Fluorinated ethylene–propylene: a complementary alternative to PDMS for nanoimprint stamps

Abstract

Polydimethylsiloxane (PDMS) is used by many for nanoimprint applications due to its affordability, ease of preparation, mechanical flexibility, compatibility with imprint resists and transparency to UV light. However PDMS is notoriously flexible, tacky and permeable to air. Here fluorinated ethylene-propylene (FEP) is considered as a viable and versatile alternative material for nanoimprint stamps. FEP possesses many of the desirable nanoimprint attributes associated with PDMS but crucially also features a range of complementary characteristics, including an order of magnitude more mechanical strength allowing it to handle higher loads than PDMS, an intrinsically non-stick surface and is compatible with oxygen sensitive resists. Unlike elastomeric polymers, FEP is glassy so patterning may be realised via hot embossing. Not only is this a facile and rapid means of physical structuring but it also facilitates combinatorial patterning, providing a versatility beyond that of traditional casting materials. Due to the intrinsically slow creep of FEP both micro- and nanopatterning are successfully performed sequentially. Feature sizes from 45 nm were successfully realised via the hot-embossing method. To further demonstrate the potential of the material, a modified computer numerical control machine is used. It is capable of photo-, nanoimprint- and laser lithography in conjunction with patterned FEP foils. The tool is used to perform pattern transfer into a developmental nanoimprint resist from Micro Resist Technology, mr-NIL210 XP, and Nano SU-8 3005 negative tone photo resist from MicroChem. Ultimately three-tier lithography is performed in unison and advantageous step-and-repeat performance is achieved with fabricated FEP imprint stamps as they demould more compliantly and resist pressure and contamination better than PDMS.

Development of a Hybrid Polymer-Based Microfluidic Platform for Culturing Hepatocytes towards Liver-on-a-Chip Applications

“…In particular, for liver-on-a-chip applications, a hybrid COC-based device in combination with another oxygen-permeable material (FEP) was reported for primary human hepatocyte (PHH) culture in recirculating flow conditions [ 22 ]. However, the used material, FEP, requires temperatures higher than 250 °C, so the material’s casting can be hazardous compared to using PDMS that can be cast at room temperatures [ 23 ]. While the device showed increased functions of the cultured PHHs in flow, the platform is specifically designed for high-throughput screening based on 96-well individual wells and pumps.…”

Design and Use of a High‐Pressure Stirred IR Cell for Operando Studies in Homogeneous Catalysis

“…They are more expensive than Viton O-rings, but considerably cheaper than Kalrez ones. Though still relatively rigid at room temperature, FEP has a glass transition temperature of 80 °C, [28] over which it becomes flexible enough to be adapted to the windows. Briefly warming the O-ring on a heating gun (setting the air temperature to 100 °C) is enough to allow for this.…”

EHMP-DLP: multi-projector DLP with energy homogenization for large-size 3D printing

“…After each layer is cured, the platform is moved upwards (vertically along the z -axis) to form a small gap between the fabricated object and the bottom of the tank. To prevent the cured layer adhering to the tank, a fluorinated ethylene propylene layer (Greer et al , 2016) is used to coat the bottom surface of the tank. This mask image projection and resin curing process is applied iteratively to print the model layer by layer.…”