A CARTRIDGE FOR CONTAMINATION-FREE DISPENSING AND DELIVERY SYSTEMS

Abstract: The invention relates primarily to a process for making a cartridge for dispensing flowable material such as liquids, solutions, dispersions, suspensions, gels and pastes, while maintaining the sterility and integrity of the flowable material. The process includes molding a housing (12) of a rigid and inert material, the housing having an outlet port (58). Further, a delivery block (30) is molded with at least two asymmetrical components to give a parting line on the delivery block and an internal channel (34, 40, 42) connecting an inlet (32) and outlets (36, 38). The next step in the process is the molding of an elastomeric sheath (44), the sheath having two asymmetrical components to give a parting line on the sheath. The sheath is placed over the delivery block to envelope the delivery block and to cover the outlet of the delivery block and then the sheath covered delivery block is placed in the housing so that in use an outlet valve (56) of the sheath directs the flowable material through the housing outlet port (58). The sheath and the delivery block have contact surfaces in contact with each other but the parting lines of both the delivery block and the sheath are on non-contact surfaces so that the parting lines are away from any smooth and sealing surfaces to ensure that in use the flowable material is not contaminated.

Description: A CARTRIDGE FOR CONTAMINATION- FREE DISPENSING AND DELIVERY SYSTEMS BACKGROUND OF THE INVENTION Field of Invention The field of the invention relates generally to devices for conrrolling the flow of flowable materials such as liquids, solutions, dispersions, suspensions, gels, pastes and other fluids. More particularly, the field of the invention relates to a dispensing system for delivering multiple doses of flowable materials and for preventing the influx of external contaminants during and between deliveries, thereby maintaining the sterility and integrity of the flowable material and extending the useful life of the material to be substantially equivalent to its shelf life. 2. Description of the Related Art The dispensing of flowable materials in a contarnination-free manner, especially over prolonged periods of time or in a repetitive manner such as delivery of multiple doses, presents many difficulties. The main problems relate to precise flow control and prevention of back flow or reflux. In fact, external contaminants easily can enter a container with the back flow at the end of the delivery cycle. Most collapsible or volumetrically reducible containers for flowable materials have a discharge port such as a hole, nozzle, spout or other type of opening. The contents, such as pastes, liquids or other fluids exit through the discharge port propelled by internal pressure. This method of dispensing the flowable material is frequently inaccurate and does not prevent the entry of external contaminants into the container. Hence, additional pouring or dispensing devices are surmounted on the discharge port when precise control of the dispensing characteristics is desired. These devices must be simple, effective and low-cost, especially if intended for widespread commercial and domestic use. Typically, a dispensing apparatus has a valve mechanism to ensure precise delivery. In U.S. Patent No. 5,033,655. Brown teaches how to dispense fluid products from a non-collapsible container by employing a system with a slit valve. The system admits air to prevent the collapse of the container as fluid is delivered to the user. Thus, external contaminants borne by air are forced into the solution remaining in the container. Clearly, such a dispensing apparatus is not suitable for contamination-free dispensing from collapsible containers. A simple solution in the form of a squeeze valve with augmented sealing is presented by Vorhis in U.S. Patent No. 5,265.847. This apparatus is adapted for containers whose contents are expelled under the force of gravity. In U.S. Patent No. 5,099,885, Nilsson discloses a flapper valve, which delivers viscous fluids by means of a pump. This solution is not applicable to all types of liquids and fluids. Likewise, in U.S. Patent No. 5,346,108, Pasinski discloses a gauged dispensing apparatus to deliver a predetermined amount of generally viscous fluid. The apparatus has a flexure with a bi-stable orientation, concave to convex. Airborne contaminants can enter the apparatus as the flexure returns to its original position. In addition to the shortcomings already discussed, the above conventional solutions to the problem of preventing airborne contaminants from entering a flowable medium are not specifically designed to prevent back flow. Haviv teaches in his U.S. Patent No. 5,080,138 a valve assembly relying on a sleeve valve and comprising of multiple components. Back flow is thwarted by a sheath which permits the flowable material to flow out of the valve but prevents any back flow into the container. Unfortunately, this device is complicated, costly to manufacture and difficult to assemble. A simple discharge nozzle is presented by Latham in U.S. Patent No. 5,398,853. The nozzle is adapted for the delivery of pastes such as toothpaste. Although Latham does attempt to eliminate the transfer of germs between the discharge opening and the secondary surface where the paste is applied, his nozzle will not arrest the influx of bacteria. For example, bacteria can enter when the nozzle is immersed in a solution. More effective methods of contamination- free dispensing are disclosed in U.S. Patent Nos. 5,305.786 and 5.092.855 issued to Debush and Pardes. respectively. Debush discloses a modification to the applicant's prior U.S. Reissue No. 34,243 relying on an expandable elastomeric sleeve tightly fitted about a valve body with entry and exit ports. Debush's improvement is aimed at simplifying the assembly. Unfortunately, his solution requires more material to manufacture the valve. In addition, it is difficult to produce a discoid-shaped valve for this invention and adapt the apparatus to collapsible containers. Pardes discloses a rigid enclosing sleeve to retain the elastomeric sheath against the valve body, thus providing a seal between the sheath and the valve body. This is closely related to the applicant's teaching in U.S. Reissue No. 34,243. Pardes' valve operates through two sets of ports within a valve body, thus rendering the device unnecessarily complex. None of the these conventional dispensing devices is low-cost, simple in construction and capable of delivering a flowable material, ranging from low to high viscosity. Furthermore, these conventional devices can not be easily adapted to collapsible containers which do not produce an internal vacuum when their contents are expelled. Such conventional dispensing devices also cannot maintain a sterile condition, once the apparatus is used or opened to. the atmosphere. Nor do such conventional methods provide proof of the ability to maintain sterility or integrity of a flowable material during multiple uses. Thus, it is desirable to provide a contamination-free multiple dose dispensing cartridge for dispensing a flowable material from a collapsible container. Further, it is desirable to provide a dispensing cartridge which prevents the back flow or reflux of the flowable material, thereby preventing external contaminants from entering the container through the dispensing cartridge during and after delivery of the flowable material. It is also desirable to provide a dispensing system having a contamination-free cartridge that is simple in construction and easy to mount on various types of collapsible containers. It also would be desirable to provide experimental validation of a system's effectiveness for maώtaiaing the sterility and integrity of a flowable material. SUMMARY OF THE INVENTION The present invention provides a multiple-dose dispensing cartridge for dispensing a flowable material from a collapsible container, i.e., a container which does not produce an internal vacuum as the flowable material is dispensed. The multiple-dose dispensing cartridge prevents external contaminants from entering the container during and between deliveries. In particular, the cartridge has a housing and an attaching mechanism for attaching the housing to a delivery port of the container in an airtight manner. A delivery block located inside the housing has an input port for receiving the flowable material exiting the container through the delivery port. An internal channel commencing at the input port and terminating in at least one output port runs through the delivery block. An elastomeric sheath envelops the delivery block such that a portion of the sheath covers the output port or ports to form one or more sleeve valves which permit only the outflow of the flowable material from the output port or ports. In a preferred embodiment, the cartridge has an outlet valve formed by an end of the elastomeric sheath downstream of the one or more sleeve valves. The outlet valve also permits only the outflow of the flowable material. Typically, the outlet valve formed by the end of the sheath is a duck bill valve, a slit valve or a flapper valve. In another embodiment the outlet is formed by the end of the elastomeric sheath without creating a valve. The cartridge of the present invention further comprises a dispensing port defined by the housing for dispensing the flowable material exiting from the outlet valve or outlet created by the elastomeric sheath. The cartridge of the present invention can be mounted on collapsible containers such as tubes, bags, infusion containers, syringes, pouches, collapsible reservoirs, bellows-type containers and the like. The attachment mechanism will depend on the type of container and may generally be constituted by an adhesive seal, a screw-on neck, a press-fit neck, a bonding seal, a heat seal, an ultrasonic weld, or other joining material or element. The housing is preferably made of a moldable material and is rigid. This is necessary to aπest the expansion of the elastomeric sheath and prevent abrasion of the sheath as the flowable material is being dispensed. The elastomeric sheath is preferably made of a moldable thermoplastic elastomer. Exemplary materials which can be utilized in making the sheath include styrene-butadiene styrene, silicone, urethane, kraton, rubber and the like. Furthermore, the sheath is affixed on the delivery block to prevent slip-off and ensure proper operation of the sleeve valve or valves. This can be accomplished with an O-ring and a corresponding groove formed in the delivery block or a protrusion in the sheath for fitting into an analogous groove in the delivery block. Alternatively, the sheath is pinched between the delivery block and the housing. In all cases, however, the inner diameter of the sheath in undistended state is smaller than the outer diameter of the delivery block such that the sheath will fit tightly around the delivery block. The preferred range of inneT diameters of the sheath is 0.5 to 0.8 times the outer diameter of the delivery block. Alternatively, the housing may be eliminated by modifying the fluid container and thereby reducing the cartridge to only two components: the delivery block and the elastomeric sheath. When provides, the housing serves to protect the elastomeric sheath from contract abrasion, to prevent rupture of the elastomeric sheath by preventing excessive expansion of the elastomeric sheath, and to compress the elastomeric sheath onto the delivery block to form a fluid- tight seal between the elastomeric sheath and the delivery block to prevent leakage or backflow of the flowable material from its path. Each of these functions of the housing can be achieved by modifying the inner surface of the neck of the container adjacent to the delivery port of the container. The inner surface of the reservoir neck, in the case of bottles and tubes, or inner surface of the fitment or fixture joined to the delivery port, in the case of a bag, pouch, syringe or piston, can be modified to provide the functions and features of the housing. Alternatively, separate adapters can be made for insertion into the delivery port of the container, allowing the attachment of the two-component cartridge thereto. By use of the adapter, one or only a few sizes of cartridges could fit most containers. The cartridge of the present invention is effective in preventing the entry of air and its constituents, oxygen, nitrogen, water vapor and other atmospheric gases as well as other air-borne contaminants including smoke, dust, pollen and microorganisms. Thus, the contents of the collapsible or volumetrically reducible container are protected from degradation due to these types of external contaminants. In a particularly advantageous embodiment of the present invention, the dispensing cartridge can be permanently bonded to the container by the manufacturer, for example, thermally, ultrasonicaily with adhesives or lasers, such that the container and cartridge constitute an integrated dispensing system. In addition, the present invention provides experimental validation of its ability to maintain the sterility and integrity of flowable product even when challenged by static and dynamic immersion in concentrated solutions of bacteria or virus. The system advantageously utilizes an optimal geometry of the delivering block as used at the elastomer sheath which provides a constant stress along the length of the delivery blank to thereby provide a seal effective against the backflow of any external contaminants, including air or microbes. The invention also includes a novel process for eliminating all discontinuities as nonconformities in component parts which otherwise could provide paths for the entry of microorganisms. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional perspective view of a dispensing cartridge according to the present invention. FIG. 2 is a cross-sectional view of the dispensing cartridge of FIG. 1 before delivery. FIG. 3 is a cross-sectional view of the dispensing cartridge of FIG. 1 during delivery. FIG. 4 is a perspective view of the tip portion of the cartridge of FIG. 1. FIG. 5 is a perspective view of a portion of the outlet valve. FIG. 6 is a perspective view of a delivery block for the cartridge of the present invention. FIG. 7 is a cross-sectional view of a dispensing cartridge according to the present invention mounted on a tube. FIG. 8 is a cross-sectional view of a dispensing cartridge according to the present invention mounted on a syringe. FIG. 9 is a cross-sectional view of a dispensing cartridge according to the present invention without an outlet valve. FIG. 10 is a cross-sectional view of another dispensing cartridge according to the present invention without an outlet valve. FIG. 11 is a cross-sectional view of yet another dispensing cartridge according to the present invention mounted on a bellows-type container. FIG. 12A is a cross-sectional view of another dispensing cartridge according to the present invention without an outlet valve. FIG. 12B is an exploded perspective view of the dispensing cartridge of FIG. 12A. FIG. 13 is a cross-sectional view of another dispensing cartridge according to the present invention. FIG. 14 is a cross-sectional view of another dispensing cartridge according to the present invention. FIG. 15A is a perspective view of the delivery block of the dispensing cartridge of FIG. 12A. FIG. 15B is a perspective view of the elastomeric sheath of the dispensing cartridge of FIG. 12 A. FIG. 15C is a perspective bottom view of the elastomeric sheath of the dispensing cartridge of FIG. 12A. FIG. 15D is a perspective view of the housing of the dispensing cartridge of FIG. 12A. FIG. 16A is a top view of the delivery block of the dispensing cartridge of FIG. 12A. FIG. 16B is a top view of the elastomeric sheath of the dispensing cartridge of FIG. 12A. FIG. 16C is a bottom view of the housing of the dispensing cartridge of FIG. 12A. FIG. 17A shows a modified atmosphere packaging system for removing the original atmosphere of the container. FIG. 17B shows a modified atmosphere packaging system for filling a container with a controlled atmosphere. FIG. 17C shows a modified atmosphere packaging system in which a filled container contains a controlled atmosphere. DETAILED DESCRIPTION A preferred embodiment of a dispensing cartridge 10 is shown in FIG. 1. The dispensing cartridge 10 comprises a housing 12 made of a moldable material which is rigid and inert. The dispensing cartridge 10 is shown to be mounted on a collapsible container 14 of which only the top portion is shown. Although the cartridge 10 is shown to be much larger than a neck 16 of the container 14, it may be desirable to reduce the dimensions of cartridge 10 considerably, such that the container 14 constitutes a small extension of neck 16 or protrudes into or be embedded in neck 16. In the embodiment shown, neck 16 has a neck threading 18 which cooperates with cartridge threading 20 on a lower portion of housing 12. Thus, cartridge 10 is mounted on container 14 in an air-tight mariner by screwing housing 12 onto neck 16. A flowable material 22 is stored in container 14. Typically, material 22 is a liquid or fluid which requires careful dispensing and protection from external contaminants 26. These contaminants 26 can be broken down into paπiculates or other matter 28 such as air and its constituents such as oxygen, nitrogen, water vapor and other atmospheric gases, as well as airborne contaminants including smoke, dust, pollen and microorganisms. Airborne microorganisms may include yeasts, molds, bacteria, protozoa and diverse viruses. Many flowable products. such as medicines, chemicals, health-care materials, personal hygiene materials, edibles and other flowable goods, require protection from at least one of the above-listed contaminants 26. These products are encountered in domestic, commercial and industrial settings. Neck 16 terminates in an opening or delivery port 24. Flowable material 22 exits container 14 through port 24 to enter dispensing cartridge 10. Cartridge 10 includes a delivery block 30 whose lower portion defines an input port 32 for receiving material 22. Delivery port 24 is pressed firmly and tightly against the bottom of delivery block 30 when cartridge 10 is mounted on container 14 to allow flowable material 22 to be directly introduced from the delivery port 24 into input port 32. Delivery block 30 has an internal channel 34 which commences at input port 32 and splits into two branches 40 and 42, each branch terminating in an output port 36 and 38, respectively. In this embodiment output ports 36 and 38 are arranged on diametrically opposite faces of delivery block 30. This geometrical placement of ports 36 and 38 is preferred because it is easily manufactured and ensures their largest circumferential separation between the ports 36 and 38. Elastomeric sheath 44 stretches over or envelops delivery block 30. Preferably, the material of elastomeric sheath 44 is a moldable thermoplastic elastomer. Although a person with average skill in the art will be able to find other suitable elastics, the most preferred ones include styrene-butadiene styrene. silicone, urethane. kraton and rubber. To ensure that sheath 44 fits tightly around delivery block 30, it is important that in the undistended state the inner diameter of sheath 44 be smaller than the outer diameters of block 30. This ensure that when sheath 44 is placed over delivery block 30, it will stretch to tightly envelop delivery block 30. Preferably, the inner diameter of sheath 44 in the undistended state is between approximately 0.5 to 0.8 times the outer diameter of delivery block 30. The taut fit around block 30 achieved by the diameter differential ensures good operation of sleeve valves 46 and 48 described below. Another provision for securing sheath 44 in place over delivery block 30 includes an inward bulge or protrusion 50 extending circumferentially around delivery block 30. Correspondingly, delivery block 30 has a groove 52 for receiving protrusion 50. Sheath 44 is securely fixed when protrusion 50 is lodged or seated in groove 52 along the circumference of delivery block 30. In essence, protrusion 50 serves to attach or affix sheath 44 to delivery block 30 at a location below output ports 36 and 38. Alternatively, sheath 44 can be attached to delivery block 30 by ultrasonic welding or a thermal heat seal. When properly mounted, sheath 44 extends over the sides of delivery block 30 to cover both output ports 36 and 38 to form two sleeve valves 46 and 48 at the interface between the sheath 44 and ports 36 and 38, respectively. The sleeve valves 46 and 48 are one-way valves and operate when forced open by pressure at ports 36 and 38. Downstream of sleeve valves 46 and 48 and generally above delivery block 30, sheath 44 constricts and terminates at an end 54. At end 54, the elastic material of sheath 44 preferably narrows down to a thin neck, which is normally closed as the elastic material adheres to itself. As shown in FIG. 1, end 54 of sheath 44 forms an outlet valve 56. The outlet valve 56 may be, for example, a duck bill valve, a slit valve or a flapper valve. A person with average skill in the art will appreciate that the exact geometry and parameters of outlet valve 56 can vary depending on the way the material of sheath 44 comes together. Outlet valve 56 is a one-way, normally closed valve to permit only the outflow of flowable material 22 when pressure causes the adhering walls at end 54 to open outlet valve 56. Housing 12 has a dispensing port 58 in the form of a circular opening at the point of exit of outlet valve 56. Depending on the application, dispensing port may surround outlet valve 56 and protect end 54 of sheath 44 from contact with external objects. Alternatively, end 54 may protrude beyond the wails of dispensing port 58. particularly if periodic cleaning of outlet valve 56 is desired. The general shape of housing 12 preferably conforms to the shape of sheath 44 when delivering flowable material 22. Thus, the housing 12. in addition to general protection of the elements of cartridge 10 from the external environmental hazards, also serves to arrest the expansion of sheath 44. Such function of the housing 12 prevents sheath 44 from rupturing and ensures proper flow delivery characteristics of flowable material 22. The inner diameter of housing 12 is preferably selected to be greater than the outer diameter of delivery block 30 by an amount depending on the desired rate of delivery of flowable material 22 from outlet valve 56, the viscosity of flowable material 22 and the elasticity and rupture point of sheath 44. Adequate doses of flowable material 22 are possible with expansion in the diameter of sheath 44 of as little as 500 μm. The inner diameter of housing 12 relative to the outer diameter of delivery block 30 may be chosen depending upon the specific application. The internal surfaces of the housing 12 are preferably smooth to protect sheath 44 from abrasion when flowable material 22 is being delivered. The operation of dispensing cartridge 10 is best explained with reference to FIGS. 2 and 3. In FIG. 2. the cartridge 10 is disabled although flowable material 22 is present in internal channel 34 and branches 40 and 42. As indicated by arrow A, flowable material 22 has passed through neck 16 and delivery port 24 into internal channel 34 through input port 32. Sleeve valves 46 and 48 at ports 36 and 38 are closed as sheath 44 tightly envelops delivery block 30. The magnified view of sleeve valve 46 illustrates flowable material 22 wetting sheath 44. Due to insufficient pressure, flowable material 22 is unable to open sleeve valve 46 or 48. Meanwhile, outlet valve 56 remains closed and there is no flowable material 22 downstream of outlet valve 56. To activate cartridge 10. as shown in FIG. 3. pressure is exerted either on container 14 or on flowable material 22. Pressure may be exerted on the container 14 by compressing container 14 by manual or mechanical methods such as with a peristaltic pump. Pressure may be exerted on the flowable material 22 by pumping or other internal method of pressure deliver.'. Both sleeve valves 46 and 48 are forced open by the pressure exerted by the flowable material 22. Sheath 44 expands as flowable material 22 fills the space downstream of sleeve valves 46 and 48. Simultaneously, housing 12 prevents excessive expansion of sheath 44 and its rupture or abrasion. As the flowable material travels toward end 54 of the sheath 44, the pressure of flowable material 22 trapped under sheath 44 operates to opens outlet valve 56. Thus, flowable material 22 is dispensed through outlet valve 56 as indicated by arrow B. When the pressure of the flowable material 22 drops below a minimum threshold pressure necessary to keep sleeve valves 46 and 48 open, the flowable material 22 remaining between the housing 12 and the sheath 44 will be expelled through outlet valve 56. This occurs due to the pressure exerted by sheath 44 as it contracts back to snugly envelop delivery block 30. The arrangement of sleeve valves 46 and 48 with outlet valve 56 in tandem is clearly advantageous. There is no back flow of flowable material 22 through either sleeve valve 46 or 48. All flowable material 22 remaining under sheath 44 is expelled through outlet valve 56. Thus, there is no back flow through outlet valve 56 either. As a result, the operation of dispensing cartridge 10 is contamination-free. No particles 28 of external contaminants 26 can enter through outlet valve 56 and sleeve valves 46 or 48 to end up inside container 22. The operation of dispensing cartridge 10 is the same during subsequent cycles, since all flowable material 22 trapped downstream of sleeve valves 46 and 48 will always be expelled through outlet valve 56. Dispensing cartridge 10 is thus suitable for delivering multiple-doses. Depending on the application, dispensing cartridge 10 can be mounted on container 14 by the manufacturer or consumer. For example, when flowable material 22 is a paste, medicinal fluid or edible substance intended for the general consumer market, cartridge 10 can be conveniently factory-installed. Alternatively, the end user may decide when cartridge 10 is to be utilized to dispense a particular liquid or fluid. The construction of dispensing cartridge 10 ensures its operation with materials spanning a wide range of viscosities. Consequently, dispensing cartridge 10 is highly effective and universal. Its contamination-free operation renders it useful in preserving the purity of virtually any flowable material which is delivered from a container that does not produce an internal vacuum when its contents are expelled. The construction and materials required to produce dispensing cartridge 10 are low-cost and straightforward to assemble and the finished product can be easily mounted on or in any collapsible or reducible container. To mount the dispensing cartridge 10 in a container, the dispensing cartridge 10 can be modified for air-tight seating inside neck 16. The modifications required are straightforward and easily implemented by a person of average skill in the art. In the permanently mounted state, dispensing cartridge 10 and container 14 form a highly effective integrated dispensing system. Such system is of great value in dispensing flowable materials intended for domestic or commercial consumption. That is because the consumer call be offered a ready-to-use product for delivering multiple-doses in a contamination-free manner. The preferred embodiment of FIGS. 1-3 can be modified in several ways to render it more suitable for specific applications. For example. FIG. 4 shows the tip portion of housing 12 with an elevated or raised dispensing port 60. In this case, an outlet valve 62 formed by an end 64 of sheath 44 is completely protected by the high wall of dispensing port 60. This embodiment is more suitable for applications where outlet valve 62 should remain inaccessible from the exterior. FIG. 5 affords a more detailed view of an end 66 of a sheath 68 forming an outlet valve 70. In this embodiment, sheath 68 narrows down to a rectangular opening constituting a slit valve. Of course, different shapes of the opening created by end 66 will produce different valves with differing flow characteristics. Other valves, such as duck bill valves and flapper valves, can be formed by the end 66 of sheath 68. One of average skill in the art can utilize other types of valves as well as determine which particular valve type is best suited for the flowabie material to be delivered and the dispensing conditions. FIG. 6 illustrates a delivery, block 72 with numerous output ports 74. In this case, output ports 74 are located circumferentially. at equal spacings along a top portion 76 of delivery block 72. Below the top portion 76 is located a groove 78 for attaching an elastomeric sheath 44. Delivery block 72 has a lower portion 80 and a bottom protective layer 82 for improved contact with neck 16 oi container 14. An input port 84 at an end of an internal channel 86 is shown at the bottom of delivery block 72. Delivery block 72 is particularly well-suited for higher throughput of flowable materials. FIG. 7 shows another embodiment of a dispensing cartridge 90 mounted on a neck 92 of a tube 94. This arrangement is designed to dispense a paste 96, e.g., toothpaste. It should be noted that the actual size of dispensing cartridge 90 for mounting on a toothpaste tube would be preferably much smaller. As in the preferred embodiment, dispensing cartridge 90 has a housing 98 inside which an elastomeric sheath 100 envelops a delivery block 102. In this embodiment, sheath 100 is fixed by pinching it in an air-tight manner between housing 98 and delivery block 102. The bottom of housing 98 has a press-fit neck 104 which fits inside neck 92 of tube 94. An additional adhesive seal 106, e.g.. an adhesive agent, can be provided around press-fit neck 104. Delivery block 102 has an internal channel 106 which commences at an input port 108 and splits into two branches 110 and 112. The two branches 110 and 112 terminate in output ports 114 and 116 to form two sleeve valves 118 and 120. respectively. An end 122 of sheath 100 forms an outlet valve 124. Housing 98 has a dispensing port 126 which protects outlet valve 124 from the external environment. FIG. 7 shows dispensing cartridge 90 in the delivery mode and the operation of dispensing cartridge 90 is analogous to that of the preferred embodiment described above. In the delivery mode, sleeve valves 118. 120 and outlet valve 124 are open and paste 96 is dispensed from dispensing port 126. The pressure supplied by the user squeezing tube 94 as shown forces open sleeve vaives 118 and 120 and ejects paste 96 from tube 94 through outlet vaive 124. The additional advantage of the embodiment shown in FIG. 7 resides in its simplicity. The pinching of sheath 100 to keep it in place around delivery block 106 is a low-cost solution. Furthermore, the press-lit established between neck 92 and press-fit neck 104 renders this embodiment suitable for pre-mounting of delivery cartridge 90 by the manufacturer. FIG. 8 shows cartridge 90 of FIG. 7 mounted on a syringe 130. The only difference between the previous embodiment is that cartridge 90 is attached to a neck 132 of syringe 130 by a bonding seal 134. The bonding seal 134 is preferably applied from a dispensing unit (not shown once cartridge 90 is placed into place on neck 132. The bonding seal 134 can be any adhesive agent or an epoxide. Alternatively or additionally, an ultrasonic weld joint or a heat seal may ¬ be utilized where the bonding material is melted around neck 132. A superior connection is achieved where neck 132 is itself made of a plastic or other material which can partially melt together with the bonding material. During operation, the pressure provided by a plunger 136 causes a flowable material 97 to be dispensed by cartridge 90 as described above. This embodiment is well-suited for delivering medicinal lluids in nousenoiα ana hospital settings. FIG. 9 illustrates yet another embodiment of the invention. FIG. 9 shows a housing 152 of dispensing cartridge 150 housing a delivery block 154 enveloped by an elastomeric sheath 156. As in the preferred embodiment, two sleeve valves 158 and 160 are formed at output ports 162 and 164 of delivery block 154. An end of sheath 156 in this embodiment produces an outlet 168. In distinction to the preferred embodiment, however, outlet 168 does not produce a valve. During operation, sleeve valves 158 and 160 operate similar to sleeve valves as described above and outlet 168 allows the flowable material to exit through a dispensing port 170. After dispensing the flowable material, sheath 156 constricts tightly around delivery block 154. Constriction of the sheath 156 prevents external contaminants 28 from entering the space downstream of sleeve valves 158 and 160 between sheath 156 and delivery block 154. The constriction also expels the remaining flowable from that space. Consequently, the operation of this embodiment is analogous to the preferred embodiment but does not require the additional outlet valve. FIG. 10 shows yet another embodiment of a dispensing cartridge 170 without an outlet valve. In this embodiment branches 174 and 176 of an internal channel 172 form a Y-shape in a delivery block 171. An elastomeric sheath 178 covers up output ports 180 and 182 to form sleeve valves 184 and 186, respectively. Sheath 178 has a groove 188 for seating a protrusion 189 of delivery block 171. This method of affixing sheath 178 on delivery block 171 is different from the other embodiments where the groove is found in the delivery block. FIG. 11 shows a dispensing cartridge 190 mounted on a bellows-type container 192. A housing 194 protects a delivery block 196 which is enveloped by an elastomeric sheath 198. A seat 200 is provided for mounting delivery block 196 inside housing 194 and for providing an air-tight seal against a neck 202 of container 192. Sheath 198 defines an O-ring 204 and delivery block 196 defines a corresponding groove 206 for seating O-ring 204. Attachment of sheath 198 using O-ring 204 is more secure than in the other embodiments described above. Therefore, dispensing cartridge 190 is especially well-suited for dispensing flowables under conditions which place a high stress on sheath 198. FIG. 12A shows another embodiment of a dispensing cartridge 220. Cartridge 220 generally provides contamination-free unidirectional dispensing from a container holding a flowable medium. The cartridge 220 further protects the flowable medium in the container from airborne contamination and against oxidation or degradation due to exposure to air as well as from contamination by fluid immersion. This can also allow the flowable medium to be reformulated without preservatives, cleaning agents, or bacterial killing agents. Cartridge 220 generally comprises a housing 230 and an elastomeric sheath 240 which envelopes a delivery block 250 inside housing 230. Cartridge 220 may either be integrally formed with the container or provided separately. The housing 230 provides protection to the elastomeric sheath 240 from puncture or rupture by over-expansion. The delivery block 250 has an internal channel 252 commencing at input port 253 and splits into branches 254 and 256. Branches 254 and 256 terminate at output ports 258 and 260. respectively. The elastomeric sheath 240 cover output ports 258 and 260 to form sleeve valves at output ports 258 and 260. When dispensing cartridge 220 is closed, as shown in FIG. 12A. the sleeve valves formed by the elastomeric sheath 240 at output ports 258 and 260 form a fluid- tight seal. Elastomeric sheath 240 is made of a material having elastic properties. The elastic or resilient nature of the elastomeric sheath 240 enables it to squeeze the delivery block 250, covering output ports 258 and 260 to form fluid-tight sleeve valves when the dispensing cartridge is intended to be closed. When flowable material is being dispensed, the flowable material opens the sleeve valves formed at output ports 258 and 260, exits through output ports 258 and 260, moves downstream through outlet 242 and exits a port 232 of housing 230. The sleeve valves at output ports 258 and 260 are opened by creating an internal pressure in the flowable material sufficient to overcome the elasticity or resiliency of the elastomeric sheath 240 and/or by displacing the sheath 240. allowing flowable material to exit due to. for example, hydrostatic pressure. Once the dispensing is terminated, however, the elastomeric sheath 240 quickly returns toward or to its undeformed state, squeezing the delivery block 250 and preventing any backflow. While the sheath 240 returns toward or to its undeformed or closed state, flowable material is forced downstream of the output ports due to residual flow. Thus, the direction of flowable material is essentially one-way or unidirectional flow. To provide even greater sealing force, elastomeric sheath 240 has a collar 244 which provides an increased resilience. The thickness of collar 244 can be optimally designed based on the amount of force required to prevent fluid from exiting output ports 258 and 260. Specifically, a thicker collar provides greater tension and is more suitable for applications requiring a higher cracking pressure, i.e.. the minimum pressure required to open the dispensing cartridge so that flowable material can exit. As discussed above, the elastomeric sheath 240 squeezes the delivery block 250. Hence, it is undesirable for the delivery block 250 to have any sharp protrusions which could puncture the sheath. Accordingly, the delivery block 250 has a concave tip 268 to ensure that any remnants from the injection molding process will not protrude into the elastomeric sheath 240. Elastomeric sheath 240 is held in place between housing 230 and the delivery block 250. Housing 230 defines a lip 236 which cooperates with a flange 264 of delivery block 250 to attach the delivery block 250 to the housing 230. Alternatively, other suitable attaching mechanisms may be used including, for example, ultrasonic welding, adhesives, press-fits, and heat seals to attach the delivery block 250 to the housing 230. The sheath 240 is further supported by a ridge 266 defined by the delivery block 250 which acts as a stop for sheath 240. The elastomeric sheath 240 defines a smooth O-ring 246 which is press- fitted between a hood 234 of housing 230 and the flange 264 of delivery block 250. The surface of the hood 234 contacting the O-ring 246 is preferably smooth to form a fluid-tight seal. This smoothness can be attained by highly polishing the mold in which housing 230 is formed, as will be described. Dispensing cartridge 220 can be integrally provided with a container or 5 can be attached thereto. Preferably, a neck 262 of delivery block 250 is tapped or threaded. Alternatively, neck 262 may be adapted to form a luer-type connection. Attaching dispensing cartridge 220 to the container may be further facilitated by a protrusion, such as a peg, defined by the delivery block 250 which fits into a hole defined by the housing 230. A peg and hole combination, or any other suitable 10 lock and key combination, prevents rotation of the housing 230 about the delivery block 250 when, for example, the dispensing cartridge 220 is tightened onto a container. FIG. 13 shows another embodiment of a dispensing cartridge 280 generally comprising a housing 282 and an elastomeric sheath 284. In this 1: embodiment, the dispensing cartridge 280 is generally the same as the dispensing cartridge 220 shown in FIG. 12A except that dispensing cartridge 280 is substantially cone-shaped. FIG. 13 further shows a perspective view of the elastomeric sheath 284 of the dispensing cartridge 280. The cone-shape of the dispensing cartridge 280 may enhance the dispensing cartridge by providing a 20 smoother contour of the surface of the cartridge with no sharp disjunctions and permitting a uniform strain on the elastomer sheath throughout the fluid expulsion cycle. FIG. 14 shows yet another embodiment of a dispensing cartridge 300 having an elastomeric sheath 302 enveloping a delivery block 306. The ?5 elastomeric sheath 302 is secured by tongue 304 press-fitted between a protrusion 308 defined by the delivery block 306 and a groove 312 defined by the housing 310. Thus, the cooperation of tongue 304, protrusion 308 and groove 312 secure the elastomeric sheath 302 in place as well as provide fluid-tight sealing. Manufacture and Assembly of Dispensing Cartridges While each part or component of any of the dispensing cartridges described above or any variations thereof may be manufactured by conventional machining techniques, injection molding is a preferred method. When manufactured by injection molding, the mold or cavity should comprise asymmetrical component parts which form a parting line away from any smooth or sealing surfaces. FIGS. 15A-15D and FIGS. 16A-16C illustrate certain features specific to the manufacturing of the dispensing cartridge of the present invention. For illustrative purposes only, the dispensing cartridge shown in FIGS. 15A-15D and FIGS. 16A-16C correspond to the embodiment of FIGS. 12A and 12B. However, it is to be understood that one of ordinary skill in the art can easily apply the general manufacturing and processing concepts and principles described herein to any of the other embodiments and/or to any other variations thereof. FIGS. 15A-15D show by cross-hatching the functional surfaces of the delivery block 250. the elastomeric sheath 240, and the housing 230. respectivelv. These functional surfaces should be free of ejector pin marks, witness lines, and tool marks. The fluid-tight seal between the elastomeric sheath 240 and the delivery block 250 may be enhanced by polishing the mold for at least a portion of these functional surfaces. For example, the functional surfaces include the contacting surfaces between the elastomeric sheath 240 and the delivery block 250. Polishing the functional and/or contacting surfaces makes them smooth and enhances sealing. At a minimum, an interior surface of the elastomeric sheath 240 and an exterior sealing surface of the delivery block 250 should be polished. Smoothness is important particularly near the sealing regions because any surface imperfections can act as sites for microbial adhesion or provide pathways for microbial migration. Eliminating surface imperfections prevents microbes from migrating along the interface between the elastomeric sheath 240 and the delivery block 250 and possibly to the source fluid supply. Thus, reduction in surface imperfections particularly near the sealing regions enhances sealing. Desirable smoothness can be attained by conventional finishing techniques including but not limited to lapping, polishing, grinding or honing. Each of these processes can attain roughness heights in the range of 1-30 microinches. To further ensure that the functional surfaces are free of ejector pin marks, witness lines and tool marks, any mold parting lines, flow lines, and ejector pin marks should be placed away from these functional surfaces. In particular, the mold parting lines indicated as PL for each of the delivery block 250. the elastomeric sheath 240, and the housing 230 are shown in FIGS. 15A-15D, respectively. The parting lines PL are disposed such that the mold components for each component of the dispensing cartridge are asymmetrical. Further, FIGS. 16A, 16B and 16C illustrate the preferred circular lay direction for the delivery block 250. the elastomeric sheath 240. and the housing 230. respectively. Each component of the dispensing cartridge can have extensive coring to ensure even shrinkage and minimal distortion during the injection molding cycle. Preferred and more preferred process parameters are shown in TABLE 1 and TABLE 2. respectively. TABLE 1 Preferred Process Parameters TABLE 2 More Preferred Process Parameters The mold for delivery block 250 is preferably gated at the concave tip to provide more symmetrical mold filling. Suitable materials include thermoplastic or thermosetting materials or moldable polymeric resins such as PMMA, ABS. PC. and GPPS. The elastomeric sheath is preferably made from a hermalplastic or thermalsetting elastomer having a Durometer Hardness in the range of 20 to 80 Shore A. more preferably approximately 48 Shore A. Processes for fabricating the dispensing cartridge can also comprise etching. The components may be formed directly using reactive ion or dry etching of silicon compounds. For example, the delivery block can be made on a silicon wafer wherein micro-channels and ports are created by plasma etching. A thin film of silicon nitride may be selectively deposited on the wafer, forming resilient membranes or flexible members. The membrane-forming film can further be deposited on sacrificial layers (such as aluminum or silicon dioxide) to form elaborate bridges and valve structures. Therefore, it is another aspect of the present invention to size the dispensing cartridge so that extremely small amounts of flowable material (less than a microliter) can be delivered without backflow or external contamination. Alternatively, chemical etching may be employed to create better molds. A wet chemical etching process can achieve more accurate dimensions than some conventional mold-making techniques. Therefore, many of the benefits of conventional injection molding can still be realized using chemical etching. Modified Atmospheric Packaging (MAP) With reference to FIGS. 17A-17C. the use of two dispensing cartridges of the present invention in a system for modified atmospheric packaging (MAP), the packaging of goods in a controlled atmosphere, will now be described. By utilizing MAP, the life of packaged goods can be lengthened by eliminating damage-causing elements often found in ordinary packaging. Even small amounts of moisture, such as an amount of water in air. can cause premature spoiling or rusting of live produce. Other examples of goods that may benefit from MAP include flowers and meats. FIG. 17A generally shows an embodiment of a MAP system. The MAP system generally comprises a controlled atmosphere source 570, a hermetically sealed package 500 enclosing sealed good 510, a vacuum unit 560. The MAP system further comprises a unidirectional entry valve 520 and a unidirectional exit valve 530. The entry valve 520 and exit valve 530 may be similar to the dispensing cartridges described above and may be integral with package 500. The controlled atmosphere source 570 communicates with the entry valve 520 via a first stopcock 550. Further, the vacuum unit 560 communicates with the exit valve 530 via a second stopcock 540. As shown in FIG. 17A, the original atmosphere in the package 500 is evacuated by closing the first stopcock 550, opening the second stopcock 540, and applying a vacuum with the vacuum unit 560 via exit valve 530. Because the exit valve 530 is intermediate the package 500 and the vacuum unit 560. the original atmosphere in the package 500 is removed from the package 500 without any backflow through the exit valve 530. In addition, the closed first stopcock 550 prevents any external contaminates from entering package 500 through entry vaive 520. Once the atmosphere is sufficiently evacuated from the package 500. the second stopcock 540 is closed. FIG. 17B illustrates the filling of the package 500 with suitable gases from the controlled atmosphere source 570 by having the first stopcock 550 open and second stopcock 540 closed. The gases from the controlled atmosphere source 570 are supplied to the package 500 via the open first stopcock 550 and unidirectional entry valve 520 until package 500 is filled to a desired level. Thus, the atmosphere of package 500 is controlled and the life of goods 510 contained package 500 can be enhanced. FIG. 17C shows the MAP system wherein the first stopcock 550 and the second stopcock 540 are closed and the controlled atmosphere contained in package 500 is retained by entry valve 520 and exit valve 530 for transport and storage of the goods 510 in package 500. It will be appreciated that the foregoing aspects of the invention provide a system for dispensing and delivering a wide range of flowable media including liquids, solutions, mixtures, suspensions, dispersions, lotions, creams, gels and salves. These flowable media can be either volatile or nonvolatile, aqueous or nonaqueous, inorganic or organic and/or any combinations thereof. With appropriate selection of materials for the component parts to be used in each specific application, the present invention has application as a dispensing and delivery system for fluids used in any industry. The dispensing and delivery system advantageously protects the flowable materials from the adverse effects of evaporation, oxidation, and hydrolysis and advantageously prohibits the entry into the flowable media within the dispensing and delivery system of (1) microorganisms such as protozoa, yeast, molds, bacteria, and viruses; (2) air and one or more of its constituent parts such as nitrogen, oxygen, carbon dioxide, and water; (3) dust, smokes, pollens and filamentous or other particulates; (4) air-borne or blood-borne pathogens such as. for example, HIV or Hepatitis-B viruses; and/or (5) the evaporation of the flowable material or of one or more of its constituents. Therefore, filters. antimicrobial preservatives, antioxidants and hygroscopic agents are not needed, thereby providing substantial benefits in increased purity of the material, increased ease of formulation, reduction in cost, and a reduction in damaging or harmful side reactions. The effectiveness of the system becomes most apparent from the instant that the system is opened and its first contents are dispensed throughout the period of its use in the marketplace. By continuously maintaining the purity of the flowable material during delivery, the system embodied by this invention enables the distribution of larger-sized containers, thereby permitting a reduction in cost per unit volume of the material and an economy of scale. Examples showing the effectiveness of the present invention against viral and bacterial challenges are illustrated in the following two examples. Example 1 The following example describes details for bacterial challenge testing of the delivery system of one embodiment of the present invention, specifically, Waterfall Company's MICROBARRIER™ Cartridge Model #WFIPlb SMC 97- 62A. The cartridge system design is intended to allow delivery of multiple doses of flowable materials and to prevent the influx of external contaminants during and between deliveries over prolonged periods of time. The microbiological evaluation was conducted by attaching the test cartridge to a 60 mL syringe filled with sterile growth media. To simulate use. a 1-3 mL aliquot of the sterile growth media was dispensed each day through the test cartridge. The tip of the cartridge was then contaminated by dipping it into a concentrated suspension of bacteria. The bacteria used in this study was Brevundimonas diminuta (formerly Pseudomonas diminuta) at a concentration of approximately 1 x 10 colony forming units per mL (CFU/mL). Each day, an aliquot of the fluid in the syringe was collected and assayed for the presence of the test organism. The smdy was designed to be conducted for at least 7 days, but was extended to a total of 21 days. The results were scored as '"positive " ' or "negative " , depending on whether the challenge organism was detected in the assay fluid or whether the media in the syringe became turbid. The smdy evaluated 30 cartridges. Procedure The test cartridges were sterilized by ethylene oxide gas prior to testing. Sterilization was performed according to the following parameters: Ethylene Oxide Sterilization Preconditioning: 30 minutes minimum. Temperature: 52°C ± 2°C. Relative Humidity: 55 ± 10% Gas Concentration: 600 mg/liter. Exposure Time: 4-5 hours. Degassing Time: 48 hours minimum @ 55°C ± 2°C. Approximately 100 mL of soybean casein digest broth (SCDB) was inoculated with B. diminuta and incubated with mild shaking at 37 ± 2°C for 24 ± 4 hours. The bacterial culture was diluted with nutrient broth containing 0.01% TWEEN® 80 to achieve a concentration of approximately 1 x 10 CFU/mL. The 1 x 10 8 surface tension of the nutrient broth with 0.01% Tween® 80 was 42 ± 2 dynes/cm. A new bacterial culture was made and titrated for each day of testing. This new culture was used to contaminate the tips of the cartridges. A sterile 60 mL syringe was aseptically filled with approximately 60 mL of nutrient broth with 0.01% Tween® 80 (NBT). Inside a HEPA filtered hood, 1 mL of the assay fluid was dispensed from the syringe into a sterile test tube. This initial sample was the time = 0 sample for that cartridge. After dispensing the 1 mL aliquot the syringe was aseptically attached to the sterile test cartridge. A 1-3 mL aliquot of the sterile nutrient broth was then dispensed from the syringe through the test cartridge. The procedure stated that 1 mL should be dispensed, however, it was difficult to control the amount of fluid dispensed to 1 mL. This represented a deviation to the test protocol. After dispensing, the tip of the cartridge was contaminated by immersing it about one-half inch into the culture suspension. Thirty units were tested. The entire unit (syringe and cartridge) was placed on a horizontal surface and allowed to incubate at room temperature (23 = 3°C) for 24 = 2 hours. Each day the sample collection, dispensing and contamination steps were repeated for each test unit. The testing was conducted for approximately 21 days unless the fluid in the syringe became turbid, at which point further testing for the sample was terminated. Three negative and three positive controls were included in testing program. The negative controls comprised of sterile test units (60 mL syringes and cartridges) which were prepared the same as the test units, however, the cartridges did not have exit ports. The positive controls comprised of sterile test units (60 mL syringes and cartridges) which were prepared the same as the test units, however, the cartridges had a slit in the elastomeric sheath, freely exposing entry and exit ports to challenging bacteria. The aliquot collected from the syringe was assayed qualitatively for growth by incubating the collected fluid for approximately 48 hours with shaking at 37 ± 2°C. A visual observation was conducted on the fluid after incubation. The occurrence of turbidity was scored as "positive" or "+". If no turbidity was observed the result was scored "negative ' ' or "0". Assay tubes which exhibited growth were streaked for isolation onto soybean casein digest agar (SCDA) to verify detection of the challenge organism. The SCDA plates were incubated for 24-72 hours at 37 + 2°C. Biochemical verification of B. Diminuta included a positive oxidase test and a negative Gram stain. Results No contamination was observed in any of the thirty test units during the first week of testing. The positive controls were positive and the negative controls were negative. No contamination was observed in any of the thirty test units during the second week. of testing. One sample (#18) was positive on day 16. so testing of this cartridge was discontinued. The growth in the tube responsible for the turbidity was tested and biochemically verified to be B. diminuta. No contamination was observed in any of the other twenty-nine test units during the third week of testing. The positive and negative controls remained the same for the third week. The MICROBARRIER™ Cartridge for Multidose Dispensing and Delivery Systems for Flowable Materials is designed to prevent the influx of external contaminants during and between deliveries. The potential for bacterial contamination is a concern for dispensing devices, especially for multi-use products which are used over prolonged periods of time. The selection of Brevundimonas diminuta as the challenge organism was based on its small size when grown under controlled conditions. When properly cultured, many Brevundimonas organisms will pass through 0.45 μm membrane filters. The small size of the organism represents a severe bacterial challenge to the test cartridges. The rapid motility of this flagellated challenge organism, as i well as its possession of a sensory apparatus that drives the organism to nutrients enhances the severity of the test challenge. B. diminuta is also the organism of choice for conducting membrane filter validation testing for pharmaceutical processes. The surface tension range for blood and body fluids is approximately 42- 60 dynes/cm. Therefore, in order to simulate the wetting characteristics of blood and body fluids the surface tension of the challenge suspension was adjusted to approximate the lower end of this surface tension range [42 ± 2 dynes/cm]. The selection of daily dispensing of the nutritive media represents a severe challenge. The daily contamination with a new culture and the 24 hours to permit growth through the mechanism is more severe than a test which involves only frequent dispensing steps. Summary The MICROBARRIER™ Cartridges, as described in the present invention, were challenged daily for 21 days with Brevundimonas diminuta, a small, motile bacterium. The challenge test procedure comprised of (1) dispensing of nutritive media through the cartridge. (2) contamination of the cartridge tips by immersing them into a concentrated bacterial suspension (10 8 CFU/mL), and (3) placing each cartridge and syringe on a horizontal surface for 24 hours incubation at 23 ± 2°C. The cartridges provided complete sterility for 14 days. Over a three week period, only one of 30 units allowed organisms to grow back. This corresponds to an 100% effective barrier for weeks one and two, and a 97% barrier effectiveness for week three. The unique design of the device makes comparison to other conventional microbial barriers difficult. However, the device of the present invention performed comparable or superior to that seen in the laboratory for 0.45 gm microporous membranes. Example 2 The following example describes details for viral challenge testing of the delivery system of one embodiment of the present invention, specifically, Waterfall Company's MICROBARRIER™ Cartridge Model #WFIPlb SMC 97- 62A. The cartridge system design is intended to allow delivery of multiple doses of flowable materials and prevent the influx of external contaminants during and between deliveries over prolonged periods of time. The microbiological evaluation was conducted by attaching the test cartridge to a 60 mL syringe filled with sterile growth media. To simulate use, a 1-3 mL aliquot of the sterile growth media was dispensed each day through the test cartridge. The tip of the cartridge was then contaminated by dipping it into a concentrated suspension of virus. The virus suspension comprised of the bacteriophage ΦX174 and was prepared at a concentration of approximately 1 x 10 8 plaque forming units per mL (PFU/mL). Each day, an aliquot of the fluid in the syringe was collected and assayed for the presence of the test organism. The study was designed to be conducted for at least 7 days, but was extended to a total of 21 days. The results were scored as "positive " or "negative " , depending on whether the challenge organism was detected in the assay fluid. The study evaluated 30 cartridges. Procedure The test cartridges were sterilized by ethylene oxide gas prior to testing. Sterilization was performed according to the following parameters: Ethylene Oxide Sterilization Preconditioning: 30 minutes minimum. Temperature: 52°C ± 2°C. Relative Humidity: 55 ± 10% Gas Concentration: 600 mg/liter. Exposure Time: 4-5 hours. Degassing Time: 48 hours minimum @ 55°C ± 2°C. The ΦXI74 bacteriophage was prepared by inoculating approximately 100 mL of nutrient broth with E. coli and incubating approximately 6-18 hours at 37 ± 2°C with rapid shaking at approximately 200-250 RPM. A 1/100 dilution of the culmre was prepared and incubated at 37 ± 2°C. The culture was allowed to grow to a density of =2-4 x 10 8 CFU/mL for about 4 hours. This cell density corresponds to an optical density of 0.3-0.6 at 640 nm. The bacterial culture was inoculated with 5-10 mL of the ΦX174 bacteriophage stock (ATCC #13706-B1). The ratio of bacteriophage to bacterial cells was 0.1 to 2.0. The suspension was incubated with rapid shaking for approximately 1 to 5 hours at 37 ± 2°C. Complete lysis of the host bacteria occurred when the broth cleared. The viral suspension was centrifuged at 10000 x G for 40 minutes. The supernatant was filtered through a sterile 0.22 μm filter to remove the host cell debris. The bacteriophage challenge suspension was then prepared by diluting the phage stock in sterile nutrient broth with 0.01% Tween® 80 to provide a challenge concentration of approximately 1 x 10 PFU/mL. The surface tension of the nutrient broth with 0.01% Tween® 80 was 42 = 2 dynes/cm. The titer of the culture was determined for each day of testing. A sterile 60 mL syringe was aseptically filled with -60 mL of nutrient broth with 0.01% Tween® 80 (NBT). Inside a HEPA filtered hood. 1 mL of the assay fluid was dispensed from the syringe into a sterile test tube. This initial sample was the time = 0 sample for that cartridge. After dispensing the 1 mL aliquot the syringe was aseptically attached to the sterile test cartridge. A 1-3 mL aliquot of the sterile nutrient broth was then dispensed from the syringe through the test cartridge. The original procedure stated that 1 mL should be dispensed. After dispensing, the tip of the cartridge was contaminated by immersing it about one-half inch into the culture suspension. Thirty units were tested. The entire unit (syringe and cartridge) was placed on a horizontal surface and allowed to incubate at room temperature (23 ± 3°C) for 24 ± 2 hours. Each day the sample collection, dispensing and contamination steps were repeated for each test unit. The testing was conducted for-21 days unless the plaque assay indicated consistent viral contamination, at which point further testing for the positive sample was terminated. Three negative and three positive controls were included in testing program. The negative controls comprised of sterile test units (60 mL syringe and cartridge) which were prepared the same as the test units, however, the cartridge units did not have exit ports. The positive controls comprised of sterile test units (60 mL syringe and cartridge) which were prepared the same as the test units, however, the cartridge units had a slit in the elastomeric sheath, freely exposing entry and exit ports to challenging viruses. The aliquot collected from the syringe during the sample collection step was assayed for the presence of ΦX174 by placing the 1 mL aliquot into 3 mL of molten (45 ± 2°C) top agar (TOP A). Approximately 2 drops of E. coli were added to the molten top agar which was then poured over the surface of a bottom agar plate and allowed to solidify. The plates were incubated at 37 = 2°C for 18-24 hours. Results were scored as "positive " or "negative", depending on whether the challenge organism was detected in the assay fluid. "Positive " indicates the presence of clear plaques and " negative " indicates that plaques due to ΦX174 were not seen. Results Assay results from the first week demonstrated negative results for the negative controls and positive results for the positive controls. In five of the test cartridges, six positive results were observed. These apparent breakthroughs contained only four plaque forming units or less per sample. No breakthroughs occurred on consecutive days for the same sample cartridge. Data from week two showed similar results for the test cartridges. Three cartridges and four assays demonstrated plaques. All test samples produced values of three PFU or less, probably representing "baseline" fluctuations. When assayed on day one, all three positive controls demonstrated plaques. The numbers of plaques were too large to count and tests on positive controls were discontinued. One of the negative controls demonstrated plaques in assays of samples taken on three successive days, though the values of these were low and fluctuated between one and five plaques. Data from week three only demonstrated one sample with a positive plaque assay and that contained only a single plaque. On days 17 and 18 samples were not assayed. Therefore, fewer actual analyses were performed in week three. However, the number of test cartridges with apparent breakthrough by virus was lower than in week two. All three of the negative controls demonstrated virus breakthrough. One of these, negative control #3, had apparent breakthrough as shown by higher levels of virus than were found in the test cartridges as well as the presence of viruses in successive days of sampling. Summarizing the results of the three weeks, plaques were observed in assays of eight of the cartridges on eleven separate occasions. Six of the cartridges showed a single positive assay; one cartridge had two positives and one cartridge had three positives. Six of the eleven positive assaying cartridges had only one plaque, one of the eleven positives had two plaques, three of the eleven positives had three plaques, and one had four plaques. It should be noted that the challenge organism. ΦX174, will not grow in the test systems and is nonmotile. Consequently, it can gain entry to the test aliquots in only two ways: through airborne contact during assay, i.e., via fluid aspiration whereby virai organisms are dispensed in the air and contact the assay plate and/or transferred across the cartridge by diffusion. However, the relatively low numbers of plaques observed in this smdy is probably due to cross- contamination with heavily contaminated syringes and devices. Table 3 summarizes the apparent viral breakthrough of eight test cartridges challenged by ΦX174 bacteriophage. In all cases the number of plaques observed are four or less. Since the observed assay levels are low and do not reoccur on successive days, it is thought that the low number of plaques assayed in the test samples are from environmental contamination. The test virus is very stable and survives drying well. The test samples were maintained in an open laboratory and handled daily. The observed level of contamination decreased as greater effort was expended to eliminate cross-contamination. During week three, only a single test cartridge exhibited viral breakthrough and the assay showed only a single plaque. In addition, no test samples demonstrated breakthroughs on consecutive days as would be expected if the virus had actually passed through the cartridge. TABLE3 APPARENT VIRAL BREAKTHROUGHS (1) Testing was conducted for 21 days. No plaques were observed on test days not listed nor davs left blank. Table 4 summarizes the apparent viral breakthrough of all three negative control cartridges. The exit ports of these cartridges were blocked with silicone sealant. Negative control #1 showed no breakthrough from the initiation of the challenge through day 10 as well as on days 14, 16. and 19 through 21. Negative control =?2 shows no breakthrough until days 20 and 21. On these days low assay values were observed similar to those found in the test cartridges. The last negative control. #3, assayed positively on days 19. 20. and 21. Although the number of plaques observed are considerably higher than were found in the other cartridges, they are several orders of magnitude lower than the assays of the three positive controls where breakthrough occurred on day 1. Furthermore, the assay values decreased successively over the three days. The level of detectable virus fell twenty two-fold over the three days. If virus was diffusing across the cartridge into the syringe reservoir, the number of plaques in the assay should remain constant or increase with time. TABLE 3 APPARENT VIRAL BREAKTHROUGHS (2) Testing was conducted for 21 days. No plaques were observed on test days not listed nor days left blank. Discussion The MICROBARRIER™ Cartridge for Multidose Dispensing and Delivery Systems for Flowable Materials is designed to prevent the influx of external contaminants during and between deliveries. The potential for viral contamination is a concern for dispensing devices, especially for multi-use products which are used over prolonged periods of time. The choice of a viral model to evaluate the effectiveness of the bloodbome pathogen barrier properties of cartridges is important. There are problems associated with utilizing the actual bloodbome pathogens as test organisms. HEV and HCV cannot be grown in the laboratory. HIV represents a significant safety' and liability consideration due to its high infectivity potential and requirements for extreme and expensive precautions. Therefore, a model for the bloodbome pathogens was researched. The ideal properties of a surrogate included small size, spherical or polyhedral [round] morphology, environmental stability, low or non-human infectivity, high assay sensitivity, rapid growth, and high titer. The ΦX174 bacteriophage was selected as the most appropriate surrogate for the bloodbome pathogens mentioned because it satisfies all of these criteria. The ΦX174 bacteriophage has no envelope and is 25-27 nm in size, similar to HCV, the smallest pathogen, has an icosahedral or nearly spherical morphology similar to all three viral pathogens mentioned, has excellent environmental stability, is non-infectious to humans, has a limit of detection which approaches a single virus particle, grows very rapidly where assay results can be read within as little as 12 hours, and can be cultivated to reach very high titers similar to HBV, the most concentrated pathogen mentioned. Animal virus surrogates are not used as they require specialized cell culture and enzyme assay techniques. In addition, the stability of most of the animal viruses is less than desirable and plating efficiency is low or unknown. Despite the variety of viral coats or surfaces, i.e.. lipophilic, hydrophilic, etc., they generally perform similarly in barrier or penetration tests. This is because viruses adopt the charge of the liquid in which they are suspended and are normally more affected by the liquid vehicle than by their own physical or chemical properties. The surface tension range for blood and body fluids is approximately 42- 60 dynes/cm. Therefore, in order to simulate the wetting characteristics of blood and body fluids the surface tension of the bacterial and viral challenge suspensions was adjusted to approximate the lower end of this surface tension range [42 ± 2 dynes/cm]. Summary Over the three week test period, 30 Waterfall MICROBARRIER™ test cartridges fitted to syringes were challenged daily with ΦX174 (=10 8 PFU/mL). The reservoir solutions in the syringe were tested for ΦX174 daily using a plaque assay procedure using E. coli. Eight of the 30 cartridges had one to four plaques on one or more days. This corresponds to an apparent barrier performance of 73%. However, none of the test samples assayed positive on successive days and none of the samples demonstrated more than four plaques in any assay. By comparison, the number of plaques in each of the three positive controls were too numerous to count (>300 PFU). It is thought that these eight positive test results are due to environmental contaminants representing a baseline error. As positives were noted and data analyzed, significant additional environmental controls were implemented. The number of plaque positive cartridges went from five in week one, two in week two, and one cartridge in week three. The week three test cartridge had only a single plaque. It is difficult to allow the passage of only a single virus particle through a cartridge. Conversely, it is relatively easy to aerosolize ΦX174 and have quite small numbers of viral particles contaminate the sampling process and generate small numbers of plaques. Moreover, the presence of virus in the reservoir solutions of the negative control cartridges, having silicone-plugged entry and exit ports, indicate the viral particles were airborne and did not breakthrough the cartridges. Therefore, it is thought that the test sample positives on assays resulted from environmental contamination and that Waterfall's MICROBARRIER™ cartridges were 100% effective barriers in preventing the entry of viral particles throughout the three week test period. By comparison, such barriers as surgical gloves and condoms may vary from lot to lot and range from less than 50% up to 100% barrier performance, when tested with the same virus over only 60 minutes. Applications Various flowable materials can benefit from the contamination-free delivery system of the present invention including ( 1 ■ Diood and blood products: (2) tissue and organ perfusion: (3) human and veterinary pharmaceutical preparations, both ethical and over-the-counter products, including eye ana iens care soiutions;(4) in vitro and in vivo diagnostic agents.! 5) bioiogicals. (6) personal care preparations including cosmetics and fragrances: toiletries products for the care and treatment of skin, hair and nails; shampoos; hair colorants: health and beauty care products: (7) hot or cold foods, beverages, nutritional supplements and vitamins; and (8) commercial, institutional, laboratory and industrial chemicals, including but not limited to chemical reagents, detergents. photographic solutions, adhesives, paints, varnishes, lubricants and fuels. Medicinal Devices for transporting medicinal fluids stand to benefit from the present invention. Catheters and syringes are examples of such devices. These devices are commonly used to transport aqueous solutions, blood, plasma, vaccines and other medicinal fluids into the human body. A well known danger associated with delivery of medicinal fluids is that the source can become contaminated and is subsequently delivered to the patient. Contaminating the source supply causes economic waste but more importantly, the contaminated fluid can be delivered to the patient. In the case of transporting blood, the harm is particularly acute because blood can be infected by life-threatening pathogens such as the HIV or Hepatitis-B viruses. By using the delivery cartridge of the present invention, however, the risk of contaminating the source can be dramatically reduced. In addition, the present invention provides an economic benefit because the source supply can be reused once opened, decreasing the amount of waste. The dispensing of higher viscosity medicinal materials also stands to benefit from the present invention. For example, transdermal analgesics used in the treatment of rheumatism can be delivered in the form of thick lotions or ointments. Once these materials are dispensed, they can become contaminated by external microbes and particles. Thus, there exists a need for an effective sealing mechanism for the dispensing of high viscosity medicinai materials. The dispensing system of the present invention meets this need and even urther, medicinal materials may be reformulated preservative-free since air and other airborne microbes are prevented from penetrating the fluid-tight seal. Eye & Lens Care Solutions The use of said dispensing and delivery system enables said flowable media to be reformulated free of preservatives or other protective additives facilitating the therapeutic effect of a human or veterinary pharmaceutical product. For example, it is well known that preservatives can have harmful side effects. Preservatives presently in use in eye and lens care solutions cause toxicity reactions and/or allergic reactions in eye tissues. Preservatives in prescription eye care products are known to adversely affect the post-surgery healing rate of eye tissues. The foregoing aspects of the present invention provide the advantages of a multi-dose system wherein a pharmaceutical agent can be delivered to an end-user without the need for chemical preservatives or other agents required to protect a substance from degradation due to the entry of air and air-bome contaminants. Industrial Commercial, Institutional & Laboratory Chemicals The foregoing advantages of the inventions are not limited to pharmaceuticals, but rather provide other benefits in the dispensing of industrial chemical fluids, photographic solutions, soaps and detergents, paints, varnishes, adhesives and the like substances as well. The present system advantageously maintains fluids free from contamination by air, airborne particulates such as dust, fibers, etc. and airborne microbes. Protective filters, antimicrobial preservatives, antioxidants and hygroscopic agents are not needed. Therefore, if handled properly, said dispensing and delivery system provides substantial benefits to a fluid by enabling increased purity, increased ease and efficiency of formulation and production, reduction in cost, and a reduction in harmful side reactions. Photographic Solutions The reformulation of photographic development agents without antioxidants. for exampie would provide substantial benefits in efficiency and in more cost effective formulations. The present system advantageously maintains photographic solutions free from contamination by airborne particulates such as dust, fibers, etc. as well making unnecessary the need for mechanical filters or to add antimicrobial preservatives, antioxidants and hygroscopic agents. Commercial and Institutional Soaps and Detergents Cleaners used in institutional and restaurant settings are known to be susceptible to the growth of yeasts and molds, even when preservatives are used. Naturally occurring mutations make some specimens resistant to the action of the preservative resulting in preservative-resistant strains. The foregoing advantages of the present system make the use of preservatives unnecessary providing the needed sanitation and freedom from contamination by microorganisms. Foods & Beverages Tomato catsup is an acidic medium and a poor nutrient for the growth of microbes. Therefore it is unnecessary to add preservatives. However, on contact with air tomato catsup oxidizes and turns black. The catsup also evaporates forming unsanitary encrustation around the lip of the container. Edible oils and wines are additional examples of the damaging effects of oxidation on foods and beverages. Oxygen in air causes the oils to turn rancid. The foregoing advantages of the system described herein provide the needed protection from evaporation and oxidation required by these foods and beverages. While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Further, each of the references cited herein are hereby incorporated by reference in their entireties. For example, there are many other equivalent methods of mounting the dispensing cartridge of the invention on collapsible containers. Adhesives. giues. e oxide-based pastes, ultrasonic welds, other mechanical means and any number of other well-known implements are all available for that purpose. The methods for attaching the elastomeric sheath and distribution of outlet ports on the delivery block also can be provided as desired. Accordingly, persons of ordinary skill in this field are to understand that all such equivalent structures are to be included within the scope of the following claims.

Claims: What is claimed is: 1. An asymmetrical mold comprising two components joined to form a separation plane such that a plane of symmetry of a product produced by said mold lies outside the separation plane of the mold, thereby eliminating defects such as parting lines from the surface of the product. 2. A process for making a cartridge for dispensing flowable material, comprising: forming a housing by injecting a first material into a housing mold, the housing having an outlet port; forming a delivery block by injecting a second material into a delivery block mold having at least two asymmetrical components to impart a parting line on the delivery block, the delivery block defining a channel between an inlet and an outlet: and forming a sheath by injecting a third material into a sheath mold having at least two asymmetrical components to impart a parting line on the sheath, the sheath being adapted to be placed over the delivery block such that the sheath covers " the outlet of the delivery block and the sheath and delivery block being placeable in the housing such that an outlet of the sheath directs the flowable material through the housing outlet port, the sheath and the delivery block being adapted to be placed in the housing, the sheath and the delivery block having contact surfaces in contact with each other, the parting lines of the sheath and the delivery block being on a non-contact surface. 3. The process for making a cartridge according to claim 2. further comprising finishing at least a surface of at least one of the housing, sheath and delivery block molds. 4. The process for making a cartridge according to claim 3, wherein the finishing process is selected from the group consisting of lapping, honing, grinding and polishing. > 5. The process for making a cartridge according to claim 3. wherein the finishing includes finishing the surfaces of the sheath and delivery block molds for forming the contacting surfaces of the sheath and delivery block. 6. The process for making a cartridge according to claim 3, wherein the finished surface has roughness height between 1 and 30 microinches. 7. The process for making a cartridge according to claim 3, wherein the finished mold surface has a substantially circular lay pattern. 8. The process for making a cartridge according to claim 2. wherein forming the delivery block comprises forming a concave tip approximately opposite the inlet. 9. The process for making a cartridge according to ciaim 8. wherein the delivery block mold is gated at the tip. 10. Tne process for making a caπridge according to claim 2. wherein the second material is selected from the group consisting of thermoplastic material. thermosetting material, PMMA, ABS. PC and GPPS. 1 1. The process for making a cartridge according to claim 2, wherein the third material is selected from the group consisting of styrene-butadiene styrene, silicone, urethane. kraton and rubber. 12. The process for making a cartridge according to claim 1 1, wherein the thermalplastic elastomer has a Durometer Hardness in the range of 20 to 80 Shore A. 13. The process for making a cartridge according to claim 12, wherein the thermalplastic elastomer has a Durometer Hardness of approximately 48 Shore A. 14. The process for making a cartridge according to claim 2, wherein the housing mold has at least two asymmetrical components to impart a parting line on the housing, the housing and the sheath having contact surface in contact with each other, the housing parting line being on a non-contact surface. 15. The process for making a cartridge according to claim 2, wherein forming the delivery block includes injection molding for an overall cycle time of 20 to 40 seconds, at a peak mold pressure of 15 to 25 kpsi and at a mold temperature of 110 to 200°F. 16. The process for making a cartridge according to claim 15. wherein forming trie delivery block includes injection molding for an overall cycle time of 28 to 32 seconds, at a peak mold pressure of 21 to 22 kpsi and at a mold -.emperature of 115 to 180°F. 17. The process for making a cartridge according to claim 2. wherein forming the sheath includes injection molding for an overall cycle time of 10 to 40 seconds, at a peak mold pressure of 10 to 20 kpsi and at a mold temperature of 50 to l50°F. 18. The process for making a cartridge according to claim 17, wherein forming the sheath includes injection molding for an overall cycle time of 13 to 15 seconds and at a peak mold pressure of 15 to 18 kpsi. 19. The process for making a cartridge according to claim 2, wherein forming the housing includes injection molding for an overall cycle time of 5 to 15 seconds, at a peak mold pressure of 10 to 20 kpsi and at a mold temperamre of 80 to 120°F. 20. The process for making a cartridge according to claim 19, wherein forming the housing includes injection molding for an overall cycle time of 10 to 12 seconds, at a peak mold pressure of 12 to 18 kpsi and at a mold temperature of 100 to 110°F. 21. The process for making a cartridge according to claim 19. wherein at least a portion of at least one of the housing, sheath and delivery block molds is formed bv etching. 22. The process for making a cartridge according to claim 21. wherein the etching is performing on silicon compounds. 23. The process for making a cartridge according to claim 2. further comprising placing the sheath over the delivery block such that the sheath covers the outlet of the delivery block to form a valve; and placing the sheath and delivery block in the housing such that the outlet of the sheath directs the flowable material through the housing outlet port. 24. The process for making a cartridge according to claim 23, wherein forming the sheath includes forming a region of increased thickness for maximized elastic force to seal the valve at the outlet of the delivery block. 25. The process for making a cartridge according to claim 23, wherein forming the housing includes forming a lip and forming the delivery block includes forming a circumferentially extending flange adapted to cooperate and interlock with the lip of the housing. 26. A modified atmosphere packaging system for packaging goods, comprising: a container for holding the goods; a unidirectional exit valve in fluid communication with the container; and a unidirectional entry valve in fluid communication with the container; a controlled atmosphere source in fluid communication with the entry valve: and a vacuum device in fluid communication with the exit valve. 27. The modified atmosphere packaging system according to claim 26. wherein the controlled atmosphere comprises a gas selected from the group consisting of nitrogen, oxvsen. carbon dioxide, hvdrosen and water vaϋor. 28. The modified atmosphere packaging system according to claim 26. further comprising a first stopcock in fluid communication with the entry valve and the controlled atmosphere source and a second stopcock in fluid communication with the exit valve and the vacuum device. 29. A process for modified atmosphere packaging for packaging good in container, comprising: removing atmosphere in the container by supplying a vacuum to the container via the one-way exit valve in fluid communication with the container: and supplying a controlled atmosphere to the container through a oneway entry valve in fluid communication with the container. 30. The process for modified atmosphere packaging as recited in claim 29, further comprising: closing a first stopcock in fluid communication with the entry valve and opening a second stopcock in fluid communication with the exit valve prior to removing the atmosphere in the container; and opening the first stopcock and closing the second stopcock after removing the atmosphere in the container and prior to supplying the controlled atmosphere.

Inventors: GERBER BERNARD R, GERBER, BERNARD, R.
Applicants: WATERFALL COMPANY, THE WATERFALL COMPANY
Application year: 1999
Main classification: B29C45
IPC codes: B05B11, B29C33, B29C45, B29L31, B65B31, B65D25, B65D35, B65D47, B65D83, F16K15