Method and device for nebulising high-viscosity liquids with minimal fallback
AssigneeEP Systems SA Microflow Division
InventorsAmir Feriani, Joseph Hess
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Abstract
A method of controlling evaporation of droplet cloud resulting from nebulization of a liquid expelled from a liquid droplet spray device is disclosed, wherein the liquid droplet spray device comprises a reservoir containing liquid, a perforate membrane plate, a fluid interface for feeding liquid from the reservoir to the membrane plate, an ultrasound generating mechanism for acting on the supplied liquid to cause it to be expelled as a spray of droplets through orifices of the membrane plate, and an electronic control device for controlling activation of the ultrasound generating mechanism.
Claims9
A method of controlling evaporation of droplets of a liquid nebulised as a spray of droplets from a liquid droplet spray device, wherein said liquid droplet spray device comprises a reservoir for containing the liquid, a perforate membrane plate, fluid interface means for feeding the liquid from the reservoir to the membrane plate, ultrasound generating means arranged to act on the supplied liquid to cause the liquid to vibrate and to be expelled as a spray of droplets through orifices of the membrane plate, and electronic control means for controlling activation of the ultrasound generating means, wherein the method comprises the steps of:
- (a) providing the liquid droplet spray device;
- (b) supplying the liquid to a space below the perforated membrane plate;
- (c) providing a pulsed driving signal having a period T for activating the ultrasound generating means;
- (d) activating the ultrasound generating means for a period of time Ton so the ultrasound generating means acts on the liquid and vibrates the liquid so as to cause the spray of droplets to be expelled at a maximum spray cloud height, wherein Ton consists of Tona and Tonb, and wherein vibration of the liquid by the ultrasound generating means heats the liquid;
- (e) de-activating the ultrasound generating means for a period of time Toff, where Toff≧Ton+Tevap,
- wherein Tevap is the time required for the sprayed cloud of a given liquid produced during Ton to fully evaporate, and
- wherein Tona is the time required to ultrasonically heat the liquid, Tonb is the time to spray the liquid, and Tona lasts from less than tens of milliseconds to several seconds,
- whereby an amount of unevaporated liquid that falls back on a surface surrounding the liquid droplet spray device is minimised.
A liquid droplet spray device for nebulising a liquid expelled from the liquid droplet spray device, the liquid droplet spray device comprising:
- (a) a reservoir for containing the liquid;
- (b) a perforate membrane plate;
- (c) a space for containing liquid to be expelled, wherein the space is positioned adjacent the membrane plate and is arranged to receive liquid from the reservoir;
- (d) fluid interface means for feeding the liquid from the reservoir to the space;
- (e) ultrasound generating means arranged to act on supplied liquid to cause the liquid to vibrate and to be expelled as a spray of droplets through orifices of the membrane plate;
- and
- (f) electronic control means for controlling activation of the ultrasound generating means, wherein the electronic control means is configured to drive the ultrasound generating means with a pulsed driving signal having a period T,
- wherein the electronic control means is configured to activate the ultrasound generating means for a period of time Ton so the ultrasound generating means acts on the liquid so as to vibrate the liquid and cause a spray of droplets to be expelled at a maximum spray cloud height, wherein Ton consists of Tona and Tonb, and wherein vibration of the liquid by the ultrasound generating means heats the liquid,
- wherein the electronic control means is configured to not to activate the ultrasound generating means (13) for a period of time Toff, where Toff≧Ton+Tevap,
- wherein Tevap is the time required for the sprayed cloud of a given liquid produced during Ton to fully evaporate, and
- wherein Tona is the time required to ultrasonically heat the liquid, Tonb is the time to spray the liquid, and Tona lasts from less than tens of milliseconds to several seconds,
- whereby an amount of unevaporated liquid that falls back on a surface surrounding the liquid droplet spray device is minimised.
Dependencies are inferred from the claim text.