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Normalized fluorescence intensity profiles showing bulk absorption of (a) Native PDMS and PDMS treated with (b) 5% SDS coating, (c) Titania coating, (d) combined titania and 5% SDS coating. For clarity, only 30 s, 120 s and 300 s time points are shown for each plot
Source publication
It is known for hydrophobic small molecules and proteins to be strongly adsorbed on the surface of polydimethylsiloxane (PDMS) based microdevices. However, no systematic studies have addressed issues related to the sorption of nanoparticles (NPs) on PDMS surfaces. The authors have used carboxylate-modified polystyrene nanoparticles (PS NPs), with s...
Citations
... With the introduction of replica-molding techniques 20 years ago [329][330][331], the PDMS-based microfluidic device has been predominantly used to prepare microdevices for the manipulation and analysis of biological cells. Despite its advantages in conformal sealing, gas permeability, optical transparency, and substrate elasticity, PDMS is also known for its porosity which has led to complications with hydrophobic compounds in general, and absorption issues with certain organic solvents, small molecules [332,333], proteins [334], and nanoparticles with sizes smaller than 50 nm [335]. Recent advances in microfabrication techniques have enabled various types of thermoplastics-based microfluidic devices to be produced by injection molding [336], solvent imprinting [337], hot embossing against printed circuit boards followed by chloroform-vaporassisted bonding [338], or direct laser engraving with channel features as small as 40 mm [339], which will shake the dominant position of PDMS microdevices. ...
The pivotal role of microfluidic technology in life science and biomedical research is now widely recognized. Indeed, microfluidics as a research tool is unparalleled in terms of its biocompatibility, robustness, efficient reagent consumption, and controlled fluidic, surface, and structure environments. The controlled environments are essential in assessing the complex behavior of cells in response to microenvironmental cues. The strengths of microfluidics also reside in its amenability to integration with other analytical platforms and its capacity for miniaturization, parallelization and automation of biochemical assays. Following previous review on the applications of microfluidic devices for cell-based assays in 2006, we have monitored the progress in the field and summarized the advances in microfluidic technology from 2007 to 2017, with a focus on microfluidics development for applications in cell manipulation, cell capture and detection, and cell treatment and analysis. Moreover, we highlighted novel commercial microfluidic products for biomedical and clinical purposes that were introduced in the review period. Thus, this review provides a comprehensive source for recent developments in microfluidics and presents a snapshot of its remarkable contribution towards basic biomedical research and clinical science. We recognize that although enormous amounts of evidence have reinforced the promise of microfluidic technology across diverse applications, much remains to be done to realize its full potential in mainstream biomedical science and clinical practice.
... For elastomer polydimethylsiloxane (PDMS), soft lithography [3,4] and replica molding [3,5,6] are the most common strategies in chip fabrication. Since PDMS is notorious for its severe sorption to biological compounds [7] and even nanoparticles [7], thermoplastic microdevices become promising alternatives, albeit patterned masters are always required their preparation through conventional replication techniques such as hot embossing [8,9], injection molding [10] and solvent imprinting [11]. Therefore, a low-cost and direct fabrication strategy is preferable for the fabrication of thermoplastic microdevices. ...
... For elastomer polydimethylsiloxane (PDMS), soft lithography [3,4] and replica molding [3,5,6] are the most common strategies in chip fabrication. Since PDMS is notorious for its severe sorption to biological compounds [7] and even nanoparticles [7], thermoplastic microdevices become promising alternatives, albeit patterned masters are always required their preparation through conventional replication techniques such as hot embossing [8,9], injection molding [10] and solvent imprinting [11]. Therefore, a low-cost and direct fabrication strategy is preferable for the fabrication of thermoplastic microdevices. ...
Since polydimethylsiloxane (PDMS) is notorious for its severe sorption to biological compounds and even nanoparticles, thermoplastics become a promising substrate for microdevices. Although CO2 laser engraving is an efficient method for thermoplastic device fabrication, it accompanies with poor bonding issues due to severe bulging and large feature size determined by the diameter of laser beam. In this study, a low-cost microfabrication method is proposed by reversibly sealing a 1 mm thick polymethylmethacrylate (PMMA) over an engraving substrate to reduce channel feature size and minimize bulges of laser engraved channels. PMMA, polycarbonate (PC), polystyrene (PS), perfluoroalkoxy alkane (PFA), cyclic-olefin polymers (COP) and polylactic acid (PLA) were found compatible with this sacrificial layer assisted laser engraving technique. Microchannel width as small as 40 μm was attainable by a laser beam that was 5 times larger in diameter. Bulging height was significantly reduced to less 5 μm for most substrates, which facilitated leak proof device bonding without channel deformation. Microdevices with high aspect ratio channels were prepared to demonstrate the applicability of this microfabrication method. We believe this fast and low-cost fabrication approach for thermoplastics will be of interest to researchers who have encountered problem with polydimethylsiloxane based microdevices in their applications.
Microfluidics is an emerging and multidisciplinary field that is of great interest to manufacturers in medicine, biotechnology, and chemistry, as it provides unique tools for the development of point-of-care diagnostics, organs-on-chip systems, and biosensors. Polymeric microfluidics, unlike glass and silicon, offer several advantages such as low-cost mass manufacturing and a wide range of beneficial material properties, which make them the material of choice for commercial applications and high-throughput systems. Among polymers used for the fabrication of microfluidic devices, polydimethylsiloxane (PDMS) still remains the most widely used material in academia due to its advantageous properties, such as excellent transparency and biocompatibility. However, commercialization of PDMS has been a challenge mostly due to the high cost of the current fabrication strategies. Moreover, specific surface modification and functionalization steps are required to tailor the surface chemistry of PDMS channels (e.g. biomolecule immobilization, surface hydrophobicity and antifouling properties) with respect to the desired application. While significant research has been reported in the field of PDMS microfluidics, functionalization of PDMS surfaces remains a critical step in the fabrication process that is difficult to navigate. This review first offers a thorough illustration of existing fabrication methods for PDMS-based microfluidic devices, providing several recent advancements in this field with the aim of reducing the cost and time for mass production of these devices. Next, various conventional and emerging approaches for engineering the surface chemistry of PDMS are discussed in detail. We provide a wide range of functionalization techniques rendering PDMS microchannels highly biocompatible for physical or covalent immobilization of various biological entities while preventing non-specific interactions.
