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AC Dielectrophoresis of Nanocolloids

AC Dielectrophoresis of Nanocolloids. Hsueh-Chia Chang Chemical and Biomolecular Engineering. MBT- WT. Nanoparticle Assays. Reduced Diffusion Length: Speed Enhanced Fluorescence Signal: Sensitivity. Neighboring charges cancel. Surface is induced with net positive charge.

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AC Dielectrophoresis of Nanocolloids

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  1. AC Dielectrophoresis of Nanocolloids Hsueh-Chia Chang Chemical and Biomolecular Engineering

  2. MBT- WT Nanoparticle Assays Reduced Diffusion Length: Speed Enhanced Fluorescence Signal: Sensitivity

  3. Neighboring charges cancel Surface is induced with net positive charge Surface is induced with net negative charge E AC Dielectrophoretic DEP Dielectric Induced Particle Dipole Field-Induced Dielectirc Polarization: Independent of Surface Charge E fparticle - + - + Induced dipole - + - + Negative DEP Dipolar Assembly Stretching and Compression Net Force without Space Charge Sorting with Non-Uniform Field

  4. Conductive Induced Dipolesin ElectrolytesWang, Wei & HCC, Biomicrofluidics (2008) z Fluorescent counterions Flourescent nanocolloids

  5. A Smart DEP Trap of CdSe Nanowires R. Zhou, HCC et al. J App Phys (2006)

  6. AC Electrokinetics with Embeddable Micro-Electrodes Color Images and Videos http://bmf.aip.org

  7. AC Dielectrophoresis of RBC Zhou and HCC, Electrophoresis (2006)

  8. Lastochkin et al APL (2004) DEP Microfluidic Platform

  9. Electro-Rotation of Pyramid Cylinder 50kHz 100kHz

  10. Spiral Trap Z. Gagnon and Chang Electrophoresis (2005)Video: Biomicrofluidics http:bmf.aip.org ACEO Velocity ~ cm/s

  11. Embeddable Electrodes I-F Cheng, H-C Chang, D Hou & HCC, BMF (2007)

  12. Nanocolloid DEP

  13. CNT Fractal: Gas Phase DEP

  14. HCC (2007) 10 Minute DNA Identification

  15. Surface Charge Affects DEP Cross-Over

  16. Glutaraldehyde Cross-Linking of Membrane Proteins 1 week 2,3 week Gagnon, Gordon & HCC Biomicrofluidics (2007) Electrophoresis (2008) Openning Ion Channels ?

  17. Size Dependent DEP co a-1 scaling  = 600 kHz Gagnon & HCC Electrophoresis (2004) P-DEP of bubbles Gorre-Talini et al., PRE (1997) Phenomena cannot be explained by conventional M-W theory

  18. Size-Surface Charge Independent Maxwell-Wagner Frequency 1/2 > ++++ Postive DEP ---- a -- ++ E Cross-Over Frequency θ co Negative DEP -1/2 p/p=D/2 Charge Relax Freq

  19. Conductive Induced Dipolesof Electrolytes z

  20. Conducting Particle MW theory Diffusive Layer Capacitor Pole Charging By Surface Current Insulated Particle ~ s >> s m1/2 m-1 Latex Nanocolloids inNaCl and KCl (Ks/ma) D/L ACEO Flow mM DI Green and Morgan, J Phys Chem, 1999

  21. Enhanced Particle Conductivity Tangential Current in Collapsed Layer: No Charging Collapsed Layer Conductance s s~(4RT/FEs) insulator a p=Ks/a=ss/a RC Time for Particle R~a2 RC-1~a-1 Cs=(E2s/8RT)>>CDL Ks=[EsD/5(RT/F)]

  22. 10-1 charge/nm2 Es=105 V/cm Low-Conductivity Theory m Independent Carboxylated Latex colloids * DI mM

  23. n0 > n0* External potential of Insulated particle Normal Charging of Thick Diffuse Layer Basuray and HCC Phy Rev E (2007) tangential diffusion normal charging tangential conduction R~a/m C~/ (RC)-1~D/ (a) ~m1/2

  24. nDEP 282 nm 557 nm nDEP pDEP pDEP m1/2 nDEP nDEP pDEP 93 nm 216 nm MW Theory pDEP Green & Morgan 1999

  25. Pole Charging for Thin Diffuse LayerLarger Resistance due to Diminishing Surface Current z Small Polar Capacitor

  26. High-Conductivity Collapse Green & Morgan 1999 Slope= -1 Colllapsed Layer m0 m1/2 Slope= 0 a2/D Diffuse Layer Slope= -2 Pole Charging m-1 D/a DI mM

  27. Diffuse Layer Capacitance Diffusion/Surface Charge : Collapsed and Diffuse Layer Capacitance And Conductance m1/2 Pole Capacitor Collapsed Layer Conductance m-1 * (D/L) (D/a2)(/a)2 ac=(mD/Ks)~200 nm No Adjustable Parameters Explicit Cross-Overs HCC, Basuray & Wei (2008) = s

  28. AC Electrokinetics of Nanocolloids:Tuning in the Desired Physics1 KHz <  < 10 MHzD/2, D/ sa, D/a, D/L, Dp/2 Surface Charge/Diffusion Effects Collapsed and Diffuse Debye Layers Capacitance & Conduction Surface/Membrane Molecular Characterization Diagnostics and Drug Screening Compound Particle Synthesis NanoColloid/Molecule Surface Docking

  29. Post-Docs: S. Senapati, G. Yossifon, P. Wang PhD Students: Z. Gagnon, S. Basuray, X. Cheng, N. Chetwani Collaborators: Y. E. Zhu, D. Lodge, J. Feder, D.T. Leighton. M. Kuno, D. Jena, H. Xing (ND) Weijia Wen (HKUST) Hsien-Chang Chang, I. -F. Cheng, H.-H. Wei (Cheng Kung, Taiwan) F. Plouraboue (Toulouse), Y.-L. Chen (Acad. Sinica,Taiwan) J. Kreft (UT Arlington), S-C Wang (Chong Cheng, Taiwan) Alumni (since 2000): J. Keith (Michigan Tech) *D. Kopelevich (Florida) P. Takhistov (Rutgers) *A.Minerick (Mississippi State) S. Thamida (IISci, Bangalore) *J. Wu (Tennessee) G. Arya (UC San Diego) L. Yeo (Monash Univ), S. Sengupta (Missouri) Z. Chen (Wuhan Univ, Luojia Prof) *NSF Career Awardees Y. Ben (Haliburton) R. Zhou (Rohm & Haas) P. Wang (Chevron) J. Gordon (Midwest Lab.) D. Hou (Merck) S. Maheshwari (Brookbridge)

  30. Center for Microfluidics and Medical Diagnostics www.nd.edu/~changlab

  31. (b) (a) (c) (d) High-Throughput AC Multi-Thread Spinning Yeo, Gagnon and HCC, Biomaterials (2005) Maheshwari & HCC, Adv Materials (2008) Nano-Aerosol Filtration

  32. RC Relaxation Times R • << RC-1 Conductive Current >> RC-1 Capacitor Charging Current C Capacitor Charge Accumulation due to Conductivity Gradient D/2, D/ sa, D/a, D/L, Dp/2

  33. Electrokinetic Equations --symmetric electrolyte Space Charge Density IonTransport Singular Diffusion Term Charge Ionic Strength Surface Charge & Diffusion Electromigration

  34. Nanocolloid Electrophoresis Hoffmann, Basuray, HCC and Zhu (2007) Charging of Macro-Ions  < c

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