272 Pages 92 B/W Illustrations
    by CRC Press

    The applications and use of inkjet-like microfluidic drop ejectors have grown rapidly in many fields, including biotechnology, drug discovery, combinatorial chemistry, and microfabrication. Yet to date, end users and even designers of microdrop systems for scientific applications have had no books to reference on the subject. Microdrop Generation meets the needs of all those who need to understand the physics and engineering behind microdrop technology. It also contains detailed, how-to information on the practical construction, operation, troubleshooting, and fluid formulation for microdrop ejection systems. Written by a highly experienced practitioner of the art, the book is organized as a self-contained tutorial of microdrop technology ideal for those new to the field.

    INTRODUCTION
    WHAT CAN YOU DO WITH A MICRODROP?
    Characteristics of Microdrops
    Use of Microdrops in Pure Science
    Use of Microdrops in Applied Science
    Biotechnology Applications of Microdrops
    Applications in Manufacturing and Engineering
    METHODS OF GENERATING MONODISPERSE MICRODROPS
    Acoustically Disrupted Continuous Fluid Jet
    Thermal Inkjet (Bubble Jet)
    Piezoelectric Direct Pressure Pulse
    Focused Acoustic Beam Ejection
    Liquid Spark Inkjet
    Electrohydrodynamic Inkjet
    Flextensional Aperture Plate Inkjet
    Electro-Rheological Fluid Inkjet
    Liquid Ink Fault Tolerant Process
    TopSpotÃ’ Microdrop Ejector
    Summary and Recommendations
    PARTICLE KINETICS OF EJECTED MICRODROPS
    Reynolds Number and Stokes Law
    Terminal Velocity
    Relaxation Time Constant
    Streaming
    Impact
    Brownian Motion
    Motion in Electric Fields
    ELECTRIC CHARGING OF MICRODROPS
    Rayleigh Limit to Charging Microdrops
    Drop Charging Mechanisms
    Practical Drop Charge Control Methods
    Variations in the Induced Charge
    ENGINEERING REQUIREMENTS FOR RELIABLE MICRODROP GENERATION
    Conditions Needed for Monodisperse Drop-On-Demand Operation
    Drive Pulse Amplitude
    Drive Pulse Shape
    Internal Pressure Level
    Drop Ejection Rate
    Fluid Level
    Fluid Temperature
    TROUBLESHOOTING MICRODROP EJECTORS
    Clogged Nozzles
    Damaged Nozzles
    Internal Air Bubbles
    Misdirected Jets
    Overly Wetted Meniscus
    Internal Pressure
    Insufficient Drive Amplitude
    Nonoptimal Pulse Waveform
    Pulse Rate
    Problematic Fluids
    Mechanical Mounting
    Imaging System
    Recommended Startup Procedure to Test a New Drop Generation and Imaging System
    IMAGING MICRODROPS
    Direct Viewing of Illuminated Microdrops
    Bright Background Imaging of Microdrops
    Bright Source Stroboscopically Illuminated Droplets
    Light Emitting Diode Illumination Arrays
    Imaging System Synchronization
    Optics
    Cameras
    Stroboscopic Illumination Sources
    Low-Cost Microdrop Imaging Hardware
    DROP EJECTOR DRIVE ELECTRONICS
    Gated Voltage Sources
    Linear Pulse Power Amplifiers
    FABRICATION OF EJECTION APERTURE NOZZLES
    Ejection Nozzle Requirements
    Fabricating Acute Edge Conical Glass Nozzles
    Fabricating Tapered Profile Glass Nozzles
    Silicon Micromachined Ejection Apertures
    Fabrication Sequence for Silicon Micromachined Apertures
    Electroformed Ejection Apertures
    Jewel Orifices
    Metal Optical Pinhole Apertures
    Small Hole Generating Techniques
    Anti-Wetting Surface Coatings
    DROP EJECTOR CONSTRUCTION
    Tubular Reservoir Piezoelectric Drop Ejectors
    Metal Body Drop Ejectors
    Glass, Straight Tube, Welded Aperture
    Glass, Pipette, Welded Aperture
    Glass, Miniature, Welded Aperture
    Piezoelectric Element Configuration
    Piezoelectric Disc Actuator
    Rectangular Slab Drive Elements
    Cylindrical Piezoelectric Drive Elements
    Integral Heating Elements
    PRESSURE CONTROL
    Manometer Tube Pressure Control System
    Variable Height Reservoir Pressure Control System
    Automated Pressure Control
    FLUID ENGINEERING FOR MICRODROP EJECTORS
    Problematic Fluids
    Nonclogging Fluids
    First Drop Reliability
    Jetting Stability
    Directional Stability
    Freedom from Satellite Drops
    Wide Jet Velocity Tolerance
    Drive Waveform Tolerance
    Repetition Rate
    Environmental and Temporal Stability
    Chemical Reactivity with Drop Generator
    Toxicity
    Cost
    COMPONENTS OF DROP-ON-DEMAND EJECTOR FLUIDS
    Payload
    Solvent
    Humectants
    Viscosity Modifiers
    Surfactants
    Dispersants
    Polymeric Fluid Elasticity Agents
    Anti-Fungal Agents (Biocides, Preservatives)
    Chelating Agents
    pH Controllers
    Corrosion Inhibitors
    Defoamer
    Electrical Conductivity Salts
    Additives Specific for Thermal Inkjet
    Additives Specific for Inkjet Image Printing
    MAKING JETTABLE SUSPENSIONS OF GROUND SOLIDS
    Obtaining Small Diameter Particles
    Necessary Particle Size
    Wetting and Dispersing
    Filtering and Settling
    Essential References
    Ejectability
    Final Caution - Make Sure You Have a Real Suspension
    APPENDIX I. SETTING UP A MICRODROP SYSTEM ASAP
    APPENDIX II. EXAMPLE INKJET FLUID FORMULATIONS FROM PATENT LITERATURE
    APPENDIX III. EJECTION TESTS OF BIOLOGICAL FLUIDS

    Biography

    Eric R. Lee

    "Microdrop technology has underpinned an exponential growth in a range of applications that could not have been envisaged at the time of the early inkjet printers. Current applications are as diverse as high-throughput screening for drug candidates to 3-D prototyping for nanoscale fabrication. Microdrop generation is also critical to many major industries ranging from the food, cosmetics and vaccine producers to the manufacturers of integrated circuits and displays. What continues to be exciting is that there are still undiscovered ways to create and use microdrops, many of which have huge commercial implications that have yet to be tapped.

    "Microdrop Generation by Eric R. Lee does more than justice to this complex and fascinating subject. It is essentially a practical book that provides students, scientists, and engineers with all the relevant theory - from particle physics to fluid dynamics - while never losing sight of how the theory works in reality. It covers the practicalities of how microdrops can be ejected, how drives and nozzles can be engineered, as well information on key imaging techniques and hints on troubleshooting.

    "This book is the result of nearly ten years of experiment and wide consultation by an expert in the field, and apart from being the definitive work in the area, is not only highly informative, but also highly readable. In our view Microdrop Generation must be an essential addition to the bookshelf of scientists working in many areas, as well as a valuable preparatory text for science and engineering departments alike who want to produce students who are industrially and academically useful.'"

    -Ottilia Saxl, CEO, The Institute of Nanotechnology, Scotland, UK