Group Meeting

Group Meeting

For the Summerr 2011, the Stocker lab group meetings will be held in the Macomber Room in the Parsons Lab (48-216a) on Mondays from 4-5pm (unless otherwise noted below). Feel free to sign up for a time slot to chat about your research with the group (this will be very informal). For questions or comments please contact Jeff (jguasto@mit.edu).

Materials

1.      Standard glass slides or cover slips

2.      Ethanol (70-100%)

3.      Cut PDMS channels with punched wells

4.      High Frequency Coil/plasma generator (e.g. Electro-technic products BD-20, ~$350)

5.      Canned-air, “aeroduster”, or compressed air/nitrogen

Procedure

1.      Clean a glass slide by wiping it with ethanol then a dry lab tissue and allow to dry thoroughly.

2.      Just before bonding, dust the glass surface with compressed gas.

3.      Remove Scotch tape from the channel side of the PDMS microchannel. If a non-permanent bond is sufficient, simply align and stick the channel onto the glass substrate.

4.      For a permanent bond, place the sides to be bonded on a non-conductive surface (e.g. rubber cutting mat). Ensure that they are dust free.

5.      Expose to low intensity air plasma by waving the high frequency coil ¼”-1/2” above the surface of both the glass and PDMS for ~1 minute (see notes below for more details).

6.      Align and mate the PDMS channel to the glass by laying it down on the glass surface starting from one edge. As it touches the glass, you should see the contact line propagate as the surfaces stick together.

7.      There is no permanent bond at this point. If a misalignment occurs in the mating process, simply peel them apart, re-expose to plasma, and re-bond.

8.      Place the mated channel onto a ~95^oC hotplate for up to 1 hour. Usually a permanent bond occurs within ~15 minutes if the plasma is sufficient.

9.      Allow to cool, then the channel is ready for use or storage in a dry clean container.

Notes

1.      It is best to do this procedure with powder-free gloves to avoid getting finger prints on the channels. This process should be done on a clean, dust free surface (e.g. on the cutting mat).

2.      A “non-permanent” bond between glass and PDMS is a result of van der Waals forces between the two substances. This requires that both surfaces be very clean. When using these channel, the pressure should be minimized in avoiding excessive flow rates. Alternatively, the microchannel flows may be driven by negative pressure.

3.      See Haubert et al., Lab on a Chip (2006) for more details.

4.      A permanent, covalent bond will form between the glass and PDMS will occur within ~24 hours if left undisturbed. Alternatively, this process is accelerate dramatically by heating the channel to ~95^oC for up to 1 hour.