Acoustic droplet ejection

Last updated

Acoustic droplet ejection (ADE) uses a pulse of ultrasound to move low volumes of fluids (typically nanoliters or picoliters) without any physical contact. This technology focuses acoustic energy into a fluid sample in order to eject droplets as small as a picoliter. ADE technology is a very gentle process, and it can be used to transfer proteins, high molecular weight DNA and live cells without damage or loss of viability. This feature makes the technology suitable for a wide variety of applications including proteomics and cell-based assays.

Contents

History

Acoustic droplet ejection was first reported in 1927 by Robert W. Wood and Alfred Loomis, [1] who noted that when a high-power acoustic generator was immersed in an oil bath, a mound formed on the surface of the oil and, like a "miniature volcano", ejected a continuous stream of droplets. Ripples that appear in a glass of water placed on a loud speaker show that acoustic energy can be converted to kinetic energy in a fluid. If the sound is turned up enough, droplets will jump from the liquid. This technique was refined in the 1970s and 1980s by Xerox and IBM [2] and other organizations to provide a single droplet on-demand for printing ink onto a page. Two California-based companies, EDC Biosystems Inc. and Labcyte Inc. (both now acquired by Beckman Coulter), exploit acoustic energy for two separate functions: 1) as a liquid transfer device and 2) as a device for liquid auditing.

Ejection mechanism

To eject a droplet, a transducer generates and transfers acoustic energy to a source well. When the acoustic energy is focused near the surface of the liquid, a mound of liquid is formed and a droplet is ejected. [Figure 1] The diameter of the droplet scales inversely with the frequency of the acoustic energy—higher frequencies produce smaller droplets. [3] [4] Unlike other liquid transfer devices, no pipette tips, pin tools, or nozzles touch the source liquid or destination surfaces. Liquid transfer methods that rely on droplet formation through an orifice, e.g., disposable tips or capillary nozzles, invariably lose precision as the transfer volume decreases. Touchless acoustic transfer provides a coefficient of variation (CV) that is significantly lower than other techniques and is independent of volume at the levels tested.

ADE shoots a droplet from a source well upward to an inverted receiving plate positioned above the source plate. Liquids ejected from the source are captured by dry plates due to surface tension. For larger volumes, multiple droplets can be rapidly ejected from the source (typically 100 to 500 droplets/sec) to the destination with the coefficient of variation typically <4% over a volume range of two orders of magnitude. [5]

Applications of acoustic transfer

The following applications are among those that can benefit from the features of acoustic droplet ejection:

See also

Related Research Articles

<span class="mw-page-title-main">Microfluidics</span> Interdisciplinary science

Microfluidics refers to a system that manipulates a small amount of fluids using small channels with sizes ten to hundreds micrometres. It is a multidisciplinary field that involves molecular analysis, molecular biology, and microelectronics. It has practical applications in the design of systems that process low volumes of fluids to achieve multiplexing, automation, and high-throughput screening. Microfluidics emerged in the beginning of the 1980s and is used in the development of inkjet printheads, DNA chips, lab-on-a-chip technology, micro-propulsion, and micro-thermal technologies.

<span class="mw-page-title-main">Inkjet printing</span> Type of computer printing

Inkjet printing is a type of computer printing that recreates a digital image by propelling droplets of ink onto paper and plastic substrates. Inkjet printers were the most commonly used type of printer in 2008, and range from small inexpensive consumer models to expensive professional machines. By 2019, laser printers outsold inkjet printers by nearly a 2:1 ratio, 9.6% vs 5.1% of all computer peripherals.

Flow measurement is the quantification of bulk fluid movement. Flow can be measured using devices called flowmeters in various ways. The common types of flowmeters with industrial applications are listed below:

A propellant is a mass that is expelled or expanded in such a way as to create a thrust or another motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicles, the engine that expels the propellant is called a reaction engine. Although technically a propellant is the reaction mass used to create thrust, the term "propellant" is often used to describe a substance which contains both the reaction mass and the fuel that holds the energy used to accelerate the reaction mass. For example, the term "propellant" is often used in chemical rocket design to describe a combined fuel/propellant, although the propellants should not be confused with the fuel that is used by an engine to produce the energy that expels the propellant. Even though the byproducts of substances used as fuel are also often used as a reaction mass to create the thrust, such as with a chemical rocket engine, propellant and fuel are two distinct concepts.

<span class="mw-page-title-main">Digital microfluidics</span>

Digital microfluidics (DMF) is a platform for lab-on-a-chip systems that is based upon the manipulation of microdroplets. Droplets are dispensed, moved, stored, mixed, reacted, or analyzed on a platform with a set of insulated electrodes. Digital microfluidics can be used together with analytical analysis procedures such as mass spectrometry, colorimetry, electrochemical, and electrochemiluminescense.

<span class="mw-page-title-main">Surface acoustic wave</span> Sound wave which travels along the surface of an elastic material

A surface acoustic wave (SAW) is an acoustic wave traveling along the surface of a material exhibiting elasticity, with an amplitude that typically decays exponentially with depth into the material, such that they are confined to a depth of about one wavelength.

Electrowetting is the modification of the wetting properties of a surface with an applied electric field.

A vacuum ejector, or simply ejector is a type of vacuum pump, which produces vacuum by means of the Venturi effect.

The integrated nanoliter system is a measuring, separating, and mixing device that is able to measure fluids to the nanoliter, mix different fluids for a specific product, and separate a solution into simpler solutions.

<span class="mw-page-title-main">Liquid handling robot</span>

A liquid handling robot is used to automate workflows in life science laboratories. It is a robot that dispenses a selected quantity of reagent, samples or other liquid to a designated container.

<span class="mw-page-title-main">Spray tower</span>

A spray tower is a gas-liquid contactor used to achieve mass and heat transfer between a continuous gas phase and a dispersed liquid phase. It consists of an empty cylindrical vessel made of steel or plastic, and nozzles that spray liquid into the vessel. The inlet gas stream usually enters at the bottom of the tower and moves upward, while the liquid is sprayed downward from one or more levels. This flow of inlet gas and liquid in opposite directions is called countercurrent flow.

<span class="mw-page-title-main">Spray nozzle</span> Device that facilitates dispersion of liquid into a spray

A spray nozzle or atomizer is a device that facilitates the dispersion of a liquid by the formation of a spray. The production of a spray requires the fragmentation of liquid structures, such as liquid sheets or ligaments, into droplets, often by using kinetic energy to overcome the cost of creating additional surface area. A wide variety of spray nozzles exist, that make use of one or multiple liquid breakup mechanisms, which can be divided into three categories: liquid sheet breakup, jets and capillary waves. Spray nozzles are of great importance for many applications, where the spray nozzle is designed to have the right spray characteristics.

<span class="mw-page-title-main">Ultrasonic nozzle</span> Type of spray nozzle

Ultrasonic nozzles are a type of spray nozzle that use high frequency vibrations produced by piezoelectric transducers acting upon the nozzle tip that create capillary waves in a liquid film. Once the amplitude of the capillary waves reaches a critical height, they become too tall to support themselves and tiny droplets fall off the tip of each wave resulting in atomization.

Microdispensing is the technique of producing liquid media dosages in volumes of less than one microlitre. The continuing miniaturization in almost all technical areas creates constant challenges for industry, development and research facilities. Microdispensing is one of those challenges. Ever smaller amounts of adhesive, liquid, oil, grease and a multitude of other media must be dispensed reliably and accurately in dosage and placement with short cycle times. The precise positioning and quantity of fluids such as glue, reagents or any other substance has a great influence on the overall quality of a medical device. A few examples are:

<span class="mw-page-title-main">Spray (liquid drop)</span> Dynamic collection of drops dispersed in a gas

A spray is a dynamic collection of drops dispersed in a gas. The process of forming a spray is known as atomization. A spray nozzle is the device used to generate a spray. The two main uses of sprays are to distribute material over a cross-section and to generate liquid surface area. There are thousands of applications in which sprays allow material to be used most efficiently. The spray characteristics required must be understood in order to select the most appropriate technology, optimal device and size.

The liquid droplet radiator (LDR) or previously termed liquid droplet stream radiator is a proposed lightweight radiator for the dissipation of waste heat generated by power plants, propulsion or spacecraft systems in space.

<span class="mw-page-title-main">Inkjet technology</span>

Inkjet technology originally was invented for depositing aqueous inks on paper in 'selective' positions based on the ink properties only. Inkjet nozzles and inks were designed together and the inkjet performance was based on a design. It was used as a data recorder in the early 1950s, later in the 1950s co-solvent-based inks in the publishing industry were seen for text and images, then solvent-based inks appeared in industrial marking on specialized surfaces and in the1990's phase change or hot-melt ink has become a popular with images and digital fabrication of electronic and mechanical devices, especially jewelry. Although the terms "jetting", "inkjet technology" and "inkjet printing", are commonly used interchangeably, inkjet printing usually refers to the publishing industry, used for printing graphical content, while industrial jetting usually refers to general purpose fabrication via material particle deposition.

Droplet-based microfluidics manipulate discrete volumes of fluids in immiscible phases with low Reynolds number and laminar flow regimes. Interest in droplet-based microfluidics systems has been growing substantially in past decades. Microdroplets offer the feasibility of handling miniature volumes of fluids conveniently, provide better mixing, encapsulation, sorting, sensing and are suitable for high throughput experiments. Two immiscible phases used for the droplet based systems are referred to as the continuous phase and dispersed phase.

Capillary breakup rheometry is an experimental technique used to assess the extensional rheological response of low viscous fluids. Unlike most shear and extensional rheometers, this technique does not involve active stretch or measurement of stress or strain but exploits only surface tension to create a uniaxial extensional flow. Hence, although it is common practice to use the name rheometer, capillary breakup techniques should be better addressed to as indexers.

Rotary atomizers use a high speed rotating disk, cup or wheel to discharge liquid at high speed to the perimeter, forming a hollow cone spray. The rotational speed controls the drop size. Spray drying and spray painting are the most important and common uses of this technology.

References

  1. ↑ R. W. Wood; A. L. Loomis (1927). "The Physical and Biological Effects of High Frequency Sound Waves of Great Intensity". Philosophical Magazine. 4 (22): 417–436.
  2. ↑ K. A. Krause (1973). "Focusing Ink Jet Head". IBM Technical Disclosure Bulletin. 16 (4): 1168.
  3. ↑ R. Ellson; M. Mutz; B. Browning; L. Lee; M.F. Miller; R. Papen (2003). "Transfer of Low Nanoliter Volumes between Microwell Plates Using Focused Acoustics – Automation Considerations". Journal of the Association for Laboratory Automation. 8 (5): 29–34. doi:10.1016/S1535-5535(03)00011-X.
  4. ↑ R. Ellson (2002). "Picoliter: enabling precise transfer of nanoliter and picoliter volumes". Drug Discovery Today. 7 (5): 32–34. doi:10.1016/S1359-6446(02)02176-1.
  5. ↑ J. Comley (2004). "Continued Miniaturisation of Assay Technologies Drives Market for Nanolitre Dispensing". Drug Discovery World. Summer: 43–54.
  6. ↑ Yin, Xingyu; Scalia, Alexander; Leroy, Ludmila; Cuttitta, Christina M.; Polizzo, Gina M.; Ericson, Daniel L.; Roessler, Christian G.; Campos, Olven; Ma, Millie Y.; Agarwal, Rakhi; Jackimowicz, Rick; Allaire, Marc; Orville, Allen M.; Sweet, Robert M.; Soares, Alexei S. (2014). "Hitting the target: fragment screening with acoustic in situ co-crystallization of proteins plus fragment libraries on pin-mounted data-collection micromeshes". Acta Crystallographica Section D. 70 (5): 1177–1189. doi:10.1107/S1399004713034603. PMC   4014116 . PMID   24816088.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.