A fast and simple method to fabricate circular microchannels in polydimethylsiloxane (PDMS)

Abstract

A simple method to fabricate circular microchannels in polydimethylsiloxane (PDMS) is presented. A coating of liquid PDMS is applied on the walls of rectangular microchannels, fabricated using standard soft-lithography, by introducing a pressurized air stream inside the PDMS filled microchannels. Surface tension of the liquid PDMS forces the coating to take a circular cross-section which is preserved by baking the device to cure the coated layer. Diameters ranging from a few micrometres to a few hundreds of micrometres were achieved. The method was verified to work on microchannel networks as well as in straight channels. Different coating conditions were systematically tested. Design curves are reported for one to choose appropriate coating conditions for obtaining a desired diameter. A comparison between the performance of square and circular microchannels in trapping SiHa cells (cervical cancer cell line) is shown.

A microfluidic device for simultaneous electrical and mechanical measurements on single cells

“…Since the aspiration channel in this device is not exactly circular, forming effective seal between the cell membrane and the aspiration channel is more difficult and leakage may have taken place. 65 The calculated C membrane values are consistent with those ͑roughly 1 F / cm 2 ͒ obtained from patch clamp.…”

Production of uniform droplets using membrane, microchannel and microfluidic emulsification devices

“…By tuning the distance between the two compartments during solidification of the middle fluid, it is possible to manipulate the release profile of actives (Sun et al, 2011). If the two inner compartments are far enough away from each other, the two actives will be released to the surroundings separately.…”

“…To enclose the channels, the PDMS mould is sealed to a flat surface of a glass slide or PDMS block either covalently by plasma oxydation or noncovalently by applying pressure. Cylindrical channels in PDMS can be fabricated by stereolithography (Morimoto et al, 2009), aligning and adhering two semi-circular PDMS channels face-to-face (Wilson et al, 2011), embedding a microfiber in PDMS mould before curing (Takeuchi et al, 2005) or introducing pressured air stream inside rectangular PDMS channels filled with liquid PDMS (Abdelgawad et al, 2011). PDMS is inherently hydrophobic, but can be rendered hydrophilic by oxidation of the PDMS surface (Hillborg et al, 2004), coating with inorganic materials such as silica and titania via sol-gel chemistry (Abate et al, 2008), through layer-by-layer deposition of polyelectrolytes (Bauer et al, 2010), ultraviolet graft polymerization of acrylic acid (Li et al, 2007), etc.…”

Self-assembled synthesis and characterization of microchannels in polymeric membranes

“…Circular cross-sectioned microchannels are, therefore, more appropriate for microfluidics-based electromechanical studies of living cells, like those employed in micropipette aspiration. 24 Recently, novel approaches of microchannel fabrication in PDMS membrane using self-assembly have been reported. Self-assembled polymeric particles were shown to result into nanochannels due to entropic and enthalpic changes in the system.…”