Difference between revisions of "Surface-induced droplet fusion in microfluidic devices"

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(New page: "Surface-induced droplet fusion in microfluidic devices" Luis M. Fidalgo, Chris Abell, and Wilheml T.S. Huck ''Lab Chip'', 2007, '''7''', 984-986 == Soft Matter Keywords == Microfluidic...)
 
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== Soft Matter Examples ==
 
== Soft Matter Examples ==
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[[Image:Paper9_fig1.jpg|thumb|right|300px|'''Fig.1''']]
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[[Image:Paper9_fig2.jpg|thumb|right|300px|'''Fig.2''']]
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[[Image:Paper9_fig3.jpg|thumb|right|300px|'''Fig.3''']]
  
 
Droplets in microfluidic devices have shown to be important for carrying out on-chip reactions. So far, the coalescence of two drops in a microfluidic channel have been done by either applying electric fields to polarize the interfaces of teh droplets, or by forcing physical contact of the two droplets using precise geometries. The authors here demonstrate a method of combining two droplets by altering surface energy in the microfluidic channels.  
 
Droplets in microfluidic devices have shown to be important for carrying out on-chip reactions. So far, the coalescence of two drops in a microfluidic channel have been done by either applying electric fields to polarize the interfaces of teh droplets, or by forcing physical contact of the two droplets using precise geometries. The authors here demonstrate a method of combining two droplets by altering surface energy in the microfluidic channels.  
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The authors grafteed poly(acrylic acid) (PAA) using UV photopolymerization on benzophenone-containing PDMS surfaces. Figure 1(b) shows a picture of a part of a PDMS channel that contained a patterened poly(acrylic acid) part. When water droplets (in a continuous phase of oil) flow past the patterned surface, they are trapped. When the next drop arrives, the two drops combine and mix (Fig. 2). Because the process produces no loss of material, the coalesced droplets are also monodispersed.  
 
The authors grafteed poly(acrylic acid) (PAA) using UV photopolymerization on benzophenone-containing PDMS surfaces. Figure 1(b) shows a picture of a part of a PDMS channel that contained a patterened poly(acrylic acid) part. When water droplets (in a continuous phase of oil) flow past the patterned surface, they are trapped. When the next drop arrives, the two drops combine and mix (Fig. 2). Because the process produces no loss of material, the coalesced droplets are also monodispersed.  
  
In order for a droplet to be trapped on the surface, the droplet has to have sufficient time on the surface. The authors show that if the droplet moves too fast, it will escape the trap (Fig. 3). The droplet's detachment is governed by viscous drag (<math> w \eta v </math>) and interfacial force (<math> w \gamma </math>), where w is the widtho f the pattern.
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In order for a droplet to be trapped on the surface, the droplet has to have sufficient time on the surface. The authors show that if the droplet moves too fast, it will escape the trap (Fig. 3). The droplet's detachment is governed by viscous drag (<math> w \eta v </math>) and interfacial force (<math> w \gamma </math>), where w is the widtho f the pattern. When the force produced by viscous drag (the oil moving faster than the water droplet) overcomes the interfactial force that holds the droplet to the patterned surface, the droplet breaks off and is no longer trapped.

Revision as of 23:44, 19 April 2009

"Surface-induced droplet fusion in microfluidic devices"

Luis M. Fidalgo, Chris Abell, and Wilheml T.S. Huck

Lab Chip, 2007, 7, 984-986

Soft Matter Keywords

Microfluidics, droplet, surface tension, PDMS

Overview

Refer to paper

Soft Matter Examples

Fig.1
Fig.2
Fig.3

Droplets in microfluidic devices have shown to be important for carrying out on-chip reactions. So far, the coalescence of two drops in a microfluidic channel have been done by either applying electric fields to polarize the interfaces of teh droplets, or by forcing physical contact of the two droplets using precise geometries. The authors here demonstrate a method of combining two droplets by altering surface energy in the microfluidic channels.

The authors grafteed poly(acrylic acid) (PAA) using UV photopolymerization on benzophenone-containing PDMS surfaces. Figure 1(b) shows a picture of a part of a PDMS channel that contained a patterened poly(acrylic acid) part. When water droplets (in a continuous phase of oil) flow past the patterned surface, they are trapped. When the next drop arrives, the two drops combine and mix (Fig. 2). Because the process produces no loss of material, the coalesced droplets are also monodispersed.

In order for a droplet to be trapped on the surface, the droplet has to have sufficient time on the surface. The authors show that if the droplet moves too fast, it will escape the trap (Fig. 3). The droplet's detachment is governed by viscous drag (<math> w \eta v </math>) and interfacial force (<math> w \gamma </math>), where w is the widtho f the pattern. When the force produced by viscous drag (the oil moving faster than the water droplet) overcomes the interfactial force that holds the droplet to the patterned surface, the droplet breaks off and is no longer trapped.