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SUMMARY:Stretching\, Sorting and Twisting in Microfludics - Dr Jonas Tegen
 feldt\, Lund University\, Sweden
DTSTART:20070613T080000Z
DTEND:20070613T090000Z
UID:TALK7529@talks.cam.ac.uk
CONTACT:Tracy Inman
DESCRIPTION:I will discuss my work in microfludics for DNA analysis and fo
 r sorting of particles.\nDNA forced into confinement in channels with diam
 eter approaching the persistence length of the DNA will adapt an elongated
  conformation. The end-to-end distance is proportional to the contour leng
 th of the DNA for the two prevailing models: for channels with diameters <
 < persistence length the stiffness of the DNA prevents it from folding bac
 k on itself (Odijk regime) and forB channels with diameters >> persistence
  length excluded volume effects dominate (deGennes regime). One interestin
 g recent experimental result is the strong dependence of the extension of 
 the DNA on the ionic strength. We show that a modified deGennes model base
 d on the salt-dependence of the effective width can be used to accurately 
 describe the behavior of the DNA at ionic strengths ranging from 2mM to 20
 0mM in channels with diameters 100nm or larger.\nThe benefits of stretchin
 g DNA in small channels will be discussed together with future plans such 
 as a soon to start project on a combined magnetic tweezers and nanofluidic
  channels.\nAnother field of interest in our group is microfluidic devices
  for fractionation of particles. I will discuss recent results on determin
 istic lateral displacement which is a powerful technique to separate parti
 cles in the micrometer range with uncertainties around 1%. The device work
 s like a cut-off filter\, sending larger particles in one direction and sm
 aller particles in another. To make the device adjustable we have made the
  device in an elastic material so that simply by stretching the entire dev
 ice we can adjust the cut-off size.B 
LOCATION:Small Lecture Theatre\, Cavendish Laboratory
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