Huijie Hou et al 2009 J. Micromech. Microeng. 19 127001 doi:10.1088/0960-1317/19/12/127001
Huijie Hou1, Woosik Kim2, Melissa Grunlan2 and Arum Han1,2,3
Show affiliationsPoly(N-isopropylacrylamide) (PNIPAAm) is a thermoresponsive hydrogel that has been widely used in various biomedical applications, including tissue engineering. Making PNIPAAm into a microscale structure is an effective method of increasing its thermoresponsiveness and modulating surface properties compared to bulk PNIPAAm. The commonly used method of direct photolithography combined with a photomask is challenging in creating pure PNIPAAm patterns smaller than 10 µm. Also, each time when there is a need to change the sizes of resulting PNIPAAm patterns, a new photomask is required. Here, a microfluidically controlled micropatterning method utilizing hydrophilic spots on a hydrophobic substrate was developed to create pure PNIPAAm microstructures. This method enabled the fabrication of pure PNIPAAm microstructures with a wide range of sizes from 70 µm to sub-10 µm out of the same substrate preparation by simply varying the flow speed of the hydrogel precursor solution through a microfluidic channel. Hydrogel microstructures with diameters of 12 to 59% of the hydrophilic pattern diameters were successfully fabricated using this fabrication scheme. The smallest hydrogel pattern fabricated using this method was 2.3 µm in diameter using a 5 µm diameter hydrophilic pattern at a flow speed of 100 mm s−1. This simple and versatile fabrication scheme could be an ideal method for creating large arrays of hydrogel micropatterns with varying sizes.
61.25.H- Macromolecular and polymers solutions; polymer melts
Soft matter, liquids and polymers
Issue 12 (December 2009)
Received 30 May 2009, in final form 4 August 2009
Published 20 October 2009
Huijie Hou et al 2009 J. Micromech. Microeng. 19 127001
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