Demolded hollow high aspect-ratio parylene-C micropillars for real-time mechanosensing applications

Abstract

Cells generate mechanical forces to maintain normal cellular function or play a role in developing pathological processes. The mechanical force called the traction force can be estimated from the pillar deflection using a polymeric micropillar array. Here, we develop a transparent membrane of hollow cone-shape high aspect ratio (AR) parylene-C micropillars by the molding method. The membrane of the pillar array is exposed after the etching of the silicon mold and the residual silicon serves as the cultivation chamber. The AR and spring constant (k) of micropillars are estimated to AR ≈ 10 and k ≈ 0.349 N·m−1. The spring constant of developing micropillars is 3.5-times decreased compared to cylindrical, non-hollow pillars. This slightly tune the elastic properties of micropillars. The array is further shown as the mechanosensor detecting the change of cellular tension during hyperosmotic stress. The traction force of cancerous PC-3 cells is estimated from pillar deflections by image analysis. Additionally, the cell volume and surface area are measured using a digital holographic microscope (DHM). The results show that the molding technique can be used to develop high AR parylene-C micropillars and that this array can serve as the mechanosensor of cellular processes.