A fast low-temperature micromolding process for hydrophilic microfluidic devices using UV-curable acrylated hyperbranched polymers

Abstract

A novel UV-curable low-stress hyperbranched polymer (HBP) micromolding process is presented for the fast and low-temperature fabrication of hydrophilic microfluidic devices. Process, material and surface properties of the acrylated polyether HBP are also characterized and compared to those of polydimethylsiloxane (PDMS) and cyclic olefin copolymers (COC). The HBP dispensed on a PDMS master was cured at room temperature using a 3 min UV exposure at the intensity of 22.2 mW cm−2. Thermal, mechanical and surface properties of the micromolded HBP structures have been characterized and resulted in a glass transition temperature of 55 °C, Young's modulus of 770 MPa and hydrophilic surface having a water contact angle of 54°. Micromolding of 33 µm thick HBP microstructures has been demonstrated. We achieved 14.5 µm wide vertical walls, 14.7 µm wide fluidic channels, 24.1 µm wide square pillars and 53.4 µm wide square holes. A microfluidic network device, composed of microfluidic channels and reservoirs, was fabricated and its microfluidic performance has been verified by a fluidic test.

Acrylated hyperbranched polymer photoresist for ultra-thick and low-stress high aspect ratio micropatterns

“…Similar results were obtained in the case of UV curable blends of acrylates and acrylated HBPs [15][16][17][18]. The benefit of such low-stress materials to produce high aspect ratio microstructures was confirmed in a recent work [19], although the development process and related dimensional accuracy were not specifically investigated.…”

Nanoimprint Lithography with UV‐Curable Hyperbranched Polymer Nanocomposites

“…[17,18] The process is carried out at room temperature and therefore thermal stresses which would result possible exothermic effects are usually negligible. Hyperbranched polymers (HBP) [19] were also introduced in micro-engineering applications [20] due to their reduced polymerisation shrinkage and lower internal stress compared to standard resins, [21] which proved to be a key feature for the production of a variety of microstructures with high dimensional accuracy. [22] These materials are a low-cost alternative to dendrimers, [23] with a less perfectly branched structure but same favorable behavior in terms of low Newtonian viscosity at high molecular weight.…”

Conversion and shrinkage analysis of acrylated hyperbranched polymer nanocomposites

“…21 These features proved to be the key to producing a variety of microstructures with high dimensional accuracy. 32,33 This is because HBP has a very high acrylate equivalent weight, yielding in a highly crosslinked material by forming only a few intermolecular bonds. Moreover, as a result of their globular structure HBP and dendrimers exhibit Newtonian behavior 34 that should be useful in postponing the liquid-to-solid transition, which compromises nanocomposite processing, to high nanoparticle loadings.…”