A thermoresponsive hydrogel poly(N-isopropylacrylamide) micropatterning method using microfluidic techniques
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Poly(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 m. 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 m to sub-10 m 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 m in diameter using a 5 m 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. 2009 IOP Publishing Ltd.
Journal of Micromechanics and Microengineering
author list (cited authors)
Hou, H., Kim, W., Grunlan, M., & Han, A.
complete list of authors
Hou, Huijie||Kim, Woosik||Grunlan, Melissa||Han, Arum