Roll to Roll Imprinting PDMS Microstructures Under Reduced Ambient Pressures

High-volume manufacturing of microstructures is essential for the uptake of the related scientific results for commercial use and also if hundreds or thousands of devices with repeatable performance are needed during the large-scale experimental research. Polydimethyl siloxane (PDMS) is one of the most widely used materials for academia to prepare microfluidic test devices. This has also motivated the development of roll-to-roll imprinting towards the fabrication of PDMS-based devices at high volumes. The gas bubble entrapping during the replication process has remained an issue resulting in defects in the microstructure. Performing imprinting in vacuum is a well-known method to avoid bubbles but it has not been applied in roll-to-roll processing. In this work we demonstrated a reduced ambient pressure roll to roll imprinting process using PDMS silicone elastomer as imprint resist. We observed the reduction in the number of bubble-originated defects in individual micro-features from 100 % to $<$ 1 % when the ambient pressure was reduced from 1 atm to 1/8 atm. 2023-0063