Patent Application
20100218834
This application is entitled to the benefit of and incorporates by reference essential subject matter disclosed in International Patent Application No. PCT/DK2007/000044 filed on Jan. 30, 2007.
The present invention relates to a micro fluid device comprising a substrate with a channel forming a receiving cavity, an outer chamber, and an inner chamber. The device further comprises a multi lumen hose with a free end portion which is fixed in the receiving cavity. The multi lumen hose forms a first conduit and at least one second conduit located offset from the first conduit, wherein the outer chamber is in fluid communication with at least one second conduit, and the inner chamber is in fluid communication with the first conduit and wherein the chambers are separated by an inner sealing member which seals between the substrate and the hose.
In Microsystems engineering, various processes are applied for connecting components. The processes generally involve cementing two surfaces together. To make a fluid tight connection, the parts must be fitted accurately to each other prior to the application of the cement, and obviously, proper contact between the cement and both of the surfaces which are to be joined without unintentional clogging of fluid paths is important. Particularly difficult is to connect hoses, fibres or similar flexible and relatively thin components to other components, e.g. to a fluid chip or similar substrate. In this case, it is not only important to establish fluid tightness but also to preserve the fixation of the parts over time, even when the flexibility of one of the components implies movement of the components relative to each other.
A multi lumen hose contains in one single unit, a plurality of separate conduits. Typically a centrally located first conduit is surrounded by at least one second conduit. The conduits sometimes extend coaxially so that each conduit share the same centre axis or the second conduits are located as cartridge chambers in a revolver with individual centre axes for each conduit.
Often, the conduits communicate with different chambers of the cooperating substrate. For this purpose, the hose of the existing systems are prepared for communication at two axially displaced locations. At a free end of the hose, the centrally located conduit is laid open, and before connection of the hose to the substrate, an outer portion of the hose is stripped so as to open the second conduits at a certain distance from the free end of the hose. The stripping of the hose unfortunately creates a diametric reduction of the hose, and the receiving cavity of the corresponding substrate therefore has a corresponding cross-sectional dimensional step. I.e. the substrate comprises a step between a first cross sectional size which snugly fits around the stripped portion of the hose and a second cross sectional size which snugly fits around the un-stripped portion of the hose. As previously mentioned, it is important that the bonding cement establishes contact between the outer surface of the hose and the inner surface of the groove, and it is important that the cement does not clog the chambers. It is therefore important that the dimensional tolerances between the substrate and the hose are low and the stepped shape of the groove is therefore relatively expensive to provide. In the known devices the substrate is made from an upper part and a lower part which both have a step corresponding to half of the total diametric reduction of the hose. When the two parts are assembled, the receiving cavity matches the shape of the hose precisely. Due to the combination of two parts which both have a structure which must match the structure of the other part, both the manufacturing of the two parts and the assembling of the parts are relatively expensive processes.
One document WO 2005/102005 discloses a catheter manifold being molded about a portion of an outer tubular member and a portion of an inner tubular member of a catheter. With reference to
After introduction of the molding material, the material is allowed to cure, thereby forming the manifold 22. After the manifold 22 is formed and cured sufficiently, the mold 62 may be removed and other steps in the process of fabrication performed. Again, it should be noted that the proximal end 35 of the inner tubular member 30 extends proximally from the proximal end 37 of the outer tubular member 32. As such, both the inner and outer tubular members 30/32 are attached to the manifold 22. The inner tubular member is attached by virtue of having the inner tubular member 30 extend beyond the proximal end of the outer tubular member 32.
The document therefore only describes a process of molding a manifold to a catheter, the mold being removed from the final product, and not attaching a multi lumen hose to a micro fluid device comprising a substrate with a channel forming a receiving cavity, an outer chamber, and an inner chamber, where the micro fluid device forms part of the final product.
Another document US 2009/0041624 describes a fluidic structure and a method for production of a fluidic structure. The method may comprise, in order, introducing at least one externally accessible opening into at least one base substrate of the fluidic structure, partially introducing at least one section of a fluidic conductor, which has at least one inner lumen and at least one conductor wall, in particular of a tube or flexible tube, into the at least one opening, introducing at least one curable fluid sealing material into the at least one opening, entirely or partially curing the at least one fluid sealing material, and producing at least one connecting channel between at least one inner lumen in the at least one fluidic conductor and at least one fluid channel in the fluidic structure, the at least one connecting channel passing through at least one conductor wall.
The sealing material introduced in this document, however, is seen filling the space of the at least one opening around the at least one section of a fluidic conductor, the at least one connecting channel this passing not only through at least one conductor wall, but also the sealing material. The present invention introduces a method to avoid such a connecting channel passing through conductor wall and sealing material.
It is an object of the invention to facilitate assembling of a multilumen hose and a substrate. Accordingly, the invention, in a first aspect, provides a micro fluid device wherein at least a part of the channel is formed by a groove in an upper surface of a body of the substrate, which groove is closed by an essentially plane cover which is sealed to the upper surface.
The substrate may e.g. be a fluid chip, e.g. a chip comprising a plurality of micro channels. The chip could be made from silicon or from a polymer, and the channels could be made mechanically by a cutting tool or chemically in an etching process. If the chip is made from a polymer, the channels could be made by hot embossing by pressing a heated metal or silicon die into the polymer material. The Channels may e.g. be micro channels with a cross-sectional area in the range of 20-500 μm. The receiving cavity may preferably fit closely around the hose, and for any axial location along the free end portion of the hose, the cross-sectional size of the receiving cavity could therefore be in the range of 101-130% of the cross-sectional size of the hose. In particular, a close fit between the cavity and the hose may facilitate tight sealing since a liquid sealing member may flow into correct position between the cavity and the hose due to surface tension or capillary force. The closer the hose is to the wall of the cavity, the lower a viscosity is preferred for the liquid sealing member.
The upper surface of the body could be a plane surface to which the plane cover is attached, e.g. adhesively or the cover could be welded onto the surface e.g. by ultrasonic welding. The cover could be made from a foil material, e.g. with a thickness of 20-1000 μm. Preferably, the cover is highly flexible, so that the essentially plane shape appears when the cover is applied to the plane upper surface of the body part. The hose could form any number of conduits, e.g. one centre conduit and tree, four, five or more conduits arranged circumferentially around the centre conduit. The hose could be made from one single piece in which the conduits extends, e.g. an extruded piece. Alternatively, the hose could contain a number of individual hoses which are all surrounded by an outer hose, i.e. like power cords in a power cable. The hose could e.g. be made from PTFE or PVC, e.g. from the company Zeus Industrial Products Inc. (c.f. http://www.zeusinc.com/) or from Medical Tubing SAS (c.f. http://www.medical-tubing.com/).
To bond the cover to the body part, the cover and the body part are prepared to have essentially plane matching surfaces. The two parts are located with the matching surface in mutual contact, and the parts are arranged in a fixture. Subsequently, the parts are welded in a manner known per se. If the parts are made from a polymer, laser welding may be applied in a manner known per se. If the parts are made form silicon, electrostatic bonding may be applied in a manner known per se.
That the surfaces such as that the cover are essentially plane, is to be understood in the sense were they comprises a main surface being plane for matching a second essential plane surface, but where shapes such as rifts or grooves may be shaped in the surfaces. In this manner, the essential plane cover may e.g. comprise grooves mirrored to the ones formed in the upper surface of the substrate. There may also be dowels and holes formed in the surface of the cover and the upper surface of the substrate to ensure that they align sufficiently.
The channels may e.g. have a depth into the body which corresponds to the thickness of the hose. In that way, a part of the hose is in plane with the upper surface, and the cover may bond not only to the upper surface but also to the hose.
The inner sealing member is located between the opening into the first conduit and the opening into the second conduits whereby it seals between the two chambers which communicate with the hose. The device may further comprise an outer sealing member which seals between the substrate and the hose at a location wherein the hose is not stripped, i.e. between the surrounding space and the outer chamber, and the outer sealing member thereby separates the outer chamber from a surrounding space.
The sealing members could be made from a liquid material which is introduced into the space between the receiving cavity and the hose and solidified therein. As an example, the sealing member could be made from a liquid polymeric material which can be solidified and which may bond to the cover, to the body part and to the hose. The liquid material could be introduced through an opening in the cover and subsequently be solidified therein. The solidification process may e.g. involve curing, e.g. based on electron beam or electromagnetic radiation.
To support the moulding of the liquid material directly into the receiving cavity, and to fixate the hose against axial displacement in the receiving cavity, the receiving cavity may form one or more sealing wells in which the cross-sectional size of the receiving cavity widens out. In that way, the area of contact between the sealing member and the inner wall of the receiving cavity may increase without increasing the axial length of the sealing member, and the liquid tightness and strength of the connection can be improved without increasing the risk of clogging the inner and outer chambers.
In one embodiment, the second conduits are formed by a peripheral outer portion of the hose, e.g. located radially offset from a centrally located first conduit. The outer portion is stripped off to open the second conduits at a location at a distance from the free end of the hose. At an intermediate location between the free end and the stripped portion, the outer portion is not removed and the inner sealing member is moulded onto this intermediate portion so that the sealing member seals between the outer surface of the outer portion and the wall of the receiving cavity. In this embodiment, the second conduits may be sealed individually by an internal sealing member to prevent communication between the inner and outer chamber through the second conduits. The inner sealing member could e.g. be a liquid material which is solidified in the second conduits.
In one embodiment, the outer portion of the hose is stripped off to open the second conduits at two locations at two different distances from the free end of the hose. The inner sealing member is located to seal between the inner surface of the receiving cavity and a proximal stripped off portion, i.e. the portion closest to the free end of the hose. When the hose is located in the receiving cavity, the proximal stripped off portion may serve as a mould for moulding the inner sealing member directly into the space between the hose and the receiving cavity.
To support the hose in the receiving cavity and to improve the tightness of the connection, the receiving cavity may form an inner portion with a smaller cross sectional size than the remainder portion of the receiving cavity. This allows the stripped off portion of the hose to be located in the inner portion of the receiving cavity and the un-stripped portion to be located in the remainder portion of the receiving cavity so that the distance from the inner wall of the receiving cavity and the hose is essentially constant.
To increase the length along which the hose is in contact with the wall of the receiving cavity, the receiving cavity may extend at an angle different from zero degrees to the cover. The receiving cavity could e.g. be drilled into the substrate, e.g. at 45 degrees angle to a plane defined by the essentially plane cover or to a plane defined by the upper surface of the substrate. At the bottom of the drilled bore hole, communication may preferably be provided into the inner chamber, and at a distance from the bottom of the drilled bore hole, communication could be provided to the outer chamber. The inner and the outer chambers could be provided as grooves in the upper surface which grooves are sealed by the cover.
In one embodiment, the receiving cavity forms an obstruction which limits the insertable length of the hose in the receiving cavity. The obstruction could be any kind of protrusion on the inner surface of the receiving cavity, or the receiving cavity may at a certain point be confined to prevent the hose from entering.
In a second aspect, the invention provides a method of connecting a multi lumen hose in a substrate. The method comprising: providing a substrate with an essentially plane upper surface. Providing an essentially plane cover, locating the hose in a receiving cavity which is in contact with grooves provided in the upper surface, and closing the grooves by attaching the cover to the upper surface. The method may further comprise any step related to the provision of a device according to the first aspect of the invention.
In the following, the invention will be described in further details with reference to the drawing in which:
The arrows 39, 40 indicate a flow direction into the outer chamber and second conduits and out of the first conduit and inner chamber.
While the present invention has been illustrated and described with respect to a particular embodiment thereof, it should be appreciated by those of ordinary skill in the art that various modifications to this invention may be made without departing from the spirit and scope of the present invention.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/DK07/00044 | 1/30/2007 | WO | 00 | 4/29/2010 |
