Polyimide and SU-8 microfluidic devices manufactured by heat-depolymerizable sacrificial material technique

Abstract

The following paper describes a sacrificial layer method for the manufacturing of microfluidic devices in polyimide and SU-8. The technique uses heat-depolymerizable polycarbonates embedded in polyimide or SU-8 for the generation of microchannels and sealed cavities. The volatile decomposition products originating from thermolysis of the sacrificial material escape out of the embedding material by diffusion through the cover layer. The fabrication process was studied experimentally and theoretically with a focus on the decomposition of the sacrificial materials and their diffusion through the polyimide or SU-8 cover layer. It is demonstrated that the sacrificial material removal process is independent of the actual channel geometry and advances linearly with time unlike conventional sacrificial layer techniques. The fabrication method provides a versatile and fast technique for the manufacturing of microfluidic devices for applications in the field of microTAS and Lab-on-a-Chip.

Complex three-dimensional high aspect ratio microfluidic network manufactured in combined PerMX dry-resist and SU-8 technology

“…39 Compared to bonding methods [13][14][15] that achieve the same network complexity, this approach has high alignment accuracy between the fluidic channels on different levels. Sacrificial layer techniques require complicated UV-lithography methods 17 or hightemperature steps 18,19 that increase the process complexity compared to our strategy. …”

“…Fluidic networks are also realized in a sacrificial layer technique, where fluidic channels are the result of the selective removal of material from its surrounding medium. [17][18][19] However, the complete removal of the sacrificial material from long channel networks is rather time-consuming, and the fluidic chip can be damaged due to the prolonged exposure to removal chemicals 17 or to temperatures above 200 C required for the diffusion of sacrificial material. 18,19 A different approach for the fabrication of complex fluidic networks is the lamination of dry-photoresist, [20][21][22] where a thin layer of soft baked resist is transferred onto a substrate to enclose fluidic networks.…”

“…Our technique allows three fluidic levels compared to two fluidic levels using bonding techniques 9,12 and further achieves high substrate adhesion strength of 29 MPa. Compared to the use of sacrificial layers, [17][18][19] standard and straightforward UV-lithography procedures of SU-8 and PerMX photoresist are applied. As opposed to dry-resist lamination, [20][21][22] in the presented technique it is possible to integrate thick SU-8 resist technology thus removing the need for multiple dry-resist lamination that decreases the process yield.…”

A practical guide for the fabrication of microfluidic devices using glass and silicon

“…113,114 During the curing process, voids tend to form in the polymeric film, and for this reason, polyimide is recommended for bonding at the chip scale. 102 Polyimide can be spincoated, followed by a baking process.…”

Development and Studies of Novel Microfabricated Radiation Hard Scintillation Detectors With High Spatial Resolution

“…It is composed of an EPON epoxy resin, an organic solvent and a photoinitiator. This photoresist is commonly used for MEMS [8] and microfluidic devices [9] but also for the fabrication of micro-pattern gas detectors [10] and X-ray imagers [11]- [13].…”