New family of fluorinated polymer chips for droplet and organic solvent microfluidics

Abstract

We present a new family of microfluidic chips hot embossed from a commercial fluorinated thermoplastic polymer (Dyneon THV). This material shares most of the properties of fluoro polymers (very low surface energy and resistance to chemicals), but is easier to process due to its relatively low melting point. Finally, as an elastic material it also allows easy world to chip connections. Fluoropolymer films can be imprinted by hot embossing from PDMS molds prepared by soft lithography. Chips are then sealed by an original technique (termed Monolithic-Adhesive-Bonding), using two different grades of fluoropolymer to obtain uniform mechanical, chemical and surface properties. This fabrication process is well adapted to rapid prototyping, but it also has potential for low cost industrial production, since it does not require any curing or etching step. We prepared microfluidic devices with micrometre resolution features, that are optically transparent, and that provide good resistance to pressure (up to 50 kPa). We demonstrated the transport of water droplets in fluorinated oil, and fluorescence detection of DNA within the droplets. No measurable interaction of the droplets with the channels wall was observed, alleviating the need for surface treatment previously necessary for droplet applications in microfluidic chips. These chips can also handle harsh organic solvents. For instance, we demonstrated the formation of chloroform droplets in fluorinated oil, expanding the potential for on chip microchemistry.

Towards molecular computing: Co-development of microfluidic devices and chemical reaction media

“…Contact angle measurements obtained from flat test structures produced from PDMS, NOA81, 3DP material and THV 500. Measurements were obtained by placing a droplet of deionised water on non-exposed material, material exposed to CHD BZ for 5 h, and material exposed to decane for 17 h. The values obtained for the fresh material are close to those found in the literature for PDMS (Duffy et al, 1998), NOA81 (Wägli et al, 2010) and THV (Begolo et al, 2011)-no such data exists for the 3DP material.…”

“…However, their widespread use in microfluidics has been hindered by their high melting temperatures (for PTFE, >300 • C) for moulding and embossing. A potential breakthrough could be found in a new fluoropolymer, Dyneon THV 500 (Begolo et al, 2011). A terpolymer of tetrafluoroethene, hexafluoropropylene and vinylidene fluoride, THV 500 has a melting point of 200 • C. This lower melting point allows the material to be processed in laboratory vacuum ovens, which usually have a peak temperature of around 200 • C.…”

Tumour-on-a-chip: microfluidic models of tumour morphology, growth and microenvironment

“…Most devices have been built on PDMS-based substrates, which have been outstanding for studies on biological mechanisms, but have severe limitations when used with hydrophobic drugs. Other mouldable and printable surrogates must be explored to overcome this limitation such as off-stoichiometry thiol-enes [205], epoxy resin [206] and perfluorinated polymers [207]. Systematic manipulation and automation of the physical and chemical parameters within the microfluidic device will require integration of microdevice printing experts with polymer chemists and material scientists.…”

A review of solid–fluid selection options for optical-based measurements in single-phase liquid, two-phase liquid–liquid and multiphase solid–liquid flows

“…These include THV, ETFE, and PVDF, which are all hydrophobic fluoropolymers with RIs of 1.350, 1.403, and 1.420, densities of 1970, 1730, and 1780 kg/m 3 , and air-water contact angles of θ = 99° (Begolo et al 2011), θ = 99.2° (Akinci and Cobanoglu 2009), and θ = 94° (Saarinen et al 2006), respectively. ETFE and PVDF are optically translucent rather than clear in the visible part of the electromagnetic spectrum (although slightly less clear than FEP), whereas THV is transparent.…”