Wettability control and patterning of PDMS using UV–ozone and water immersion

Ma, Kun; Rivera, Javier Oswaldo Bolaños; Hirasaki, George J.; Biswal, Sibani Lisa

doi:10.1016/j.jcis.2011.07.036

Cited by 75 publications

(66 citation statements)

References 37 publications

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“…Unless permanent grafting of hydrophilic polymers is achieved [25,26,27,28,29], the hydrophobic recovery of PDMS surfaces, i.e. their natural ability to restore their hydrophobicity after an oxidizing treatment (air/oxygen plasma [32,33,34], UV-ozone [35,21] or electric dis-charge [36,37]), is usually seen as a major impediment to wettability patterning. This phenomenon is attributed to a combination of different mechanisms, including (i) reorientation of surface polar groups towards the bulk and of non-polar groups towards the surface [32,33], (ii) elimination of hydroxyl groups by condensation of silanols [32] (iii) diffusion of low molecular weight silicone species (either preexisting or produced in situ by the oxidizing treatment) from the bulk to the surface [33,38,37,39].…”

Section: Introductionmentioning

confidence: 99%

Wettability patterning in microfluidic devices using thermally-enhanced hydrophobic recovery of PDMS

et al. 2019

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Spatial control of wettability is key to many applications of microfluidic devices, ranging from double emulsion generation to localized cell adhesion. A number of techniques, often based on masking, have been developed to produce spatially-resolved wettability patterns at the surface of poly(dimethylsiloxane) (PDMS) elastomers. A major impediment they face is the natural hydrophobic recovery of PDMS: hydrophilized PDMS surfaces tend to return to hydrophobicity with time, mainly because of diffusion of low molecular weight silicone species to the surface. Instead of trying to avoid this phenomenon, we propose in this work to take advantage of hydrophobic recovery to modulate spatially the surface wettability of PDMS. Because temperature speeds up the rate of hydrophobic recovery, we show that space-resolved hydrophobic patterns can be produced by locally heating a plasma-hydrophilized PDMS surface with microresistors. Importantly, local wettability is quantified in microchannels using a fluorescent probe. This "thermo-patterning" technique provides a simple route to in situ wettability patterning in closed PDMS chips, without requiring further surface chemistry.

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Section: Introductionmentioning

confidence: 99%

Wettability patterning in microfluidic devices using thermally-enhanced hydrophobic recovery of PDMS

et al. 2019

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“…UV-ozone treatment (UV/O 3 ) was used to modify the surface energy [25][26][27][28] of the dielectric layers after UV curing. Based on previous work [7], poor wettability was obtained for silver overprinted on the EMD 6200 dielectric layer.…”

Section: Uv-ozone Treatmentmentioning

confidence: 99%

“…As such, the purpose of using UV-ozone treatment is to improve the wettability of the silver ink overprinted onto the dielectric layer. Much literature abounds in the use of UV-ozone treatment to obtain more hydrophilic surfaces [29][30][31], with the extent of hydrophilicity dependent on the UV-ozone exposure time [25][26][27][28].…”

Section: Uv-ozone Treatmentmentioning

confidence: 99%

Surface modification of an ambient UV-cured dielectric to realise electrically conducting traces

Lim

Goh

Liu

et al. 2015

Surface and Coatings Technology

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Citation: LIM, Y.Y. ... et al, 2015. Surface modification of an ambient UVcured dielectric to realise electrically conducting traces. Surface and Coatings Technology, 266, Additional Information:• This article was accepted for publication in the journal, Surface and Coat- AbstractThere has been much interest in the printing of silver inks onto flexible substrates, for which intermediate dielectric layers are often required to achieve suitable wettability. This work seeks to realize continuous silver traces overprinted onto UV-curable dielectrics through surface modification techniques (thermal and UV-ozone post treatments), when the UV light source used for the curing is non-optimal. Two UV curable dielectric materials were deposited and the effects of curing time and curing atmosphere on the inkjet printability of a commercially available silver ink were investigated. Good wettability of the silver ink was obtained following ozone treatment of the dielectric layers, where the treatment required was found to be a function of the dielectric formulation and the curing atmosphere. Water droplet contact angle measurements were used to analyse the resulting changes in the surface conditions of the dielectric layers. The results provided an indication, but were not sufficient for predicting whether silver traces with measurable resistance could be subsequently obtained. Instead, measurable silver trace resistances were found to be influenced by the occurrence of cracks in the trace and possibly the degree of cross-linking present in the dielectric. Following these results, the authors demonstrate that electrically conductive traces can be achieved on ambient cured samples, which yields a more flexible solution compared to inert cured samples.

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“…In spite of its promising characteristics, PDMS is hydrophobic, which often limits its applicability in different areas. Various methods have been proposed to modify PDMS surface to impart hydrophilicity, for example, UV/ozone [17] or oxygen plasma [18] treatments, and subsequent functionalization or coating of the PDMS surface with hydrophilic polymers [19]. These methods are complex and required several steps.…”

Section: Introductionmentioning

confidence: 99%

Designing solid optical sensors for in situ passive discrimination of volatile amines based on a new one-step hydrophilic PDMS preparation

Jornet-Martínez

Moliner‐Martínez

Herráez‐Hernández

et al. 2016

Sensors and Actuators B: Chemical

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Wettability control and patterning of PDMS using UV–ozone and water immersion

Cited by 75 publications

References 37 publications

Wettability patterning in microfluidic devices using thermally-enhanced hydrophobic recovery of PDMS

Wettability patterning in microfluidic devices using thermally-enhanced hydrophobic recovery of PDMS

Surface modification of an ambient UV-cured dielectric to realise electrically conducting traces

Designing solid optical sensors for in situ passive discrimination of volatile amines based on a new one-step hydrophilic PDMS preparation

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