The fabrication of 3D microstructures for microfluidic devices continues to be a challenge as traditional microfabrication techniques are not suitable for the construction of these devices. For example, PDMS (polydimethylsiloxane) is one of the most common substrate materials for microfluidic devices, but standard packaging techniques are not able to bond multiple substrate layers with the high precision required.
Tingrui Pan (University of California, Davis) et al. have now come up with an easy and robust technique which they hope will make this problem a thing of the past. Their new technique, CAP (capillary-driven automatic packaging) uses the interactions between a liquid capillary bridge and the top and bottom substrates to align multiple substrate layers with high precision, and has a bonding strength comparable to standard oxygen plasma processes. The technique is also transferable to other materials, requires no thermal or mechanical treatment, nor any specialist equipment.
Illustration of the CAP-enabled microdevice fabrication process, including (a) micropatterning of a shadow mask made of dry film, (b) PDMS replica molding, (c) selective oxygen plasma treatment through the shadow mask, (d) DI water loading in the defined hydrophilic regions, and finally (e) self-alignment and self-engagement steps between two chips with identical capillary alignment patterns.
Pan et al. believe that this technique has the ability to be employed in microdevices for point-of-care diagnosis, controlled drug delivery, and combinatorial biological screening – why not take a look and see for yourself – the article’s free to access for four weeks!
Capillary-driven automatic packaging
Yuzhe Ding, Lingfei Hong, Baoqing Nie, Kit S. Lam and Tingrui Pan
Lab Chip, 2011, 11, 1464-1469
DOI: 10.1039/C0LC00710B
