Rapid fabrication of microchannels using microscale plasma activated templating (μPLAT) generated water molds

Abstract

Poly(dimethylsiloxane) (PDMS) is a common material used in fabricating microfluidic devices. The predominant PDMS fabrication method, soft lithography, relies on photolithography for fabrication of micropatterned molds. In this technical note, we report an alternative molding technique using microscale PLasma Activated Templating (microPLAT). The use of photoresist in soft lithography is replaced by patterned water droplets created using microPLAT. When liquid PDMS encapsulates patterned water and then solidifies, the cavities occupied by water become structures such as microchannels. Using this method, device fabrication is less time consuming, more cost efficient and flexible, and ideal for rapid prototyping. An additional important feature of the water-molding process is that it yields structural profiles that are difficult to achieve using photolithography.

Shrinky-Dink microfluidics: rapid generation of deep and rounded patterns

“…Achieving rounded microfluidic channels using typical photolithographic techniques, however, is complicated and requires an extra re-flow step of the photoresist at high temperatures. Most recently, Chao et al 10 demonstrated an elegant rapid prototyping approach, coined microscale plasma templating (mPLAT), using water molds. This technique enables the creation of rounded channels that are difficult to make with photolithography, but still requires micromachined masks and plasma activation.…”

Simple and low-cost fabrication of PDMS microfluidic round channels by surface-wetting parameters optimization

“…We varied the pressure, power and time (Supporting information can be obtained from the authors) to obtain channels with TCAs from 5°to 49°. However, we have found that this method was not easily reproducible, and we have encountered similar problems of mould flattening as in Chao et al (2007): water gives a good TCA before pouring PDMS (around 80°), and gives a final TCA of 49°(at best, as mentioned above) for the channel after demoulding, which means a decrease of 37%. Thus, we did not carry on this method further.…”

“…for a high inner angle ([60°) and an aspect ratio higher than 0.15, the TCA values for the channels range from 65°to 75°, which corresponds to fairly round channels. Compared to the previous attempts with liquid moulds (Tan et al 2001;Grimes et al 2008;Chao et al 2007;Liu et al 2009), the performance here represents a step forward. 2. for an inner angle below 60°and/or an aspect ratio lower than 0.15 or higher than 0.5, the conditions are pretty unstable, and the channels have lower TCA values.…”

“…We firstly tried a method to control the surface contact angle steps by exposure of PDMS substrates to O 2 plasma through shadowmasks. This was mainly motivated by the simplicity of the method previously reported by Chao et al (2007). They used microscale Plasma Activated Templating technique to create patterns on a planar PDMS surface which is locally completely degraded.…”

“…For example, West et al (2007) used microplasma patterning of glass surfaces modified with dichlorodimethylsiloxane giving rise to flat aqueous liquid straight or Y-shaped patterns. In the same way, local degradation of PDMS by O 2 exposure using microscale plasma activated templating technique (lPLAT) provided 900 lm wide channels with 15°TCA after PDMS curing (Chao et al 2007). Liu et al (2009) prepared surfaces carrying out hydrogel patterns by UV lithography.…”