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Opto-Electrowetting (OEW) Nano-Bio-Sens ing Summer Sc hoo l @ EPFL June 29 – July 3, 2009 Introduction to Optofluidics Ming C. Wu University of California, Berkeley Electrical Engineering & Computer Sciences Dept. Berkeley Sensor and Actuator Center (BSAC) [email protected] .edu Wu-1 ©2009. University of California Optofluidics • Electrowetting optics • Tunable lenses • Electronic papers • Optical trapping and manipulation • Optofluidic lab-on-a-chip • Microresonators • Photonic crystals Wu-2 ©2009. University of California Optofluidics • Integration of optics and fluidics to synthesize novel functionalities • Applications: Li, et. al., Opt. Express, 2006 – Use microfluidics to control light • Optical switches, tunable lenses • Display • Sensors – Use light t o cont rol micro flu idics, micro/nanoparticles, cells, … Wolfe, et. al., Proc. Natl. Acad. Sci. , 2004 • Optical trapping, sorting, and assembly • Non-invasive optical actuation Psaltis, et. al., Nature, 2006 Domachuck, et. al., Nature, 2005 Wu-3 ©2009. University of California “Bubble” Switches Agilent Champaign Switch • Optical crossbar switch using total internal reflection by a thermally generated bubble • 32x32 switches have been demonstrated • J. E. Fouquet, "Compact optical cross-connect switch based on total internal reflection in a fluid- containing planar lightwave circuit,“ OFC 2006 Wu-4 ©2009. University of California Optofludic Microscopy • Low-cost, high-resolution (0.8 !m), lensless on-chip microscopes • Use micro flu idic flow to de liver specimens across apertures on a metal-coated CMOS sensor X. Cui, L. M. Lee, X. Heng, W. Zhong, P. W. Sternberg, D. Psaltis, and C. Yang, "Lensless high-resolution on-chip optofluidic microscopes for Caenorhabditis elegans and cell imaging," Proceedings of the National Academy of Sciences, vol. 105, p. 10670, 2008. Wu-5 ©2009. University of California Electrophoretic Ink for All-printed Reflective Electronic Disppylays • 1 ~ 5um Charged microparticles – White: rutile titanium dioxide – Black: inorganic black pigment • Particles acquire a surface charge due to the electrical double layer • Microcapsule with diameter ~ 30 um Joseph Jacobson co-founded E Ink • Zero power consumption B. Comiskey, J. D. Albert, H. Yoshizawa, and J. Jaco bson, "A n elec trop hore tic ink for a ll-print e d reflective electronic displays," Nature, vol. 394, pp. 253-255, 1998. Wu-6 ©2009. University of California E-Ink Electronic Paper Disp lay ( EPD) www.eink.com Portable Flexible Reader Wall Clock (600x800, 167 ppi) Amazon Citizen Kindle Wu-7 ©2009. University of California Polymer Vision’s Rollable Display Flexible display made in AM-LCD facility Rollable Display http://www.polymervision.com/site/page/15/26/37/Rollable_Displays Wu-8 ©2009. University of California Electrowetting Electrowetting (1875) Electrowetting Display (Classical electrocapillarity) (Bell Labs, 1981) G. Lippmann, Relation entre les G. Beni and S. Hackwood, phénomènes électriques et "Electro-wetting displays," capillai res. Ann. Chim. Phys. 5 App lied Phys ics L ett ers, vol . 38 , (1875), pp. 494–549. pp. 207-209, 1981. Wu-9 ©2009. University of California Electrowetting on Insulator Coated Electrodes (()EICE) Electrowetting on Insulator Reversible Change of Coated Electrodes (EICE) Contact Angle B. Berge, Electrocapillarité et mouillage J. Heikenfeld, et al., « Recent progress de films isolants par l'eau. C.R.A.S. III in arrayed electrowetting optics, » Optics 317 (1993), pp. 157–163. and Photonics News, 2009 Wu-10 ©2009. University of California Electrowetting on Dielectric Macroscopic Picture Microscopic Picture 2 1 CV !!!LD#$ DA LAcos" Y cos"VY#% cos" ! LA 2 ! LA ~ 73 mN/m for air, & 50 mN/m for oil J. C. Heikenfeld, N. R. Smith, B. Sun, K. Zhou, L. Hou, Y. Lao, and B. Raj, "Flat electrowetting optics and displays," ! DA ~16 to 20 mN/m in Proc. SPIE, Vol. 6887, 2008, p. 688705 Wu-11 ©2009. University of California Video of Electrowetting http://www.varioptic.com/en/tech/ technology-demos.php Wu-12 ©2009. University of California Tunable-Focus Liquid Lens Compact auto- focus lens for cell phones, slim camera, webcam • Auto focus • Compact zoom lens www.varioptic.com Wu-13 ©2009. University of California Paper vs General Reflective Electronic Disppylay • Paper • Color pigments on white • Bright • Reflective electronic display • RGB subpixels + color filters • Efficiency < 1/3 • Not very bright P. Drzaic, "Displays: Microfluidic electronic paper," Nat Photon, vol. 3, pp. 248-249, 2009. Wu-14 ©2009. University of California Video-Speed Electronic Paper Based on Electrowetting Philips Research Eindhoven (now Philips spin-off, Liquavista ) Robert A. Hayes & B. J. Feenstra, “Video-speed electronic paper based on electrowetting,” Nature 425, 383 - 385 (2003). Wu-15 ©2009. University of California Electrofluidic Display Self-Assembly of Pigment Liquid Pigment Droplet HeikenfeldJ, ZhouK, KreitE, RajB, YangS, SunB, MilarcikA, ClappL, and SchwartzR, "Electrofluidic displays using Young-Laplace transposition of brilliant pigment dispersions," Nat Photon, vol. 3, pp. 292-296, 2009. Wu-16 ©2009. University of California Electrowetting Display • Emissive display using fluorescence oil with 400nm backlight • ITRI has recently scaled the electro-wetting display fabrication process to gg,reater than 1,700 cm2 on an active matrix backplane, using standard LCD manufacturing equipment. Jason Heikenfeld, et al. "Recent Progress in Arrayed Electrowetting Wu-17 Optics," Optics & Photonics News©2009. University 20, 20-26 of California (2009) Digital Microfluidics Based on Electrowetting on Dielectric (EWOD) C. J. Kim (UCLA) Lippmann-Young equation S. K. Cho, H. Moon, and C. J. Kim, J-MEMS2003. 11 2 cos"" (V )#% cos 0 CV ! LG 2 • Manipulate discrete droplets instead of continuous flow liquid • Droplet actuated by EWOD • Eliminate the need for pumps or valves • Require a large number of electrodes Richard Fair (Duke Univ) M.G. Pollack, et al, Applied. Phys. Lett. 2000 Wu-18 ©2009. University of California Optoelectrowetting (OEW) –– Applied AC frequency: 100Hz ~ 1kHz ( determined b y RC char ging time) P. Y. Chiou, H. Moon, H. Toshiyoshi, C.-J. Kim, and M. C. Wu, "Light actuation of liquid by optoelectrowetting," Sensors & Actuators A-Physical, vol. A104, pp. 222-8, 15 May 2003. Wu-19 ©2009. University of California Opto-Electrowetting (OEW) • Light illumination changes contact angle Bias Line via opto-electrowetting • Microdroplets follow the movement of a-Si light • Highly scalable, droplet volume from Electrode micro- to pico-liter P. Y. Chiou, Z. H. Chang, and M. C. Wu, "Droplet manipulation with light on optoelectrowetting device," Journal of Microelectromechanical Systems, vol. 17, pp. 133-138, Feb 2008. Wu-20 ©2009. University of California OEW Microfluidic Functions Droppplet Separation Multiple Drop let Manip ulation Droplets manipulation using 2 scanning laser beams Wu-21 ©2009. University of California Light-Actuated Microfluidic Circuits • Lab-on-a-Chip • Light-actuated lab-on-a-chip – Ease-of-use – Optical detection – Spee d of anal ysi s – Op tica lly act uati on (d ropl et s, – Low sample and reagent cells, nanoparticles, DNAs) consumption • Low-cost, disposable “Bio-FPGA” – Standardization and automation Agilent Wu-22 ©2009. University of California Tools for Manipulating Cell and Micro/Nano Particles • Molecular Force Clamp • Highly sought of in fields of biological and colloid science – Trapping – Sorting – Addressi ng Visscher , Nature, 1999 • Tools Available • Separation of Carbon Nanotubes – Optical Tweezers – Dielectrophoresis (DEP) Krupke, Science, 2003 Wu-23 ©2009. University of California Optical Tweezers Optical Tweezers Holographic Optical Tweezers Laser Input Objective Lens Curtis, et al., Optics Comm., Trap 2002 (U ni v. of Chi cago) Micro Center Sphere Limitations: • Small manipulation area Glass (< 100 µm) • High optical power Ashikin, Opt. Lett.,1986 (laser power ~ Watt) Wu-24 ©2009. University of California Dielectrophoresis (DEP) • Motion of polarisable particles Positive DEP Negative DEP (charged or uncharged) in non- uniform AC electric fields - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - • Co ined by P ohl i n 1951 3 * 2 Fdep # 2)a ( m Re[K (')]*(E ) * * + + + + + + + + ( $ ( ++ ++ * p m * + Neutral K (') # * * , ( # ( % Particle ( p % 2( m j' +V +V * ( p :Dielectric Constant of Particles * ( m : Dielectric Constant of Media • Unlike optical gradient force, DEP can be positive or negative – Positive DEP: particle attracted to field maximum – Negative DEP: particle attracted to field minimum • Polarity depends on the dielectric function and bias frequency Wu-25 ©2009. University of California 2-D DEP Trap Array - Manaresi, ISSCC, 2003 ++- 8.1 mm - © Silicon Biosystems- www.siliconbiosystems.com DEP • Programma ble DEP cage on CMOS array Cage – Massively parallel individual-cell operation – Programmable - - – Embedded sensors + – Channel-less - – Contactless movement – Pitch (, 20-m) limited by circuit area – Expensive ++- http://www.siliconbiosystems.com/technology/index.htm Wu-26 ©2009. University of California Optoelectronic Tweezers Principle • Based on light-induced dielectrophoresis (DEP) • Illumination creates virtual electrodes V ITO Electrode AC Liquid Z layer L AC h. – + – ZPCC Photoconductor + – + Electrode ZL <> Z ZL ZPCPC Wu-27 ©2009. University of California Optoelectronic Tweezers Optical Conveyor Belt • Programmable: Trapping and manipulation using a digital projector • 10,000x lower power than conventional optical
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