Pumps – Electrical or getter type
Reexamination Certificate
2002-05-24
2004-09-14
Freay, Charles G. (Department: 3746)
Pumps
Electrical or getter type
C417S050000, C222S251000
Reexamination Certificate
active
06790011
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a device for forming and diffusing calibrated small volumes of liquid, referred to for convenience in the text below by the generic term “drops”, serving in particular to produce drops with accurate control over drop size and drop number, for example in order to diffuse liquids into the atmosphere or onto a surface.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Numerous fields of activity exist in which it is necessary to have controlled quantities of liquid for delivery into the atmosphere which surrounds people or in their immediate environment, or onto their skin, or inside their bodies. Such liquids contain active principles, which is why diffusion thereof must be under control. The active principles can be for olfactive, medical, pesticidal, chemical, biological, etc., purposes.
A need thus arises to use a liquid substance in the form of drops in fields associated with medicine and well-being. Thus, in the context of certain treatments, active principles are diffused into the atmosphere or onto a portion of a patient's body by spraying to enable the patient to feel the effects thereof in appropriate manner. Similarly, it can be advantageous to deliver calibrated drops into a medium where, after mixing or dissolving, the active principles carried by the drops produce their effect.
Similarly, substances having a beneficial or an agreeable effect are diffused by evaporation or by being sprayed, such substances being known for their olfactive effects (essential oils, perfumes, deodorants, etc.) or their cleansing effects (insecticides, disinfectants, neutralizing agents, etc.).
Other fields of application concerned by the invention include, amongst others: the study of liquids in the form of drops, depositing liquids in the form of droplets, activating liquids, etc., in various industrial, scientific, medical, or everyday-life contexts.
A variety of techniques exist for creating and diffusing drops or droplets. Most rely on the principle of interaction between a flow of gas and a liquid from which the drops are to be extracted. That principle is used in particular in conventional perfume sprays, in aerosol cans, and in paint guns.
Although they are simple to implement, those technique do not make it possible to produce drops that a are well calibrated or to produce drops at a rate that is controlled accurately. Furthermore, apparatuses operating on the principle of causing a gas and a liquid to interact are ill-suited to miniaturization, in particular because they need to be fed with propellant gas.
Techniques also exist whereby droplets are injected on the basis of electromechanical phenomena (such as the piezoelectric effect) or thermal phenomena (such as spraying by heater resistances, as used in particular for ink jet printers). Nevertheless, apparatuses relying on those techniques are relatively complex from the mechanical point of view, if only because in many cases they use numerous delicate moving parts. Furthermore, the quality of the calibration obtained for the drops is often given by a statistical distribution of drop size.
SUMMARY OF THE INVENTION
An object of the present invention is thus to provide a device of small dimensions that can be made at low cost, enabling drops of liquid to be produced in well-controlled manner.
To this end, the present invention provides a device for diffusing calibrated small volumes or drops of at least one liquid, the device being of the type comprising:
at least one displacement path for the liquid defined by a series of pairs of close-together surfaces enabling the liquid to be retained and to be moved from one pair of surfaces to another; and
means for applying an electric field between the pairs of surfaces in order to move the liquid from one pair of surfaces to another.
According to the invention:
the series of pairs of close-together surfaces defining a displacement path, co-operate to store the liquid, to form drops of liquid, and to move liquid drops to an outlet from said path leading towards a drop destination site; and
the means for applying an electric field apply a determined sequence of electric fields between the pairs of close-together surfaces so as to form drops of liquid from the liquid storage and so as to move them to the drop outlet.
In various optional embodiments, the present invention enables one or more of the following characteristics to be implemented in various technically feasible combinations:
said liquid is a liquid containing an active principle intended in particular for applications in generating odors, in cosmetics, in medical treatments, in hygiene, in chemistry, or in medical analysis;
said liquid contains at least one essential oil and/or a pheromone;
the device is arranged to convey the calibrated small volumes towards a zone of use which is associated with the outside of the device;
at least one pair of close-together surfaces constitutes at least one reservoir, a separation pad, and a pad for forming a small volume of liquid, co-operating to constitute an extractor of said small volume;
the reservoir comprises a volume for confinement by capillary action and interface tension between two close-together surfaces, at least one sector at the periphery of a liquid-retaining zone constituting extractor-forming means, and at least one face of the retaining zone being connected to liquid-feed means;
the extractor is constituted by a liquid-retaining zone adjacent to the reservoir, and it is constituted by two parallel faces that are close together so as to produce capillary and surface tension actions therebetween, the width of said zone relative to the displacement axis of the liquid being substantially smaller than its length, and more substantially smaller both than the width of the reservoir to which it is connected and than the width of the close-together surfaces of the displacement path for the calibrated volumes of liquid to which it is connected; and
the device is made up of at least two displacement paths enabling calibrated quantities
1
,
2
,
3
, . . . , N of liquid to be extracted from at least two reservoirs and to be conveyed towards at least one other internal path of the device, the calibrated quantities
1
to N not necessarily having the same volume.
The destination site constitutes a site where the liquid transferred in this way is used and can thus benefit from all kinds of active or passive means for processing the drop. This destination site can be internal or external relative to the device of the invention.
The device of the present invention makes judicious use of the presence of electric fields distributed between the liquid source and the outlet, firstly to create a drop and secondly to conduct the drop towards the destination site by the dielectric effect.
The invention relates to all applications that require precision, such as measuring out and mixing liquids, in particular in cosmetics, biology, pharmacy, medicine, chemistry, or phytotherapy, and other industries, implementing for such purposes a so-called “lab on a chip”.
By way of non-limiting example, the invention can be used to diffuse a wide variety of liquids containing odors as active principles, such as essential oils containing plant extracts.
When the means for applying an electric field comprise at least one pair of electrodes, the electrodes of a pair of electrodes can face each other and can be biased to create an electric field between each other, and they can be separated by a gap for confining liquid in the form of a more or less flattened drop. Under such circumstances, a pair of electrodes constitutes a capacitor, and the liquid, when present, constitutes the dielectric.
In embodiments of the invention, the volume (and to some extent the shape) of the drop is determined by the shape of the electrodes that come into contact with the liquid. Thus, it is possible to obtain uniform drops of volume that is determined very precisely by the volume constituted by the gap between the electrodes and by the outline of the facing, symmetrically shap
Le Pesant Jean-Pierre
Millet Jean-Claude
Dennison Schultz Dougherty & MacDonald
Freay Charles G.
Osmooze S.A.
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