Acoustic dispensing

Wong, E.Y. and S.L. Diamond. 2009. Advancing microarray assembly with acoustic dispensing technology. Anal. Chem. 81, 509-514. 

Numerous reviews cover the selection, construction, and curation of chemical libraries, debates about their size and composition, operational costs, infrastructure, and best practices of compound management of stock solutions and dry powders [2, 3, 20]. For the purposes of implementation of automated robotic assays, the practical aspects are that the entire chemical library exists as working stocks (typically 2 mM in 100 % DMSO) of individual compounds stored in heat-sealed (see also Note 4), daughter barcoded microplates of well density format matching the final screening format (96-, 384-, or 1,536-well) in a plate material consistent w/chemical inertness (cycloelefin copolymer (COC) or polypropylene) or optimized for acoustic dispensing (Echo-certified COC or diamond plates). 

Echo 550 acoustic dispenser (Labcyte) for dispensing DMSO compound solutions at volumes as low as 2.5 nL. 

Fig. 3. Principle of acoustic dispensing. An ultrasonic transducer ejects droplets from the source well by the application of focussed sound energy. Figure reproduced with permission of Labcyte.

The throughput of the HTCP system was found to be dependent of a number of parameters. The picking rate of the acoustic dispenser ECHO 550 determines the maximum picking rate that can be achieved. However, with a cycle time of 2 min for each source plate that needs to be accessed, the retrieval of source plates from the store can become a bottleneck. Therefore, the... 

Accuracy and precision of liquid transfers from a 1536-well source plate to a 1536-well destination plate on the ECHO 550 acoustic dispenser... 

There are, of course, noncontact printing devices useful for the construction of microarrays (see Figure 4.2). These are microdispensers that eject droplets by several different mechanisms (solenoid, piezoelectric, heated jet, acoustical wave). Perhaps the best-known commercial dispensers are the syringe driven-solenoid pump (e.g., Cartesian BioDot) and piezo systems (e.g., Packard Biosciences). 

Currently, liquids are most conveniently handled by pipette tips for aspiration and dispensing into microtitre plates. Recently, acoustic energy driven liquid dispensing devices have been available (e.g. the ECHO550 or EDC system), such that liquid can be transferred in small volume (nanolitre to pL) accurately and directly from the wells on one plate into wells on another plate. 

Acoustic actuation Acoustic bubbles Droplet dispenser Droplet on demand Oscillating bubbles... 

The single-droplet drying experiments were carried out [by group XXX] using a custom-built acoustic levitator at a frequency of 42 kHz. The peripheral equipment consists of dispensers, the process chambers for controlling the ambient conditions, or different illumination techniques. The setup is described in more detail by Laackmann [32]. Figure 9.3a shows a schematic of the experimental configuration. 

For compound addition, we use an acoustical spotter (Echo 550, Labcyte Inc), which dispenses nanoliter volumes of compound directly into the wells of a 384-well plate, which already contain cells and medium in most cases. An alternative for nanoliter transfers are pintools, which also directly transfer... 

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