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Team:EPF-Lausanne/ Microfluidics
From 2008.igem.org
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Contents |
Microfluidics
Methods
Chip design and functionality
Molds fabrication - Clean room
Molds were fabricated at the [http://cmi.epfl.ch Center of MicroNanoTechnology at EPFL (CMI)] on silicon wafers. The flow wafers were coated with the AZ9260 positive resist at a thickness of 8um and the control wafers were coated with SU-8 negative photoresist at a thickness of 10um. SU-8 has the advantage to be more resistant and more stable than the positive resist. But, AZ9260 has the advantage that it can be rounded when baked and this property allows to have a better closing ability of the flow channels by the control valves.
On the meantime, two glass masks corresponding to each layer of the design (flow and control) were written using a laser pattern generator (Heidelberg DWL200). The photoresist was then removed by a standard developer, the chromium was removed on the Chr etching bench and the masks were finally cleaned in a hot bath of 1165 remover.
The masks were used to expose the corresponding wafers. Wafers were then baked slowly up to 100°C and developed with PGMEA and 2-propanol. For the positive resist (AZ9260), an additional bake was performed for 20 min at 160°C in order to round the edges of the flow channels.
PDMS chip
Cell patterning on chip
MITOMI
S.Maerkl and S. Quake recently developed a high-throughput microfluidic platform capable of detecting low affinity transient binding events on the basis of the mechanically induced trapping of molecular interactions, called MITOMI (ref. 1). In the context of our project, we decided to use this technique to precisely look at the molecular interactions between our two key trans-activator molecules involved in quorum-sensing, RhlR and LuxR. We wanted to quantify the interactions of those two molecules, bounded or unbounded to their specific AHLs, with the sequences of the pRhl and pLux promoters. MITOMI is a good way to precisely characterize promoters and define cross-talks levels.
For detailed protocols, have a look at the Notebook.
