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Designing a mold for microfluidic chips

This page describes how to design a chip using the software FluidArchitect. The instructions should help you use other CAD programs, as well.

  1. Click on the "FluidArchitect v2 pro" icon located on the desktop of the computer.
  2. After the program starts, click on the "new" icon located at the toolbar. When the first box pops up, click on Next.
  3. When asked to select a designation folder, pick where you want to save the design. Use the Browse button if necessary. Click on Next.
  4. The first default template that pops up is the one you should choose. Click on Next.
  5. 3inch wafers can take four 25mm (width and height) chips, as shown. Thus, change the width and height settings to 25mm (the default is 20mm). Click on Next.
  6. Click on Preset process and then choose Baseline. Then click on Finish. Remember that the blue color corresponds to the fluid channels and the red on the control channels. You can choose which ones you will be drawing by clicking on the scroll down box located at the toolbar.
  7. In order for the program to let you move/manipulate the channels, click on Tools, then Options, then DRC and check the "disable interactive DRC" box located at the bottom of the window. Then click Apply and then Close.
  8. There is a variety of channels and chambers provided by the software. You can find them at the toolbar and you can choose them by clicking on the appropriate box. On the grid paper, draw the channels by clicking once at the starting point, once at every corner you want the channel to have and twice at the end point.
  9. By right clicking (or by clicking the box with the arrow located at the toolbar) you can manipulate the channels.
  10. The basic channel width is 100um. Unless the design requires otherwise, keep it to this width. The set up is the following: click on Layer, then on Layer Manager, Control and then Intralayer (the last two clicks will set up the width of the control channels. In order to set up the width of the fluid channels, click on Fluid and then Intralayer.) The default channel width is 100um.
  11. The distance between a control channel and any of the fluid configurations (see figure) should be at least 50um in order for the alignment to be possible. In case of crowded designs, even a distance of 200um caused difficulties. That is, if there is enough space on the chip, take it.
  12. Caution:
    • The control line must be of the same width as the fluid channels, unless you do not want the control line to close the fluid channel, in which case you reduce the width of the control channels to 50um.
    • Do not cross two control lines!
    • For alignment purposes, the distance between two control channels should be at least 30um.
  13. Be organized with the chip (put all the holes for the control line valves at the same side of the chip, etc).
  14. If the design requires the use of control valves, remember that there are 8 valves per machine. So it will be much cheaper to control 7 or 8 channels than 9 or 10.
  15. In order to draw holes, click on Draw, then IO Ports, then 625um I/O port. First put the hole on the grid paper and then connect the channel to it. This way, the hole will take the color of the channel that it is connected to (that is, it will become blue if it is connected to a fluid channel and red if it is connected to a control channel. Note: If the hole remains white, then you will not be able to see it on the mold.
  16. Save the design as an .mdx file.
  17. Go to File and then Export. If the design does not have features that are less than 50um wide, the Output Type should be EPS. Otherwise, the Output Type should be DXF. Click on Next. Check on the wafer dimensions. The wafer size is 3inches and the chips are in two rows and two columns (as was shown in the first drawing). Click on Finish.
  18. Open the .eps/dxf file using Adobe Illustrator/AutoCad. Copy the design an many times as needed to fill the page/transparency (the price is the same). Grouping/ungrouping the design might be necessary. Make sure to leave enough space between the designs because the transparency will be cut during the making of the mold procedure. The adobe fine should be saved as .ai whereas the AutoCad file should be saved as .pdf.

    Note: When you open the .dxf file in AutoCad, check that the channels are filled and that you do not just see the outline of the channel. You will have to use the Fillet command in AutoCad in order to be able to fill the channels. It is important that you fill the channels before sending the design to the company, otherwise the mask will not be usable. This step is unnecessary if you are opening the .eps file in Adobe Illustrator, since Adobe fills the channels with color automatically.