Optofluidic Devices for Cell, Microparticle, and Nanoparticle Manipulation Aaron Takami Ohta Electrical Engineering and Computer Sciences University of California at Berkeley Technical Report No. UCB/EECS-2008-148 http://www.eecs.berkeley.edu/Pubs/TechRpts/2008/EECS-2008-148.html December 2, 2008 Copyright 2008, by the author(s). All rights reserved. Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission. Acknowledgement My research advisor, Prof. Ming C. Wu, for valuable mentorship and resources. My colleagues Prof. P.-Y. Chiou, M.-C. Tien, H.-Y. Hsu, A. Jamshidi, J.K. Valley, and Dr. S.L. Neale, and my other colleagues in the Integrated Photonics Laboratory. Collaborators outside of our research group: Drs. A.N.K. Lau and H.L. Phan; Prof. C.-M. Ho’s and Prof. C.-J. Kim’s groups from UCLA, Prof. P. Yang’s, Prof. A. Javey’s, and Prof. E. Isacoff’s groups at UC Berkeley, and Prof. T. Lue’s group from UCSF. Optofluidic Devices for Cell, Microparticle, and Nanoparticle Manipulation by Aaron Takami Ohta B.S. (University of Hawai’i at Manoa) 2003 M.S. (University of California, Los Angeles) 2004 A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Engineering - Electrical Engineering and Computer Sciences in the Graduate Division of the University of California, Berkeley Committee in charge: Professor Ming C. Wu, Chair Professor Constance Chang-Hasnain Professor Albert Pisano Professor Kevin Healy Fall 2008 The dissertation of Aaron Takami Ohta is approved: Chair __________________________________________ Date _____________ __________________________________________ Date _____________ __________________________________________ Date _____________ __________________________________________ Date _____________ University of California, Berkeley Fall 2008 Optofluidic Devices for Cell, Microparticle, and Nanoparticle Manipulation © 2008 by Aaron Takami Ohta ABSTRACT Optofluidic Devices for Cell, Microparticle, and Nanoparticle Manipulation by Aaron Takami Ohta Doctor of Philosophy in Engineering - Electrical Engineering and Computer Sciences University of California, Berkeley Professor Ming C. Wu, Chair Research in the micro- to nanoscale regimes is facilitated by technologies that enable the addressing of these tiny particles. In biological research, manipulation enables the study of single-cell behavior, as well as the sorting of specific target cells from a mixed population. In engineering applications, micro- and nanoparticles can be assembled to form electronic and optoelectronic devices. Several types of forces can be used to manipulate micro- and nanoscale objects, including optical and electrical forces. A device is presented that integrates the advantages of optical and electrical manipulation, called optoelectronic tweezers (OET). The OET device combines the advantages of both optical and electrical trapping. Optical patterns are used to create manipulation patterns and particle traps in an amorphous-silicon-based semiconductor device. The optical patterns create dielectrophoretic force in the OET device, via light- induced dielectrophoresis. Thus, OET does not directly use optical energy for trapping, allowing the use of much lower optical intensities than direct optical manipulation. These low optical intensities can be achieved by a computer projector or an LED, allowing the creation of complex optical manipulation patterns. Furthermore, unlike electrical traps, OET is capable of trapping a specific single microparticle from a larger population. 1 In this dissertation, the optoelectronic tweezers device is discussed in detail, including the operating principle, design considerations, and fabrication processes. OET manipulation is presented in the context of three major applications: sperm sorting for improving current in vitro fertilization techniques, microdisk laser assembly for CMOS- integrated optoelectronic devices, and nanowire assembly for nanowire-based displays. ____________________________________ Professor Ming C. Wu, Chair 2 TABLE OF CONTENTS TABLE OF CONTENTS ..................................................................................................... i LIST OF FIGURES ........................................................................................................... iv LIST OF TABLES ........................................................................................................... xiii ACKNOWLEDGEMENT ............................................................................................... xiv CHAPTER 1 INTRODUCTION .................................................................................. 1 1.1 METHODS OF MICRO - AND NANOPARTICLE MANIPULATION .............................................. 1 1.2 OPTOELECTRONIC TWEEZERS (OET) .................................................................................. 5 1.3 CAPABILITIES OF OPTOELECTRONIC TWEEZERS ................................................................. 8 1.3.1 Massively Parallel Manipulation ............................................................................... 8 1.3.2 Size-Based Particle Sorting ...................................................................................... 11 1.3.3 Image-Based Automated Cell Manipulation............................................................ 14 CHAPTER 2 OPTOELECTRONIC TWEEZERS DESIGN AND FABRICATION 20 2.1 INTRODUCTION .................................................................................................................. 20 2.2 DESCRIPTION OF OPTOELECTRONIC TWEEZERS DEVICE ................................................... 20 2.3 OPERATING PRINCIPLE OF OPTOELECTRONIC TWEEZERS ................................................. 22 2.4 DIELECTROPHORESIS (DEP) .............................................................................................. 25 2.5 DESIGN OF OPTOELECTRONIC TWEEZERS ......................................................................... 28 2.6 FINITE -ELEMENT MODELING ............................................................................................. 30 2.7 FABRICATION OF OPTOELECTRONIC TWEEZERS ............................................................... 37 2.8 CHARACTERIZATION OF OPTOELECTRONIC TWEEZERS PERFORMANCE ........................... 38 2.8.1 Photoconductivity Measurements ............................................................................ 39 2.8.2 Particle Velocity ...................................................................................................... 40 2.9 OTHER EFFECTS IN OPTOELECTRONIC TWEEZERS DEVICES ............................................. 44 2.9.1 Electrolysis ............................................................................................................... 44 2.9.2 Electrothermal Heating ............................................................................................ 45 2.9.3 Buoyancy Effects ..................................................................................................... 45 2.9.4 Light-induced AC Electro-osmosis (LACE)............................................................ 46 2.9.5 Figure-of-Merit for OET Forces .............................................................................. 47 CHAPTER 3 MANIPULATION OF CELLS............................................................. 49 3.1 MOTIVATION ...................................................................................................................... 49 3.2 ISSUES WITH CELLULAR MANIPULATION .......................................................................... 49 3.2.1 Media Conductivity and Osmotic Pressure .............................................................. 50 3.2.2 Non-Specific Cell Adhesion .................................................................................... 52 3.3 SURFACE TREATMENTS FOR OPTOELECTRONIC TWEEZERS .............................................. 52 3.4 TEFLON / BOVINE SERUM ALBUMIN SURFACE TREATMENT ............................................. 54 3.5 POLY (ETHYLENE GLYCOL ) SURFACE TREATMENT ............................................................ 55 3.6 CELL PATTERNING ............................................................................................................. 61 3.7 SEPARATION OF LIVE AND DEAD WHITE BLOOD CELLS ................................................... 63 3.8 SEPARATION OF LIVE JURKAT AND HELA CELLS ............................................................. 66 i CHAPTER 4 SPERM SORTING FOR IN VITRO FERTILIZATION ...................... 71 4.1 MOTIVATION ...................................................................................................................... 71 4.2 EXPERIMENTAL SETUP ...................................................................................................... 73 4.3 OET RESPONSE OF LIVE NON -MOTILE SPERM AND DEAD SPERM ................................... 75 4.4 CHARACTERIZATION OF DNA DAMAGE ON SPERM .......................................................... 76 4.5 FUTURE WORK ................................................................................................................... 78 CHAPTER 5 LATERAL-FIELD