Patent Application
20170173579
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.
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.
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.
The disclosure advantageously provides improved apparatus and methods for metering and vaporizing fluids.
The present disclosure relates to methods and apparatus for metering and vaporizing fluids.
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.
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.
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.
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.
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:
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.
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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
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.
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.
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.
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.
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.
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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.
