Dial-A-Wave User Manual (LabVIEW 7.1)
The main purpose of this software is to control the relative concentration of a chemical in a microfluidic device. This purpose is achieved by controlling the positions of two syringes each mounted to a vertically mounted linear actuator. This document will go in detail on how to setup and run an experiment using the DAW system. As can be seen in Fig.1 the software has three main subsets within one window: Channel Setup (blue), Run Data Setup (green), and Calibration (blue). Each subset will be discussed in a separate section.
How to run an experiment
At this point the microfluidic chip should be already installed in the microscope and all the fluidic connections securely inserted into the chip.The system controls two syringes: one with inducer and one without the inducer. For ease of convention we will assign the inducer syringe to Axis 1 and regular media to Axis 2.
|Axis 2||Background media|
To properly setup your system, perform the following steps:
- While monitoring the fluid levels through the microscope, adjust the heights of individual axes so that the fluid levels are equal at 50% each.
- Record this value in the Calibration Table by assigning 50 to the Value (%) cell. Then press the corresponding black arrow button to record the physical positions of the actuators. Refer to figure below.
- Adjust the axis positions to find positions for 0, 10, 20…100% of the inducer level, and record the corresponding positions in the table just like in Step 2. The calibration requires at least two points, however increasing the number of calibration points will make the calibration more precise. It is recommended to have at least three points.
- Once all the calibration data is acquired, click the Fit to Curve button. You should see two curves in the rightmost graphing area.
- Setup a desired waveform for your signal using the Run Data Setup area.
- Push the Run button.
- You should hear the linear actuators start to move, and see the green and red dot move along the signal graphs.
- Refer to individual sections below for more detailed information.
Part I: Channel Setup
- Calibration Table Allows for input of the signal (in percent) and the relative positions of the actuators. Add and Delete buttons let you change the number of calibration points you would like to use. Minimum number of calibration points is 2 and maximum is 11. The values can be manually entered into the cells, however the position values can be automatically recorded by pressing the black arrow button immediately to the left of the table. Pressing the button will record the current actuator positions into the table. Sometimes it seems as though clicking the button does nothing. In this case just hold the button down a bit longer, and everything should be fine.
- Curve Fitting Once you have entered the calibration data points, you need to press the Fit to Curve button. This will create a function that translates each signal point to physical positions of the acutators.
If the number of points is less than four, the Fit to Curve will produce a linear function. However, if the number of calibration points is higher than four then Fit to Curve will produce a polynomial function with the highest order specified by the polynomial order box. The default polynomial order is 4, and increasing the order has not been shown to be beneficial.
Once the curves are calculated, they will be shown in the two corresponding text boxes: Curve Fit Axis 1 and Curve Fit Axis 2, as well as graphically represented in the graphing region (see Part 5 below).
- Actuator Position Controls This area allows for the control of the physical positions of each axis independently or linked. As you can see in the figure, most of the controls are mirrored for each axis. The Current position box shows the physical position of the carriage. In our case the linear actuators are mounted in such a way that the minimum position (0.00 mm) is located at the bottom, and the maximum position (800.00 mm) is located at the top.
Entering a value between 0 mm and 800 mm into the Go to Position box and pressing the GOTO position button will move the carriage on the linear actuator to the specified position. Once the operation is done, the value in the Current Position and Go to Position boxes should be the same, ±0.01 mm.
Jog + and Jog – move the carriage up and down the actuator respectively. Pressing the buttons once will move the carriage a specific distance predetermined by the Moving Distance (mm) slider bar. You can change the step size by sliding the bar to right or left. The maximum step size is 100 mm and the minimum is 0.01 mm.
Until the LINK? checkbox is checked, each actuator is independently controlled. Once the LINK? function is activated, the change in the position of either of the actuators will result in equal but opposite change in the position of the other linear actuator.
The green LED lights up when the linear actuators are in motion.
- Linked Actuators Control This function can only be used if the actuators have been calibrated and the calibration data has been Fit to Curve.
This slider bar allows for a quick movement of the actuator between its maximum and minimum limits.
If the axes are not linked, only Axis 1 actuator will move. If the axes are linked, then both will respond.
- Calibration Curve Fit Graph This area contains the graphing region which displays the polynomials that relate signal values to physical position values. Overall, the two graphs should make a figure that looks like X.
This area also contains the Load Settings and Save Settings buttons.
Save Settings button saves the values of calibration table and curve fits to a file that can be later open using the Load Settings button.
Part II: Run Data Setup and Experiment Control
- Run Data Setup
- This tab option is presented in the figure below.
- First you need to select the type of signal. “Signal Type” refers to the type of continuous function that can be used. The options include “Sine Wave”, “Triangle Wave”, “Square Wave”, and “Sawtooth Wave”. Next enter the amplitude of the signal in the “Amplitude” box. Entering any number other than zero is acceptable and will provide the same results, since the functions are automatically scaled to be oscillate between 0 and 1.
- Next, enter the length of one cycle of the wave function in the “Period (minutes)” box.
- Click “Generate Signal” button to create a signal based on the previously input parameters.
- You should see graphical representation of your signal in the graphing region right above the tabs.
NOTE: if you only see one signal in the graphing region, your axes are NOT linked.
- This tab option is presented in the figure below.
- In this case you can enter pretty much any function. We have compiled a List of tested functions.
- Here is an example of the F(t)=ln(t+5), 0 < t < 45. The values of the function are automatically normalized so that within the given time period no value exceeds a value of one (1). The smaller graph in the top part of the figure projects what the actual run will be like.
- This tab option allows the user to input run data in form of a custom file.
- The data in the file should be a set of points of times with the specific values of the DAW function (0 – 1).
- The file should be created using the following guidelines:
- There should be two columns
- First column is Time in minutes
- Second column is the DAW value – from 0 to 1
- There should be a TAB between the columns
- The bottom figure shows how this file would look like when loaded into iDAW. The red curve represents the actual data, and if the axes are linked the green curve shows the data for the second axis.
- The data is automatically linearly extrapolated to one second temporal resolution.
- Graphing Region
- Experiment Control and Info
- Run button: starts the experiment. There is no time limit, the software will loop the data that is shown in Graph A until the STOP button is pressed.
- Proposed Run Time (hrs): controls the timescale for Graph B. It has no effect on the total run-time of the experiment.
- Current Time (min): displays the elapsed time since the start of the experiment in minutes.
- Reset Alarm button: If the linear actuators are not responding to any command from the software, and there is a red LED on the communication modules. In case pressing this button has no effect, the user has to unplug the linear actuators from the wall socket to restart them.
- Save Data?: checking this box will allow the user to store the position data of both actuators for the entire length of the experiment.
- Position Table: This table lists the theoretical and actual positions of the linear actuators for each time cycle. Visible? checkboxes control the display of axis data on Graphs A and B.
This area allows the user to input a signal that will drive the linear actuators. There are three ways to input the proposed signal.
The figure above shows an example sine wave with a period of 20 minutes. Axis 1 (Inducer) is shown in red and Axis 2 (Background) is shown in green. The smaller graph at the top of the figure extrapolates the single period for a present amount of time, in this case for 3 hours or 180 minutes.
There are two graphing areas, A and B, as can be seen in the figure to the right. Graph A shows one period of whatever function is loaded. Graph B shows how a time series of the experiment would look. In this case we have data with a 30 minute period. Graph B shows the same cycle repeated for 240 minutes (4 hours).
Part III: Calibration (Optional)
The calibration option depends on the microscope you use and if you can save the fluorescence data into an Excel or CSV file.