Fabrication of high-aspect-ratio microstructures in polymer microfluid chips for in vitro single-cell analysis

Technologies and methods of prototyping microfluidic devices are widely used in solving many biological problems and testing of operability of new microanalytic systems. This study is devoted to analyzing the features of the formation of microstructures in SU-8 photoresist and the preparation of replicas in polydimethyl siloxane by the soft lithography method. It has been shown that the aspect ratio of the resultant microstructures is determined by their shape, size, and the force of resist adhesion to the silicon substrate and the efficiency of the circulation of the developer around microstructures. In the replication of complex microstructures, an aspect ratio of $\sim$25 is attained. The technology considered here is used to prepare microfluidic chips with mechanical traps for fixation and the in vitro analysis of living cells.