http://spie.org/x648.html?product_id=621197
http://web.media.mit.edu/~ayb/6637report.pdf
http://iopscience.iop.org/1367-2630/7/1/033/fulltext/#nj186247bib3
http://www.biomedsearch.com/nih/Templating-hydrogels/19816529.html
http://www.nature.com/nature/journal/v493/n7431/full/nature11710.html