LAB Introduction to Lab-On-A-Chip - Lab Procedure

INTRODUCTION

The purpose of this lab is to provide the student with an opportunity to experiment with an existinggeneric lab-on-a-chip design. The student will utilize de-ionized (DI) water to test channels and overall chip design and functionality using a provided generic polydimethylsiloxane (PDMS) chip and minimal tools and equipment.

Students will note nuances of the generic design and its performance and use insight gleaned from this lab to understand design considerations in building a better chip and understand the importance of proper equipment and procedure.

PROCEDURE

For this lab, it is suggested that, assuming a team of four:

  • One teammate maintains the PDMS chip seal (manual pressure)
  • Another pumps with the syringe
  • Another notes observations (should be many issues to report)
  • The fourth can clean, fetch fluids, help with miscellaneous tasks, etc. (optional)
  1. FILL the CUPS with clear and dyed water. If mini-cups are used, fill them; if full-sized drinking cups are used, only fill to around ¼ full.
  1. CLEAN the PDMS CHIP with WATERand KIM WIPES. Try to avoid touching the surface of the designed side of the PDMS chip and the underside of the lid (the surfaces that contact each other) with your hands.
  1. Put the lid (with the access holes) on top of the bottom (with the design) such that the holes line up with the staging and waste wells and the two pieces form a seal.

  1. Note the different features on the chips. The smallest are the capillary check valves (Figure 1 shows a close-up diagram). All the features are shown on the diagram of the
  1. EXPERIMENT with genericPDMS CHIPS.

Each team will be given a prototype lab-on-a-chip to operate and get a feel for how liquid flows through the channels, how well the device seals, and to generate ideas for their own chip layout and design.

  1. Fluids are provided (tap and colored water). These will be used to determine how easily the fluid flows through the channels and how completely it is displaced in the wells.
  1. In the lid of the PDMS chip there is a hole for each of the four staging wells. To get fluid in the wells and pump it through the channels, there is a syringe with an attachable tapered tip that can be used to create a seal on the access port in the lid so that fluid goes into the PDMS chip rather than all over the lid. The tip of the attachment may need to be cut to be able to create this seal. Use the exacto knife if some trimming is needed.
  1. PERFORM the following TASKS and TAKENOTES describing in your own words the procedure for loading the wells with fluid and pumping fluid into the detection well.
  1. FILL one STAGINGWELL with COLOREDWATER using the syringe. Note whether the well completely fills and if not, note how large the void space is. Note whether extraneous fluid flows to other parts of the PDMS chip.
  1. Carefully PUSH the FLUID out of the well with fluid from the syringe so that it flows past the check valve (if applicable) and fills the detection well. Note whether the check valve worked or not. Did the fluid stop momentarily at the check valve? Did the detection well fill completely? If not, note the location of any void space or bubbles. Also, note any leakage between either of the wells and the lid.
  1. PUMP clear water from the staging well into the DETECTIONWELL to flush out thecolored water. Note the operation of the check valves on every well. Alsonote any leakage between the lid and the PDMS chip (if it leaks, it may be a sign thewell is too large for this type of device, the device is not sealing properly, etc.). Note how well the colored fluid isdisplaced from the detection well (completely or partially, as separate distinct quantities or gradually diluted).
  1. ALLOWotherTEAMMEMBERS to repeat steps a-d using the otherstaging wellson the PDMS chip. Note the wells/type of channel that perform best under different circumstances, e.g., some channels may offer less resistance to pumping, some may leak, some have check valves and some do not, etc. Be sure to note any procedural or equipment issues as well!!!
  1. TAKE the LID off your PDMS chip and dryoff the wells with a Kim Wipe when you are finished with your experiments.
  1. Use the 5x magnifier and light box to identify dirt, debris, damage to the PDMS, etc. and note the potential effects on chip performance.