Ultrasonic sprayer

The ultrasonic sprayer can be used to deposit a layer of nanoparticles over a surface to detect and characterize contaminants. Contaminated silicon plates were generated by depositing 10 pL of a dilute solution of test an ytes... 

Figure 2. (a) Photograph and (b) schematic diagram of an ultrasonic sprayer based deposition system. 

Figure 3. Optical micrographs of glass slides showing the formation of silver islands after multiple depositions of Ag sol with ultrasonic sprayer (a) and (b) Substrates with Ag nanoparticles sprayed-on (c) adenine (d) Rhodamine 6G.

There is a very wide range of designs for nebulizers, but most are based on some form of gas/liquid sprayer or on ultrasonics. 

Fig. 11.4. Different sprayers for ESI. (a) Pure electrospray, (b) ESI with sheath liquid, (c) pneumatically assisted ESI, and (d) ultrasonic nebulizer. Adapted from Ref. [5] (p. 109) by permission. John Wiley Sons, Inc. 1997.

The combination of the electrospray ion source with HPLC has without a doubt become the LC/MS interface in recent years. It is a particularly powerful combination, since this ionization technique covers a wide range of samples [38] that are commonly separated by HPLC [39] or electrophoresis [40]-[44]. The ESI source exhibits concentration-dependent behavior and thus gives optimal signals at most flow rates. The principle of the ionization process is discussed in Section 20.4.9. The most important feature of this interface is aspray needle which can be connected directly to the separation column, if the flow rates are compatible. Initially the major limitation was that only low flow rates (a few pL/min) could be used, but now flow rates of 1 mL/min or more are possible by using heated sprayers or ultrasonic devices. Splitting of the flow is possible as well, allowing two detectors to be used simultaneously. Since buffers can be used as long as they are volatile and not too concentrated, a sheath flow... 

Instead of a separate sample sprayer, an ultrasonic nebulizer may also deliver a sample-containing aerosol, which is transported and admixed to the electrospray mist by action of a mild stream of nitrogen. As the droplets of both origins are fused inside a small housing enclosing the spray, this approach has been termed jused-droplet electrospray ionization, and thus, led to the the somewhat confusing acronym FD-ESI [39,40]. 

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