Fluid handling – Destructible or deformable element controlled – Destructible element
Reexamination Certificate
1999-07-20
2001-06-19
Buiz, Michael (Department: 3753)
Fluid handling
Destructible or deformable element controlled
Destructible element
C424S449000, C604S020000, C607S153000
Reexamination Certificate
active
06247485
ABSTRACT:
The present invention concerns a miniature valve, a device for filling a reservoir including a valve of this kind and a method of manufacturing said valve. The present invention also concerns apparatus for transdermal administration of medication including a device of this kind for filling a reservoir with a solution of an active principle to be administered.
For transdermal administration of a medication, a reservoir containing an active principle is generally applied to the skin of the patient, this reservoir routinely comprising a layer of a hydrophilic product such as a hydrogel carried by a suitable support. When administration of the medication is assisted by inophoresis, the active principle is in ionic solution. The ionic solution is stored in a sachet that is emptied into the reservoir immediately before administration. This procedure is necessary because the solution loses its stability in the hydrogel constituting the reservoir and therefore cannot be loaded into the latter ab initio.
The problem then arises of emptying the sachet of the active principle ionic solution into the reservoir. Various mechanical means have been designed for this, for example syringe type means in which actuation of a piston expels the ionic solution from the syringe to inject it into the reservoir. Flexible sachets have also been designed that are opened by puncturing or tearing them and emptied into the reservoir by applying pressure to the sachet.
It is therefore apparent that, whatever means are employed to empty the sachet of ionic solution into the reservoir, human intervention is required, which is impractical and does not lend itself to automatic initiation immediately prior to starting treatment. Moreover, the mechanical means referred to hereinabove are subject to deficiencies where sealing is concerned and do not always assure complete emptying of the sachet into the reservoir.
Transdermal administration of medication assisted by ionophoresis often employs equipment in the form of a bracelet worn by a patient, the bracelet carrying all of the units needed for this administration, so as to assure the autonomy of the patient. The bracelet therefore carries, in addition to the reservoir applied to the skin of the patient, electrodes, electronic control means for the electrodes and a battery electrical power supply for these means, which necessarily hold a limited quantity of electrical energy. It would be desirable for the emptying of the ionic solution into the reservoir mentioned above, also known as “hydrating” the reservoir, to be controlled by the electronic means incorporated into the bracelet so as to automate this emptying prior to a treatment, without this additional function of these means consuming more electrical energy than the battery can provide.
One aim of the present invention is to provide a miniature valve adapted to assure said “hydration” of the reservoir automatically, under the control of said electronic means, for a minimal expenditure of electrical energy that is not likely to compromise the operation of the portable equipment used for transdermal administration assisted by ionophoresis.
Another aim of the present invention is to provide a valve of this kind that eliminates the problems of sealing and of incomplete emptying of the sachet that sometimes affect the mechanical means for hydrating the reservoir used in the prior art.
Another aim of the present invention is to provide such a valve that can be manufactured industrially with a very low or event zero reject rate.
These aims of the invention, and others that will emerge from a reading of the following description, are achieved with a miniature valve comprising a) a substrate, b) a charge of a combustible material disposed on the substrate facing a passage to be opened through the latter, c) an electrical resistance in contact with the combustible charge so that supplying a predetermined electrical energy to this resistance assures the combustion of the charge and the opening of the passage by localised rupture of said substrate due to the pressure of the gases of combustion of the charge.
As will emerge below, placing a plurality of such valves between a sachet of an active principle solution and a reservoir to be charged with the solution provides means for automatic initiation of hydration of the reservoir immediately prior to a treatment without human intervention, simply by electronically commanding opening of these valves.
In accordance with other features of the present invention, the resistance is filamentary and the charge extends over and beyond the resistance, so that the heat generated by the resistance when supplied a predetermined quantity of electrical energy is initially concentrated in the portion of the charge that surrounds the resistance. Said predetermined electrical energy is less than 10 Joules. An expenditure of energy of this magnitude does not significantly drain the charge of the battery power supply of portable apparatus for transdermal application of medication assisted by ionophoresis and is therefore compatible with other demands for energy from the battery.
In accordance with another feature of the present invention, the charge and the resistance are disposed on the same side of a thinner area of the substrate, the thickness and the surface area of which are chosen so that the pressure of the gases due to the combustion of the charge fragments this area and opens it to the passage of said gases and possibly other fluids.
The invention therefore provides a device for filling a reservoir with a fluid contained in a sachet adjacent the reservoir, comprising at least one miniature valve in accordance with the invention disposed so as to block fluid communication between the sachet and the reservoir and means for selectively commanding energisation of the electrical resistance of the valve and thereby to cause the opening of said communication to the fluid contained in the sachet through the passage opened in the substrate of the valve by the combustion of the charge that it carries.
In accordance with another feature of this device, it further comprises at least one flexible envelope inside the sachet, this envelope containing a miniature valve in accordance with the present invention, the control means selectively initiating combustion of the charge carried by this valve so as to inflate the envelope with the combustion gas so as to assist the emptying of the sachet through the valve or valves disposed in fluid communications between said sachet and said reservoir.
The invention also provides a method of manufacturing the valve in accordance with the invention, wherein:
a) a substantially plane face of a semiconductor material substrate is covered with an etch stop layer resistant to a solution for etching said material;
b) said etch stop layer is covered with an electrically insulative layer if the etch stop layer is not electrically insulative;
c) an electrical resistance is formed on said electrical insulation layer,
d) the substrate is etched from the face of the substrate opposite that which carries said resistance as far as the etch stop layer, and
e) a combustible charge is deposited on top of the electrical resistance.
REFERENCES:
patent: 3184097 (1965-05-01), Kilmer et al.
patent: 5135479 (1992-08-01), Sibalis et al.
patent: 5186001 (1993-02-01), Muntz et al.
patent: 5310404 (1994-05-01), Gyory et al.
patent: 0 513 879 (1992-11-01), None
patent: WO94/21314 (1994-09-01), None
Esteve Daniel
Mikler Claude
Millot Philippe
Rossi Carole
Teillaud Eric
Buiz Michael
Krishnamurthy Ramesh
Laboratoires d'Hygiene et de Dietetique (L.H.D.)
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