Rapid, simple, and cost-effective treatments to achieve long-term hydrophilic PDMS surfaces

Hemmilä, Samu; Cauich-Rodríguez, Juan Valerio; Kreutzer, Joose; Kallio, Pasi

doi:10.1016/j.apsusc.2012.06.044

Cited by 133 publications

(97 citation statements)

References 52 publications

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“…PDMS pre-polymer and cross-linker were mixed in a ratio of 10:1 (w/w), stirred thoroughly and degassed under vacuum, before being poured onto the SU-8 masters. After curing at 80˝C for 1 h, the PDMS replica was peeled off from the master and irreversibly bonded to a microscope glass slide after an oxygen plasma treatment using a FEMTO Plasma System (Type B, 0-1000 W, Diener Electronic, Ebhausen, Germany) at a power of 300 W for 60 s. Hydrophilic microchannels were obtained by modifying the PDMS surface with PVP, as described elsewhere [29]. Right after the plasma bonding, an aqueous solution of commercially available PVP 10% (w/w) was flowed through the two inlets with a syringe pump for 30 min.…”

Section: Fabricationmentioning

confidence: 99%

Generation of Oil Droplets in a Non-Newtonian Liquid Using a Microfluidic T-Junction

et al. 2015

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Abstract:We have compared the formation of oil drops in Newtonian and non-Newtonian fluids in a T-junction microfluidic device. As Newtonian fluids, we used aqueous solutions of glycerol, while as non-Newtonian fluids we prepared aqueous solutions of xanthan, a stiff rod-like polysaccharide, which exhibit strong shear-thinning effects. In the squeezing regime, the formation of oil droplets in glycerol solutions is found to scale with the ratio of the dispersed flow rate to the continuous one and with the capillary number associated to the continuous phase. Switching to xanthan solutions does not seem to significantly alter the droplet formation process. Any quantitative difference with respect to the Newtonian liquid can be accounted for by a suitable choice of the capillary number, corresponding to an effective xanthan viscosity that depends on the flow rates. We have deduced ample variations in the viscosity, on the order of 10 and more, during normal operation conditions of the T-junction. This allowed estimating the actual shear rates experienced by the xanthan solutions, which go from tens to hundreds of s´1.

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Section: Fabricationmentioning

confidence: 99%

Generation of Oil Droplets in a Non-Newtonian Liquid Using a Microfluidic T-Junction

et al. 2015

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“…In the future we are aiming to replace plasma-patterning with chemical surface patterning to produce the guidance traces. This should reduce the observed variations in the propulsion effect and will also extend the overall applicability of the platform by increasing the long-term stability of the hydrophilic treatment [11]. In addition, we are currently evaluating a wide variety of other luminescence-based sensing systems relevant to biochemical applications.…”

Section: Resultsmentioning

confidence: 99%

Biochemical sensing assays based on coalescence-induced self-propulsion digital microfluidics

Nock

Müller

Sellier

et al. 2013

2013 Seventh International Conference on Sensing Technology (ICST)

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Abstract-This work reports on coalescence-induced selfpropulsion as a driving mechanism to actuate microfluidic droplet assays. We demonstrate multi-droplet translation and assay-type sensing on a digital microfluidics platform by use of surface tension gradients alone. These gradients arise during the coalescence of two droplets of liquid having different compositions and therefore surface tensions. We demonstrate a chemiluminescence blood-detection reaction based on the mixing of two carrier droplets containing solutions of synthetic blood and luminol sensor solution. Presence of iron in the blood solution is recorded using digital imaging and analyzed via offline image processing. The results demonstrate the capability of the propulsion mechanism to propel droplets over several millimeters, thus enabling one to design a new family of chip-based biochemical sensor assays.Microfluidics; sensor assay; chemiluminescence; luminol; image processing.

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“…Oxygen plasma treatment is used prior to casein application; however, this surface modification has a limited temporal stability. Thus, we are currently investigating the use of more permanent treatments to reduce the surface energy of the mould, such as the use of polyvinylpyrrolidone, 21 which may help to improve resolution.…”

Section: B Replication Of Regular Features Onto Casein Filmsmentioning

confidence: 99%

Fabrication of free-standing casein devices with micro- and nanostructured regular and bioimprinted surface features

Hashemi

Mutreja

Alkaisi

et al. 2015

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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This work introduces a novel process for the fabrication of free-standing biodegradable casein devices with micro-and nanoscale regular and biomimetic surface features. Fabrication of intermediate polydimethylsiloxane (PDMS) moulds from photoresist masters and liquid-casting of casein is used to transfer arbitrary geometrical shapes onto the surface of casein devices. Casein film composition was optimized for mechanical stability and pattern resolution. It was found that 15% casein in 0.2% NaOH solution, mixed with 10% glycerol, and cross-linked by addition of 2% glutaraldehyde produced the best pattern transfer results. Biomimetic cell-like shapes were transferred onto casein by use of bioimprinting of two-dimensional cell-cultures into PDMS. To demonstrate this process, C2C12 mouse myoblasts were cultured on microscope slides, replicated into PDMS and casein using liquid casting and drying. Recessed alignment grids were integrated into the microscope glass slides to facilitate direct comparison of original cells and their bioimprints on PDMS and casein. Optical microscopy and atomic force microscopy confirmed the transfer of micron-scale morphological features, such as cell outlines, nuclei and larger lamellipodia, into the casein surface. Nanoscale feature resolution in casein was found to be limited compared to the PDMS intermediate moulds, which was attributed to limited wetting of the aqueous casein solution. Strategies to increase resolution of the casein transfer step, as well as degradation behavior of the fabricated devices in cell culture media are currently underway. Substrates fabricated with this process have applications in stem cell engineering, regenerative medicine, and implantable devices.

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Rapid, simple, and cost-effective treatments to achieve long-term hydrophilic PDMS surfaces

Cited by 133 publications

References 52 publications

Generation of Oil Droplets in a Non-Newtonian Liquid Using a Microfluidic T-Junction

Generation of Oil Droplets in a Non-Newtonian Liquid Using a Microfluidic T-Junction

Biochemical sensing assays based on coalescence-induced self-propulsion digital microfluidics

Fabrication of free-standing casein devices with micro- and nanostructured regular and bioimprinted surface features

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