Manufacturing of Substrates with Different Surface Roughness for Cell Migration Test by Two-Photon Polymerization Method

In this paper, cell substrates with different assigned surface roughness are manufactured by two-photon polymerization (TPP) method. The surface roughness of substrate can be controlled by changing the laser power, voxel distance, and scan line gap of the 3D printing process in TPP system. The micro substrate structure manufactured by TPP will be used as a master sample for reproducing multiple replica samples by nanoimprint lithography (NIL). In nanoimprint lithography, first a polypropylene (PP) thin sheet will be placed on the surface of the master sample to reproduce the image copy of the surface, called PP mold. Then polydimethylsiloxane (PDMS) will be poured on the PP mold to reproduce copies of the master sample, called PDMS mold. Finally the PDMS mold will be filled with liquid PP and the PP substrate will be separated from PDMS mold. The surface characteristics of TPP master samples and PP substrates are analyzed from 3D shapes measured by confocal microscope. It shows that surface roughness of PP substrates is quite similar to those of TPP master samples. TPP is a slow fabrication process. By using nanoimprint lithography to reproduce copies of the master sample, it solves the problem of TPP mass production. The final PP substrates with different surface roughness can be used in studying cell migration test.