Fabrication of an SU-8 based microfluidic reactor on a PEEK substrate sealed by a 'flexible semi-solid transfer' (FST) process

A continuous flow polymeric microfluidic reactor utilizing SU-8 as a photoresist on a PEEK (polyetheretherketone) substrate was fabricated by standard UV lithography. Embedded multilayer structures were fabricated between the substrate and the inlets and outlet of the microfluidic reactor that facilitated fabrication of the entire microfluidics using SU-8, resulting in improved bonding between the substrate and the pattern. A 'flexible semi-solid transfer' (FST) process, based on a reduced exposure dosage, was developed to seal the microfluidic channels. Scanning electron microscopy (SEM) images and photographs revealed no trace of blockages in channels due to the sealing process. The maximum pressure drop without any leakage was found to be 2.1 MPa. The microfluidic reactor withstood temperatures as high as 150 degreesC and was found to be suitable for carrying out wet chemical synthesis.