FACULTY    Martin Z. Bazant (Chemical Engineering and Mathematics)    Todd Thorsen (Mechanical Engineering) POSTDOC    Chien-Chih Huang (Applied Math and Mech. Eng.) PhD STUDENTS    Damian Burch (Applied Mathematics)    Xiaochuan Yang (Chemical Engineering) COLLABORATORS    Armand Ajdari (ESPCI, Paris)    Todd Squires (UCSB)    Brian Storey (Olin College)    Orlin Velev (NC State) ALUMNI    Mustafa Sabri Kilic (PhD Applied Mathematics 2008)    John Paul Urbanski (PhD Mechanical Engineering 2008)    Jeremy A. Levitan (PhD Mechanical Engineering 2005)    Kevin Chu (PhD Applied Math 2005)    Yuxing Ben (Postdoc 2004-2005)    Jakub Kominiarczuk (BS Physics 2007)    Matt Fishburn, Brian Wheeler, Andrew Jones (UROP)

100 micron/sec ICEO flow around a 25 micron gold post in a polymer microchannel driven by a 300 Hz 100 V/cm electric field from an experiment by J. Levitan. (Movie available below.)

Research

Press

• `Two-faced' particles act like tiny submarines, Science News, Mar. 3, 2008.
• Big lab on a tiny chip, by C. Q. Choi, Scientific American, October 2007, pp. 100-103.
• Fast Moving Front: Induced-charge electrokinetic phenomena, Thompson Scientific, Sept. 2007.
• Battery-powered lab-on-a-chip could be near, by R. C. Johnson, EE Times, Nov. 27, 2006.
• Portable 'lab on a chip' could speed blood tests MIT press release, October 16, 2006.
• Micropumps create a "fluid conveyor belt", press release by the Institute for Soldier Nanotechnologies, September 20, 2006.
• Fast three-dimensional pumps for microfluidics, Microsystems Technology Laboratories Annual Report 2006.
• Induced-charge electro-osmotic pumps and mixers for portable or implantable microfluidics, MTL Annual Report 2005.
• Team Combines Modeling and Experimentation to Improve Microfluidics ISN News, February 2, 2004.

Images

Simulation of 3D ACEO flow around stepped electrodes (by Yuxing Ben). Top: the electric field in phase with the AC forcing at the optimal pumping frequency. Bottom: The time-averaged streamlines showing the "fluid conveyor belt" which allows fast pumping. [Bazant & Ben, Lab on a Chip (2006).]

SEM image of a 3D ACEO pump, consisting of a periodic array of interdigitated stepped gold microelectrodes on a glass substrate (by J.P. Urbanski). Experiments confirm an order of magnitude increase in flow rate versus standard planar ACEO pumps, but also reveal a double-peaked frequency spectrum and flow reversal, not predicted by the standard theory. [Urbanski et al., Applied Physics Letters (2006).] Our latest devices, with theoretically optimized geometries [Burch & Bazant 2008] achieve > mm/sec velocities and 1 % atm pressure in water with only 1 Volt rms without flow reversal, and have been applied to DNA microarrays. [Huang, Bazant, Thorsen 2009]

Movies

• Experiments. The following movies show 0.5 micron fluorescent tracer particles in various ICEO flows, visualized with an optical microscope whose focal plane cuts through the interior of a PDMS microfluidic channel on glass. These kinds of movies are used to measure complete velocity profiles by micro-particle-image velocimetry, as described by Levitan et al. (2005). The typical applied electric fields are 100 V/cm at 300 Hz AC with slip velocities of order 100 micron/sec or more.
  • One vortex in quadrupolar ICEO flow around an electroplated gold post (20 microns tall, 150 microns in diameter).
  • Fixed-potential ICEO flow over an electroplated gold surface pattern (100 micron diameter) at 3 mm/sec.
  • (low resolution) Two ICEO vortices around 100 micron platinum wire in the experiment of Levitan et al. (2005). The movie shows the focal plane, parallel to the channel walls and perpendicular to the wire axis, at first cutting through the wire, showing converging flow, and then sweeping slowly up and away from the wire, eventually showing diverging flow, in a convection roll out of the plane.

• Simulations. Finite-element numerical simulations of electrochemical relaxation and ICEO flow around a metal cylinder in a suddenly applied uniform background electric field, modeled by the Poisson-Nernst-Planck equations and Navier-Stokes equations with electrostatic stresses, respectively. Debye length/ cylinder radius = 0.005. (Simulation by Yuxing Ben in FEMLAB, 2004.)
  • Evolution of the electric field around the metal cylinder. Notice how the bulk field lines are expelled from the double layer as it charges, although they turn sharply and always touch perpendicular to the surface, which remains an equipotential surface.
  • Evolution of the ICEO fluid velocity showing the formation of a quadrupolar Stokes flow outside the double layer, due to effective slip just outside the double layer, while maintaining the no-slip condition at the metal surface.

Slides

• Electrokinetics and Electrohydrodynamics of Microsystems
  Summer School, June 22-26, 2009, International Cent re for Mechanical Sciences, Udine, Italy
  PDF Slides:
  1. Introduction
  2. Low Voltage Theory
  3. Particle Motion
  4. Fluid Motion
  5. Large Voltage Theory

• Paris-Sciences Chair Lecture Series
  January 7 - February 14, 2008, ESPCI, Paris, France
  HTML Slides:
  1. Introduction to nonlinear electrokinetics
  2. Induced-charge electrophoresis in colloids
  3. AC electro-osmosis in microfluidics
  4. Theory at large applied voltages

The slides from these public lectures are available online, subject to the copyright restrictions below.

Publications

Induced-Charge Electro-osmosis

1. Induced-charge electro-kinetic phenomena: Theory and microfluidic applications, M. Z. Bazant and T. M. Squires, Phys. Rev. Lett. 92, art. no. 066101 (2004). This paper triggered a Fast Moving Front of research. (Thompson Scientific.) (PDF)
2. Induced-charge electro-osmosis, T. M. Squires and M. Z. Bazant, J. Fluid. Mech. 509, 217-252 (2004). (PDF)
3. Experimental observation of induced-charge electro-osmosis around a metal wire in a microchannel, J. A. Levitan, S. Devasenathipathy, V. Studer, Y. Ben, T. Thorsen, T. M. Squires, and M. Z. Bazant, Colloids and Surfaces A 267, 122-132 (2005). (PDF)
4. Electrostatic and electrokinetic contributions to the elastic moduli of a driven membrane, D. Lacoste, G. I. Menon, M. Z. Bazant, and J. F. Joanny, European Physical Journal E 28, 243-264 (2009). (PDF)
5. Nonlinear electrokinetics at large voltages, M. Z. Bazant, M. S. Kilic, B. Storey, and A. Ajdari, New Journal of Physics 11, 075016 (2009). (PDF)
6. Towards an understanding of nonlinear electrokinetics at large applied voltages, M. Z. Bazant, M S Kilic, B Storey, and A Ajdari, Advances in Colloid and Interface Science 152, 48-88 (2009). (PDF)
7. Effective zero-thickness model for a conductive membrane driven by an electric field, F. Ziebert, M. Z. Bazant, and D. Lacoste, submitted.

Induced-Charge Electrophoresis

8. Breaking symmetries in induced-charge electro-osmosis and electrophoresis, T. M. Squires and M. Z. Bazant, J. Fluid Mech. 560 65-101 (2006). (PDF)
9. Induced-charge electrophoresis of metallo-dielectric particles, S. Gangwal, O. J. Cayre, M. Z. Bazant, and O. D. Velev, Phys. Rev. Lett. 100, 058302 (2008). (PDF)
10. Induced-charge electrophoresis near an insulating wall, M. S. Kilic and M. Z. Bazant. (PDF)

Electro-osmotic Micropumps

11. Theoretical prediction of fast 3D AC electro-osmotic pumps, M. Z. Bazant and Y. Ben, Lab on a Chip, 6, 1455-1461 (2006). (PDF)
12. Fast AC electro-osmotic pumps with non-planar electrodes, J. P. Urbanski, T. Thorsen, J. A. Levitan, and M. Z. Bazant, Applied Physics Letters 89, 143508 (2006). (PDF)
13. The effect of step height on the performance of AC electro-osmotic microfluidic pumps, J. P. Urbanski, J. A. Levitan, D. N. Burch, T. Thorsen, and M. Z. Bazant, Journal of Interface and Colloid Science 309, 332-341 (2007). (PDF)
14. Electrolyte dependence of AC electro-osmosis, M. Z. Bazant, J. P. Urbanski, J. A. Levitan, K. Subramanian, M. S. Kilic, A. Jones, and T. Thorsen, Proceedings of MicroTAS, Paris (2007). (PDF)
15. Experimental study of electrolyte dependence of AC electro-osmotic pumps, K. Subramanian, J. P. Urbanski, J. A. Levitan, T. Thorsen, and M. Z. Bazant, Proceedings of the International Conference on Micro, Meso, and Nanoengineering, Trivandrum, India (2007). (PDF)
16. Steric effects on ac electro-osmosis in dilute electrolytes, B. Storey, L. R. Edwards, M. S. Kilic, and M. Z. Bazant, Phys. Rev. E 77, 036317 (2008). (PDF)
17. Design principle for improved three-dimensional ac electro-osmotic pumps, D. Burch and M. Z. Bazant, Phys. Rev. E 77, 055303(R) (2008). (PDF)
18. Numerical studies of nonlinear kinetics in induced-charge electro-osmosis, M. M. Gregersen, M. Z. Bazant, and H. Bruus, XXII ICTAM Proceedings, Adelaide, Australia (2008). (PDF)
19. Topology and shape optimization of induced-charge electro-osmotic micropumps M M Gregersen, F Okkels, M Z Bazant, and H Bruus, New Journal of Physics 11, 075019 (2009) . (PDF)
20. Ultrafast high-pressure AC electro-osmotic micropumps for portable biomedic al microfluidics, C. C. Huang, M. Z. Bazant, and T. Thorsen, Lab on a Chip 10, 8 0-85 (2010). (PDF)

    Reviews

21. Induced-charge electrokinetic phenomena, M. Z. Bazant and T. M. Squires, Current Opinion in Colloid and Interface Science, to appear. (PDF)
22. Nonlinear electrokinetic phenomena, M. Z. Bazant, in Li, Dongqing (ed), Encyclopedia of Microfluidics and Nanofluidics, Part 14, pp. 1461-1470 (Springer, Berlin, Heidelberg, New York, 2008). (PDF)
23. AC Electro-osmotic flow, M. Z. Bazant, in Li, Dongqing (ed), Encyclopedia of Microfluidics and Nanofluidics, Part I, pp. 8-14 (Springer, Berlin, Heidelberg, New York, 2008). ( PDF)
24. Electrokinetic motion of polarizable particles , M. Z. Bazant, in Li, Dongqing (ed), Encyclopedia of Microfluidics and Nanofluidics, Part 5, pp. 522-529 (Springer, Berlin, Heidelberg, New York, 2008). ( PDF)
25. Electrokinetic motion of heterogeneous particles, M. Z. Bazant, in Li, Dongqing (ed), Enc yclopedia of Microfluidics and Nanofluidics, Part 5, pp. 518-522 (Springer, Berlin, Heidelberg, New York, 2008). (PDF)

Ph.D. Theses

26. J. A. Levitan,Experimental Investigation of Induced-Charge Electro-osmosis, Doctoral Thesis in Mechanical Engineering, MIT (2005).
27. K. T. Chu, Asymptotic Analysis of Extreme Electrochemical Transport, Doctoral Thesis in Applied Mathematics, MIT (2005).
28. Mustafa Sabri Kilic, Induced-charge electrokinetics at large voltages. Doctoral Thesis in Applied Mathematics, MIT (2008).

    Patents

29. M.I.T. Case # 9576 - T. M. Squires and M. Z. Bazant, Microfluidic pumps and mixers driven by induced-charge electro-osmosis, US Patent 10/319,949 issued in 2006, filed in 2002. International Patent PCT/US02/40290.
30. M.I.T. Case # 11683 - J. A. Levitan, T. Thorsen, M. Schmidt, and M. Z. Bazant, Microfluidic pumps and mixers driven by induced-charge electro-osmosis, US Patent Application 11/252,871 filed in 2005.
31. M.I.T. Cases #12056, 12057, 12058 (combined into one patent) - M. Z. Bazant, Y. Ben, J. A. Levitan, and J. P. Urbanski, Induced-charge electro-osmotic microfluidic devices, US Patent Application 11/700/949, filed in 2007.
32. M.I.T. Case #12513 - M. Z. Bazant and J. A. Levitan, Temporal modulation of electrokinetic pumps for mixing applications, US Patent Application, filed in 2007.
33. M.I.T. Case #12639 - M. Z. Bazant, Induced-charge electrokinetics with high-slip polarizable surfaces, US Patent Application 60/996/245 filed in 2007.
34. M.I.T. Case # 12949T - M. Prakash and M. Z. Bazant, Multiphase microfluidic devices, 2009.

Support

• National Science Foundation, Contract DMS-0707641 with the Division of Mathematical Sciences (2007-present)
• MIT Insitute for Soldier Nanotechnologies, Contract DAAD-19-02-0002 with the U.S. Army Research Office (2002-present)
• MIT-France Program, seed grant (2004)
• MIT-Spain Program, seed grant (2008)
• MIT Microsystems Technology Laboratories

Disclaimer

Copyright