Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
  • A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
  • A61M5/168—Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body
  • A61M5/16877—Adjusting flow; Devices for setting a flow rate
  • A61M5/16881—Regulating valves
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
  • G05D7/00—Control of flow
  • G05D7/01—Control of flow without auxiliary power
  • G05D7/0106—Control of flow without auxiliary power the sensing element being a flexible member, e.g. bellows, diaphragm, capsule
  • G05D7/0113—Control of flow without auxiliary power the sensing element being a flexible member, e.g. bellows, diaphragm, capsule the sensing element acting as a valve
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M2205/00—General characteristics of the apparatus
  • A61M2205/02—General characteristics of the apparatus characterised by a particular materials
  • A61M2205/0244—Micromachined materials, e.g. made from silicon wafers, microelectromechanical systems [MEMS] or comprising nanotechnology
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/494—Fluidic or fluid actuated device making

Definitions

• the present invention is in the field of drug delivery in liquid form. It concerns more precisely the flux regulators used for this purpose.
• FIGS. 1 and 2 The operating principle of a flow regulator of the state of the art (see FIGS. 1 and 2) is described in particular in the patent application WO 99/38552. It is a membrane 4 pierced at its center 6, which is deflected by the pressure of the reservoir and which comes into contact with a substrate 1 on which is etched a fluidic channel 5, the latter being p. ex. in the form of a spiral. The membrane 4 thus closes this channel 5 after contact, with the exception of the location where the central hole 6 is located. The liquid of the reservoir therefore flows through the central hole 6 and then along the channel 5.
• the membrane 4 the distance between the membrane 4 and the substrate 1 and the channel 5 are dimensioned so that the fluid resistance of the channel 5 varies proportionally with the pressure in the tank.
• the flux is therefore constant in a certain pressure range. It does not depend on the pressure. In case of overpressure, the channel 5 closes completely and the flow is interrupted.
• the regulator described in WO 99/38552 is manufactured by etching, e.g. ex. chemical, or by ionic type dry fastener, the central hole 6 of the membrane 4, the membrane 4 itself, the spacer 3 between the membrane 4 and the substrate 1 and the channel 5 itself.
• the membrane 4 and the spacer 3 are created simultaneously from the same element.
• an error on the thickness of the membrane 4 also affects the thickness of the spacer 3 and vice versa.
• the present invention relates to a new flow regulator structure and a new method which simplifies the assembly of the different parts of the regulator and which makes it possible to achieve better manufacturing tolerances by the same method used.
• the flow regulator according to the invention successively comprises a substrate, a channel, a spacer and a membrane, the latter comprising a central hole communicating with the channel.
• the regulator is characterized in that it is made from at least two distinct elements, the first element comprising the membrane and the second element comprising the spacer.
• sheets of controlled thickness and low roughness are stacked, each sheet having a particular function.
• These sheets are for example obtained by rolling, then by wire cutting or stamping, and then by mirror polishing.
• the stack consists of a flat substrate with only one exit hole, a thin sheet with the through channel, a thin sheet with a disk pierced for the spacer, a thin sheet pierced in the center for the membrane.
• This stack makes it possible to master before assembly all the thicknesses, such as for example the membrane, the spacer and the depth of the channel, which is thus perfectly defined by the thickness of the sheet chosen for this function.
• the flow rate varies as the power of four on the side of this square in the approximation of the laminar regime for a Newtonian fluid and at constant temperature.
• the tolerance on the depth is perfectly mastered and there remains only the tolerance on the width of the channel, that is to say that which was already rather well mastered previously.
• the regulator according to the invention makes it possible to achieve flow accuracies which were not attainable by the standard machining methods of silicon or Pyrex.
• the exit hole can also be offset on the edge of the membrane to have the inlet and the outlet of the fluid on the same side.
• the regulator according to the invention can be completely clogged at a defined pressure in order to avoid overdoses. This threshold pressure is reached when the channel is completely covered by the membrane.
• the regulator according to the invention may comprise means for measuring the deflection of the membrane, for example using strain gauges placed in the Wheatstone bridge configuration on the membrane. These gauges can be made by ion implantation or diffusion if the membrane is silicon. External gauges may also be placed on the membrane, for example by gluing, if said membrane is not made of a piezo-resistive material.
• FIG. 1 already described above, illustrates a flow regulator of the state of the art in the rest position.
• FIG. 1 illustrates the regulator of Figure 1 in active mode, when the membrane is deformed.
• FIG. 3 presents an exploded and schematic view of a first embodiment of a flux regulator according to the invention.
• FIG. 4 shows a second embodiment of a flux regulator according to the invention.
• FIG. 5 illustrates the steps of a method for producing a substrate-channel assembly according to the invention.
• FIG. 3a A first embodiment of the flux regulator according to the invention is illustrated in FIG. 3a. This is formed from four sheets 1 to 4, a first sheet intended to form the substrate, a second sheet 2 intended to contain the channel 5, a third sheet 3 having a large central opening 7 intended to form the spacer 4 and a fourth sheet acting as a membrane 4.
• the membrane 4 may be made of polished silicon, a material that has excellent mechanical properties, but also metal or any other material that has a high elastic limit.
• the piercing of the membrane 4 may be carried out by chemical etching or by very short-pulse laser drilling, such as for example the femtosecond laser, which avoids plastic deformation by heating the membrane 4.
• the direction of the laser drilling is important because a bead may be present on the periphery of the hole 6.
• a circular recessed portion whose diameter is at least equal to the hole 6 of the membrane 4, which allows on the one hand increase the tolerances on the positioning of the membrane 4 with respect to the channel 5 and also to prevent this eventual bead from creating a spacing and thus a poor sealing of the channel 5 at the level of the hole 6.
• the spacer 3, the channel 5 and the substrate 1 can be made for example of metal, such as for example steel, or more advantageously ceramic LTCC. These co-cured ceramics are in fact drilled, for example by laser, machined, aligned, serigraphed on the surface and then pressed in the green state, which allows three-dimensional stacks, and then the hot sintering makes it possible to assemble permanently and without leakage the different elements.
• the final assembly method for example for rolled sheets of metal, can be a recess, a weld or a bonding. For large systems it is preferred to use a recess via two precision circular parts which enclose the different sheets, for example by clamping with screws. The upper part has to be recessed to create a cavity 9 above the membrane and pierced in the center for the arrival of the fluid.
• the fluid outlet can be arranged in the lower part or in the upper part of the regulator.
• exit holes 10 and 11 are respectively formed in the sheet 2 containing the channel 5 as well as in the substrate 1.
• the membrane sheet 4 When the outlet is located on the same side as the inlet, the membrane sheet 4 also includes an outer hole of larger diameter than the central hole for the outlet.
• the alignment is obtained either by additional centering holes, or by the substrate 1 itself. Indeed there is no tolerance on its thickness or its width. It is easy to imagine a kind of cavity in which the sheets would fit. Alignment pins can be used for large systems. Alignment is facilitated if the edges of the leaves are circular and the housing of the substrate in which these sheets fit.
• the surface roughness of the membrane 4, the channel 5 and the substrate 1 must be much smaller than the characteristic dimensions of the component, that is to say the depth of the channel 5, the thickness of the spacer 3, the thickness of the membrane 4 and the diameter of the inlet hole 6.
• the use of laminated sheets, machined and already mirror polished before the final assembly substantially reduces leaks during operation.
• the channel 5 itself can be made by electroplating directly on the substrate 1, for example by lithographically making the negative channel 1 to achieve the deposition of the metal hook layer, which after growth will define the channel 5 embossed .
• the negative part of the spacer 3 can also be made by electroplating. The surface roughness obtained by electroplating is entirely compatible with the proper functioning of the component. In order to preserve the layer assembly principle whose thickness is well controlled, it is possible to carry out the growth of the channel 5 negative on a sacrificial layer which will be dissolved before assembly on the substrate 1.
• FIG. 4 represents an assembly of a passive flux regulator with the spacer 3, the channel 5 and the substrate 1 made in one piece, for example by plastic or ceramic injection, or by plastic embossing.
• the cover 8 can also be made in this way.
• the cover 8 includes a cavity 9 which allows a good distribution of the pressure above the membrane 4.
• the membrane 4 is made of a material having a high elastic limit and advantageously the minimum of internal stresses.
• the method according to the invention has many advantages compared to the machining methods of the state of the art. With the method according to the invention, the relative tolerances are wider, in particular for the micro machining of silicon or metal.
• the method according to the invention consists mainly in the production of a single mold of required dimensions, for example by one or two electroplating operations. nickel on a positive or negative channel and spacer. Replication of the components by plastic injection or embossing from this mold achieves excellent relative tolerances and good surface roughness, with suitable process parameters such as pressure cooling and injection time. embossing. This method significantly reduces manufacturing costs and the number of process steps.
• a coating may be necessary on all parts of the components to ensure their biocompatibility, for example a diamond layer, a layer of gold or titanium.
• the various elements are then assembled by direct bonding plastic / silicon or plastic / metal, or by bonding, embedding.
• a groove or a groove can be arranged in the plastic or ceramic substrate to be able to extend the glue.
• the membrane 4 is then positioned on the substrate 1 for the polymerization with possibly a pressing pressure to maintain the assembly tolerances.
• the difficulty is essentially reduced to a single critical alignment, namely that of the membrane 4 on the replicated part.
• a self-centering technique via a groove or extra thickness on the replicated part can be used. Alignment holes may also be drilled in the membrane 4 and the replicated portion of the regulator.
• FIG. 5 illustrates an exemplary embodiment of the master, including a deposition of SU8 after dry etching of the channel, followed by a photolith and possibly a metallization.
• the invention is not limited to the embodiments illustrated and discussed in the present text.

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• 2009
  • 2009-02-06 EP EP09709010A patent/EP2242524A1/de not_active Withdrawn
  • 2009-02-06 WO PCT/EP2009/051414 patent/WO2009098314A1/fr active Application Filing
  • 2009-02-06 US US12/866,840 patent/US20100324504A1/en not_active Abandoned

Non-Patent Citations (1)

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