Whole-Teflon microfluidic chips

Abstract

Although microfluidics has shown exciting potential, its broad applications are significantly limited by drawbacks of the materials used to make them. In this work, we present a convenient strategy for fabricating whole-Teflon microfluidic chips with integrated valves that show outstanding inertness to various chemicals and extreme resistance against all solvents. Compared with other microfluidic materials [e.g., poly(dimethylsiloxane) (PDMS)] the whole-Teflon chip has a few more advantages, such as no absorption of small molecules, little adsorption of biomolecules onto channel walls, and no leaching of residue molecules from the material bulk into the solution in the channel. Various biological cells have been cultured in the whole-Teflon channel. Adherent cells can attach to the channel bottom, spread, and proliferate well in the channels (with similar proliferation rate to the cells in PDMS channels with the same dimensions). The moderately good gas permeability of the Teflon materials makes it suitable to culture cells inside the microchannels for a long time.microchips | on-chip cell culture | solvent resistive chip T his report describes a convenient method for the fabrication of whole-Teflon microfluidic chips; we also integrate microvalves into the chips and demonstrate a few key applications of the whole-Teflon microfluidic chips with various organic solvents and biomolecules, and for culturing biological cells.Microfluidics (1) emerged during the early 1990s with channel networks in silicon or glass. Microprocessing of these materials is labor-intensive and time-consuming, it requires sophisticated equipment in a clean room, and often involves hazardous chemicals. The subsequent use of poly(dimethylsiloxane) (PDMS) greatly simplified the fabrication of microchips (2) and led to the rapid development of the field. PDMS has other attractive properties, such as being elastic (easy to make efficient microvalves), permeable to gases, and compatible with culturing biological cells. Despite these advantages, applications of PDMS chips are severely limited by a few drawbacks that are inherent to this material: (i) strong adsorption of molecules, particularly large biomolecules, onto its surface (3); (ii) absorption of nonpolar and weakly polar molecules into PDMS bulk; (iii) leaching of small molecules from PDMS bulk into solutions; and (iv) incompatibility with organic solvents. Therefore, special attention must be paid when quantitative analysis is needed (materials lost on channel walls and into the PDMS bulk) or organic solvents are involved. Because many drug molecules are small with relatively low polarity and cells can be very sensitive to their environment, data interpretation requires particular caution when cell-based drug screening and cell culturing are performed on PDMS microchips. Various techniques (4-8) have been proposed to modify PDMS bulk and surface properties, but they normally complicate the fabrication and still cannot effectively solve the problems. Most other plastics (9-11) have simi...

Convenient surface functionalization of whole-Teflon chips with polydopamine coating

“…8 We first fabricated the SU-8 micropattern on silicon wafer, then 500 lm thick PDMS (5:1 weight ratio of components A and B) layer was spin coated onto the pattern, and the PDMS master was fabricated after transferring this fully cured PDMS membrane to glass slide and further cured in a 250 C oven (KSW5-12-A, Zhonghuan Experiment Electric Stove, China) for 1 h. The Teflon FEP plates were thermal molded at 265 C for 5 min using a hot compressor (TM-101F, Taiming, Inc, China). After drilling holes for connection and washing with acetone by sonication, two FEP plates were thermal bonded in the oven (260 C, 1 h).…”

“…46 Generally, non-wetting substrates, such as PE and PTFE, are not favorable for cell adhesion and proliferation. 47 In our previous work, 8 cells adhered to the surface of PFA channels that were pretreated with concentrated sodium hydroxide overnight, which is time consuming with involvement of corrosive reagents. Our above results proved that PDA coating can greatly improve the wetting properties of FEP surface, but the cell viability and activity on PDA-coated FEP channels are still needed to be investigated.…”

“…[4][5][6][7] Recently, we developed a novel fabrication method to construct wholeTeflon microfluidic chips in fluorinated ethylene propylene (FEP) and perfluoroalkoxy (PFA) with integrated valves and pumps. 8 Compared with the widely used PDMS devices, Teflon chips offer unique advantages of having no small molecule adsorption and little adsorption of biomolecules, excellent anticorrosion, and compatibility with organic solvents; these merits make the whole-Teflon chip a potentially ideal platform for applications such as on-chip organic reactions and bioanalyses. 9,10 Native Teflon materials, however, are well known for their chemical inertness.…”

Droplet microfluidics: A tool for biology, chemistry and nanotechnology

“…The choice of the materials is made based on the desired properties. Cyclic-olefin copolymer is optically transparent and has low background fluorescence [16]; PMMA is biologically compatible and gas impermeable [17]; FEP has good solvent resistance [18].…”

Research on the Forming Mechanism of Micro/Nano Features during the Cast Molding Process

“…The second approach has been widely developed since imprint lithography was proposed, such as soft lithography [6] and UV imprint lithography [7][8][9]. By the use of fabricated templates, many complicated micro/nano structures can be replicated in a large variety of materials and in large area efficiently, such as polymethylmethacrylate, ceramics, polystyrene, polyurethane and Teflon [10][11][12][13][14][15].…”