Abstract:
A vaporization device, including a fluid supply containing a vaporizable fluid; a plurality of bubble pumps operative to pump fluid from the fluid supply to outlets of the bubble pumps; and a fluid vaporization heater located adjacent the outlets of the bubble pumps to receive fluid from the bubble pumps.

Description:
FIELD 
       [0001]    This disclosure relates generally to methods and apparatus for metering and vaporizing a fluid. More particularly, this disclosure relates to fluid vaporization structures that utilize bubble pumps to transport fluid to a vaporization structure. 
       BACKGROUND 
       [0002]    Improvement is desired in the field of microfluidic structures of the type used to dispense a solution from a storage supply to another device where a secondary function may be performed. An example of one secondary function is vaporization of the solution using a heater such that the contents of the solution can be delivered to complete its function in a gaseous state. Such microfluidic structures have many applications, such as for providing vapor therapy, flavored e-cigarettes, chemical vapor reactions, and the like. 
         [0003]    Conventional structures for dispensing fluid from a fluid supply to a vaporization heater structure desire improvement. For example, conventional devices are often unreliable in providing consistent and desired amounts of fluid to the vaporization heater structure. As part of this, clogging of the flow path and causes of incomplete travel of fluid are common, resulting in uncertainty of the amount of fluid that reaches the vaporizing element. 
         [0004]    The disclosure advantageously provides improved apparatus and methods for metering and vaporizing fluids. 
       SUMMARY 
       [0005]    The present disclosure relates to methods and apparatus for metering and vaporizing fluids. 
         [0006]    In one aspect, there is disclosed a vaporization device, including a fluid supply containing a vaporizable fluid and a plurality of bubble pumps. Each bubble pump has an inlet in flow communication with the fluid supply for receiving fluid therefrom. Each bubble pump also has a fluid flow path and flow sequencing heaters located within the fluid flow path, and an outlet. Each bubble pump is operative to pump fluid from the fluid supply to the outlet of the bubble pump. A fluid vaporization heater is located adjacent the outlets of the bubble pumps. The fluid vaporization heater has a heated fluid contact surface to receive fluid from the outlet of the bubble pump and to heat and thereby vaporize the received fluid. 
         [0007]    In another aspect, there is disclosed a vaporization device, including a plurality of fluid supplies each containing a vaporizable fluid and a plurality of bubble pumps. Each bubble pump has an inlet in flow communication with one of the fluid supplies for receiving fluid therefrom, and each bubble pump also includes a fluid flow path, flow sequencing heaters located within the fluid flow path, and an outlet. Each bubble pump is operative to pump fluid from the fluid supply to which it is in fluid communication with to the outlet of the bubble pump. A fluid vaporization heater is located adjacent the outlets of the bubble pumps. The fluid vaporization heater has a heated fluid contact surface to receive fluid from the outlet of the bubble pump and to heat and thereby vaporize the received fluid. 
         [0008]    In yet another aspect, there is disclosed a vaporization device, including a fluid supply containing a vaporizable fluid; a plurality of bubble pumps operative to pump fluid from the fluid supply to outlets of the bubble pumps; and a fluid vaporization heater located adjacent the outlets of the bubble pumps to receive fluid from the bubble pumps. The vaporization heater is operative to heat and thereby vaporize the received fluid. 
         [0009]    In a further aspect, there is disclosed a method of vaporizing fluid, including as steps: providing a fluid supply containing a vaporizable fluid; providing a plurality of bubble pumps in fluid communication with the fluid supply and operating the bubble pumps to pump fluid from the fluid supply to outlets of the bubble pumps; providing a fluid vaporization heater adjacent the outlets of the bubble pumps to receive fluid from the bubble pumps, and operating the vaporization heater to heat and thereby vaporize the received fluid. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    Further advantages of the disclosure are apparent by reference to the detailed description in conjunction with the figures, wherein elements are not to scale so as to more clearly show the details, wherein like reference numbers indicate like elements throughout the several views, and wherein: 
           [0011]      FIGS. 1-2  show a fluid vaporization device according to the disclosure in which a vaporizer is located in a plane substantially parallel to a plane defined by a plurality of bubble pumps. 
           [0012]      FIG. 3  shows an alternate embodiment of fluid vaporization device in which a vaporizer is located in a plane substantially perpendicular to a plane defined by the bubble pumps. 
           [0013]      FIGS. 4 and 5  show yet another alternate embodiment of fluid vaporization device in which an angle between a plane defined by vaporizers and a plane defined by a plurality of bubble pumps is varied. 
           [0014]      FIG. 6  shows a further embodiment of a fluid vaporization device having a fluid supply inlet located at an edge of the device. 
           [0015]      FIG. 7  shows a still further embodiment of a fluid vaporization device having a fluid supply inlet located at an edge of the device, with an angle between a plane defined by a vaporizer and a plane defined by a plurality of bubble pumps of the device is varied. 
           [0016]      FIG. 8  shows another alternate embodiment of a fluid vaporization device having multiple bubble pumps and multiple fluid supplies. 
           [0017]      FIG. 9  shows a further alternate embodiment of a fluid vaporization device having multiple bubble pumps, with each bubble pump having its own fluid supply. 
           [0018]      FIGS. 10 and 11  show another embodiment of a fluid vaporization device in which the bubble pumps and the vaporizer are fabricated on the same substrate. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    The disclosure relates to fluid vaporization structures that utilize a plurality of bubble pumps to transport fluid from one or more fluid supplies to a discrete fluid vaporization structure. 
         [0020]    With reference to  FIGS. 1-2 , there is shown a fluid vaporization device  10  having a fluid supply  12 , a plurality of bubble pumps  14 , and a vaporizer  16 . The device  10  is configured so that the bubble pumps  14  desirably transport fluid from the fluid supply  12  directly onto the vaporizer  16 . 
         [0021]    The device  10  is incorporated onto a printed circuit board  18  to provide a single assembly containing the fluid supply  12 , the bubble pumps  14 , and the vaporizer  16 . Each of the bubble pumps  14  has a length axis that generally defines a plane, and the vaporizer is provided on a substrate generally defining a plane. As will be noted, in the embodiment of  FIGS. 1-2 , the common plane defined by the bubble pumps  14  and the plane defined by the vaporizer  16  are substantially parallel to one another. 
         [0022]    The fluid supply  12  is configured as a fluid storage vessel located on a cover substrate  20  of each of the bubble pumps  14 . The fluid supply  12  is charged with a desired vaporizable fluid and is generally vented to the atmosphere and contains a desired volume of a fluid, typically a liquid at ambient conditions. As one example, the fluid may be a liquid of a type utilized for vapes or e-cigarettes in a volumetric amount suitable for such usage. A supply inlet  22  is defined between the fluid supply  12  and the cover substrate  20  to provide a fluidic path for desired travel of fluid from the fluid supply  12  to each of the bubble pumps  14 . 
         [0023]    Each of the bubble pumps  14  is configured for pumping fluid from the fluid supply  12  to the vaporizer  16 . In addition to the cover substrate  20 , each bubble pump  14  includes an inlet  30 , a base substrate  32 , flow sequencing resistive heaters  34 , and an outlet  36 . During manufacture, a flow feature layer is initially deposited on the base substrate  32 . The flow feature layer is then selectively etched to provide the heaters  34  and to define a flow channel  38 . The base substrate  32  may be a semiconductor silicon substrate that is suitable for providing bubble pumps and logic circuits thereon. The cover substrate  20  may be made of silicon or a polymeric material such as polyimide. The resistive heaters  34  and vaporizer  16  may be made of TaAlN, TaAl or other thin film resistor material. The preferred material for the flow feature layer for providing the resistive heaters  34  is TaAlN deposited on the base substrate  32  as by sputtering. The vaporizer  16  may be formed in a similar manner. 
         [0024]    Electrical connections and logic circuits are integrated onto the device  10  to control and operate the heaters  34  of the bubble pumps  14  and the vaporizer  16 , and to otherwise control the transfer of fluid from the fluid supply  12  to the vaporizer  16 . For example, voltage pulses may be applied to the heaters  34  in a desired manner to form and transport thermal bubbles of the fluid along the flow channel  38  to deliver fluid as desired to the vaporizer  16  for vaporization of the delivered fluid. Examples of preferred bubble pumps are shown in U.S. Pat. No. 8,891,949, issued Nov. 18, 2014, entitled Micro-fluidic pump, and incorporated by reference herein in its entirety. 
         [0025]    In basic operation of the bubble pumps  14 , a voltage pulse is applied to each of the heaters  34  in sequence to generate thermal bubbles in a predetermined manner. For example, every heater  34  can form a bubble from the inlet  30  to the outlet  36  of the channel  38  in sequence to transport fluid as desired from the supply  12  to the vaporization heater  16 . Each heater  34  is also desirably permitted to cool down before the next firing sequence in order to prevent overheating and boiling of fluid within the bubble bump  14 . The bubble pumps  14  may be operated to cooperate to provide transport of fluid to the vaporizer  16 . 
         [0026]    The vaporizer  16  is configured as a microfluidic electrical heating element designed specifically to vaporize the fluid received from the fluid supply  12 . The vaporizer  16  is located adjacent and below the outlets  36  of the bubble pumps  14 . A slot or other flow path is formed through the circuit board  18  for travel of fluid from the outlet  36  of the bubble pump  14  to the vaporizer  16 . The vaporizer  16  has a heated fluid contact surface that is open and exposed to the air or other local environment. The heated fluid contact surface heats the received fluid to vaporize the received fluid into the atmosphere or other local environment. It will be appreciated that the vaporizer  16  may be provided by a single or multiple vaporizer structures. 
         [0027]    Turning now to  FIG. 3 , there is shown an alternate embodiment of a fluid vaporization device  50 . The device  50  has a fluid supply  52 , bubble pumps  54 , and a vaporizer  56 . The fluid supply  52  and the bubble pumps  54  are incorporated onto a printed circuit board  58 . The fluid supply  52 , the bubble pumps  54 , and the vaporizer  56  substantially correspond to the fluid supply  12 , the bubble pumps  14 , and the vaporizer  16 . However, the vaporizer  56  is spaced from the end of the circuit board  58  so as to be in a plane that is substantially perpendicular to a fluid flow plane defined by the bubble pumps  54 . 
         [0028]    Turning now to  FIGS. 4 and 5 , there is shown another alternate embodiment of a fluid vaporization device  60 . The device  60  substantially corresponds to the device  50 , and includes the fluid supply  52 , bubble pumps  54 , and the vaporizer  56 , except the circuit board  58  with the bubble pump  54  thereon is oriented at an angle A or an angle A′ or both relative to a plane defined by the vaporizer  56 . The angles A and A′ may each vary from about 0 degrees to about 90 degrees. In this regard, it will be appreciated that the depicted angles are provided to show that the angular orientation between the bubble pumps  54  and the vaporizer  56  may be varied in any of the three dimensions. 
         [0029]    Turning now to  FIG. 6 , there is shown yet another embodiment of a fluid vaporization device  70 . The device  70  substantially corresponds to the device  50 , and includes the bubble pumps  54 , the vaporizer  56  and the circuit board  58 . However, a fluid supply  72  is provided having an inlet  74  located at a distal end of the assembly of the bubble pump  54  and the circuit board  58  opposite the vaporizer  56 . 
         [0030]    Turning now to  FIG. 7 , there is shown another alternate embodiment of a fluid vaporization device  80 . The device  60  substantially corresponds to the device  70 , and includes the fluid supply  72 , bubble pumps  54 , and the vaporizer  56 , except the circuit board  58  with the bubble pumps  54  thereon is oriented at an angle B relative to the plane defined by the vaporizer  56 . The angle B may vary from about 0 degrees to about 90 degrees. As in the case of the device  60 , the angle B may be in one or more dimensions, as explained in connection with the angles A and A′ of  FIGS. 5 and 6 . 
         [0031]    Turning now to  FIG. 8 , there is shown another alternate embodiment of a fluid vaporization device  90 . The device  90  substantially corresponds to the device  10 , except the device  90  includes the plurality of bubble pumps  14  in flow communication with a plurality of the fluid supplies  12 . It will be appreciated that each of the fluid supplies  12  may include a different vaporizable fluid or fluids having different characteristics or mixtures of fluids. 
         [0032]    Turning now to  FIG. 9 , there is shown another alternate embodiment of a fluid vaporization device  100 . The device  100  substantially corresponds to the device  90 , except the device  110  includes the plurality of bubble pumps  14  with the same number of fluid supplies  12 . Each of the bubble pumps  14  is in flow communication with a corresponding one of the fluid supplies  12 . It will be appreciated that each of the fluid supplies  12  may include a different fluid or fluids having different characteristics or mixtures of fluids. 
         [0033]    Turning now to  FIGS. 10 and 11  there is shown another alternate embodiment of a fluid vaporization device  110 . The device  110  substantially corresponds to the device  10 , and includes the fluid supply  12 , the bubble pumps  14 , the vaporizer  16 , and the circuit board  18 . However, the device  110  is constructed with the bubble pumps  14  and the vaporizer  16  fabricated on the same substrate. 
         [0034]    The foregoing description of preferred embodiments for this disclosure has been presented for purposes of illustration and description. The description and embodiments are not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments are chosen and described in an effort to provide the best illustrations of the principles of the disclosure and its practical application, and to thereby enable one of ordinary skill in the art to utilize the disclosure in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the disclosure as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.