Patent Document

BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    Embodiments are directed to microfluidic delivery systems that utilize refillable cartridges and methods of making and using the same. 
         [0003]    2. Description of the Related Art 
         [0004]    It is often desired to provide scent dispersal systems in a home, particularly in a workroom or bathroom to improve the air quality and comfort of people in the home. Scent dispersal systems provide a scented fluid into the air for scenting an environment. Scent dispersal systems usually do not provide adequate control of the scented fluid being dispersed. Typically, scent dispersal systems disperse scented fluid by evaporation. As the scented fluid evaporates into the air, the scent disperses in the environment. These systems, however, do not provide consistent quality of the scented fluid over a period of time. For instance, the scented fluid often changes in consistency if allowed to evaporate for thirty days or more. Additionally, a significant amount of the scented fluid is wasted due to the evaporation. Although some systems may include a hot plate to control the rate of evaporation, these systems still use evaporation for dispersing the sent, thereby limiting the quality of systems. 
       BRIEF SUMMARY 
       [0005]    One or more embodiments are directed to a microfluidic delivery system that dispenses a fluid in a direction that, at least in part, opposes gravity. In one embodiment, the microfluidic delivery system includes a microfluidic refill cartridge that is configured to be placed in a housing. The microfluidic refill cartridge includes at least one nozzle that faces upward or off to a side. The microfluidic refill cartridge includes a fluid transport member that allows fluid to travel upward from a fluid reservoir in opposition to gravity. A fluid path is located above the fluid transport member placing an end of the fluid transport member in fluid communication with a chamber and a nozzle. In response to the microfluidic delivery system receiving an electrical signal, an ejection element, such as a heating element, piezoelectric element, or ultrasonic ejection element, is configured to cause fluid to be expelled through the nozzle. In response to the fluid being expelled from the nozzle, fluid may be pulled up through the fluid transport member and through the fluid path to refill the chamber. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0006]    In the drawings, identical reference numbers identify similar elements. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. 
           [0007]      FIG. 1  is a schematic isometric view of a microfluidic delivery system in accordance with one embodiment. 
           [0008]      FIGS. 2A-2B  are schematic isometric views of a microfluidic refill cartridge and a holder in accordance with one embodiment. 
           [0009]      FIG. 3  is a cross-section schematic view of line  3 - 3  in  FIG. 2A . 
           [0010]      FIG. 4  is a cross-section schematic view of line  4 - 4  in  FIG. 2B . 
           [0011]      FIGS. 5A-5B  are schematic isometric views of a microfluidic delivery member in accordance with an embodiment. 
           [0012]      FIG. 5C  is an exploded view of the structure in  FIG. 5A . 
           [0013]      FIG. 6  is a schematic top view of a die in accordance with one embodiment. 
           [0014]      FIG. 7A  is a cross-section schematic view of line  7 - 7  in  FIG. 6 . 
           [0015]      FIG. 7B  is an enlarged view of a portion of  FIG. 7A . 
           [0016]      FIG. 8A  is a cross-section schematic view of line  8 - 8  in  FIG. 6 . 
           [0017]      FIG. 8B  is an enlarged view of a portion of  FIG. 8A . 
           [0018]      FIG. 9  is a schematic top view of the lid of the microfluidic refill cartridge without the microfluidic delivery member in accordance with one embodiment. 
           [0019]      FIG. 10  is a cross-section schematic view of a fluid path of a microfluidic refill cartridge in accordance with one embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]      FIG. 1  illustrates a microfluidic delivery system  10  in accordance with one embodiment of the disclosure. The microfluidic delivery system  10  includes a housing  12  having an upper surface  14 , a lower surface  16 , and a body portion  18  between the upper and lower surfaces. The upper surface of the housing  12  includes a first hole  20  that places an environment external to the housing  12  in fluid communication with an interior portion  22  of the housing  12 . The interior portion  22  of the housing  12  includes a holder member  24  that holds a removable microfluidic refill cartridge  26 . As will be explained below, the microfluidic delivery system  10  is configured to use thermal energy to deliver fluid from within the microfluidic refill cartridge  26  to an environment external to the housing  12 . 
         [0021]    Access to the interior portion  22  of the housing is provided by an opening  28  in the body portion  18  of the housing  12 . The opening  28  is accessible by a cover or door  30  of the housing  12 . In the illustrated embodiment, the door  30  rotates to provide access to the opening  28 . Although the opening and door are located on the body portion of the housing, it is to be appreciated that the opening and door may also be located on the upper surface and the lower surface of the housing. Furthermore, it is to be appreciated that in other embodiments, the housing has two or more separable parts for providing access to the interior portion. 
         [0022]    The holder member  24  includes an upper surface  32  and a lower surface  34  that are coupled together by one or more sidewalls  36  and has an open side  38  through which the microfluidic refill cartridge  26  can slide in and out. The upper surface  32  of the holder member includes an opening  40  that is aligned with the first hole  20  of the housing  12 . 
         [0023]    The holder member  24  holds the microfluidic refill cartridge  26  in position when located therein. In one embodiment, the holder member  24  elastically deforms, thereby gripping the microfluidic refill cartridge  26  in place when located in the holder member. In another embodiment, the holder member  24  includes a locking system (not shown) for holding the microfluidic refill cartridge in place. In one embodiment, the locking system includes a rotatable bar that extends across the open side of the holder member to hold the microfluidic refill cartridge in place. 
         [0024]    The housing  12  includes conductive elements (not shown) that couple electrical components throughout the system as is well known in the art. The housing  12  may further include connection elements for coupling to an external or internal power source. The connection elements may be a plug configured to be plugged into an electrical outlet or battery terminals. The housing  12  may include a power switch  42  on a front of the housing  12 . 
         [0025]      FIG. 2A  shows the microfluidic refill cartridge  26  in the holder member  24  without the housing  12 , and  FIG. 2B  shows the microfluidic refill cartridge  26  removed from the holder member  24 . A circuit board  44  is coupled to the upper surface  32  of the holder member by a screw  46 . As will be explained in more detail below, the circuit board  44  includes electrical contacts  48  ( FIG. 3 ) that electrically couple to contacts of the microfluidic refill cartridge  26  when the cartridge is placed in the holder member. The electrical contacts  48  of the circuit board  44  are in electrical communication with the conductive elements. 
         [0026]      FIG. 3  is a cross-section view of the microfluidic refill cartridge  26  in the holder member  24  along the line  3 - 3  shown in  FIG. 2A . With reference to  FIG. 2B  and  FIG. 3 , the microfluidic refill cartridge  26  includes a reservoir  50  for holding a fluid  52 . The reservoir  50  may be any shape, size, or material configured to hold any number of different types of fluid. The fluid held in the reservoir may be any liquid composition. In one embodiment, the fluid is an oil, such as a scented oil. In another embodiment, the fluid is water. It may also be alcohol, a perfume, a biological material, a polymer for 3-D printing, or other fluid. 
         [0027]    A lid  54 , having an inner surface  56  and an outer surface  58 , is secured to an upper portion  60  of the reservoir  50  to cover the reservoir  50 . The lid  54  may be secured to the reservoir in a variety of ways known in the art. In some embodiments, the lid  54  is releasably secured to the reservoir  50 . For instance, the lid  54  and the upper portion  60  of the reservoir  50  may have corresponding threads, or the lid  54  may snap onto the upper portion  60  of the reservoir  54 . Between the lid  54  and the reservoir  50  there may be an O-ring  62  for forming a seal therebetween. The seal may prevent fluid from flowing therethrough as well as prevent evaporation of the fluid to an external environment. 
         [0028]    A microfluidic delivery member  64  is secured to an upper surface  66  of the lid  54  of the microfluidic refill cartridge  26  as is best shown in  FIG. 2B . The microfluidic delivery member  64  includes an upper surface  68  and a lower surface  70  (see also  FIG. 4 ). A first end  72  of the upper surface  68  includes electrical contacts  74  for coupling with the electrical contacts  48  of the circuit board  44  when placed in the holder member  24 . As will be explained in more detail below, a second end  76  of the microfluidic delivery member  64  includes a fluid path for delivering fluid therethrough. 
         [0029]    In reference to  FIG. 3 , inside the reservoir  50  is a fluid transport member  80  that has a first end  82  in the fluid  52  in the reservoir and a second end  84  that is above the fluid  52 . The fluid  52  travels from the first end  82  of the fluid transport member  80  to the second end  84  by capillary action. In that regard, the fluid transport member  80  includes one or more porous materials that allow the fluid to flow by capillary action. The construction of the fluid transport member  80  permits fluid to travel through the fluid transport member  80  against gravity. Fluid can travel by wicking, diffusion, suction, siphon, vacuum, or other mechanism. The second end  84  of the transport member is located below the microfluidic delivery member  64 . The fluid transport member  80  delivers fluid  52  from the reservoir  50  toward the microfluidic delivery member  64 . 
         [0030]    As best shown in  FIG. 4 , the second end  84  of the fluid transport member  80  is surrounded by a transport cover  86  that extends from the inner surface of the lid  54 . The second end  84  of the fluid transport member  80  and the transport cover  86  form a chamber  88 . The chamber  88  may be substantially sealed between the transport cover  86  and the second end  84  of the fluid transport member  80  to prevent air from the reservoir  50  from entering the chamber  88 . 
         [0031]    Above the chamber  88  is a first through hole  90  in the lid  54  that fluidly couples the chamber  88  above the second end  84  of the fluid transport member  80  to a second through hole  78  of the microfluidic delivery member  64 . The microfluidic delivery member  64  is secured to the lid  54  above the first through hole  90  of the lid  54  and receives fluid therefrom. 
         [0032]    In some embodiments, the fluid transport member  80  includes a polymer; non-limiting examples include polyethylene (PE), including ultra-high molecular weight polyethylene (UHMW), polyethylene terephthalate (PET), polypropylene (PP), nylon 6 (N6), polyester fibers, ethyl vinyl acetate, polyvinylidene fluoride (PVDF), and polyethersulfone (PES), polytetrafluroethylene (PTFE). The fluid transport member  80  may be in the form of woven fibers or sintered beads. It is also to be appreciated that the fluid transport member of the present disclosure is of smaller size than is typically used for fluid transport members for refillable cartridges. 
         [0033]    As shown in  FIG. 4 , the fluid transport member  80  may include an outer sleeve  85  that surrounds radial surfaces of the fluid transport member  80  along at least a portion of its length while keeping the first and second ends  82 ,  84  of the fluid transport members  80  exposed. The sleeve  85  may be made from a non-porous material or a material that is less porous than the fluid transport member  80 . In that regard, the sleeve  85  may prevent or at least reduce air in the reservoir from entering the fluid transport member  80  by radial flow. 
         [0034]    The outer sleeve  85  may be a material that is wrapped around the fluid transport member  80 . In other embodiments, the material  85  is formed on the fluid transport member  80  in an initial liquid state that dries or sets on the fluid transport member. For instance, the material may be sprayed on the fluid transport member or the fluid transport member may be dipped into a liquid material that dries. The outer sleeve may be a polymer sheet, a Teflon tape, a thin plastic layer, or the like. Teflon tape has particular benefits since it provides a fluid-tight seal, is flexible to wrap, is strong, and also makes it easy to slip member  80  into place. 
         [0035]    The fluid transport member  80  may be any shape that is able to deliver fluid  52  from the reservoir  50  to the microfluidic delivery member  64 . Although the fluid transport member  80  of the illustrated embodiment has a width dimension, such as diameter, that is significantly smaller than the reservoir, it is to be appreciated that the diameter of the fluid transport member  80  may be larger and in one embodiment substantially fills the reservoir  50 . 
         [0036]      FIGS. 5A and 5B , respectively, are top and bottom views of the microfluidic delivery member  64  in accordance with one embodiment.  FIG. 5C  illustrates the microfluidic delivery member  64  in exploded view. The microfluidic delivery member  64  includes a rigid planar circuit board, which can be a printed circuit board (PCB)  106  having the upper and lower surfaces  68 ,  70 . The PCB  106  includes one or more layers of insulative and conductive materials as is well known in the art. In one embodiment, the circuit board includes FR4, a composite material composed of woven fiberglass cloth with an epoxy resin binder that is flame resistant. In other embodiments, the circuit board includes ceramic, glass or plastic. 
         [0037]    The upper surface  68  of the second end  76  of the printed circuit board  106  includes a semiconductor die  92  above the second through hole  78  and leads  112  located proximate the die  92 . Electrical contacts  74  at the first end  72  of the microfluidic delivery member  64  are coupled to one or more of the leads  112  at the second end  76  by electrical traces (not shown). 
         [0038]    The upper and lower surfaces  68 ,  70  of the PCB  106  may be covered with a solder mask  124  as shown in the cross-section view of  FIG. 4 . Openings in the solder mask  124  may be provided where the leads  112  are positioned on the circuit board or at the first end  72  where the electrical contacts  74  are formed. The solder mask  124  may be used as a protective layer to cover electrical traces. 
         [0039]    The die  92  is secured to the upper surface  68  of the printed circuit board  106  by any adhesive material  104  configured to hold the semiconductor die to the PCB. The adhesive material may be an adhesive material that does not readily dissolve by the fluid in the reservoir. In some embodiments, the adhesive material is activated by heat or UV. In some embodiments, a mechanical support (not shown) may be provided between a bottom surface  108  of the die  92  and the upper surface  68  of the printed circuit board  106 . 
         [0040]    As best shown in  FIG. 6 , the die  92  includes a plurality of bond pads  109  that are electrically coupled to one or more of the leads  112  by conductive wires  110 . That is, a first end of the conductive wires  110  is coupled to a respective bond pad  109  of the die  92  and a second end of the conductive wires  110  is coupled to a respective lead  112 . Thus, the bond pads  109  of the die  92  are in electrical communication with the electrical contacts  74  of the microfluidic delivery member  64 . A molding compound or encapsulation material  116  may be provided over the conductive wires  110 , bond pads  109 , and leads  112 , while leaving a central portion  114  of the die  92  exposed. 
         [0041]    As best shown in  FIG. 4 , the die  92  includes an inlet path  94  in fluid communication with the second through hole  78  on the second end  76  of the delivery member  64 . With reference also to  FIGS. 7 and 8 , which illustrate corresponding cross sections of the die of  FIG. 6 , the inlet path  94  of the die  92  is in fluid communication with a channel  126  that is in fluid communication with individual chambers  128  and nozzles  130 , forming a fluid path through the die  92 . Above the chambers  128  is a nozzle plate  132  that includes the plurality of nozzles  130 . In a first embodiment, each nozzle  130  is located above a respective one of the chambers  128  and is an opening in the nozzle plate  132  that is in fluid communication with an environment outside of the microfluidic refill cartridge  26 . The die  92  may have any number of chambers  128  and nozzles  130 , including one chamber and nozzle. In the illustrated embodiment, the die  92  includes 18 chambers  128  and 18 nozzles  130 , each chamber associated with a respective nozzle. Alternatively, it can have 10 nozzles and 2 chambers, one chamber providing fluid for a bank of five nozzles. It is not necessary to have a one-to-one correspondence between the chambers and nozzles. In one embodiment, the nozzle plate  132  is 12 microns thick. In some embodiments, In some embodiments, the nozzle  130  has a diameter between 20-30 microns. 
         [0042]    As is best shown in  FIG. 8B , proximate each chamber  128  is a heating element  134  that is electrically coupled to and activated by an electrical signal being provided by a bond pad of the die  92 . In use, when the fluid in each of the chambers  128  is heated by the heating element  134 , the fluid vaporizes to create a bubble. The expansion that creates the bubble causes a droplet to form and eject from the nozzle  130 . Other ejection elements may be used for causing fluid to be ejected from the nozzle  130 . For instance, piezoelectric elements or ultrasonic fluid ejection elements may be used to cause fluid to be ejected through the nozzles  130  as is well known in the art. Each nozzle  130  is in fluid communication with the fluid in the reservoir by a fluid path that includes the first end  82  of the fluid transport member  80 , through the transport member to the second end  84 , the chamber  88  above the second end  84  of the transport member, the first through hole  90  of the lid, the second through hole  78  of the PCB, through the inlet path  94  of the die, through the channel  126 , to the chamber  128 , and out of the nozzle  130  of the die  92 . 
         [0043]    In reference again to  FIG. 4 , a filter  96  may be positioned between the chamber  88  and inlet path  94  of the die  92 . The filter  96  is configured to prevent at least some particles from passing therethrough, thereby preventing and/or reducing blockage in the fluid path, most particularly in the nozzles  130  of the die  92 . In some embodiments, the filter  96  is configured to block particles that are greater than one third of the diameter of the nozzles. 
         [0044]    The filter  96  may be any material that blocks particles from flowing therethrough and does not break apart when exposed to the fluid, which could create further particles to block the fluid path. In one embodiment, the filter  96  is a stainless steel mesh. In other embodiments, the filter  96  is a randomly weaved mesh and may comprise polypropylene or silicon. 
         [0045]    Referring now to  FIG. 10 , there is provided a close up view of a portion of a microfluidic refill cartridge  26  illustrating a flow path with a filter  96  between the second end  84  of the fluid transport member  80  and the die  92  in accordance with one embodiment. 
         [0046]    The filter  96  is separated from the lower surface  70  of the microfluidic delivery member  64  proximate the second through hole  78  by a first mechanical spacer  98 . The first mechanical spacer  98  creates a gap  99  between the bottom surface  70  of the microfluidic delivery member  64  and the filter  96  proximate the through hole  78 . In that regard, the outlet of the filter  96  is greater than the diameter of the second through hole  78  and is offset therefrom so that a greater surface area of the filter  96  can filter fluid than would be provided if the filter was attached directly to the bottom surface  70  of the microfluidic delivery member  98  without the mechanical spacer  98 . It is to be appreciated that the mechanical spacer  98  allows suitable flow rates through the filter. That is, as the filter clogs up with particles, the filter will not slow down the fluid flowing therethrough. In one embodiment, the outlet of the filter is 4 mm 2  or larger and the standoff is 700 microns thick. 
         [0047]    The first mechanical spacer  98  may be a separate rigid support, a protrusion formed on the lower surface  70  of the microfluidic delivery member  64 , such as the solder mask, or adhesive material that conforms to a shape that provides an adequate distance between the filter  96  and the lower surface  70  of the microfluidic delivery member  64 . The adhesive material may be an adhesive material that does not readily dissolve by the fluid in the reservoir. In some embodiments, the adhesive material is activated by heat or UV. The adhesive material may be the same or different from the adhesive material used to secure the die to the microfluidic delivery member. 
         [0048]    It is to be appreciated that in some embodiments, the fluid transport member  80  is made from one or more materials that do not react with the fluid. Thus, the fluid transport member  80  does not introduce contaminants into the fluid that could block fluid flow through the microfluidic delivery member  64 . In one embodiment, the fluid transport member  80  may replace the filter, so that a separate filter  96  is not needed. 
         [0049]    As shown in  FIG. 10 , the second through hole  78  of the microfluidic delivery member  80  may include a liner  100  that covers exposed sidewalls  102  of the PCB  106 . The liner  100  may be any material configured to protect the PCB from breaking apart, such as to prevent fibers of the PCB from separating. In that regard, the liner  100  may protect against particles from the PCB  106  entering into the fluid path and blocking the nozzles  130 . For instance, the second through hole  78  may be lined with a material that is less reactive to the fluid in the reservoir than the material of the PCB. In that regard, the PCB may be protected as the fluid passes therethrough. In one embodiment, the through hole is coated with a metal material, such as gold. 
         [0050]    Prior to use, the microfluidic refill cartridge  26  may be primed to remove air from the fluid path. During priming, air in the fluid path is replaced with fluid from the reservoir  50 . In particular, fluid may be pulled up from the fluid transport member  80  to fill the chamber  88 , the first through hole  90  of the lid  54 , the second through hole  78  of the microfluidic delivery member  64 , the inlet path  94  of the die  92 , the channel  126 , and the chamber  128 . Priming may be performed by applying a vacuum force through the nozzles  130 . The vacuum force is typically performed with the microfluidic refill cartridge in an upright position for a few seconds. In some embodiments, a vacuum force is applied for 30 to 60 seconds. The microfluidic refill cartridge  26  may also be primed by applying air pressure through a hole  140  ( FIG. 9 ) in the lid  54  of the cartridge that is in fluid communication with the reservoir  50  to increase the air pressure on the fluid in the reservoir  50 , thereby pushing fluid up the fluid transport member  80  through the fluid path. It is to be appreciated that the hole is sealed with a cover  120  (see  FIG. 2B ), such as elastic material that fits into at least a portion of the hole, after priming. 
         [0051]    Once primed, the nozzles  130  may be sealed to prevent de-priming of the fluid path. De-priming may occur when air enters the fluid path. In that regard, a cover (not shown) may be placed over the nozzles  130  to prevent air from outside of the microfluidic refill cartridge  26  from entering the fluid path. It is to be appreciated that in some embodiments, the outer sleeve  85  of the fluid transport member  80  may prevent de-priming of the fluid transport member  80 . That is, the sleeve  85  prevents air from entering the fluid transport member  80  along its radial surface. 
         [0052]    Once primed, during use, when fluid exits the nozzle  130 , fluid from the reservoir  50  is pulled up through the fluid path by capillary action. In that regard, as fluid exits the chamber  128 , fluid automatically refills the chamber  128  by being pulled through the fluid path by capillary action. 
         [0053]    As indicated above, the transport cover  86  in combination with the second end  84  of the fluid transport member  80  form a seal that fluidly isolates the chamber  88  from the reservoir  50  to assist in keeping the microfluidic refill cartridge  26  primed. It is to be appreciated that the chamber  88  may be at a different pressure than the reservoir  50 . 
         [0054]    It is to be appreciated that in many embodiments, the fluid transport member  80  is configured to self-prime. That is, fluid may travel from the first end  82  of the fluid transport member  80  to the second end  84  without the aid of a vacuum force or air pressure as discussed above. 
         [0055]    The microfluidic refill cartridge  26  includes a vent path that places the reservoir in fluid communication with the external environment of the microfluidic refill cartridge  26 . The vent path equalizes the air pressure in the reservoir  50  with the air pressure of the external environment. That is, as fluid exits the microfluidic refill cartridge  26  through the nozzles  130 , air from the external environment fills the space in the reservoir  50  that is made by the removed fluid. In that regard, the air pressure above the fluid in the reservoir remains at atmosphere. This allows the microfluidic refill cartridge to remain primed and prevents or at least reduces back pressure in the fluid path. That is, by equalizing the pressure in the reservoir, the reservoir does not create a vacuum that pulls the fluid from the fluid path back into the reservoir. 
         [0056]    Referring now to  FIG. 9 , the vent path includes a first vent hole  142  in the lid  54  of the microfluidic refill cartridge and a second vent hole  144  in the microfluidic delivery member  64  (See  FIGS. 5A and 5B ). The first and second vent holes  142 ,  144  are not aligned with each other but are in fluid communication with each other by a channel  146  formed in the upper surface  66  of the lid  54 . It is to be appreciated that in another embodiment, the lower surface  70  of the microfluidic delivery member  64  could alternatively or additionally include a channel that places the first vent hole  142  in fluid communication with the second vent hole  144 . It is to be appreciated that separating the first vent hole  142  from the second vent hole  144  by the channel  146  reduces the evaporation rate of the fluid in the reservoir  50  through the vent path. 
         [0057]    Upon depletion of the fluid in the reservoir  50 , the microfluidic refill cartridge  26  may be removed from the housing  10  and replaced with another microfluidic refill cartridge  26 . Alternatively, the microfluidic refill cartridge  26  may be refilled through the hole  140  in the lid  54  as best shown in  FIG. 9 . 
         [0058]    The various embodiments described above can be combined to provide further embodiments. All of the U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet are incorporated herein by reference, in their entirety. Aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, applications and publications to provide yet further embodiments. 
         [0059]    These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.

Technology Category: 1