expected to behave similarly to the calculations done previously on MATLAB; however based on the previous system’s data, it is possible to see some spikes in pressure as the fluid flows through the system due to an initial pressure required to push flow through the membranes before leveling off to a lower and more stable pressure value. Since the flow and the temperature will remain constant throughout the system, the difference in pressure will be the varied value.

  1. System Set up

2.1.Part breakdown

2.2.Frame Assembly

2.3.System Assembly

Once all the pieces have been organized, the system can be constructed based on the schematic breakdown shown in section 2.1. For this assembly, a set of metric socket head cap screws, a Philips head screwdriver, and an adjustable wrench is required for its construction and for stabilizing pieces connected to the frame.

  1. First, connect a luer lock onto the syringe exit and connect with then on clear plastic ¼ inch piping .
  1. Connect the movable arm onto the frame railing using hexagonal screws
  1. Unscrew the bolts from the ¼ inch through coupling and put it into the movable arm clamp
  1. Put back the bolts onto the through coupling and tighten both sides using a wrench
  1. Tighten the hexagonal bolt on top of the clamp to secure the coupling into place
  1. Connect the plastic tubing from the syringe pump into the ¼ inch though coupling and tighten the connection using the adjustable wrench
  1. Connect the T-coupling and the 0-100psi transducer together. Make sure the transducer threads have threading tape before connecting. Tighten the connection thoroughly using the adjustable wrench.
  1. Put the transducer into the L-bracket. Fit the cord through the opening first, and feed the transducer through until it is snug in place.
  1. Connect a ¼ inch stainless steel pipe between the through coupling and the T-coupling.
  1. Place the L-bracket onto the system frame and screw the bracket onto the frame.
  1. Tighten all confections as well as the set screw on top of the L-bracket once everything is properly aligned
  1. Connect the custom pipe to thread piece to the T-coupling
  1. Connect the T-luer lock to the custom piece using the thread luer lock caps.
  1. Connect the threaded ¼ inch stainless steel piping to the T- luer lock
  1. Connect the membrane holder to the threaded ¼ inch stainless steel piping using a threaded luer lock cap
  1. Connect the clear ¼ inch tubing onto the membrane holder. This connection is purely suction based
  1. Connect the two pipe to ¼ inch thread to opposite sides of the ¼ inch thread cross fitting
  1. Connect the 0-30 psi transducer and the thermocouple the remaining ends of the ¼ inch thread cross fitting
  1. Put the transducer through the L-bracket in the same fashion as the previous one.
  1. Connect the ¼ inch clear plastic tube to one of the couplings attached to the cross fitting
  1. Connect the L-bracket to the frame, making sure the second transducer is positioned on the same side as the previous one.
  1. Connect a stainless steel pipe to the other side of the cross fitting
  1. Put the ¼ inch tube adapter on the entrance of the flow sensor, making sure that the direction of the flow arrow located on the side of the sensor is pointing in the correct direction.
  1. Connect the ¼ inch adapter to the ¼ inch stainless steel pipe from the cross fitting.
  1. Put a luer threaded luer lock at the exit of the flow sensor
  1. Connect the ¼ inch plastic tubing to the luer lock
  1. Put a luer lock at the end of the plastic tube and submerge into a beaker filled with water.

2.4.Connecting Sensors

After completing the assembly of the main components of the system, the sensors are then connected to their respective power sources.

2.4.1 Pressure Transducer to DAQ

  1. Connect the black wire from the 0-100 psi transducer and the purple wire from the power source to the fist port on the DAQ.
  2. Loosen the clamps inside the hole using a flat head screwdriver
  3. Place the wire into the port.
  4. Tighten the port to clamp
  5. Connect the white wire from the same transducer to the second port
  6. Repeat this process for the second transducer, connecting the black wire to the fourth port and the white wire to the fifth. Also place the blue wire into the fourth port
  7. Connect the two red wires from both transducers to the orange wire from the power source. This connection may need to be soldered.

2.4.2Pressure Transducer to DAQ

  1. Pump Set up

In order to induce the fluid flow into the system, the syringe pump has to be set up correctly so that the value shown for the flow is indeedcorrect. The pump must also be stabilized so that during the procedure the syringe does not shift or move.

3.1.Syringe Set Up

The syringe pump can be set up properly by the following:

  1. Remove syringe from pump by unscrewing the back plate on top of the pump and twisting the clamp away from the syringe.
  2. Fill an empty syringe with desired fluid, taking care to remove air bubbles by inverting the syringe to point up, and push air out.
  3. Place the syringe back onto the top of the pump, making sure the plastic ends of the plunger are placed inside the notches at both ends of the syringe pump loader.
  4. If the back plate loader is not aligned correctly, press and hold down the white tab located on the side of the back loader and adjust the distance.
  5. Attachthe back syringe by first screw it on the quick turn barb on the incoming line to the system. Press it into place and secure with the screw back and spring clamp.
  6. Place the twist clamp back on top of the syringe to secure it in place.

3.2.Syringe Pump Usage

  1. To activate the syringe pump, flip the switch on the back of the pump
  2. To select a flow rate, push the rate button on the front panel of the pump, then use the up arrows to select rate.
  3. To change units, hit the rate button twice, and use the arrows to select the desired units.
  4. To change the diameter of the syringe being used, press the diameter button on the front panel and use the arrows to specify the correct size diameter.
  5. Note, make sure to check the inner diameter of the syringe being used by referring to the back of the syringe pump user manual
  6. The pump can be purged if it is in the stop setting by momentarily holding down the start button. It will run normally for a second, then go into an overdrive in order to flush the system.
  1. Software

To successfully measure and calculate the values obtained in the experiment, a LabVIEW program was written and used to capture and export all collected data points and maintain organization between the sensor readings. Before using this program however, it is important to note a few important aspects of the program to ensure the analysis made is correct.

4.1. Using the LabVIEW Program:

  1. Make sure all Sensors are properly connected as per Section 2.4
  2. Open the LabVIEW File “MainTestingCode” located at BLAH using LabVIEW 2010.
  3. In the File Path Dialogue Field, enter a file path for the data output
  4. Note: File path must include “.xls” at the end. This makes it far easier to open later in

Excel. Without this file extension the spreadsheet cannot be opened as Windows does not recognize the format. Renaming the file with “.xls” manually later may remedy a good data set that was not given the extension beforehand.

  1. If no path is given, the program will open a window where you can chose the path

manually. This will occur twice; once on start and once on stop. This is supposed to happen, as the code writes column labels upon starting before it takes data. It then writes the data upon stopping to the same file under those labels. Again, specify the file as an Excel Workbook.

  1. Adding a file path reduces the processing power required and can help prevent crashing.
  2. Note: Make sure to change the file name between runs, otherwise the current run will save over the last.
  1. In the “Flow Sensor Controls” section, make sure all the fields read as follows for standard flow rate measurement:
  2. aMeasure Type = Flow
  3. aResolution = 14 (14 is recommended, the default of 16 also functions)
  4. aHeater Mode = Always on
  5. aCalib Field = 0
  6. aLinearization = enabled
  7. COMPort= 3 (May change depending on set up. A wrong COMPort will report a
  8. DLL call error when ran. Simply iterating to find the active COM can help to resolve this)
  9. Under the “Timing Information Section,” one can input a desired time step. Depending on computer set up limitation, complexity of the Sensirion Driver and USB port version, a minimum achievable time step may occur that is higher than input value.
  10. Run the Program using the small “RUN” arrow at the top of the screen.
  11. To stop program, use the large “Stop Run & Save Data” button. This will stop the program at the end of the current iteration, and save the data to the given file path.
  12. Note: DO NOT use the stop button at the top of the screen next to the run arrow. This causes the program to stop in the middle of the current iteration and will not prompt the program to save the current run. Your data will be lost.

4.2. Other Commands and Error debugging:

  1. Right clicking the charts on the screen will reveal the drop down menu. From here, one can click properties to change timing time, axis scale, auto-scaling and other things. If the program is running, a “Clear Chart” option will appear in the drop down menu. Clearing the chart merely wipes the chart clear of any existing data, but does not affect what is output to Excel when the run is stopped.
  2. Crashing may occur when using the program. To reduce this chance, close other unneeded applications, close the block diagram if it is open, and run the program from the Front Panel.
  3. A possible “DLL Call Error” may occur during a run at a random point in time. It is recommended that the runs are watched closely when in progress. If this error occurs, simply click “continue.” The faster this is done, the less data lost, as the program does not record data while this error message is open. Data gathered during a run with an error is still accurate, and as long as the continue command was clicked within seconds of it occurring, only one or two data points will be lost, depending on chosen time step.
  4. The “DLL Call Error” may occur upon first start. Stopping the program and restarting can normally resolve this bug. If error occurs again, hit continue. If the program doesn’t run, proceed to step 5. Error 3 and 4 are most likely the same error. At times, the program has trouble pinging the USB port, and does not close the COMPort (as per the last command in the Sensirion portion of the block diagram.) When the next iteration tries to run, the COMPort is already open and reports an error. By clicking continue, you resume the current iteration as normal, and have most likely fixed the error by simply letting the iteration finish.
  1. If the DLL Call error reports again as soon as continue is clicked, and does this several times, it is no longer a simple bug in the program, but an actual problem in the coding. Change the active COMPort to one of the other choices until you find the Sensor. Also, by installing the software that came with the sensor, you can narrow down the COMPorts to only the currently used ones.
  2. If you are sure the current COMPort is correct then read the following. In the BLAH folder where the MainTestingCode is stored, there is also a folder called “Sensirion_RS485SensorCable.” In this folder is a folder called “Support.” In this folder, is a file called “SensorCableDriver.dll”.
  3. Open the block diagram of the Main Testing Code. The Sensirion portion is clearly marked by the sub VI’s all adorned with a green “S”. By double clicking one of these sub-VI’s (not the numeric indicators that are also marked with an “S”), you open another VI (This is one of the controls, some named the same as the settings in Step 4 of the “Using the LabVIEW Program” Section).
  1. From this VI, view the block diagram. There is a yellow and white VI is at the heart of every one of these Control Sub-Vi’s. A constant is wired to this VI that has the name of a file path. Make sure that this file path is the same as the current path for the “SensirionCableDriver.dll” file. If you are getting this error, then more than likely this file path has been changed, and the program no longer can reference the driver needed to talk to the Com Port. Simply changing all the controls to have the new file path will fix this error. Note: This can be a lengthy process as there are around 20 of these controls, each needing to be fixed if this is the case.
  1. Recalibrating the Pressure Transducers: If the Transducers are recalibrated, the internal formula in the software Block Diagram will no longer be valid. Changing the constants in the block diagram shown here should be enough to remedy this. If the formula is no longer linear, another block for an “x2” may need to be added in line. This would be done by first using a “Multiply” block to times the signal by itself. Next, a multiply block to scale it by a constant, and then lastly an addition block to add it to the “formula”.
  1. Experimentation Guide

5.1.Procedure