V11 Electrokinetic III Dielectrophoresis WS 23 PDF

V11 11 Electrokinetic III Dielectrophoresis (DEP) Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 1 Contents and Learning Targets V11 Contents and Learning Targets 11.1 Int...

V11 11 Electrokinetic III Dielectrophoresis (DEP) Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 1 Contents and Learning Targets V11 Contents and Learning Targets 11.1 Introduction  Principle  Clausius-Mossotti factor 11.2 Applications 11.2.1 Capture 11.2.2 Transport 11.2.3 Sorting Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 2 V11 11.1 Introduction Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 3 11.1 Dielectrophoresis - Introduction V11 Describes the manipulation of a polarizable Dielectrophoresis* - DEP - particle in an nonuniform electric field due to the influence of the electric field on the induced charge at the interface particle/medium FDEP = 0 https://pratted.wordpress.com/tag/dielectrophoresis/ * First described by H.A. Pohl: J. Appl. Phys. 22 (7) 869-871 (1951) Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 4 11.1 Dielectrophoresis - Introduction 5 www.foresight.org V11 Dielectrophoresis  Polarizable particle in medium  Application of nonuniform electric field on the particle  Electric field polarizes the particle  Dipoles are generated  Nonuniform electric field generates a force on the polarized particle http://www.mdpi.com/1424-8220/15/6/13201/htm G. Zhu et al.: Mirco and Nanosystems 2 202-216 (2010) Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 11.1 Dielectrophoresis - Introduction V11 6 Application of an Electric Field Across Two Electrodes Generates Electric Field Lines Electric flux density D 𝐸 + -  describes the density of electric field lines per unit area Permittivity in vacuum ε0 D  0  E ε0 … Permittivity in vacuum, ε0 = 8.854187 * 10-12 F/m Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 in vacuum 11.1 Dielectrophoresis - Introduction V11 7 In most media dipoles exist  When an electric field is applied across a medium + -  Dipoles align with the field  Electric polarization density 𝑃 has to be added D  0  E  P  𝑃 expresses the density of the permanent χe… Electric susceptibility, and induced electric dipole moments in the medium is a measure of how easy a dielectric material  The polarizability of a medium is described by the electric polarizes in response to an electric field susceptibility χe ε0 … Permittivity of vacuum P   0  e  E E … Electric field strength Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 11.1 Dielectrophoresis - Introduction D  0  E  P P   0   e E D   0  E   0  e E D   0  (1   e ) E → e   r  1 D  0  r  E    E Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V11 8 χe… Electric susceptibility, is a measure of how easy a dielectric material polarizes in response to an electric field ε0 … Permittivity of vacuum εr … Relative permittivity ε … Permittivity E … Electric field strength + … See Annex 1 11.1 Dielectrophoresis - Introduction V11 Polarizable Particle Generates Dipoles with Application of an AC Electric Field AC fields applied to dipoles  Dipoles align instantaneously with the alternating fields at low frequencies  At higher frequencies, dipoles are too slow to orientate with the electric field instantaneously. They rotate out of phase with the incident electric field Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 9 11.1 Dielectrophoresis - Introduction Complex permittivity ε* V11 10  *   '  j   '' j  1 describes Ohmic current and frequencydependent polarization Real part (Re)  Motion of free charges in the medium along with the applied electric field  Corresponds to Ohm’s current Imaginary part (Im)  Corresponds to motion of bound charges (dipoles) with the electric field  Displacement current  ε‘ is called dielectric constant ε … Permittivity j … Imaginary unit Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 11.1 Dielectrophoresis - Introduction     j  * Complex permittivity ' V11 11 ''     ' j  j  1 *  *   0 r  j ω… Angular frequency ε0 … Permittivity of vacuum εr … Relative permittivity σ … Conductivity   Imaginary part (Im) describes polarization effects Displacement current  is high at low frequencies (dipoles follow electric field)  Energy is transferred from the electric field to the medium, e.g., heat  is smaller at higher frequencies (medium has not the time to polarize)  Less energy is transferred from the electric field to the medium Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 11.1 Dielectrophoresis - Introduction Induced dipole moment p on a small sphere by application of an AC electric field E With Dielectrophoretic force F p …..... Dipole moment r …….. Radius of particle ε*p...... Complex permittivity of particle FDEP (t )  ( p ) E (t ) * *    p(t )  4  r 3   m  ( *p m* )  E (t )  p  2 m 1 E ( E )  E 2 2 * *    F DEP (t )  2  r 3   m  ( *p m* ) E 2  p  2 m ε*m ….. Complex permittivity of medium E… Electric field Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 G.H. Markx et al.: J. Phys. D: Appl. Phys. 30 2470-2477 (1997) Y. Huang et al.: Biophysical Journal 73 1118-1129 (1997) Dielectrophoretic force F V11 12 11.1 Dielectrophoresis - Introduction V11 13 p Clausius-Mossotti Factor  *  2 m* p Rudolf Clausius (1822-1886) also called „polarization coefficient“ en.wikipedia.org fCM   *   m* en.wikipedia.org * *    F DEP (t )  2  r 3   m  ( *p m* ) E 2  p  2 m fCM describes  the relation of the dielectric properties of a particle in relation to those of the surrounding medium  the competition between polarizability of particle and medium B.C. Gierhart et al.: Langmuir 23 12450-12456 (2007) Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 Ottaviano-Fabrizio Mossotti (1791-1863) 11.1 Dielectrophoresis - Introduction ! Real part, not Reynolds number ! Time-averaged DEP force F DEP * *    2  2  r 3   m  Re( *p m* ) Erms  p  2 m square root (r) T With Erms 1    E (t )2dt T 0 square (s) Time average (m) r …….. Radius of particle ε*p...... Complex permittivity Re ….. Real part, not Reynolds number ε… Dielectric constant E… Electric field Erms … Root-mean-square electric field strength T ……... Time of one period of AC electric field Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 G.H. Markx et al.: J. Phys. D: Appl. Phys. 30 2470-2477 (1997) Y. Huang et al.: Biophysical Journal 73 1118-1129 (1997) V11 14 11.1 Dielectrophoresis - Introduction Re( fCM )  Re( V11 15  *   m* p  *  2 m* ) www.lme.ei.tum.de p Re fCM > 0  Polarizability of particle is higher that that of medium  Particle is attracted by high of electric field strength Re fCM < 0  Polarizability of medium is higher than that of particle  Particle is pushed in direction of low electric field strength Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 11.1 Dielectrophoresis - Introduction Re V11 16  *   m* p  *  2 m* p Note: for f < 10 kHz  εp depends on frequency of the electric field  Dispersion is mainly due to the relaxation time τ of the counter ions in EDL surrounding the particle (see also S56 in V09) ε* …..  Re(fCM) is therefore depending on frequency, ε… σ…  cannot be described analytically ω… m… (situation is too complex) p ……... R. Pethig et al.: J. Phys. D: Appl. Phys. 24 881-888 (1992)τ … J. Berthier et al.: ISBN 1-58053-961-0 Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 Permittivity Dielectric constant Conductivity Angular frequency Medium Particle Time constant associated with the build-up charges in the EDL 11.1 Dielectrophoresis - Introduction Re  *   m* p   2 * p * m  V11 17 ( p   m )   2 2 ( p  2 m )(1    ) 2 2  ( p   m ) ( p  2 m )(1   2 2 ) Note: for f > 10 kHz   Counter ions in EDL do not have enough time to move ( p  2 m ) ( p  2 m )  Particle and medium are non-disperse (εp, εm, σp, σm are not depending on frequency)  Re(fCM) is then related to the difference in dielectric constants between particle and medium R. Pethig et al.: J. Phys. D: Appl. Phys. 24 881-888 (1992) J. Berthier et al.: ISBN 1-58053-961-0 Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 ε* ….. ε… σ… ω… m… p ……... Permittivity Dielectric constant Conductivity Angular frequency Medium Particle 11.1 Dielectrophoresis - Introduction V11 18 ( p   m ) ( p  2 m ) Re  *   m* p  *  2 m* p  ( p   m )   2 2 ( p  2 m )(1   2 2 )  ( p   m ) ( p  2 m )(1   2 2 ) cross-over frequency Re f CM positive DEP Re( fCM ) negative DEP f CM( f  0.5Im  Re CM )  1 ( p   m ) ( p  2 m ) http://www.foresight.org/Conference/MNT7/Papers/Hughes/ J. Berthier et al.: ISBN 1-58053-961-0 Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 11.1 Dielectrophoresis - Introduction Re  *   m* p   2 * p * m  V11 19 ( p   m )   2 2 ( p  2 m )(1    ) 2 2  ( p   m ) ( p  2 m )(1   2 2 ) Electrical conductivity σm of medium 2 µm polystyrene bead  p  2.5   0  p  6.7 1014  m  80.2   0 R. Pethig et al.: J. Phys. D: Appl. Phys. 24 881-888 (1992) J. Oh et al.: Lab Chip 9 62-78 (2009) Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 S m 11.1 Dielectrophoresis - Introduction F DEP V11 20 * *    p m 2  2  r 3   m  (Re * )  E rms  p  2 m*  DEP force acts only, when an electric field gradient exists:  DEP force independent of polarity of applied electric field E  AC fields are favored to suppress  Electrophoretic forces  Electrolysis and electrochemistry at surfaces Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 Erms  0 11.1 Dielectrophoresis - Introduction F DEP * *    2  2  r 3   m  (Re *p m* ) Erms  p  2 m  FDEP ~ Volume of particle  Very high field gradients are necessary for very small particles so that DEP force is significantly higher than Brownian motion  High field gradients can be realized with thin-film electrodes  Small sizes and gaps  Prevent heating (e.g. MV/m for ΔT = 1 °C possible) Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V11 21 V11 22 11.2 Dielectrophoresis - Applications Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 11.2 DEP - Applications V11 23 Dielectrophoresis Capture Transport* Sorting of Polarizable Particles, esp. Cells * by travelling waves Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 11.2.1 DEP Applications - Capture 11.2.1 V11 24 DEP Capture Quadrupole Castellated Area Electrodes Electrodes Electrodes Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 11.2.1 DEP Applications - Capture V11 25 Capture at Quadrupole Electrodes Quadrupole Arrangement Electric Field Cage Top view Planar micro electrodes Electric field strength at a and c in same phase, at b and d 180° phase-shifted http://www.foresight.org/Conference/MNT7/Papers/Hughes/ Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 11.2.1 DEP Applications - Capture V11 26 Electric Field Cage Surface of constant vertical force acting on a particle Sedimentation (buoyancy and gravitation) Force Particle n-DEP Force F DEP * *    2  2  r 3   m  (Re *p m* ) Erms  p  2 m For trapping, negative Re fCM for Th. Schnelle et al.: Naturwissenschaften 83 172-176 (1996) Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 n-DEP is required 11.2.1 DEP Applications – Capture V11 27 Electrorotation DEP with Application of a Travelling Wave to the Electrodes of a Field Cage 90° phase shift of electric field at each electrode Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 11.2.1 DEP Applications – Capture V11 28 Electrorotation 1. Generate n-DEP (levitation of particle) 2. Apply traveling wave (rotation) If electric field E rotates fast,  The induced dipoles M lack behind the electric field by an angle (phase shift), which is related to the trailing relaxation of the dipoles  The interaction between the electric field and the trailing dipoles induces a torque G in the particle, causing the particle to rotate  Phase shift is represented by the imaginary part of fCM https://foresight.org/Conferences/MNT7/Papers/Hughes/index.html Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 11.2.1 DEP Applications – Capture Torque Γ on a sphere due to tw-DEP V11 29 G   4   m  r 3  Im( fCM )  E 2 m    Im( fCM )  E 2 2 https://foresight.org/Conferences/MNT7/Papers/Hughes/index.html Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 Rotation frequency 11.2.1 DEP Applications – Capture V11 30 Electrorotation Principle was commercialized in Cytocon 400 of Evotec Technologies, Germany, but the device was withdrawn from the market after the company was taken over by Perkin Elmer G. Grandl et al.: Proc. Micro Total Analysis Systems (2000), p. 443-446 Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 11.2.1 DEP Applications - Capture V11 31 Capture at Castellated Electrodes Top view to castellated electrodes Plot of electric field strength at electrode surface 6 µm 4 µm Electrode 1V = 2,5*105 V/m N.G. Green et al.: J. Phys. D: Appl. Phys. 30 L41-L84 (1997) Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 11.2.1 DEP Applications - Capture Re(fCM) for Yeast Cells (Multiple Shell Model) G.H. Markx et al.: Enzyme and Microbial Technology 25 161-171 (1999) Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V11 32 11.2.1 DEP Applications - Capture V11 33 f > 200 kHz σm = 150 µS/cm Electrode 10 kHz < Yeast Cells f < 100 kHz Electrode f < 500 Hz Electrode R. Pethig et al.: J. Phys. D: Appl. Phys. 24 881-888 (1992) Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 11.2.1 DEP Applications - Capture p-DEP ↔ n-DEP Depending on relation between permittivity of medium and particle f CM   *   m* p  *  2 m* p Separation of a suspension of two cell types with very different conductivities σp and adjustment of medium conductivity σm in between G.H. Markx et al.: Microbiology 140 585-591 (1994) Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V11 34 11.2.1 DEP Applications - Capture V11 35 Capture of Cell Varieties f CM   *   m* p  *  2 m* p σm = 550 µS/cm pDEP nDEP Before application of an electric field Micrococcus lysodeikticus (σp = 1557 µS/cm @ 15 kHz) Saccharomyces sphaeroids (σp = 16 µS/cm @ 10 kHz) G.H. Markx et al.: Microbiology 140 585-591 (1994) Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 8 Vpp @ 10 kHz after a few seconds 11.2.1 DEP Applications - Capture V11 36 Capture at Area Electrodes Blood cancer cells m = 10 mS/m T-Lymphocytes He-60 T-Lymphocytes He-60 m = 10 mS/m n-DEP Y. Huang et al.: Biophysical Journal 73 1118-1129 (1997) Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 p-DEP 11.2.2 DEP Applications – Transport 11.2.2 Transport of Polarizable Particles by Travelling-Wave DEP (tw-DEP) Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V11 37 11.2.2 DEP Applications – Transport V11 38 Tw-DEP Translation  In standard DEP setups, the transport of polarizable particles over long distances remains challenging  For transport of particles over large distances, tw-DEP is favorable Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 11.2.2 DEP Applications – Transport V11 39 Tw-DEP Translation  Electrodes in symmetrical parallel arrangement  Apply n-DEP  Apply a travelling wave electric field (translation)  Polarizable particle under influence of the electric field  When travelling wave frequency faster than relaxation frequency of dipoles  the induced dipole M will lag behind the electric field E (phase shift)  Inducing a force F in the particle  Force in direction of travelling wave or opposite to it https://foresight.org/Conferences/MNT7/Papers/Hughes/index.html Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 11.2.2 DEP Applications – Transport V11 40 Principle was commercialized in Cytocon 400 of Evotec Technologies, Hamburg, Germany Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 11.2.2 DEP Applications – Transport V11 41 Total Force on Polarizable Particle in tw-DEP FDEP  2  r   m  (Re fCM )E 3 2 rms Create force for n-DEP (levitation)  4   m  r 3   (Im fCM )   Ex2 x  E y2 y  Ez2 z  Create force for tw-DEP (rotation or lateral movement) λ ………… Wavelength of the travelling electric field, repetitive distance between electrodes of the same phase Ex, Ey, Ez… Components of the electric field vector φx, φy, φz … Phase angles if the electric field is spatially phase-shifted Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 11.2.2 DEP Applications – Transport FDEP  2  r   m  (Re fCM )E 3 2 rms  4   m  r 3  V11 42 fCM for polystyrene particles in H20  (Im fCM )   Ex2 x  E y2 y  Ez2 z  Two requirements for tw-DEP 1. Re fCM < 0 (n-DEP) 2. Im fCM ≠ 0 (particle lateral movement / rotation) σm = 40 mS/m D. Liu et al: Nanoscale and Microscale Thermophysical Eng. 13 109-133 (2009) R. Pethig et al.: IEEE Eng. Med. Biol. Magazine Nov. 2003 Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 11.2.3 DEP Applications – Sorting DEP Sorting Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V11 43 11.2.3 DEP Applications – Sorting V11 44 Cell (E. coli) Cell (E. coli) labeled with dielectrophoretically responsive label n-DEP force is weak  Long electrodes  Long channels X. Hu et al.: PNAS 102 (44) 15757-15761 (2005) Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 11.2.3 DEP Applications – Sorting V11 45 FDEP Fhyd Θ 2 F DEP  2  r 3   m  Re( fCM ) Erms > M. Dürr et al.: Electrophoresis 24 722-731 (2003)) Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 F hyd  6     r  v  sin  11.2.3 DEP Applications – Sorting Not any more available on youtube V11 46 https://www.youtube.com/watch?v=fr0fDWnj57U Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 11.2.3 DEP Applications – Sorting V11 47 Sorting in Cytometers (FACS*) http://www.youtube.com/watch?v=4zsSET80jpQ * Fluorescence Activated Cell Sorting Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 Conclusion V11 48 Conclusion  DEP is useful to manipulate polarizable particles, esp. cells by using AC electric fields  DEP force depends on  Particle volume  Clausius-Mossotti factor  (Gradient) electric field strength  Frequency  Travelling wave electric fields Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V11 49 One Minute Paper 1. What was the most important topic you understood? 2. What was the topic you didn‘t catch? Lecture „Microfluidic Systems - Bio-MEMS“ – Electrokinetic III - Dielectrophoresis Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23