20210319 3Dcell labnotes

Casting PDMS 10:1

• poured about 40 ml into disposable beaker on the balance: 32.2g
• poured curing agent by hand until weight was 35.4 g
• mixed. lots of bubbles in mixture
• put beaker in vacuum chamber
• cycled vacuum / air several times to make and break bubbles
• continued until almost all bubbles gone
• poured carefully over mask and put into oven

Preparing for the next steps

Making the mufluid circuits

In room 118

• 4 medium and 2 big circuits made were not destroyed by breaking the wafer
• Find cover slips and clean. They all fit on 18x24mm cs found in drawer by plasma machine
• Cut loose and peel off master
• punch holes for 1/16" tubes (which punch? test!)
• clean with tape
• plasma treat PDMS and CS
• bond
• connect tubes

Filling with water and gel

In laf bench in room 431, or maybe in 118 is OK?

It should be fairly sterile as well... If we wait long time between bonding the circuit and filling it the PDMS will become hydrophobic. The main idea of the procedure is that the PDMS should be slightly hydrophobic, but not too much to get the gel into the side chambers, but not to pass the column.

Idea for gel filling on/under microscope.

• collagen preparations need ice!!!! Ice is available in the chemistry department
• plug non-hydrogel inlets/outlets
• connect output to syringe with air to allow control of high or low pressure
• fill ungelled solution in pipette
• enter pipette in input tube and press solution through to outlet
• if solution does not enter lamella, increase pressure at outlet and keep pressing in solution, increase pressure until lamella are filled
• remove pipette and gently aspire gel solution from channel, leaving gel in lamellae

Questions:

• How to control inflow of such small amounts?
• A pipette is perhaps too brutal?
• Test with water in another circuit first?
• should I use the pressure control system?
  • fill 1-2 cm of tube with solution. How do I do that? If this is only 10 nl I can not control this with a pipette. Check out our special syringes!

Aliquoting

• Should be in final volume samples. How large? For gels in mufluid I now need max 2mm x 10mm x 0.1 mm = 2 mm^3 = 2 nl plus the entry volumes. Entry volumes: Ø 1 mm tube x 10 mm = 10 nl. This means that 1 ul is much more than enough!
• As a first trial, Ibid recommends using a 1.5 mg/ml Collagen I gel
• Pure or diluted
  • Pure can be diluted to whatever later
  • Diluted
    • is a larger volume and easier to handle
    • Dilute 99-100% acetic acid to 17.5 mM. How?
    • Need DI water (new) for dilution