Small-step high-resolution aerosol generation system and method

Abstract

The aerosol-generating device includes a circuit or microcontroller for detecting a vibration frequency of the electronic transducer and adjusting it to a determined resonant frequency that varies during operation of the device.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 390,209, filed on July 18, 2022, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates generally to aerosol generating devices including a vibrating transducer such as a piezoelectric transducer. Examples include droplet delivery devices that deliver fluids inhaled into the mouth, throat, nose, and / or lungs. Background Art

[0004] Aerosol generating devices can include vibrating transducers, such as piezoelectric transducers, to produce aerosolized droplets for various applications. Some aerosol generating devices include droplet delivery systems intended for treatment and non-therapeutic purposes. Current droplet delivery systems include systems of various inhaler types. Some examples are metered dose inhalers (MDIs), pressurized metered dose inhalers (p-MDIs), pneumatic devices, and ultrasonically driven devices. Such droplet delivery systems are intended for treatment and non-therapeutic purposes, and can include mouthpieces and nosepieces provided for inhaling fluid droplets. Summary of the invention

[0005] In one embodiment of the invention, an aerosol generating device comprises: a reservoir configured to supply a volume of fluid; a grid in fluid communication with the reservoir and operably coupled to a vibrating member; an electronic transducer coupled to the vibrating member, the electronic transducer configured to operate at a first frequency that oscillates the vibrating member to generate a stream of spray droplets through the grid; and a circuit board or microcontroller that provides a plurality of tuning signal waves to the electronic transducer during a tuning mode and measures the current provided at a constant voltage; and wherein the circuit board or microcontroller determines the resonant frequency detected when the highest current draw is detected and selects the resonant frequency detected at the highest current draw to drive the electronic transducer. In an embodiment, the electronic transducer is a piezoelectric transducer.

[0006] In yet further embodiments, an aerosol generating device of the present invention comprises a membrane coupled between a vibrating member and a grid.

[0007] In yet further embodiments, the aerosol generating device of the present invention is a droplet delivery device comprising a mouthpiece and a nosepiece configured for inhalation.

[0008] In yet further embodiments, the aerosol generating device of the present invention comprises a detected resonant frequency having a step size lower than the first frequency.

[0009] In another embodiment, an aerosol generating device of the present invention comprises: a piezoelectric transducer operable to generate droplets from a fluid in the device; an ejector mechanism coupled to the piezoelectric transducer and configured to receive the fluid; and an automatic tuning circuit or microcontroller configured to adjust a first drive frequency of the piezoelectric transducer to a second drive frequency of the piezoelectric transducer to compensate for resonant frequency drift.

[0010] In yet other embodiments, the aerosol generation further comprises an auto-tune or microcontroller configured to perform a current analysis on the piezoelectric transducer during operation and to adjust the second drive frequency based on a measure of the highest current draw at various frequencies tested during the current analysis.

[0011] In an embodiment of the present invention, an ejector mechanism includes an orifice plate coupled to a piezoelectric transducer.

[0012] In yet other embodiments, the second driving frequency has a lower step size than the first driving frequency.

[0013] In another embodiment of the present invention, an aerosol generating device includes: a reservoir configured to supply a certain volume of fluid to a grid of an ejector mechanism; an electronic transducer operable to operate at a first frequency based on a signal wave generated by a circuit, wherein the signal wave has a step size of less than about 200 Hz, and wherein the transducer is operable to vibrate the grid and generate at least one droplet from the fluid supplied to the grid from the reservoir; a microcontroller or circuit that provides multiple signal waves to the electronic transducer during a tuning mode and measures the current provided at a constant voltage, determines the resonant frequency detected when the highest current draw is detected from the multiple signal waves provided, and selects the detected resonant frequency to drive the electronic transducer.

[0014] In an embodiment of the invention, the electronic transducer is a piezoelectric transducer.

[0015] The aerosol generating device in various embodiments is a droplet delivery device comprising a mouthpiece and a nosepiece configured for inhalation.

[0016] In an embodiment, the aerosol generating device further comprises a membrane coupled between the piezoelectric transducer and the aperture plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The novel features of the present disclosure are set forth in detail in the appended claims. The features and advantages of the inventive concept will be better understood by referring to the following detailed description of illustrative examples of utilizing the principles of the present disclosure and the accompanying drawings, in which:

[0018] Figure 1 An example graph illustrating driving a piezoelectric transducer at two frequencies to select the transducer with the highest current in an embodiment of the present invention is shown.

[0019] Figure 2 An example graph of current versus frequency for a 100 Hz current curve in an embodiment of the present invention is illustrated.

[0020] Figure 3 An example graph of the displacement of a piezoelectric transducer at different frequencies in an embodiment of the present invention is illustrated.

[0021] Figure 4 is a cross-sectional view of the main components of a droplet delivery device according to an embodiment of the present disclosure.

[0022] Figure 5 Illustrated is a cross-sectional view of a vibrating member housing of a droplet delivery device utilizing membrane driven aerosolization according to one embodiment of the present disclosure.

[0023] Fig. 6A Illustrated is a side view of an exemplary orifice plate and annular ring according to an embodiment of the present disclosure.

[0024] Figure 6B Illustrated is a top view of an exemplary orifice plate and annular ring according to an embodiment of the present disclosure.

[0025] Figure 6C Illustrated are cross-sections of exemplary orifice plates and annular ring structures according to embodiments of the present disclosure. DETAILED DESCRIPTION

[0026] As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, product, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, process, article, or apparatus. In addition, unless expressly stated otherwise, "or" refers to an inclusive or and not an exclusive or. For example, a condition A or B is satisfied by any of the following: A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), and both A and B are true (or exist).

[0027] As used herein, the term "substantially" is defined as conforming substantially to a particular dimension, shape, or substantially modified such that the part does not require precision other words. For example, substantially cylindrical means that the object resembles a cylinder, but may have one or more deviations from a true cylinder.

[0028] The term "coupled" is defined as connected, whether directly or indirectly through intermediate components, and is not necessarily limited to physical connections. The connection may be such that the objects are permanently connected or releasably connected. The term "comprising" means "including but not necessarily limited to"; it specifically indicates open inclusion or membership in a stated combination, group, series, etc.

[0029] The droplet delivery device includes an ejector mechanism having a mesh, orifice plate, or similar substrate having holes of a desired size and producing a desired surface contact angle, and generating droplets from liquid passing through the mesh when a kinetic transducer acts on the liquid and the ejector mechanism. In some devices, the membrane can be oscillated by the kinetic transducer to push the liquid through the mesh and generate droplets ("push mode"), while in other devices, the transducer can be directly coupled to oscillate the mesh to generate droplets. Examples of devices including such an ejector mechanism with a substrate having holes are disclosed in U.S. Patent Application Publication No. US2022 / 0401661, published on December 22, 2022, entitled “DELIVERY DEVICE WITH PUSH EJECTION,” International Publication No. WO2020 / 264501, published on December 30, 2020, entitled “DELIVERY OF SMALL DROPLETS TO THE RESPIRATORYSYSTEM VIA ELECTRONIC BREATH ACTUATED DROPLET DELIVERY DEVICE,” and International Publication No. WO2020 / 264501, published on November 12, 2020, entitled “ULTRASONIC BREATH ACTUATEDRESPIRATORY DROPLET DELIVERY DEVICE AND METHODS OF USE.” 2020 / 227717, all of which are incorporated herein by reference in their entirety, including by reference to such publications and patent applications cited in the cited disclosures and incorporated by reference or relied upon.

[0030] The technology can be implemented in different configurations. In one example, the technology implements a vibrating member, such as a piezoelectric transducer with a horn (which can also be coupled to a membrane, as in a "push mode" technique), that pushes liquid through a fixed grid to generate droplets. The configuration of the horn and grid and other components can vary, but at least one example is given herein. In another example, the technology implements a vibrating grid that is operable to move in and out of liquid, thereby generating a jet of liquid that leaves the grid and becomes droplets.

[0031] In one example, the present technology implements a piezoelectric transducer to eject liquid through a mesh. In at least one example, the ejection of the liquid results in the formation of at least one droplet.

[0032] The present technology implements a circuit with one or more clocks, which may have a clock frequency. In some embodiments, additional circuit systems may be used to further refine the (one or more) clocks as needed. The piezoelectric transducer has a specific resonant frequency at which it operates to have a maximum amplitude, thereby maximizing liquid injection. In addition, the transducer is operable to provide the most consistent amount of liquid injection. The circuit board is operable to generate a signal wave sent to the piezoelectric transducer. The signal wave is operable to drive the piezoelectric transducer to operate in a specific manner. The circuit board is operable to generate a specific frequency step to generate the signal wave. The step size is determined by the clock frequency of the circuit. In at least one example, the clock frequency may come from a microcontroller. In another example, the clock frequency may come from a circuit board. The present technology implements a high clock frequency to provide enhanced step resolution. For example, the present technology can reduce the existing step size from about 400Hz to 1Hz. The step size reduction allows the applied frequency to be closer to the resonant frequency of the piezoelectric transducer assembly, which maximizes mass injection. The present technology can implement a smaller step size to improve performance.

[0033] The present technology can also operate to find a piezoelectric transducer and drive the piezoelectric transducer at its resonant frequency. When manufacturing and selecting different piezoelectric transducers, the resonant frequency may be different during the production process, or further different between production processes. In addition, there are other factors that change the resonant frequency of the piezoelectric transducer. For example, the resonant frequency can change based on the temperature of the piezoelectric transducer. In addition, when the piezoelectric device vibrates during operation, the temperature of the piezoelectric transducer changes. Therefore, during operation and liquid injection, the resonant frequency of the piezoelectric transducer undergoes changes. Additional factors that can change the resonant frequency include the amount of liquid injected and the type of liquid.

[0034] Current analysis can compensate for the drop in the resonant frequency of the piezoelectric transducer during actuation due to temperature increase. This is achieved by refreshing at specific time intervals (e.g., 1ms, 10ms, 100ms, 250ms, 500ms, 1000ms). The refresh monitors the current of the piezoelectric transducer actuation in a frequency range around the previously found resonant frequency. The drive frequency is set to the new frequency to compensate for the resonant frequency drift. It can be assumed that the resonant frequency will only drop during actuation, so only the frequencies below the initial resonant frequency need to be monitored to effectively compensate for the resonant frequency shift.

[0035] The present technology implements an auto-tune feature whereby the circuit tries multiple frequencies and selects the frequency that is closest to the resonant frequency. To determine the resonant frequency, the circuit can use a sensor to determine the resonant frequency. For example, the resonant frequency can be defined as the point where the impedance is lowest. The circuit can also use a fixed voltage to drive the piezoelectric device and detect when the current is highest at multiple frequencies. Determining when the current is highest at a particular frequency will provide the resonant frequency. For example, the auto-tune mode can drive the piezoelectric transducer at multiple frequencies and measure the current at each frequency. The auto-tune feature can then select the one with the highest current. An example of a drive frequency variation is Figure 1 The device can be configured to automatically tune at a predetermined time and / or based on temperature measurements of the piezoelectric transducer. Automatic tuning allows the liquid to be ejected at a resonant frequency, thereby maximizing the amount of liquid ejected and providing the most consistent ejection.

[0036] The above description applies to a configuration of the present technology that implements a piezoelectric transducer, a speaker, and a liquid assembly, and reference will be made to Figure 4 and Figure 5 They are further described. In other examples, the present technology can implement a piezoelectric transducer, mesh, and liquid assembly. The present technology implements a controller, circuit board, clock, and / or microcontroller having the above features to drive a piezoelectric transducer, which then causes the mesh to vibrate. When the mesh vibrates, the fluid is expelled through the mesh in the form of a jet. The jet becomes a droplet. Reference below Figures 6A-6C Give more details about this configuration.

[0037] Figure 1 Two different step sizes for drive frequency selection are illustrated. The lower resolution frequency change is about 400 Hz. The higher resolution frequency change is about 100 Hz. Measuring the impedance allows the resonant frequency to be determined, and the resonant frequency can be more closely approximated with the higher resolution. Therefore, achieving smaller step sizes in frequency generation allows for better approximation and matching of the resonant frequency to generate the best possible signal to control the piezoelectric transducer. In embodiments of the present invention, the smaller step sizes are below about 200 Hz, and preferably are about 100 Hz, and in some embodiments even below 1 Hz steps, so that the more precise step sizes can more accurately determine the resonant frequency of the electronic / piezoelectric transducer. In reference to Figure 1 The described embodiment wherein the resonant frequency of the piezoelectric transducer is determined by actuating the transducer at several different frequencies and analyzing the current draw at each frequency in the system is not technically a full impedance analysis.

[0038] refer to Figure 2, the 100 Hz current profile graph shows data extracted from a microcontroller of an aerosol generating device of the present invention having a piezoelectric transducer to verify that the resonant frequency is determinable, ie the frequency chosen is the peak current found in the data shown.

[0039] Figure 3 The graph of is a graph of the displacement of the piezoelectric transducer at different frequencies. The data were measured by a laser vibrometer (MV-H TM The results are collected using a series of vibrometers and show how a precise frequency step of 100 Hz can affect the mechanical displacement of the piezoelectric transducer. Figure 3 The peak-to-peak voltage of the measured data is about 5V.

[0040] An example device according to the present technology can be described as follows and Figure 4. The droplet delivery device having a membrane mated with a grid also includes a PZT-based ultrasonic transducer coupled to a vibrating member having a tip portion made of at least one of a grade 5 titanium alloy, a grade 23 titanium alloy, and titanium of about 99% or greater purity. In some embodiments, the tip of the vibrating member includes titanium of about 99% or greater purity sputtered on the outer layer, providing a smooth tip surface configured to contact the lower bottom surface of the membrane, which is opposite to the outer top surface of the membrane closest to the grid to help reduce wear of the membrane and increase the life and operational consistency of the membrane (and possibly the tip portion of the vibrating member). The transducer can be configured to have a desired higher frequency as described above. The vibrating member 1708 and the transducer 26 work in conjunction with the membrane 25 and the grid 22 to aerosolize the fluid 901, which is retained in the reservoir 1200 and supplied to the grid 22 using various methods (e.g., wicking materials, hydrophilic coatings, capillary action, etc.). Preferably, the vibrating member is coupled to the transducer such as by bonding (e.g., adhesive, etc.), welding, gluing, physical connection (e.g., brackets and other mechanical connectors), etc. The transducer and the vibrating member interact with the membrane to push the fluid through the grid. As shown and described in various embodiments, the membrane can contact the grid in some cases while also "pushing" the fluid through the holes in the grid, and can be separated without contacting the grid in other cases to push the liquid through the holes in the grid. The transducer may include one or more of various materials (e.g., PZT, etc.). In some embodiments, the transducer is made of lead-free piezoelectric material to avoid the production of unwanted or toxic materials in droplet delivery devices for human inhalation. The vibrating member may be made of one or more of a variety of different materials (e.g., titanium, etc.). The grid may be one or more of a variety of materials (e.g., palladium nickel, polyimide, etc.). After the fluid is pushed through the grid, a droplet spray is formed and ejected through the mouthpiece port, carried by entrained air.

[0041] like Figure 5 As shown in , the body of the second example includes a vibration member and transducer assembly 2603. The vibration member and transducer assembly 2603 is wrapped by a vibration member front cover 2602 and a vibration member rear cover 2604. The covers 2602, 2604 are held together by circular caps called front and rear vibration member cover brackets 2605, 2608. The wrapped vibration member is then placed into a vibration member housing 2601, then into a vibration member assembly spring 2606, and finally seated in a vibration member device bracket 2607. The vibration member housing allows the spring to press the vibration member and transducer assembly onto the membrane.

[0042] Figures 6A-6CAn orifice plate assembly 1200 is illustrated, which includes an orifice plate 1216 (e.g., palladium nickel) supported by a stainless steel ring 1218. The orifice plate is welded or bonded 1220 to the stainless steel ring 1218, thereby together allowing for a thicker support material that is much cheaper than the orifice plate material (e.g., palladium nickel) alone. The stainless steel and orifice plate are bonded 1220 to a piezoelectric material 1222, with all components forming the orifice plate assembly 1200.

[0043] Although the present invention has been described with reference to exemplary embodiments, it will be appreciated by those skilled in the art that various changes may be made and equivalents may be substituted for its elements without departing from the scope of the present invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings without departing from the basic scope thereof. Therefore, the present invention is not intended to be limited to the specific embodiments disclosed as the intended best mode for carrying out the present invention, but the present invention will encompass all embodiments within the scope of the appended claims.

Claims

1. An aerosol generating device comprising: a reservoir configured to supply a volume of a fluid; a grid in fluid communication with the reservoir and operably coupled to a vibrating member; an electronic transducer coupled to the vibrating member, the electronic transducer configured to operate at a first frequency that oscillates the vibrating member to generate a jetted stream of droplets through the grid; as well as a circuit board or microcontroller that provides a plurality of tuning signal waves to the electronic transducer during a tuning mode and measures the current provided at a constant voltage; and Wherein the circuit board or microcontroller determines the resonant frequency detected when the highest current draw is detected and selects the resonant frequency detected when the highest current draw is detected to drive the electronic transducer.

2. The aerosol generating device of claim 1 , further comprising: A membrane is coupled between the vibrating member and the mesh.

3. An aerosol generating device according to claim 2, wherein the aerosol generating device is a droplet delivery device comprising a mouthpiece and a nosepiece configured for inhalation.

4. The droplet delivery apparatus of claim 3, wherein the detected resonant frequency has a lower step size than the first frequency.

5. The droplet delivery apparatus of claim 1, wherein the detected resonant frequency has a lower step size than the first frequency.

6. An aerosol generating device comprising: a piezoelectric transducer operable to generate droplets from a fluid in the device; an ejector mechanism coupled to the piezoelectric transducer and configured to receive the fluid; as well as An automatic tuning circuit or microcontroller is configured to adjust the first driving frequency of the piezoelectric transducer to a second driving frequency of the piezoelectric transducer to compensate for the resonant frequency drift.

7. An aerosol generating device as claimed in claim 6, further comprising: The autotune or microcontroller is configured to perform a current analysis on the piezoelectric transducer during operation and to adjust the second drive frequency based on a measure of the highest current draw among various frequencies tested during the current analysis.

8. An aerosol generating device as claimed in claim 7, wherein the ejector mechanism comprises an orifice plate coupled to the piezoelectric transducer.

9. An aerosol generating device as claimed in claim 8, wherein the aerosol generating device is a droplet delivery device comprising a mouthpiece and a nosepiece configured for inhalation.

10. The droplet delivery apparatus of claim 9, wherein the second drive frequency has a lower step size than the first drive frequency.

11. An aerosol generating device as claimed in claim 6, wherein the ejector mechanism comprises an orifice plate coupled to the piezoelectric transducer.

12. An aerosol generating device as claimed in claim 11, further comprising a membrane coupled between the piezoelectric transducer and the aperture plate.

13. An aerosol generating device according to claim 12, wherein the aerosol generating device is a droplet delivery device comprising a mouthpiece and a nosepiece configured for inhalation.

14. An aerosol generating device as claimed in claim 8, further comprising a membrane coupled between the piezoelectric transducer and the aperture plate.

15. An aerosol generating device comprising: a reservoir configured to supply a volume of fluid to the grid of the ejection mechanism; an electronic transducer operable to operate at a first frequency based on a signal wave generated by a circuit, wherein the signal wave has a step size of less than about 200 Hz, and wherein the transducer is operable to vibrate a mesh and generate at least one droplet from a fluid supplied to the mesh by the reservoir; A microcontroller or circuit provides a plurality of signal waves to the electronic transducer during a tuning mode and measures the current provided at a constant voltage, determines a detected resonant frequency when a highest current draw is detected from providing the plurality of signal waves, and selects the detected resonant frequency to drive the electronic transducer.

16. An aerosol generating device as claimed in claim 15, wherein the electronic transducer is a piezoelectric transducer.

17. An aerosol generating device according to claim 16, wherein the aerosol generating device is a droplet delivery device comprising a mouthpiece and a nosepiece configured for inhalation.

18. An aerosol generating device according to claim 17, further comprising: A membrane is coupled between the piezoelectric transducer and the aperture plate.

19. The aerosol generating device of claim 16, further comprising: A membrane is coupled between the piezoelectric transducer and the mesh.

20. The aerosol generating device of claim 15, further comprising: A membrane is coupled between the piezoelectric transducer and the mesh.

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