A versatile system for stable generation of uniform droplets

Abstract

A system for the production of liquid droplets of uniform size and velocity is described. The precise control of the operating fluid provided by this system allows the generator to function in a droplet-on-demand, burst, or continuous mode of operation. The basic component of the uniform droplet generator is a radially contracting piezoelectric cylinder which forces liquid through a glass-capillary nozzle. Droplet diameters ranging from 5 to 500 μm have been produced by appropriate selection of nozzle aperture and operating mode. Further control of size, velocity, and interdroplet spacing is exercised through the voltage- and fluid-control elements of the system. In addition to its ability to operate in any orientation, the droplet generator is designed with a small cross section and a water cooling feature for operation in coflowing, elevated-temperature environments. The uniform-droplet-generation system has exhibited long-term stability in operations ranging from a single isolated droplet to a stream of calibration-standard droplets separated by center-to-center spacings of less than two diameters. Its capabilities in controlling droplet development and dynamics make it an attractive candidate for use in a wide range of liquid-droplet applications.

Polymeric capacitive transducers and arrays for gas coupled operation

“…Carefully controlling the time of heat the capillary causes the end of the shrink to form a nozzle. The nozzle is polished using 1 m alumina to create a flat surface at the outlet [10]. Figure 1.…”

Droplets, vapours and clouds - A new approach to capacitive transducer manufacture

“…Once the droplet pattern had been deposited, the polystyrene sample was exposed to toluene vapor to create the desired cavity depth in line with the data in Figure 4. After the solvent exposure, washing and drying, the polystyrene substrate is then electroded on all faces with silver using an electroless process with a tin sensitizer [9]. The micropatterned polystyrene was then fitted with 8 micron Kapton membrane (Goodfellow, Huntingdon, UK) the outer face of the dielectric membrane has a sputtered aluminum electrode.…”

Piezoelectric dispenser based on a piezoelectric-metal-cavity actuator

“…15,16 In the past, many designs of fluid ejectors with different geometries have been studied. There are two major geometries: tubular design [17][18][19] and flat plate design. 20,21 Each of them has its corresponding merits and demerits.…”