A device for aerosolizing liquids

Abstract

The present disclosure provides an apparatus (100) for aerosolizing a liquid, comprising one or more inputs (110) and a plurality of droplet emitters (126) in fluid communication with the one or more inputs (110). Each droplet emitter comprises a nozzle portion and a piezoelectric actuator. The one or more inputs are for receiving one or more liquids. Each nozzle portion defines a nozzle outlet in fluid communication with the one or more inputs. Each piezoelectric actuator is operable to eject the liquid received from one of the one or more inputs as one or more droplets from a respective nozzle outlet, thereby generating an aerosol containing the one or more droplets ejected by each droplet emitter.

Description

[Technical Field]

[0001] The present invention relates to a device for aerosolizing a liquid. [Background technology]

[0002] There are many applications in which it is advantageous to convert a single volume of liquid into multiple droplets, such as an aerosol or mist. Such conversion may be done to increase the surface area of ​​the liquid, and / or to provide droplets that do not exceed a maximum size, and / or to allow the liquid to be entrained in an air stream so that it can be easily delivered to a target area.

[0003] Conventional techniques for producing multiple droplets (e.g., aerosols) can use atomizer pressure nozzles, in which a liquid is expelled from a nozzle under high pressure to form droplets. Another known nozzle technology is ultrasonic nozzles, which, for a given nozzle geometry and liquid, produce droplets having a predetermined median droplet size.

[0004] It is against this background that the present invention was devised. Summary of the Invention

[0005] An apparatus for aerosolizing a liquid includes one or more inputs that receive one or more liquids and a plurality of droplet emitters in fluid communication with the one or more inputs, each droplet emitter including a nozzle portion defining a nozzle outlet in fluid communication with one of the one or more inputs, and a piezoelectric actuator, each piezoelectric actuator operable to eject the liquid received from one of the one or more inputs as one or more droplets from a respective nozzle outlet, thereby generating an aerosol including the one or more droplets ejected by each droplet emitter.

[0006] Thus, by providing multiple droplet emitters rather than a single droplet emitter, a given number of nozzle outlets are allocated among the multiple droplet emitters. In other words, each droplet emitter ejects one or more liquids from only a portion of the total number of nozzle outlets in the device. As a result, unwanted non-uniformity in the ejection of droplets from different regions of the device can be reduced or even eliminated. Furthermore, separate control signals can be provided to each of the piezoelectric actuators, allowing for more precise control of the set of droplets ejected from the nozzle outlets. This allows a greater proportion of droplets in the aerosol to be controlled to have sizes that more accurately reflect the desired ejection parameters. Typically, the size of droplets ejected from a given droplet emitter depends on the drive signal used to control the piezoelectric actuator of the given droplet emitter. In this way, varying the drive signal can eject droplets of different sizes (or even the same size droplets from different liquids).

[0007] It will be appreciated that the one or more liquids received by the one or more outputs and dispensed as an aerosol by the device may, in some embodiments, include solid particles suspended in the liquid.

[0008] In some embodiments, the device may be connected to one or more additional components for use. Specifically, any device including multiple droplet emitters and one or more inputs described herein can typically be considered a device for aerosolizing a liquid. Stated differently, a device for aerosolizing a liquid can be considered a refill for a larger device that includes one or more additional components. This larger device provides a working device that can utilize the generated aerosol.

[0009] The term aerosol, as used herein, is understood to mean substantially any droplets small enough to be entrained in an air current, e.g., small enough to be dispersed into the surrounding atmosphere / air. The term "aerosolizing apparatus" is understood to mean any aerosolizer, i.e., any device capable of generating the aerosols described herein.

[0010] The one or more inputs typically receive a single liquid at each input, however, in some embodiments, a first liquid may be received at the input at a first time and a second liquid may be received at the input at a second time subsequent to the first time.

[0011] It will be appreciated that when one or more droplets are ejected from the nozzle outlet, it is not necessary that the droplets be imparted with sufficient momentum to travel a significant distance from the device during ejection, but rather that the ejection of the droplets only causes the formation of an aerosol.

[0012] At least 50% of the plurality of droplet emitters may each define only one nozzle outlet. Each of the plurality of droplet emitters may each define only one nozzle outlet. Thus, each piezoelectric actuator, when activated, causes droplets to be ejected from only a single nozzle outlet, thereby providing particularly effective control over droplet size. The nozzle outlet defined by each of the plurality of droplet emitters may be in fluid communication with one of the one or more inputs.

[0013] The device may further comprise a storage portion defining one or more cavities for storing one or more liquids, the one or more cavities being in fluid communication with each nozzle outlet and the one or more inputs, such that liquids can be stored in the one or more cavities prior to ejection by the droplet ejector.

[0014] The reservoir portion may be removable. The reservoir portion may be replaceable, thereby allowing for easy refilling of the liquid by replacing an empty reservoir portion with a new, full reservoir portion. Furthermore, the same device may be used with multiple different liquids by replacing a first reservoir portion filled with a first liquid with a second reservoir portion filled with a second liquid. In other embodiments, the reservoir portion may be refillable, thereby allowing for the device to be reused by refilling the reservoir portion. It will be appreciated that in many situations, replacing the reservoir portion is preferable to refilling the reservoir portion in-situ to ensure a protective environment is maintained (i.e., the liquid is not contaminated).

[0015] The device may further include a housing that supports the plurality of droplet emitters. Typically, the housing provides an outer casing for the device. As such, the plurality of droplet emitters can be considered to be in fluid communication with an environment external to the device. The housing typically protects the internal components of the device from the external environment and provides structural support to which the components of the device can be mounted.

[0016] The reservoir may be part of the housing, such that the reservoir is held securely relative to the one or more inputs, thereby more easily maintaining fluid communication between the one or more cavities and the one or more inputs.

[0017] The device may further comprise an outlet portion defining an aerosol outlet through which the aerosol can be output from the device, such that the generated aerosol is output from the device.

[0018] Typically, the aerosol is output from the outlet portion as part of an airflow that flows through the multiple droplet emitters, thereby entraining droplets emitted by each droplet emitter in the airflow. The device may further include one or more air inlets that allow air to enter the device and pass through the multiple droplet emitters. The one or more air inlets may be located within the housing and thus in fluid communication with the outlet portion. The one or more air inlets may be located at an inlet portion of the device, such as an inlet portion of the housing. The airflow may be activated only when the device is in use.

[0019] The outlet portion may be part of the housing, thus allowing the aerosol to be conveniently output from the device using a defined portion of the device's existing housing, without the need for an additional separate component.

[0020] The outlet portion may define an aerosol outlet channel to direct aerosol output from the device in a first direction.

[0021] The device may further comprise a power circuit portion. The power circuit portion is arranged to provide power to the piezoelectric actuator of each of the plurality of droplet emitters. The power circuit portion may comprise a battery compartment arranged to receive a battery, or a power port for connecting a power source. The power circuit portion may comprise a power source, such as a battery. The battery may be a rechargeable battery. The device may further comprise a power source that provides power to the power circuit portion. Thus, the device may be easily moved to different locations. In some embodiments, the device may be portable, for example handheld.

[0022] The power supply circuit portion may be supported by the housing. The power supply circuit portion may be housed within the housing. Thus, the power supply circuit portion can be at least partially protected by the housing.

[0023] The device may further include a switch for activating the plurality of droplet emitters, such that the plurality of droplet emitters are activated only when needed. The switch may be user operable or may be operated in response to control logic from a controller.

[0024] The switch may be a flow switch responsive to the flow rate through the aerosol outlet. Accordingly, it can be considered that the plurality of droplet emitters may be configured to activate in response to gas flow. The plurality of droplet emitters may be configured to deactivate in response to cessation of gas flow. In this manner, waste of aerosolized liquid can be reduced or entirely eliminated, and the volume of liquid provided as an aerosol can be easily determined.

[0025] In a first configuration, the switch may be in a first state that activates the piezoelectric actuator of the droplet emitter to generate aerosol, and in a second configuration, the switch may be in a second state that corresponds to no aerosol being generated by activation of the piezoelectric actuator. The device may be configured to toggle the switch between the first and second states in response to detection of a gas flow. Thus, the multiple droplet emitters may be activated only in the presence of a gas flow. This ensures that the entirety of the generated aerosol is entrained in the gas flow, thereby reducing excessive aerosol generation.

[0026] The device may further include a controller that controls (e.g., is configured to control) operation of the plurality of droplet emitters, which may be in response to a sensor input, such as a state of a switch.

[0027] The controller may include one or more processors and a memory configured to store instructions that, when executed by the one or more processors, cause the device to perform the functions of the controller described herein. The memory may be a non-transitory computer-readable memory. The memory may have instructions stored therein. The invention extends to a non-transitory computer-readable medium (e.g., a memory) having stored thereon instructions for controlling the device described herein. The memory may be a solid-state memory. The controller may be provided on a single device. In other embodiments, the controller may be distributed having multiple processors. A first processor may be distributed and separate from a second processor. Where the controller is distributed across multiple separate devices, the device may be formed from multiple separate devices.

[0028] The controller may be configured to generate the liquid aerosol at multiple discrete times in response to an actuation signal (e.g., one or more actuation signals), such that the liquid aerosol may be arranged to be delivered in bursts as needed.

[0029] The actuation signal (e.g., one or more actuation signals) may be received from a remote device that is remote from the apparatus. Thus, operation of the apparatus may be controlled based on the signal received from the remote device. The remote device may be a sensor device. Alternatively, the remote device may be a user-operable device.

[0030] A first consecutive subset of the plurality of discrete times may be regularly spaced apart. A second consecutive subset of the plurality of discrete times immediately following the first consecutive subset may be regularly spaced apart. The second consecutive subset may be spaced apart from a first adjacent subset by a greater distance than the distance between the first consecutive subsets. Thus, the aerosol may be generated in a plurality of discretely spaced bursts.

[0031] The one or more actuation signals may cause the liquid aerosol to be generated discretely or continuously for a period of more than 30 minutes. The first consecutive subset of the plurality of discrete times may extend for a period of more than 30 minutes. The period may be more than 1 hour. The period may be more than 12 hours. The period may be more than 24 hours. The period may be less than 1 year. The period may be less than 6 months.

[0032] At least one of the nozzle outlets has a maximum cross-sectional dimension of 150 x 10 -6 More than 50% of the nozzle outlets may have a maximum cross-sectional dimension of less than 150 x 10 meters (150 microns). -6 Each of the plurality of nozzle outlets may have a maximum cross-sectional dimension of less than 150 x 10 meters (150 microns). -6 It may be less than a meter (150 microns).

[0033] At least one of the nozzle outlets has a maximum cross-sectional dimension of 100 x 10 -6 More than 50% of the nozzle outlets may have a maximum cross-sectional dimension of less than 100 x 10 meters (100 microns). -6 Each of the plurality of nozzle outlets may have a maximum cross-sectional dimension of less than 100 x 10 meters (100 microns). -6 It may be less than a meter (100 microns).

[0034] At least one of the nozzle outlets has a minimum cross-sectional dimension of 0.1 x 10 -6 More than 50% of the nozzle outlets may have a minimum cross-sectional dimension of 0.1 x 10 meters (0.1 microns). -6 Each of the plurality of nozzle outlets may have a minimum cross-sectional dimension of greater than 0.1×10 meters (0.1 microns). -6 It may be greater than a meter (0.1 microns).

[0035] At least one of the nozzle outlets has a minimum cross-sectional dimension of 1 x 10 -6More than 50% of the nozzle outlets have a minimum cross-sectional dimension of 1 x 10 -6 Each of the plurality of nozzle outlets may have a minimum cross-sectional dimension of greater than 1×10 meter (1 micron). -6 It may be greater than a meter (1 micron).

[0036] At least one of the nozzle outlets has a minimum cross-sectional dimension of 5 x 10 -6 More than 50% of the nozzle outlets have a minimum cross-sectional dimension of 5 x 10 -6 Each of the plurality of nozzle outlets may have a minimum cross-sectional dimension of 5×10 -6 It may be greater than a meter (5 microns).

[0037] At least one of the nozzle outlets has a minimum cross-sectional dimension of 7 x 10 -6 More than 50% of the nozzle outlets may have a minimum cross-sectional dimension of 7 x 10 -6 Each of the plurality of nozzle outlets may have a minimum cross-sectional dimension of greater than 7×10 meters (7 microns). -6 It may be greater than 7 microns (meters).

[0038] At least one of the nozzle outlets has a cross-sectional area of ​​20 x 10 -9 m 2 (0.02mm 2 ) more than 50% of the nozzle outlets may have a cross-sectional area of ​​less than 20 x 10 -9 m 2 (0.02mm 2 Each of the plurality of nozzle outlets may have a cross-sectional area of ​​less than 20×10 -9 m 2 (0.02mm 2 ) may be less than

[0039] At least one of the nozzle outlets has a cross-sectional area of ​​10 x 10 -9 m 2 (0.01mm2 ) more than 50% of the nozzle outlets may have a cross-sectional area of ​​less than 10 × 10 -9 m 2 (0.01mm 2 Each of the plurality of nozzle outlets may have a cross-sectional area of ​​less than 10×10 -9 m 2 (0.01mm 2 ) may be less than

[0040] At least one of the nozzle outlets has a cross-sectional area of ​​0.02 x 10 -12 m 2 (0.02μm 2 ) more than 50% of the nozzle outlets may have a cross-sectional area of ​​0.02 × 10 -12 m 2 (0.02μm 2 Each of the plurality of nozzle outlets may have a cross-sectional area of ​​greater than 0.02×10 -12 m 2 (0.02μm 2 ) may be greater than 10 ...

[0041] At least one of the nozzle outlets has a cross-sectional area of ​​25 x 10 -12 m 2 (25μm 2 ) more than 50% of the nozzle outlets may have a cross-sectional area of ​​25 x 10 -12 m 2 (25μm 2 Each of the plurality of nozzle outlets may have a cross-sectional area of ​​greater than 25×10 -12 m 2 (25μm 2 ) may be greater than 10 ...

[0042] Typically, each of the nozzle outlets has a substantially similar cross-sectional shape, which may be rounded, such as circular.

[0043] A nozzle outlet is understood to be the location at which the nozzle portion ejects one or more droplets from the droplet emitter, and thus references to the cross-sectional dimension or area of ​​the nozzle outlet refer to the area of ​​the nozzle portion that is last contacted by the liquid that is to be ejected as one or more droplets before the droplets are released from the droplet emitter.

[0044] At least 90% of the droplets that make up the liquid aerosol have a volume of 2 × 10 -12 m 3 The one or more droplets that make up the liquid aerosol may each have a volume of less than 2×10 -12 m 3 At least 90% of the one or more droplets that make up the liquid aerosol may have a volume of less than 2×10 -15 m 3 The one or more droplets that make up the liquid aerosol may each have a volume of less than 2×10 -15 m 3 It may be less than.

[0045] At least 90% of the droplets that make up the liquid aerosol have a volume of 0.5 × 10 -21 m 3 The one or more droplets that make up the liquid aerosol may each have a volume of 0.5×10 or more. -21 m 3 At least 90% of the one or more droplets that make up the liquid aerosol have a volume of 2×10 -18 m 3 The one or more droplets that make up the liquid aerosol may each have a volume of 2×10 -18 m 3 It may be super.

[0046] In some embodiments, at least 90% of the one or more droplets comprising the liquid aerosol have a volume of less than or equal to 0.5×10 -18 m 3 The one or more droplets that make up the liquid aerosol may each have a volume of less than 0.5×10 -18 m 3At least 90% of the one or more droplets that make up the liquid aerosol may have a volume of less than 2×10 -15 m 3 The one or more droplets that make up the liquid aerosol may each have a volume of 2×10 -15 m 3 It may be super.

[0047] The plurality of droplet emitters may be formed on a common substrate, in other words, all of the nozzle portions and piezoelectric actuators of the plurality of droplet emitters may be formed on a common substrate.

[0048] Typically, the substrate has a first surface and an opposite second surface. The substrate comprises CMOS control circuitry and multiple layers on the first surface of the substrate. A piezoelectric actuator is formed by one or more of the layers and a nozzle portion defining a hole (e.g., a nozzle outlet) through the one or more layers, and the piezoelectric actuator displaces the one or more layers and the nozzle portion in use to eject droplets. Thus, the droplet ejector is typically configured to eject droplets in an inertial mode. The hole may extend through the piezoelectric actuator.

[0049] The piezoelectric actuator typically operates to displace an elastically deformable membrane which defines at least a portion of the nozzle outlet, thereby causing the ejection of a droplet from the nozzle portion upon operation of the actuator, and in this way the elastically deformable membrane may be considered to be part of the nozzle portion.

[0050] In this manner, typically, a piezoelectric actuator is coupled to each nozzle portion. Deformation of the piezoelectric actuator during use therefore moves a region of the nozzle portion, which in turn causes droplets to be ejected from the nozzle outlet. Typically, an elastically deformable membrane comprises a piezoelectric actuator and defines at least a region of the nozzle portion. Thus, the elastically deformable membrane defines at least a portion (e.g., a wall) of a chamber in fluid communication with the nozzle outlet. Typically, the piezoelectric actuator is disposed adjacent to, for example, the periphery of the nozzle outlet. Actuation of the piezoelectric actuator typically causes the elastically deformable membrane defining the nozzle outlet to deflect. Thus, the elastically deformable membrane and the nozzle portion move during use, causing droplets to be ejected from the nozzle outlet in the chamber. Typically, the device comprises a nozzle-defining layer formed on a substrate, the nozzle-defining layer comprising a piezoelectric actuator and defining the nozzle outlet. The nozzle-defining layer typically comprises at least one piezoelectric layer and one or more electrodes in electrical contact with the at least one piezoelectric layer.

[0051] In other possible configurations, the piezoelectric actuator is associated with a location remote from the nozzle outlet, and / or the nozzle outlet and the piezoelectric actuator are on different walls of the chamber (e.g., the nozzle outlet is on one wall of the fluid chamber, and the actuator is on the opposite wall of the same chamber, thereby remote from the nozzle outlet). When the piezoelectric actuator is not coupled to / removed from the nozzle outlet, a large actuation force is required to compress almost the entire liquid stored in the chamber to eject droplets from the nozzle outlet. This operation therefore relies on a compression mode. In contrast, using an inertial mode, a small actuation force is required to displace the liquid at the nozzle outlet without disturbing most of the liquid in the chamber. The liquid is then ejected as droplets from the nozzle outlet primarily due to inertial forces (i.e., inertial ejection). Note that ejection due to inertial forces can also be referred to as inertial ejection or inertial mode ejection. When a piezoelectric actuator is coupled to each nozzle section, ejection of liquid (from each nozzle) occurs in an inertial mode rather than a compression mode.

[0052] It will be appreciated that inertial mode ejection (i.e., inertial ejection) has a number of closely related advantages. First, the low actuation force required allows for the use of low-temperature processable piezoelectric materials (i.e., piezoelectric materials processable below 450°C or even below 300°C) with low piezoelectric constants. The low applied force of piezoelectric actuators comprising low-temperature processable piezoelectric materials results in relatively low applied fluid pressures, which partially or completely alleviates the problem of acoustic crosstalk (i.e., adjacent actuators and fluid chambers interacting with each other through fluid pressure waves). The low level of acoustic crosstalk in turn allows for close integration of adjacent ejectors for compact device construction.

[0053] All of the multiple drop emitters of the device may be provided on a single drop emitter chip, for example on a single substrate.

[0054] The nozzle portion of each drop emitter and the piezoelectric actuator may be integrally formed during the manufacturing process.

[0055] The device may further include a drive circuit that controls operation of the piezoelectric actuators in response to the received control signals. Thus, the piezoelectric actuators may be individually actuated by the drive circuit. The drive circuit may be at least partially fabricated together with the piezoelectric actuators. Thus, many of the components required to provide and control the multiple drop emitters may be integrally formed, rather than having to separately form each drop emitter or separately apply drive circuitry to multiple pre-formed drop emitters, advantageously reducing the manufacturing costs of the device.

[0056] The plurality of droplet emitters may be at least four droplet emitters. The plurality of droplet emitters may be at least 25 droplet emitters. The plurality of droplet emitters may be at least 100 droplet emitters. The plurality of droplet emitters may be at least 500 droplet emitters. The plurality of droplet emitters may be less than 10,000 droplet emitters. The plurality of droplet emitters may be less than 1,000 droplet emitters. Thus, an aerosol having a relatively high density of droplets can be generated.

[0057] Multiple droplet emitters may be arranged to provide a grid arrangement of nozzle outlets, such that the droplets generated have a particularly predictable distribution, making it easier to generate an aerosol with a desired set of properties, such as droplet density.

[0058] The plurality of droplet ejectors may be arranged to provide a regular array of nozzle outlets. The plurality of droplet ejectors may define a substantially rectilinear array, such as a rectangular or square array. In some examples, the plurality of droplet ejectors may define a substantially square array, such as a substantially parallelogram array.

[0059] The apparatus further comprises a signal generator configured to generate a drive signal having a repeating waveform, and a drive circuit configured to relay the drive signal through a plurality of switches to the piezoelectric actuators and control the plurality of switches to selectively apply the drive signal to individual piezoelectric actuators to eject droplets of liquid, The drive signal may be determined to cause the piezoelectric actuators to eject droplets of different volumes and / or velocities as indicated by the control signals.

[0060] At least one of the plurality of switches may be associated with a plurality of piezoelectric actuators. Therefore, at least one of the switches can be used to control multiple piezoelectric actuators. In other words, a drive signal can be relayed to multiple piezoelectric actuators through a single switch. In this way, the total number of switches required to control a given number of piezoelectric actuators can be less than the number of piezoelectric actuators. This is because the inventors recognized that individual and independent control of all piezoelectric actuators is not necessary for an aerosolizer. Therefore, reducing the total number of switches required can reduce manufacturing costs and complexity compared to providing a dedicated switch for every piezoelectric actuator. At least 50% of the plurality of switches may be associated with a respective one of the plurality of piezoelectric actuators. Each switch of the plurality of switches may be associated with a respective one of the plurality of piezoelectric actuators. It is understood that a first plurality of piezoelectric actuators associated with a first switch of the plurality of switches is typically mutually exclusive with a second plurality of piezoelectric actuators associated with a second switch of the plurality of switches. The first plurality of piezoelectric actuators and the second plurality of piezoelectric actuators are respective subsets of the plurality of piezoelectric actuators. There may be multiple mutually exclusive groups of piezoelectric actuators in the plurality of piezoelectric actuators, each group associated with a distinct respective switch of the plurality of switches. There may be at least three groups.

[0061] At least one of the plurality of piezoelectric actuators may be associated with only one switch. Thus, typically, multiple switches are not connected to the same piezoelectric actuator. At least 50% of the plurality of piezoelectric actuators may each be associated with only one switch. Each piezoelectric actuator may be associated with only one switch. In other words, the number of switches in the plurality of switches may be less than the number of piezoelectric actuators in the plurality of piezoelectric actuators.

[0062] It is understood that each switch of the plurality of switches is any circuit element (e.g., electrical component) that is electronically actuable between a closed state and an open state in response to a control signal applied to the switch. Each switch may comprise (or be) a switchable circuit element, such as a semiconductor component, e.g., a transistor.

[0063] Preferably, the device includes a drive circuit configured to relay the drive signal. In other words, the drive circuit can be part of the device. Furthermore, the wiring complexity of the device can be reduced because separate control wiring to each piezoelectric actuator only needs to be provided from the drive circuit and not internal to the device. Control commands for any piezoelectric actuator of the device can be provided to the device via a single wiring connection to the drive circuit on the device (if they need to be received externally).

[0064] In some embodiments, the drive circuitry may comprise CMOS circuitry (ie, complementary metal oxide semiconductor) and a plurality of circuit elements, each associated with a drop emitter.

[0065] In some embodiments, the drive circuitry may comprise CMOS circuitry (ie, complementary metal oxide semiconductor) and a plurality of circuit elements associated with a plurality of drop emitters.

[0066] Each drop emitter may be associated with only one circuit element, or each circuit element may be associated with multiple drop emitters.

[0067] The drive circuitry may be integrally formed with the nozzle portion. In other words, the drive circuitry, nozzle portion, and (optionally) the piezoelectric actuator may be formed simultaneously, rather than requiring the assembly of multiple separately assembled components. By using an integrated circuit to provide the drive circuitry, the drive circuitry can be located adjacent to the nozzle portion, thereby making the device compact.

[0068] The drive circuit may include (a) a digital register. The drive circuit may include (b) a voltage trimming calculation circuit and / or register. The drive circuit may include (c) a temperature measurement circuit. The drive circuit may include (d) a fluid chamber fill detection circuit.

[0069] The digital register may be, for example, a shift register or a latch register. In operation, data may be stored in or read from a register in the drive circuit. In operation, temperature may be measured using a temperature-sensitive component of the temperature measurement circuit. In operation, the fill level of a fluid chamber may be measured.

[0070] The drive circuitry may be configured to modify the voltage pulses applied to one or more electrodes of the one or more piezoelectric actuators in response to data stored by the drive circuitry or measurements from one or more sensors typically present in the device. In operation, the drive circuitry may measure the voltage pulses applied to one or more electrodes of the one or more piezoelectric actuators in response to data stored by the drive circuitry or measurements from one or more sensors typically present in the device.

[0071] Modifying the voltage pulse may include shifting the voltage pulse in time. Modifying the voltage pulse may include compressing or expanding the voltage pulse. Modifying the voltage pulse may include changing the magnitude of the voltage pulse. Modifying the voltage pulse may include swapping between multiple (typically repetitive) sequences of received actuator drive pulses with different profiles. The drive circuitry is typically configured to modify the voltage pulses applied to one or more electrodes of one or more individual piezoelectric actuators in response to data about the individual piezoelectric actuators stored by the drive circuitry or measurements from one or more sensors.

[0072] The drive circuit may comprise at least one circuit element. The at least one circuit element may be an ejection transistor. The drive circuit may comprise at least one circuit element associated with a plurality of droplet emitters. The drive circuit may comprise a plurality of circuit elements, each circuit element associated with a plurality of droplet emitters. The drive circuit may comprise a plurality of circuit elements, each circuit element associated with at least one droplet emitter. The circuit elements may be ejection transistors.

[0073] The drive circuit may include a plurality of circuit elements. At least one of the plurality of circuit elements may be associated with a plurality of droplet emitters. At least 50% of the plurality of circuit elements may be associated with a respective plurality of droplet emitters. Each of the plurality of circuit elements may be associated with a respective plurality of droplet emitters.

[0074] At least one droplet emitter may be associated with only one circuit element. At least 50% of the plurality of droplet emitters may each be associated with only one respective circuit element. Each of the plurality of droplet emitters may each be associated with only one respective circuit element.

[0075] In some embodiments, the drive circuitry comprises a plurality of circuit elements each associated with a droplet emitter. The circuit elements may be ejection transistors. In such embodiments, the ejection transistors are typically in direct electrical communication with electrodes of the piezoelectric actuator (not through switched semiconductor junctions). In operation, the ejection transistors may be controlled such that a potential output from the ejection transistor is applied directly to the electrodes of the piezoelectric actuator.

[0076] The drive circuitry may be configured to receive input control signals from outside the plurality of droplet emitters, such as from outside the device, and to output actuator control signals to each of the plurality of actuators to control the ejection of droplets from the plurality of nozzle outlets.

[0077] The device may further comprise an electrical input for receiving an actuator drive pulse.In operation, the device may receive an actuator drive pulse.

[0078] The device may include a controller for controlling the device. The controller may include one or more microcontrollers or microprocessors, which may be integrated or distributed, in communication with or including memory for storing program code.

[0079] The control unit may include a signal generator configured to generate (typically a series of) actuator drive pulses. Each device typically includes an electrical input connected to the control unit that receives the actuator drive pulses. In operation, the device assembly may generate (e.g., in the control unit) and conduct the actuator drive pulses to the device via the electrical connection.

[0080] The actuator drive pulse is typically an analog signal and typically includes a periodically repeating voltage waveform.

[0081] The drive circuit may be configured to switch at least one electrode of the plurality of piezoelectric actuators or each of the plurality of piezoelectric actuators in connection with or disconnection from the received actuator drive pulses, thereby selectively actuating the piezoelectric actuators. In operation, the device may switch at least one electrode of the plurality of piezoelectric actuators or each of the plurality of piezoelectric actuators in connection with or disconnection from the received actuator drive pulses, thereby selectively actuating the piezoelectric actuators.

[0082] The controller may comprise one or more pulse generators that generate a plurality of series of actuator drive pulses, the electrical inputs of the plurality of droplet emitters may receive the plurality of series of actuator drive pulses (generated by the one or more pulse generators) through a plurality of electrical connections to the controller, and the drive circuitry may be configured to switch at least one electrode of the plurality of piezoelectric actuators, or each of the plurality of piezoelectric actuators, to a received actuator drive pulse selected from a plurality of different received series of actuator pulses. In operation, the device may generate (e.g., in the controller) a plurality of different series of actuator drive pulses and conduct them to the plurality of droplet emitters via separate electrical connections, and switch at least one electrode of the plurality of piezoelectric actuators, or each of the plurality of piezoelectric actuators, to one or more received actuator drive pulses received from a variable (and selectable) one of the plurality of different series of actuator drive pulses.

[0083] The selection of which of the received series of actuator pulses the at least one electrode of a piezoelectric actuator is connected to may be determined in response to stored data specific to each piezoelectric actuator and / or in response to operational measurements of each piezoelectric actuator. Thus, in some embodiments, the drive circuitry typically selects whether each piezoelectric actuator will eject a droplet at each of a series of periodic droplet ejection decision points. A decision point refers to a time before the start of an actuator drive pulse at which a decision is made as to whether to transmit that actuator drive pulse to at least one electrode of a particular piezoelectric actuator.

[0084] Typically, the actuator drive pulse is periodically repeated. The actuator drive pulse may be amplified by the control unit. The actuator drive pulse may not be amplified by the device. The device may not generate the actuator drive pulse.

[0085] Typically, pulses from a pulse generator are conducted to multiple control circuits, so a single pulse generator circuit may drive multiple piezoelectric transducers on the same substrate.

[0086] The digital actuation control signals are typically received from a controller, typically via one or more flexible connectors, and may be received in serial form and converted to parallel control signals using shift registers within the driver circuitry.

[0087] The control unit includes a pulse generator configured to generate actuator drive pulses that are conducted to the plurality of droplet emitters and digital control signals that are conducted to the plurality of droplet emitters, the digital control signals being processed by drive circuitry of the device to determine actuator drive pulses that are conducted to at least one electrode of a piezoelectric actuator of the plurality of droplet emitters to cause the ejection of a droplet.

[0088] In operation, the device may generate (e.g., in a control unit) actuator drive pulses and digital control signals, conduct both the actuator drive pulses and the digital control signals to a drive circuit for the device, which processes the digital control signals and, in response, conducts selected actuator drive pulses to at least one electrode of a piezoelectric actuator of a plurality of droplet ejectors to cause the ejection of droplets.

[0089] Thus, analog actuator drive pulses and digital control signals are typically input by the drive circuitry, which typically uses the digital control signals to selectively switch the analog actuator drive pulses, thereby selectively transmitting them to the piezoelectric actuators.

[0090] In some embodiments, the drive circuitry is configured to switchably connect one or more grounds and a single fixed non-zero voltage line, or multiple fixed voltage lines of different voltages (one or more of which may be ground), to one or both electrodes of the piezoelectric actuator to eject droplets of liquid. For example, the drive circuitry may switch the electrodes between connection to ground and connection to a fixed voltage or multiple fixed voltage lines of different voltages, and back to ground again, to eject droplets of liquid.

[0091] Switching the electrodes between connection to ground and a fixed voltage, or between fixed voltage lines, may involve operating a latch.

[0092] The drive circuitry may be configured to individually and selectively actuate at least twice the number of piezoelectric actuator elements as the number of signal conductors over which the drive circuitry receives actuation control signals.

[0093] The drive circuitry may be configured to individually and selectively actuate at least 128 (or at least 256) piezoelectric actuator elements, and the drive circuitry may receive actuation control signals over up to 64 (or up to 32) signal conductors.

[0094] The drive circuitry may include a serial-to-parallel converter circuit configured to convert digital signals received in serial form over one or more signal conductors into selections of piezoelectric actuators that are activated to eject droplets simultaneously (i.e., in parallel), and the serial-to-parallel converter circuitry typically includes one or more shift registers.

[0095] One of the one or more liquids may be a non-aqueous solution. In other words, at least one of the one or more liquids may include a liquid other than water. Each of the one or more liquids may be a non-aqueous solution.

[0096] The device may be fixedly mounted to a support member. The device may be fixedly mounted inside a reaction chamber or to a wall of a building.

[0097] The apparatus may be industrial apparatus. Industrial apparatus is understood to be apparatus used in an industrial process, such as a chemical reaction process. An industrial process is understood to be any process that typically produces an item (e.g., a product or material). Typically, an industrial process is carried out on a large scale.

[0098] The power supply may be mains powered, so the device does not need to be battery powered.

[0099] The device may comprise an airflow generator that entrains the generated aerosol and carries the aerosol away from the device. The airflow generator may be a fan.

[0100] In one embodiment, the aerosolization device may be an air purifier.

[0101] The present disclosure further extends to a liquid adapted for use with the devices described herein. The present disclosure also extends to a refill capsule for use with the devices described herein. The refill capsule may contain a liquid.

[0102] The present disclosure also extends to a method of controlling an apparatus for aerosolizing a liquid as described herein. The apparatus is substantially the same as previously described herein. The method includes receiving a control signal indicating a request to initiate aerosolization and causing the apparatus to eject a plurality of droplets of the liquid. The plurality of droplets is ejected by actuation of a plurality of droplet ejectors, for example, by applying a drive waveform as described herein (or another drive waveform) to piezoelectric actuators of the plurality of droplet ejectors. In another aspect, the present disclosure can also be considered to extend to a method of aerosolizing a liquid using an apparatus as described herein. [Brief explanation of the drawings]

[0103] [Figure 1] 1 is a perspective view of an apparatus for aerosolizing a liquid according to an embodiment of the present invention. [Figure 2]1 is a cross-sectional view of an apparatus for aerosolizing a liquid according to an embodiment of the present invention. [Figure 3] FIG. 1 is a perspective view of an aerosolizer tip according to an embodiment of the present invention. [Figure 4] 4 is a top view of a portion of the aerosolizer chip of FIG. 3, focusing on a subset of the plurality of droplet emitters of the aerosolizer chip of FIG. 3. [Figure 5] FIG. 5 is a perspective cross-sectional view of one of the droplet emitters shown in FIG. 4. [Figure 6] FIG. 1 is a schematic diagram illustrating an arrangement of a piezoelectric actuator, a nozzle portion, and a drive circuit as disclosed herein. [Figure 7] 7(a) and 7(b) show actuator states for a piezoelectric actuator as used in an embodiment of the present invention. [Figure 8] 4A-4C show possible drive waveforms for driving a piezoelectric actuator according to an embodiment of the present invention. [Figure 9] 1 illustrates a simplified manufacturing process flow for forming a droplet emitter according to an embodiment of the present invention. [Figure 10] 1 is a system diagram of an apparatus for aerosolizing a liquid according to an embodiment of the present invention. [Figure 11] 1 is a flowchart illustrating a method of operation of an apparatus for aerosolizing a liquid according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0104] Exemplary embodiments of the present invention will now be described with reference to the following drawings.

[0105] FIG. 1 is a perspective view of a device for aerosolizing a liquid according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the device shown in FIG. 1. Device 100 comprises a housing 102 that encloses the internal components of device 100. Housing 102 comprises a front portion 104 in the form of a front sidewall 104 and an upper portion 106. Upper portion 106 of housing 102 is movable (e.g., removable) relative to front portion 104 of the housing to expose an opening to cavity 110 (best shown in FIG. 2). Cavity 110 can receive and store liquid to provide the input for device 100. Device 100 further comprises an aerosol outlet 108. Aerosol outlet 108 is defined by an aerosol outlet wall 109 that extends inwardly into housing 102 from an opening defined by front portion 104 of housing 102 and is in fluid communication with the external environment through aerosol outlet 108.

[0106] The aerosol outlet 108 is in fluid communication with the cavity 110 via a droplet ejection portion 112. As shown in Figure 2, the droplet ejection portion 112 includes a liquid channel 124 that directs liquid from the cavity 110 to an aerosolizer tip 126, which includes multiple droplet ejectors (also part of the droplet ejection portion 112, but not shown in Figures 1 and 2). When the multiple droplet ejectors are operated, multiple droplets are generated from the liquid in the cavity 110 and the liquid channel 124 and ejected into the aerosol outlet 108. The multiple droplet ejectors are further described with reference to additional figures below.

[0107] Device 100 further includes control circuitry 114 configured to control aerosolization by providing control signals to the plurality of droplet emitters. The control circuitry typically includes a circuit board 115 having electronic components mounted thereon and includes a processor 116 in the form of a microprocessor 116, such as an integrated circuit chip 116. Control signals for the plurality of droplet emitters are communicated from control circuitry 114 via wired connections 118. As described below, aerosolizer chip 126 may itself include additional control circuitry for converting control signals received from control circuitry 114 via wired connections 118 into individual control signals for directly controlling each respective droplet emitter. In particular, multiple control circuits may be provided on aerosolizer chip 126, with each droplet emitter having its own dedicated control circuit.

[0108] The device 100 further includes a switch 120 mounted on the front portion 104 of the housing 102 and an external electrical connector 122 mounted on the housing 102. Although not shown, the switch 120 and the electrical connector 122 are each electrically connected to the control circuit 114.

[0109] It will be appreciated that one or more gas inlets (not shown) are provided in the aerosol outlet wall 109 to provide fluid communication with the external environment, thus allowing gas to flow through the aerosol outlet 108, as will be described below.

[0110] The operation of device 100 to generate a liquid aerosol will now be described. In the case of a pre-filled device 100 in which the cavity 110 is pre-filled with liquid, device 100 is oriented so that the liquid enters droplet ejection portion 112 through liquid channel 124 and contacts the side of the aerosolizer tip 126 exposed to liquid channel 124. Device 100 is activated via electrical switch 120 to operate control circuit 114 in an operational configuration. In the operational configuration, control circuit 114 transmits control signals to the multiple droplet ejectors, causing the multiple droplet ejectors to eject multiple droplets of liquid into aerosol outlet 108. A gas flow is supplied to aerosol outlet 108 via one or more air inlets. The liquid aerosol droplets ejected from the multiple droplet ejectors into aerosol outlet 108 are entrained in the gas flow and thus move from aerosol outlet 108 to the external environment.

[0111] The device 100 can then be deactivated using the switch 120 .

[0112] It will be appreciated that the control signals sent from control circuitry 114 to aerosolizer tip 126 may be determined based on the desired regimen of liquid stored in cavity 110. The desired regimen (or data indicative thereof) is typically communicated to control circuitry 114 via electrical connector 122. While device 100 shown in Figures 1 and 2 is refillable, it will be appreciated that a non-refillable (i.e., single-use) version may be desirable in certain applications. To refill device 100 with liquid, upper portion 106 of housing 102 is partially, or in some cases completely, removed to allow additional liquid to be added to cavity 110.

[0113] Figure 3 is a perspective view of an aerosolizer chip according to an embodiment of the present invention. Figure 4 is a top view of a portion of the aerosolizer chip of Figure 3, focusing on a subset of the droplet emitters of the aerosolizer chip of Figure 3. Figure 5 is a perspective cross-sectional view of one of the droplet emitters shown in Figure 4. The aerosolizer chip 226 shown in Figures 3-5 is an implementation of the aerosolizer chip 126 of Figures 1 and 2.

[0114] The aerosolizer chip 226 includes a substrate 240 in the form of a silicon substrate 240 having disposed thereon a plurality of droplet emitters 242. The plurality of droplet emitters 242 are arranged in a plurality of rows, including a first row 244 and a second row 246. Each row is parallel to each other and aligned with each other, such that the rows of the plurality of droplet emitters 242 are arranged in a rectangular grid.

[0115] The aerosolizer chip 226 further includes a plurality of lower portion bond pads 248 aligned perpendicular to the row of the plurality of droplet emitters 242 and positioned adjacent a first side of the plurality of droplet emitters 242 for communicating control signals between the plurality of droplet emitters 242 and additional control circuitry (not shown in FIG. 3 ) located separately from the aerosolizer chip 226. The aerosolizer chip 226 further includes a plurality of upper portion bond pads 250 aligned parallel to the plurality of lower portion bond pads 248 and positioned adjacent a second side of the plurality of droplet emitters 242. The plurality of upper portion bond pads 250 are spaced apart from the plurality of lower portion bond pads 248. The plurality of upper portion bond pads 250 are for communicating control signals between the plurality of droplet emitters 242 and additional control circuitry (not shown in FIG. 3 ) located separately from the aerosolizer chip 226. The first and second sides are opposed to one another, and an array of droplet ejectors 242 extends from the first side to the second side. The plurality of lower portion bond pads 248 includes a first lower portion bond pad 252 that communicates control signals between the first two columns 244, 246 of droplet ejectors 242 and additional control circuitry located separately from the aerosolizer chip 226 (not shown in FIG. 3 ). The plurality of upper portion bond pads 250 includes a first upper portion bond pad 254 that communicates control signals between the first two columns 244, 246 of droplet ejectors 242 and additional control circuitry located separately from the aerosolizer chip 226 (not shown in FIG. 3 ).

[0116] The aerosolizer chip 226 further comprises a plurality of lower portion interconnects 258 extending between the plurality of lower portion bond pads 248 and the plurality of drop emitters 242 to provide electrical communication therebetween. In this manner, control and / or power signals received at the plurality of lower portion bond pads 248 can be communicated to the plurality of drop emitters 242. Similarly, feedback signals from the plurality of drop emitters 242 can be communicated to the plurality of lower portion bond pads 248 via the plurality of lower portion interconnects 258. The plurality of lower portion interconnects 258 comprises a first lower portion interconnect 260 extending between the first lower portion bond pad 252 and the first and second columns 244, 246 of the plurality of drop emitters 242. The first lower portion interconnect 260 comprises a trunk portion 260A extending from the first lower portion bond pad 252, a first branch portion 260B extending from the aforementioned trunk portion 260A to the first row 244 of the plurality of droplet emitters 242, and a second branch portion 260C extending from the aforementioned trunk portion 260A to the second row 246 of the plurality of droplet emitters 242.

[0117] The aerosolizer chip 226 further comprises a plurality of upper portion interconnects 262 extending between the plurality of upper portion bond pads 250 and the plurality of drop emitters 242 and providing electrical communication therebetween. In this manner, control signals and / or power signals received at the plurality of upper portion bond pads 250 can be communicated to the plurality of drop emitters 242. Similarly, feedback signals from the plurality of drop emitters 242 can be communicated to the plurality of upper portion interconnects 262 via the plurality of upper portion interconnects 262. The plurality of upper portion interconnects 262 comprises a first upper portion interconnect 264 extending between the first upper portion bond pad 254 and the first and second columns 244 and 246 of the plurality of drop emitters 242 and providing electrical communication therebetween. The first upper portion interconnect 264 comprises a trunk portion 264A extending from the first upper portion bond pad 254, a first branch portion 264B extending from the trunk portion 264A to a first row 244 of the plurality of droplet emitters 242, and a second branch portion 264C extending from the trunk portion 264A to a second row 246 of the plurality of droplet emitters 242.

[0118] The second column 246 of the plurality of droplet emitters 242 includes a droplet emitter 270 having an actuator portion 272 (best shown in FIGS. 4 and 5 ). The actuator portion 272 is in electrical communication with the second branch portion 260C of the first lower portion interconnect 260 via a lower portion metallization contact 274 of the droplet emitter 270, and is in electrical communication with the second branch portion 264C of the first upper portion interconnect 264 via an upper portion metallization contact 276 of the droplet emitter 270. The droplet emitter 270 further includes an outer passivation layer 278 that encases and electrically stabilizes the actuator portion 272. The lower portion metallization contact 274 and the upper portion metallization contact 276 are in electrical communication with the actuator portion 272 through holes in the outer passivation layer 278 through which the lower portion metallization contact 274 and the upper portion metallization contact 276 pass.

[0119] The actuator portion 272 comprises a lower electrode 280 in electrical communication with the lower portion metallized contact 274 and an upper electrode 282 in electrical communication with the upper portion metallized contact 276, and a piezoelectric layer 284 disposed therebetween can be subjected to a potential difference to contract or expand the piezoelectric layer 284, thereby actuating the actuator portion 272 in a direction transverse to the plane of the piezoelectric layer.

[0120] The droplet emitter 270 is formed on an underlying passivation layer 286 in the form of a nozzle-defining layer 286 that defines an inner portion of a nozzle outlet 290. An outer portion of the nozzle outlet 290 is defined by a protective front surface 288 that covers and protects the droplet emitter 270 and is provided to abut a surface 286A of the underlying passivation layer 286.

[0121] A droplet emitter cavity 292 is defined within the droplet emitter 270 in fluid communication with the nozzle outlet 290. In operation, operation of the droplet emitter 270 causes liquid within the droplet emitter cavity 292 to be expelled through the nozzle outlet 290, as described below with reference to Figure 6.

[0122] FIG. 6 is a schematic diagram illustrating the configuration of a piezoelectric actuator, nozzle portion, and drive circuitry of a droplet emitter used in an embodiment of the present invention. While FIG. 6 is a schematic illustration, it is understood that, unless otherwise described below, the configuration and operation of the droplet emitter are similarly applicable to the embodiments described above with reference to FIGS. 3-5, provided they are not substantially inconsistent. The droplet emitter 301 shown in FIG. 6 includes a silicon substrate 340 having a drive circuit 330 formed on a first surface 340A of the silicon substrate 340. The drive circuit 330 is for receiving control signals and generating drive signals to control operation of the piezoelectric actuator. The drive circuit 330 is typically an integrated circuit 330 in the form of a CMOS circuit 330. Those skilled in the art will appreciate that a CMOS circuit includes both doped regions of the substrate and metallization layers and interconnects formed on the first surface of the substrate. Formed on the first surface 340A of the silicon substrate 340 are several layers, generally designated 332. Layer 332 is a CMOS metallization layer and includes metal conductive traces and a passivation insulator such as SiO2, SiN, or SiON. Droplet emitter 301 further includes an actuator portion 372 in the form of a piezoelectric actuator 372 comprising a piezoelectric layer 384, which in this example is formed from AlN or ScAlN, but may be formed from another suitable piezoelectric material that can be processed at temperatures below 450°C. Piezoelectric actuator 372 forms a diaphragm with a layer of material such as silicon, silicon oxide, silicon nitride, or derivatives thereof, and has a passivation layer 386 (sometimes referred to as a nozzle outlet defining layer 386 or nozzle plate 386) that prevents an applied electrical potential from contacting the liquid.

[0123] At least one metallization layer 332 includes interconnects that conduct signals from an external control to a first portion 330A of the drive circuit 330 via bond pads 352, and from a second portion 330B and a third portion 330C of the drive circuit 330 via electrical interconnects 360 to the piezoelectric actuator 372, specifically the bottom electrode 380 and top electrode 382 that are arranged to apply a potential difference across the piezoelectric layer 384 to activate it. An opening 384A is defined in the piezoelectric layer 384 for passing the electromagnetic interconnect 360 between the third portion 330C of the drive circuit 330 and the top electrode 382.

[0124] In some embodiments, bond pad 352 and second portion 330A of drive circuit 330 may be associated with a single drop emitter. In other embodiments, bond pad 352 and second portion 330A of drive circuit 330 may be associated with two or more drop emitters. In such embodiments, second portion 330A of drive circuit 330 typically comprises switchable circuit elements to provide switchable drive signals to the associated drop emitters.

[0125] The piezoelectric actuator 372 and associated nozzle outlet-defining layer 386 define walls of a droplet emitter cavity 392 in the form of a liquid chamber 392, which receives liquid from a liquid chamber inlet 394 that is in fluid communication with at least one of the one or more inputs described above. The liquid chamber 392 is further in fluid communication with a nozzle outlet 390, which ejects the liquid. The piezoelectric actuator 372 and the nozzle outlet-defining layer 386 further define walls of the nozzle outlet 390. The liquid chamber inlet 394 forms at least a portion of a liquid manifold that provides a liquid communication path between the cavity (not shown in FIG. 6 ) and the nozzle outlet 390 (as well as additional nozzle outlets, not shown in FIG. 6 in the exemplary embodiment), via the liquid chamber 392. The liquid chamber inlet 394 is defined by the silicon substrate 340, the metallization layer 332, and the nozzle outlet-defining layer 386. A protective front surface 388 provides the outer surface of drop emitter 301, covers and protects piezoelectric actuator 372, and abuts surface 386A of nozzle outlet-defining layer 386. Protective front surface 388 is perforated to define nozzle outlet 390 (as well as further nozzle outlets not shown in FIG. 6 ). Piezoelectric actuator 372, liquid chamber 392, and nozzle outlet 390 together form drop emitter 301.

[0126] Typically, CMOS control circuits contain patterned regions of doped silicon and layers of metallization. The number of metallization layers depends on the complexity of the CMOS control circuit, but three layers are sufficient for many applications.

[0127] For clarity, only one nozzle outlet 390 and piezoelectric actuator 372 is shown in Figure 6, however, it will be understood that multiple nozzle outlets 390 and corresponding piezoelectric actuators 372 are typically provided together as multiple droplet emitters on the same substrate 340. Each piezoelectric actuator 372 is configured to control the ejection of liquid from a respective nozzle outlet 390.

[0128] The droplet ejector 301 of FIG. 6 ejects liquid from a nozzle outlet 390. The piezoelectric actuator 372 is located within a nozzle outlet-defining layer 386 that moves with the nozzle outlet 390. Thus, the surface of the liquid chamber 392 containing the nozzle outlet 390 is the moving surface during actuation. This contrasts with devices in which the surface containing the nozzle outlet is stationary and another surface, e.g., the opposing surface, is actuated. As a result, less actuation force is required to displace the liquid within the nozzle outlet portion. The liquid is then ejected from the nozzle outlet primarily due to inertial forces (i.e., inertial ejection), which may also be referred to as inertial ejection or inertial-mode ejection. Liquid ejection is primarily determined by the density and viscosity of the liquid, not compressibility, as occurs when another surface is actuated to displace and eject the entire chamber.

[0129] In use, the droplet emitter 301 is mounted on a support that includes a liquid manifold that supplies liquid to the liquid chamber inlet 394. The fluid pressure at the liquid chamber inlet 394 is typically slightly negative, causing the liquid chamber 392 to "prime" or fill with liquid, typically by capillary action due to surface tension. The nozzle outlet 390 primes the liquid to the exterior surface of the protective front face 388 by capillary action once the liquid chamber 392 is primed. The combination of the negative fluid pressure and the geometry of the nozzle outlet 390 prevents liquid from migrating beyond the nozzle outlet 390 onto the exterior surface of the protective front face 388.

[0130] In some embodiments, the second portion 330B and the third portion 330C of the drive circuit 330 control the application of voltage pulses to the bottom electrode 380 and the top electrode 382, ​​respectively, according to timing signals from the first portion 330A of the drive circuit 330. In other embodiments, the second portion 330B and the third portion 330C of the drive circuit 330 relay the voltage pulses generated in the first portion 330A of the drive circuit 330 to the bottom electrode 380 and the top electrode 382, ​​respectively. Application of an electrode voltage to the piezoelectric layer 384 generates an electric field. This application of the electric field causes the piezoelectric layer 384 to deform. The deformation can be either tensile or compressive, depending on the orientation of the electric field relative to the polarization direction of the piezoelectric material. The induced strain caused by the expansion or contraction of the piezoelectric layer 384 induces a strain gradient across the thickness of the nozzle plate 386, the piezoelectric actuator 372, and the protective front surface 388, resulting in movement or displacement in a direction parallel to the axis defined by the nozzle outlet 390.

[0131] JPEG2026500658000002.jpg39166

[0132] 6 is illustrated as showing a single droplet emitter 301, it will be appreciated that multiple piezoelectric actuators 372 may be provided connected to a single bond pad 352 and first portion 330A of drive circuit 330. In such an embodiment, each piezoelectric actuator 372 is provided with a second portion 330B and a third portion 330C of drive circuit 330, with the multiple second portions 330B and third portions 330C of the drive circuit connected together to first portion 330A of drive circuit 330. First portion 330A of drive circuit 330 includes switchable components that generate drive signals that are relayed to each of the multiple piezoelectric actuators 372, such that the multiple piezoelectric actuators 372 connected to the single first portion 330A of drive circuit 330 are controlled together.

[0133] Application of a DC or steady electric field can cause a net positive or negative displacement of the nozzle plate 386. A positive displacement of the nozzle plate is shown in Figure 7(a).

[0134] Application of a pulsed electric field can cause the nozzle plate 386 to vibrate. The vibration of the nozzle plate 386 induces pressure in a liquid chamber 392 below the nozzle plate 386, causing droplets to be expelled from the nozzle outlet 390. The frequency and amplitude of the vibration of the nozzle plate 386 depend primarily on the mass and stiffness properties of the nozzle plate 386, the piezoelectric actuator 372, and the protective front surface 388, the properties of the liquid (e.g., density, viscosity (Newtonian or non-Newtonian) and surface tension), the geometry of the nozzle outlet 390 and liquid chamber 392, and the configuration of the drive pulse to the piezoelectric actuator.

[0135] Figures 7(a) and 7(b) show the movement of a piezoelectric actuator. A voltage pulse is applied to the bottom electrode 380 and top electrode 382, ​​causing the movement shown. The electric field direction is labeled E and the deflection is labeled X.

[0136] 7(a), application of a steady-state or DC electric field between the electrodes causes the piezoelectric layer 384 to contract, causing the nozzle plate 386 to deflect at steady state away from the liquid chamber inlet 394. The fluid pressure below the nozzle plate 386 is the same as the supply pressure from the liquid chamber inlet 394. Strain energy is stored in the nozzle plate 386, the piezoelectric actuator 372, and the protective front surface 388.

[0137] The electric field is then removed and a reverse electric field pulse is applied, which releases the stored strain energy and causes additional expansion of the piezoelectric material in the piezoelectric layer 384. As shown in Figure 7(b), the piezoelectric actuator 372 moves toward the liquid chamber inlet 394. This creates a positive pressure at the liquid chamber inlet 394 and in the nozzle area, causing a droplet to be ejected from the nozzle outlet 390. The reverse electric field pulse may be applied immediately after the removal of the DC pulse or with a slight delay.

[0138] When the electric field applied to the piezoelectric layer 384 is finally removed, the nozzle plate 386 returns to a position free of induced strain.

[0139] By controlling two electrodes on any nozzle-actuator-nozzle plate in this device, the direction of the applied electric field can be easily switched with respect to the intrinsic polarization of the piezoelectric material. This allows the device to utilize the strain energy stored in the nozzle plate 386 and piezoelectric actuator 372 structure. The release and integration of this stored strain energy enhances the volumetric displacement during the drop-ejecting vibration of the nozzle plate. This increase in volumetric displacement is achieved without increasing the applied voltage and electric field.

[0140] The DC electric field configuration described above can also be replaced with a pulsed electric field configuration. This configuration has the advantage of minimizing the effects of applied distortion over a longer period of time. An additional advantage of the dual-pulse approach is that it can be controlled by the timing of the electric field pulses. As shown in Figure 7(a), the application of the first pulse induces an oscillation that initially moves the nozzle plate away from the liquid inlet. This oscillation creates a negative fluid pressure below the nozzle plate, inducing a net liquid flow toward the nozzle and further enhancing the liquid ejection flow through the nozzle.

[0141] Figure 8 shows a possible drive waveform that can be used to drive the piezoelectric actuator described herein. The x-axis is time (microseconds, μs), the right y-axis is the signal amplitude (volts, V), and the left y-axis is the resulting displacement of the piezoelectric actuator (micrometers, μm). The signal starts with an initial voltage of 0 V at point A, rises first to a positive potential peak at point B (to deform the piezoelectric actuator in one direction), and then drops to a negative potential valley at point C (to deform the piezoelectric actuator more in the opposite direction). The signal is further ramped back to a positive potential peak at point D, and then ramped down to a magnitude of approximately 35 V and held there for approximately 1.2 μs from point E to point F. The signal is then ramped down to 0 V at point G and held there as shown at point H. Using a drive waveform of this shape, the actuator is displaced as shown by the dashed line in Figure 8, and a droplet is ejected between points E and G. Thus, it can be seen that the displacement of the piezoelectric actuator follows the initial increase in voltage amplitude of the input signal from point A to point E with a slight delay, and then increases in amplitude as the input signal increases. As the input signal drops to zero at point G, the displacement of the piezoelectric actuator decays. Of course, it will be appreciated that other drive waveforms can be used and may vary for different liquids and droplet emitter geometries.

[0142] Figure 9 illustrates stages in a simplified manufacturing process flow for forming a droplet emitter according to embodiments described herein. Droplet emitter 401 is substantially similar to droplet emitter 301 shown in Figure 6, except for differences described below. Similar features are similarly numbered, with the hundreds digit of the features in Figure 6 changed to a 4 in Figure 9 (e.g., nozzle plate 386 in Figure 6 is nozzle plate 486 in Figure 9). Specifically, droplet ejection portion 401 includes a silicon substrate 440, first and second portions 430A and 430B of drive circuitry 430, bond pads 452, nozzle plate 486, piezoelectric actuator 472, a protective front surface 488, a liquid chamber 492, and a liquid chamber inlet 494.

[0143] 9(A), the first manufacturing step is to create a driver circuit 430 and an interconnect layer 433, e.g., a CMOS driver circuit 430 and interconnect 433, on the surface of a silicon substrate 440. The CMOS driver circuit 430 is formed by standard processes, e.g., ion implantation into a p-type or n-type substrate, followed by creation of a wiring interconnect layer by standard CMOS fabrication processes (e.g., ion implantation, chemical vapor deposition (CVD), physical vapor deposition (PVD), etching, chemical mechanical planarization (CMP), and / or electroplating).

[0144] Subsequent fabrication steps define the configuration and structure of the droplet ejection device. Subsequent steps are selected so as not to damage the structures formed in previous steps. A key fabrication parameter is the peak processing temperature. Problems with CMOS processing at high temperatures include degradation of impurity (dopant) mobility and degradation of interconnect wiring schemes. While CMOS electronics are known to be able to withstand temperatures as high as 450°C, much lower temperatures (i.e., less than 300°C) are desirable for high yields.

[0145] 9(b), a nozzle plate 486, a piezoelectric actuator 472, a protective front surface 488, and bond pads 452 are formed on the interconnect layer 433. The nozzle plate 486 is deposited using a CVD or PVD process.

[0146] Forming CMOS compatible piezoelectric material within piezoelectric actuator 472 is particularly important since it is the key driving element of the actuator.

[0147] ZnO, AlN, and AlN compound (e.g., ScAlN) materials can be deposited using low-temperature PVD (e.g., sputtering) processes that do not require post-treatment such as annealing. These materials also do not require poling.

[0148] JPEG2026500658000003.jpg33166

[0149] The piezoelectric electrode material is deposited using a CMOS compatible process such as PVD (including low temperature sputtering). Typical electrode materials include titanium (Ti), platinum (Pt), aluminum (Al), tungsten (W) or alloys thereof. The electrodes of the piezoelectric actuator 472 are defined by standard patterning and etching methods.

[0150] The protective material can be deposited and patterned using spin and cure methods (suitable for polyimide or other polymeric materials). Some materials, such as PTFE, may require more specific deposition and patterning techniques.

[0151] The bond pads are deposited using methods such as CVD or PVD (eg, sputtering).

[0152] The liquid chamber and liquid chamber inlet are defined using high aspect ratio deep reactive ion etching (DRIE) techniques to the shape shown in Figure 9(c). The liquid chamber is aligned to the nozzle outlet using a front-to-back wafer alignment tool. The wafer may be attached to a handle wafer during the front-to-back alignment and etching process.

[0153] 10 is a schematic diagram of an apparatus for aerosolizing a liquid according to an embodiment of the present invention. The apparatus 500 comprises multiple components, including multiple droplet emitters 510 and a controller 520. The controller 520 is configured to exchange signals 515 with the multiple droplet emitters 510 and control the multiple droplet emitters 510 according to input signals received by the controller 520, for example, from a regimen preprogrammed into the apparatus 500. The controller 520 in this embodiment is implemented by one or more processors 530 and a computer-readable memory 540. The memory 540 stores instructions that, when executed by the one or more processors 530, cause the apparatus 500 to operate as described herein.

[0154] 11 is a flowchart illustrating a method for controlling a device for aerosolizing a liquid described herein. Method 600 is a method for controlling a device having multiple droplet emitters that generate an aerosol from a supply of liquid. Specifically, method 600 includes step 610 of receiving a control signal. The control signal may be received from a computer program stored in memory, may be received as a result of user input indicating a request to begin aerosolization, or may be received from an external device. Method 600 further includes step 620 of causing the device to eject multiple droplets of liquid. The ejection of the multiple droplets is caused by actuating the multiple droplet emitters, for example, by applying a drive waveform described herein (or another drive waveform) to piezoelectric actuators of the multiple droplet emitters.

[0155] In summary, the present disclosure provides an apparatus (100) for aerosolizing a liquid, comprising one or more inputs (110) and a plurality of droplet emitters (126) in fluid communication with the one or more inputs (110). Each droplet emitter comprises a nozzle portion and a piezoelectric actuator. The one or more inputs are for receiving one or more liquids. Each nozzle portion defines a nozzle outlet in fluid communication with the one or more inputs. Each piezoelectric actuator is operable to eject liquid received from one of the one or more inputs as one or more droplets from a respective nozzle outlet, thereby generating an aerosol including the one or more droplets ejected by each droplet emitter.

[0156] Throughout the description and claims, the terms "comprise" and "contain" and variations thereof mean "including but not limited to" and are not intended to exclude other elements, integers or steps. Throughout the description and claims, the singular encompasses the plural unless otherwise specified. In particular, where the indefinite article is used, it is understood that the plural as well as the singular is envisaged unless otherwise specified.

[0157] It is understood that any configuration, integer, feature, or grouping described in connection with a particular aspect, embodiment, or example of the invention is applicable to any other aspect, embodiment, or example described herein, except where incompatible therewith. All configurations and / or all steps of any disclosed method or process disclosed herein (including any accompanying claims, abstract, and drawings) may be combined in any combination, except mutually exclusive combinations. The invention is not limited to the details of the foregoing embodiments. The invention extends to any novel one or any novel combination of configurations, or any novel one or any novel combination of steps of any disclosed method or process, disclosed herein (including any accompanying claims, abstract, and drawings).

Claims

1. 1. A device for aerosolizing a liquid, comprising: one or more inputs for receiving one or more respective liquids; a plurality of droplet emitters in integral fluid communication with the one or more inputs, each droplet emitter comprising: a nozzle portion defining a nozzle outlet in fluid communication with one of the one or more inputs; a plurality of drop emitters including a piezoelectric actuator; Equipped with wherein each piezoelectric actuator is operable to eject a respective liquid received from said one of said one or more inputs as one or more droplets from a respective nozzle outlet, thereby generating a liquid aerosol including the one or more droplets ejected by each droplet ejector.

2. each of the plurality of droplet emitters defining only one nozzle outlet; The apparatus of claim 1 , wherein the nozzle outlet is in fluid communication with the one of the one or more inputs.

3. a storage portion defining one or more cavities for storing the one or more respective liquids; the one or more cavities are in fluid communication with each nozzle outlet and the one or more inputs; 3. The device of claim 1 or claim 2, optionally wherein the storage portion is removable.

4. a housing supporting the plurality of droplet emitters; 4. The device of claim 1, wherein the storage portion is optionally part of the housing.

5. an outlet portion defining an outlet through which the liquid aerosol can be output from the device; 5. The device of claim 1, wherein the outlet portion is optionally part of the housing.

6. a power supply circuit portion that supplies power to the piezoelectric actuator of each of the plurality of drop emitters; Optionally, the power supply circuit portion is supported by the housing; Additionally or alternatively, the apparatus according to any one of claims 1 to 5, further comprising a power supply for supplying power to the power supply circuit portion.

7. a switch for actuating the plurality of droplet emitters; 7. Apparatus according to any one of claims 1 to 6, wherein optionally the switch is a flow switch responsive to flow rate through the outlet.

8. a controller for controlling the operation of the plurality of droplet ejectors; Optionally, the control unit is configured to generate the liquid aerosol at a plurality of discrete times in response to one or more actuation signals; Further optionally, the one or more activation signals are received from a remote device remote from the apparatus; Additionally or alternatively, the first consecutive subset of the plurality of discrete times are regularly spaced; Additionally or alternatively, the one or more activation signals cause the liquid aerosol to be generated discretely or continuously for a period of more than 30 minutes; 8. The apparatus of claim 1, wherein the first contiguous subset of the plurality of discrete times optionally extends over a period of more than 30 minutes.

9. At least one of the plurality of nozzle outlets, e.g., more than 50%, or each of the plurality of nozzle outlets, has a maximum cross-sectional dimension of 100×10 －６ less than a meter (100 microns), Additionally or alternatively, at least one of the plurality of nozzle outlets, e.g., more than 50%, or each of the plurality of nozzle outlets, has a maximum cross-sectional dimension of at least 5×10 －６ 9. The device of claim 1, wherein the thickness is greater than 5 microns.

10. for each droplet emitter, the nozzle portion and the piezoelectric actuator are integrally formed during a manufacturing process; Additionally or alternatively, the apparatus according to any one of claims 1 to 9, further comprising a drive circuit for controlling operation of the piezoelectric actuator in response to one or more received control signals.

11. the drive circuit comprises a plurality of switchable circuit elements and is configured to control operation of the plurality of piezoelectric actuators via the plurality of switchable circuit elements to thereby eject droplets of the liquid; The apparatus of claim 10 , wherein at least one of the plurality of switchable circuit elements is configured to control operation of a subset of the plurality of piezoelectric actuators.

12. 12. The apparatus of claim 1, wherein the piezoelectric actuator is arranged around the nozzle outlet, and deformation of the piezoelectric actuator moves the nozzle portion.

13. the plurality of drop emitters is at least 100 drop emitters; 13. The apparatus of claim 1, wherein optionally, the plurality of droplet emitters is at least 500 droplet emitters.

14. 14. The apparatus of claim 1, wherein the plurality of droplet emitters are arranged such that the nozzle outlets are provided in a grid arrangement.

15. 15. The device of claim 1, wherein one of the one or more liquids is a non-aqueous solution.

16. 16. Apparatus according to any one of claims 1 to 15, wherein the apparatus is fixedly mounted to a support member.

17. 17. Apparatus according to any one of claims 1 to 16, wherein the apparatus is an industrial apparatus for use in an industrial process.

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