Normally closed fluidic valve type device

Abstract

The invention relates to a normally closed fluidic valve device comprising a support (3) in which a fluidic passage is formed for the passage of a fluid (F), said device comprising: a deformable diaphragm (4) capable of moving between a closed position of the fluidic passage and an open position of the fluidic passage; mechanical means for holding the diaphragm (4) in the closed position; the mechanical means comprising a first element (10_1, 10_2, 10_3) made of a phase-change material capable of changing from a solid to a liquid state under the effect of heat, and a second element (20_1, 20_2, 20_3). Figure to be published with the abbreviation: Figure 2B

Description

Title of the invention: Normally closed fluidic valve type device Technical field of the invention

[0001] The present invention relates to a normally closed fluidic valve type device. State of the art

[0002] Documents US2012 / 064597A1, US2013 / 130262A1, US2007 / 166199A1 and US2006 / 076068A1 disclose microfluidic devices comprising a microfluidic network of capsules and channels connecting the capsules to each other. Each microfluidic capsule comprises a chamber into which an inlet channel opens and from which an outlet channel emerges. A deformable membrane is controlled between two positions to confer two distinct states to the capsule, a first state in which the inlet channel communicates with the outlet channel via the chamber allowing a transfer of fluid, and a second state in which the membrane blocks the communication between the two channels, preventing the flow of fluid and the filling of the chamber of the capsule. The membrane is controlled between its two states using pneumatic means, for example by exerting a positive pressure or a negative pressure on it.

[0003] Patent application EP3326717A1 proposes another solution in which the valve is created by adding a liquid into a cavity intended to form an element made of deformable material. The actuating mechanism of the invention is controlled by a control and processing unit to deform the element made of deformable material of each capsule, for example by exerting pressure or a pressure pulse by means of a pressure fluid, and in particular a pressure gas via the actuating holes of each capsule.

[0004] These different valve solutions are pneumatically actuated and require complex external means to be actuated. These means generally include external pumps or compressors as pressure sources, pressure regulators, and sometimes also solenoid valves. These means are external to the microfluidic devices so that sealed pneumatic connections must be ensured. In addition, these means must be controlled and regulated by dedicated mechanisms or even driven by electronic circuits and possibly software.

[0005] It may be advantageous to have a valve mechanism whose actuation is simple and reliable, without resorting to complex means requiring piloting or regulated, nor to moving electromechanical components sensitive to vibrations, and without relying on pneumatic connections which may have sealing defects.

[0006] Patents US7338028B2, US8585013B2 and US7748962B2 describe fluidic valves, actuable by magnetic effect by moving a permanent magnet. The valve comprises a metallic or magnetic part actuable under the effect of the permanent magnet. These different fluidic valves are not necessarily satisfactory insofar as they require the integration of metallic elements or the use of magnetic materials in a component made of polymer materials. However, the integration of materials of different natures is non-trivial and makes recycling processes more complex. It may therefore be advantageous to have a microfluidic device made of materials that follow the same recycling channel, or even the same recycling process.

[0007] Another approach is based on the use of paraffin or similar fusible, phase-change compounds ("PCM-Phase Change Material") to achieve microfluidic actuation and control. The review "Review on miniaturized paraffin phase change actuators, valves, and pumps" (S. Ogden et al., 2013) provides a detailed description.

[0008] Thermal actuation using paraffin as a phase change material is relatively popular due to its simple actuation principle, low manufacturing cost, relatively good biocompatibility and ability to provide large strokes and high actuation forces on a small scale (see previously cited publication).

[0009] The referenced publication “Self-Contained, Fully Integrated Biochip for Sample Preparation, Polymerase Chain Reaction Amplification, and DNA Microarray Detection” presents the operation of two types of valves. The operating principle of these two types of valve is the same. A solidified paraffin plug is heated by a heating zone of comparable size to the valve. The molten plug is transported by the pressurized fluid to cooler zones where it solidifies. In the second type of valve, a volume of air is trapped by the paraffin. During the heating necessary for the phase transition, this volume of air expands and pushes the paraffin into the fluid channel.

[0010] The referenced publication "Edwin T. Carlen and Carlos H. Mastrangelo, Surface Micromachined Paraffin-Actuated Microvalve, Journal of microelectromechanical Systems, 11, No. 5, October 2002", proposes a solution to isolate the phase change material from the fluid whose flow is to be regulated. This solution is based on a flexible polymer membrane. When heated above its melting temperature, the phase change material loses its shape calibrated which was given to it by construction and comes to block the flow of fluid in the valve.

[0011] However, these current valves which use a phase change material have disadvantages: - The phase change material used is often in contact with the fluid, which it allows or prevents from passing through. However, this material is not necessarily completely inert on a chemical or biochemical level. It is therefore systematically necessary to ensure its compatibility with the reagents and analytes sought during the design phase. - The phase change material generally does not have the same mechanical and thermal properties as the material forming the fluid channel. A shock or a variation in temperature can then cause the formed plug to loosen and therefore a micro-leak. - It is difficult to arrange a precise quantity of phase change material to form the desired plug(s) in fluid circuits with micro-channels.

[0012] It therefore remains relevant to have a fluidic valve type device using a phase change material and capable of overcoming the drawbacks of previous solutions. The device must in fact: - Prevent fluid pollution, - Be easy to implement, in particular thanks to easy deposition of the compound in phase change material, - Be arranged to form a normally closed valve. Statement of the invention

[0013] The invention thus relates to a normally closed fluidic valve type device comprising a support in which a fluidic passage is made intended to be crossed by a fluid, said device comprising: - A deformable membrane, capable of moving between a position of closing the fluid passage and a position of opening the fluid passage, - Means of mechanically holding the membrane in the closed position, - The mechanical holding means comprising a first element made in a phase change material, capable of changing from a solid state to a liquid state under the effect of heat and a second element (20_l, 20_2, 20_3), - In the solid state, the first element being positioned between said second element and the membrane in an amount sufficient to, in cooperation with the second element, apply a mechanical stress against the membrane in order to keep it in the closed position, - In the liquid state, the first element is configured to release the mechanical stress exerted against the membrane, creating sufficient space for the membrane to move to its open position.

[0014] According to a first variant embodiment, the second element is made of a non-porous material.

[0015] According to a second variant embodiment, the second element is made of a porous material with open cells, the first element in the solid state being in contact at least partially with the second element and, in the liquid state, capable of penetrating into the open cells of the second element, freeing said space necessary for the membrane to move to its open position.

[0016] According to a particular feature, the second element is forced into a well of the support.

[0017] According to another feature, the fluid passage is produced between a fluid inlet and a fluid outlet, produced in the support.

[0018] According to another feature, the first element is produced in the form of a ball of material deposited against the membrane, directly above the fluid inlet or the fluid outlet.

[0019] According to another feature, the phase change material is chosen from a paraffin, ice, a polymer such as low density polyethylene, PLA (for "Polylactic Acid") and ABS (for "Acrylonitrile Butadiene Styrene").

[0020] According to one particularity, the paraffin is chosen from one or more of the following compounds: tetracosane, heneicosane, Docosane, Tricosaene, Pentacosane, Hexacosane, Heptacosane, Octocosane, Triacontane, Dotriacontane, Tritriacontane.

[0021] According to another feature, the second element is made from a material chosen from a polyethylene with a very high molar mass, PLA and ABS.

[0022] According to another feature, the membrane is made of a material chosen from Ecoflex (registered trademark), silicone, PDMS, cellophane, rubber, elastomer and PTFE.

[0023] It should be noted that it is not trivial to propose a device that uses a compound made of a phase change material for a normally closed type valve. Indeed, naturally, the phase change material tends to expand with increasing temperature, which makes it more easily usable in a normally open type valve. Brief description of the figures

[0024] Other characteristics and advantages will appear in the detailed description which follows, given with reference to the appended drawings in which: - Figures 1A and 1B show a first variant embodiment of the device of the invention, respectively with the valve in the closed state and in the open state; - Figures 2A to 2C show a second variant embodiment of the device of the invention, respectively with the valve in the closed state, in the process of opening, and in the open state; - [Fig.3] shows a third variant embodiment of the device of the invention, with the valve in the closed state;

[0025] Detailed description of at least one embodiment

[0026] The invention relates to a device of the fluidic valve type V_1, V_2, V_3 normally closed.

[0027] For the remainder of the description, it should be noted that a valve is said to be in the open state (state 1 or ON) when it allows the fluid to pass through and it is said to be in the closed state (state 0 or OFF) when it blocks the passage of the fluid. In a so-called normally closed mode, the valve is in the closed state in the absence of a command and blocks the passage of the fluid. When the valve is commanded, it goes to the open state, allowing the passage of the fluid to be released.

[0028] The device comprises a fluid circuit comprising at least one fluid passage, through which a fluid F is caused to circulate. This fluid passage is for example arranged between a fluid inlet IN and a fluid outlet OUT. The valve V_1, V_2, V_3 is arranged to control the passage of the fluid between this inlet and this outlet, i.e. to block the passage of the fluid F between the inlet and the outlet when it is in the closed state or to release the passage of the fluid F between the inlet and the outlet when it is in the open state.

[0029] The fluid inlet IN and the fluid outlet OUT may each be formed in the form of a channel, for example oriented vertically, each opening into a transverse channel of the fluid circuit.

[0030] The device comprises a support 3, such as a component or a fluidic card, in which the fluidic circuit and therefore the fluidic inlet and the fluidic outlet are created.

[0031] In a non-limiting manner, the support 3 can be made of a material of the PMMA (Polymethyl methacrylate), silicon, COC ("Cyclic Olefin Copolymer"), PDMS (Polydimethylsiloxane), glass, PEEK (Polyetheretherketone), PS (Polystyrene) type. The fluid circuit can be made by milling, molding or other suitable techniques. The device, and in particular the support 3, can be obtained by assembling several components or plates.

[0032] The device also comprises a deformable membrane 4, capable of moving between two positions, a closed position in which it tightly blocks the passage of the fluid F between the fluid inlet IN and the fluid outlet OUT and an open position in which it releases the passage of the fluid F between the fluid inlet IN and the fluid outlet OUT. The membrane 4 has an inner face oriented towards the fluid side and intended to be in contact with the fluid F which circulates through the fluid passage, and an opposite outer face, not in contact with the fluid.

[0033] The membrane 4 can be made of a very elastically deformable material, such as for example Ecoflex (registered trademark), but also silicone, PDMS, cellophane, rubber, elastomer, PTFE (Polytetrafluoroethylene).

[0034] The membrane 4 is arranged in the fluidic support 3, for example by being taken between two plates of the support.

[0035] In normally closed mode, the membrane 4 is maintained in its closed position. In the invention, this closed position is maintained by the exercise of a mechanical stress.

[0036] The device also comprises a first element 10_l, 10_2, 10_3 made of a solid-liquid phase change material, which may also be called a fusible material. This type of material is configured to change from a solid state to a liquid (or molten) state when heated to a certain temperature, called the melting temperature (referenced Tf below).

[0037] In a non-limiting manner, this solid-liquid phase change material is for example a paraffin, for example chosen from tetracosane, heneicosane (melting temperature Tf=40.5°C), Docosane (Tf=44.4°C), Tricosane (Tf=47°C), Pentacosane (Tf= 54°C), Hexacosane (Tf= 56.4°C), Heptacosane (Tf= 59.5°C), Oc-tocosane (Tf=64.5°C), Triacontane (Tf= 65.8°C), Dotriacontane (Tf= 69.7°C), Tri-triacontane (Tf= 72°C). It could also be ice, a polymer such as low-density polyethylene, PLA (for "Polylactic Acid") or ABS (for "Acrylonitrile Butadiene Styrene").

[0038] In a non-limiting manner, this first element 10_l, 10_2, 10_3 can be deposited hot, cold, by sintering, molding or by 3D printing.

[0039] The device also comprises a second element 20_l, 20_2, 20_3 made of a material which may be at least partially porous with open cells or non-porous (see the two embodiments below). This second element 20_l, 20_2, 20_3 cooperates with the first element in the solid state to apply a mechanical stress on the membrane in order to maintain it in its closed position.

[0040] In a non-limiting manner, this second element may be made from a material such as a very high molecular weight polyethylene (commonly called UHMPE). It could also be a material such as PLA or ABS.

[0041] In a non-limiting manner, this second element can be produced by 3D printing, by machining, or by casting.

[0042] The first element 10_l, 10_2, 10_3 and the second element 20_l, 20_2, 20_3 can be produced in the form of two independent parts.

[0043] The membrane 4 is held in place by using the first element 10_l, 10_2, 10_3 made of solid-state phase-change material and the second element 20_l, 20_2, 20_3, fixed relative to the support 3. The second element is advantageously fixed to the support but it should be understood that it could be mounted on a chassis separate from the support 3, kept fixed by any means relative to the support 3. In the attached figures, it is for example forced into a well 31 of the support 3 in the form of a plug.

[0044] In the solid state, the first element 10_l, 10_2, 10_3 is positioned between said second element and the membrane in a quantity sufficient to, in cooperation with the second element 20_l, 20_2, 20_3, apply a mechanical stress on the membrane 4 in order to maintain it in the closed position.

[0045] The transition to the liquid (or molten) state of at least a portion of the material making up the first element 10_1, 10_2, 10_3 makes it possible to release the mechanical stress on the membrane 4, by creating a space of non-zero volume in which the membrane 4 is able to move, and thus allow the opening of the fluid passage.

[0046] When the second element 20_l is made of a non-porous material, the space freed by the phase change of the material of the first element 10_l is created by the simple phase change of the material making up this first element. In other words, the phase change of the material makes it possible to modify the volume occupied by the first element 10_l and to free up sufficient space for the deformation of the membrane 4 towards its open position.

[0047] When the second element 20_2 is made of a porous material, the phase change material in the liquid state of the first element 10_2 is able to penetrate into the open cells of the second element 20_2, thus freeing up said space sufficient for the membrane 4 to be able to deform and open the fluid passage.

[0048] The second element 20_2 made of porous material must advantageously have a wetting character sufficient to absorb the first element 10_2 when the latter has passed into the liquid state. In a known manner, a material is said to have a wetting character with respect to another material when its surface exposed to the liquid has a contact angle which is less than 90°.

[0049] In this latter configuration, the presence of a vent 30_2 will be necessary to ensure the penetration of the liquid into the open cells of the second element 20_2.

[0050] Figures 1A and 1B show a first variant embodiment of the device of the invention, using a valve V_l, in which the second element 20_l is made of a material which is chosen to be non-porous.

[0051] In [Fig. 1A], the first element 10_l is for example deposited directly on the upper face of the membrane 4 and fills the space present between the second element 20_l and the membrane 4 when the latter is in the closed position. The second element 20_l is housed in the well 31, for example made in the support 3.

[0052] The second element 20_l can be inserted by force into the well 31, thus allowing it to be fixed and to exert the mechanical stress against the first element 10_l in the solid state and therefore against the membrane 4 to maintain it in its closed position. It can also be fixed by blocking in the well 31, using an additional part, or even glued. Being isolated from the fluid by the membrane, the choice of material and possibly of the glue are free and do not risk causing pollution phenomena of the fluid.

[0053] In [Fig. 1B], the first element 10_l is heated and passes into the liquid state. By becoming liquid, the first element 10_l deforms, the latter then not being constrained in at least one direction can flow in this direction, thus releasing the mechanical stress on the membrane 4. In other words, in this liquid state, the space occupied by the first element 10_l is modified, allowing the mechanical stress exerted on the membrane 4 to be released and to be released, so that it can deform to its open position, aided in this by the pressure of the liquid injected into the fluid inlet.

[0054] Figures 2A to 2C show a second variant embodiment of the device, using a valve V_2 in which the second element 20_2 is made of a porous material with open cells according to the characteristics defined above.

[0055] In [Fig.2A], the arrangement is similar to that of [Fig.1A] above, except that the second element 20_2 is made of a porous material with open cells. The presence of a vent 30_2 is also necessary, this opening into said well 31. In this second embodiment, the first element must be at least partially in mechanical contact with the second element. A holding part 32_2 of the second element 20_2 is also added to ensure its holding in the support 3. This part 32_2 is however optional and force-fitting can also be used, as in the previous embodiment.

[0056] In [Fig.2B], the first element 10_2 is heated to pass into the liquid state.

[0057] By affinity with the porous nature of the second element 20_2 and possibly aided by the pressure of the fluid F injected into the circuit, the liquid material forming the first element 10_2 impregnates the second element 20_2, occupying its open cells. Thus, the mechanical stress exerted against the membrane 4 is released, by releasing a space in which the membrane is able to move to its open position.

[0058] In [Fig.2C], the liquid material forming the first element 10_2 has completely penetrated the second element 20_2, leaving the membrane 4 all the space to deform.

[0059] The first element 10_l, 10_2 made of phase change material can be made in any form such as paste, powder, chips, or any other more or less large particles, the objective being that this first element: - In the solid state, at least partially fills a space present between the second element and the membrane and, - In the liquid state, releases the mechanical stress exerted on the membrane.

[0060] It should be noted that intermediate layers / parts may be present between the first element 10_l, 10_2 and the membrane 4.

[0061] In this second embodiment, the quantity of phase change material can remain limited. The shape of this material is also unconstrained (chips, powder, etc.).

[0062] [Fig. 3] shows another alternative embodiment of the device. According to this alternative, the first element 10_3 is in the form of at least one ball of fusible material positioned between the membrane 4 and the second element 20_3, directly above the fluid inlet IN or the fluid outlet OUT. In [Fig. 3], the ball of material is in mechanical contact with the membrane 4 and is arranged to, on one side, bear against the second element 20_3 and on the other side to exert pressure against the membrane 4, so as to maintain it in its closed position (when the ball is in the solid state). This alternative embodiment makes it possible to relax constraints on the precision of the volume of phase change material to be dispensed.

[0063] It should be noted that: - The layer of phase change material advantageously has a maximum thickness strictly greater than the thickness of the membrane 4. Indeed, the mechanical stress exerted by the second element and the first element tends to compress the membrane. When this mechanical stress is released by melting of the phase change material, sufficient space must be created so that the membrane 4 can deform and release the fluid passage. - The application of mechanical stress to the elastic and deformable membrane 4 makes it easier to manage the mechanical uncertainties of the system. In other words, this principle of applying mechanical stress provides guarantees on the closure of the fluid passage. - The melting temperature of the phase change material must be chosen lower than the melting temperature of the support 3. If the material of the support 3 is an assembly of layers assembled and bonded together by thermal sealing, the melting temperature of the fusible material must be much lower than the glass transition temperature of the materials constituting the support. - The melting temperature of the phase change material must be lower than the glass transition temperature of the membrane 4. - Membrane 4 must have a significant elastic component to deform elastically without tearing. - If the fluid F under pressure is an aqueous solution, the membrane 4 must be impervious to water vapor.

[0064] The device described appears to be particularly well suited to controlling the release of a fluid contained in a pressurized tank.

[0065] The device can be coupled with a suitable heating system (not shown) which can be either common to several devices of the same support or each independent. It is also possible to use a heating system which comprises several distinct resistive branches, each dedicated to the actuation of a distinct device.

[0066] The device has many advantages, including: - A valve having a design without risk of pollution of the fluid by the phase change material, the latter not being in direct contact with the fluid; - A valve having a design without control by a moving part, the diaphragm being displaced by the pressure of the fluid when the space necessary for the displacement of the diaphragm is freed by the melting of the phase change material of the first element; - A solution that guarantees reliable operation and does not suffer from uncertainties in the design and mechanical production of the device, wear or fatigue of electromechanical components, or even sealing defects in joints;

Claims

Claims

1. Normally closed fluidic valve type device comprising a support (3) in which a fluidic passage is made intended to be crossed by a fluid (F), said device comprising: - A deformable membrane (4), capable of moving between a position of closing the fluid passage and a position of opening the fluid passage, - Means for mechanically holding the membrane (4) in the closed position, Said device being characterized in that: - The mechanical holding means comprise a first element (10_l, 10_2, 10_3) made of a phase change material, capable of passing from a solid state to a liquid state under the effect of heat and a second element (20_l, 20_2, 20_3), - In the solid state, the first element (10_l, 10_2, 10_3) is positioned between said second element (20_l, 20_2, 20_3) and the membrane (4) in a quantity sufficient to, in cooperation with the second element, apply a mechanical stress against the membrane (4) in order to maintain it in the closed position, - In the liquid state, the first element (10_l, 10_2, 10_3) is configured to release the mechanical stress exerted against the membrane (4), creating sufficient space for the membrane (4) to move to its open position, - The second element (20_2, 20_3) is made of a porous material with open cells, the first element (10_2, 10_3) in the solid state being in contact at least partially with the second element and, in the liquid state, capable of penetrating into the open cells of the second element, freeing said space necessary for the membrane (4) to move to its open position.

2. Device according to claim 1, characterized in that the second element (20_l, 20_2, 20_3) is forced into a well (31) of the support.

3. Device according to claim 1 or 2, characterized in that the fluid passage is produced between a fluid inlet (IN) and a fluid outlet (OUT), produced in the support (3).

4. Device according to claim 3, characterized in that the first element (10_3) is produced in the form of a ball of material deposited against the membrane (4), directly above the fluid inlet or the fluid outlet.

5. Device according to one of claims 1 to 4, characterized in that the phase change material is chosen from a paraffin, ice, a polymer such as low density polyethylene, PLA (for "Polylactic Acid") and ABS (for "Acrylonitrile Butadiene Styrene").

6. Device according to claim 5, characterized in that the paraffin is chosen from one or more of the following compounds: tetracosane, he-neicosane, Docosane, Tricosaene, Pentacosane, Hexacosane, Hep-tacosane, Octocosane, Triacontane, Dotriacontane, Tritriacontane.

7. Device according to one of claims 1 to 6, characterized in that the second element (20_l, 20_2, 20_3) is made of a material chosen from a polyethylene with a very high molar mass, PLA (for "Polylactic Acid") and ABS (for "Acrylonitrile Butadiene Styrene").

8. Device according to one of claims 1 to 7, characterized in that the membrane (4) is made of a material chosen from Ecoflex (registered trademark), silicone, PDMS, cellophane, rubber, elastomer and PTFE.

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