First time users of hydrogels may find it challenging to work with viscous fluids. We recommend the following techniques to ensure pipetting accuracy and to keep the solution bubble-free.
- Always prepare slightly more hydrogel than you need before you start the gel filling step. You do not want to run into a situation where there is insufficient hydrogel to fill the last gel channel on a chip due to pipetting errors or other reasons. You will not have the luxury of time to prepare another vial of hydrogel as hydrogel usually polymerizes quickly at room temperature.
- Always limit your filling volume of hydrogel to 10 µl per gel channel to prevent the hydrogel from overflowing into the flanking media channels.
- Use a fresh pipette tip to fill each new gel channel. Due to the high viscosity of hydrogel, usually there is leftover gel in the pipette tip after the gel filing step. If the same tip is reused, bubbles may be created in the pipette tip and may get injected into the next filling site.
- Do not depress the plunger till second stop (blow out) while filling gel to avoid creating bubbles in the gel channel.
- Hold the plunger firmly while removing the micropipette from the gel inlets. Early release of the plunger creates a negative pressure that will suck up the unpolymerized
- Consider breaking the gel filling step into shorter and more manageable sessions especially if you need to fill a larger number of chips with a hydrogel that polymerizes quickly.