# US 11,998,678 B2 · End-of-dose detection in nebulizers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,998,678 B2 - Document ID: US11998678B2 - Status: Granted - Kind: B2 - Application number: 17/194,369 - Filed: 2021-03-08 - Published: 2021-06-24 - Granted: 2024-06-04 - Earliest claimed: 2015-09-29 - Assignees: Stamford Devices Limited - Applicants: Stamford Devices Limited - Inventors: Joseph Grehan; Michael Casey; Shaun Porter; Niall Smith - Web page: https://patentgrep.com/patent/US11998678B2 ## CPC - A61M 11/00: Sprayers or atomisers specially adapted for therapeutic purposes (in general B05B; {aerosol containers B65D83/14}) - A61M 11/005: {using ultrasonics (spraying or atomising liquids using ultrasonic vibrations in general B05B17/06)} - B05B 15/14: Arrangements for preventing or controlling structural damage to spraying apparatus or its outlets, e.g. for breaking at desired places; Arrangements for handling or replacing damaged parts - B05B 17/0646: {Vibrating plates, i.e. plates being directly subjected to the vibrations, e.g. having a piezoelectric transducer attached thereto} - B05B 17/0669: {Excitation frequencies} - B06B 1/0253: {taken directly from the generator circuit} - A61M 2205/3317: Electromagnetic, inductive or dielectric measuring means - A61M 2205/3386: Low level detectors - A61M 2205/50: with microprocessors or computers - A61M 2205/583: by visual feedback - B05B 12/081: {responsive to the weight of a reservoir or container for liquid or other fluent material; responsive to level or volume of liquid or other fluent material in a reservoir or container} - B06B 2201/77: Atomizers - A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)} - B05B: SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES (spray-mixers with nozzles B01F25/72; processes for applying liquids or other fluent materials to surfaces by spraying B05D) - B06B: METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, {e.g.} FOR PERFORMING MECHANICAL WORK IN GENERAL (for particular applications, see the relevant subclasses, e.g. B07B1/40, B23Q17/12, B24B31/06; measurement of mechanical vibrations G01H; in direction finding, locating, distance or velocity measuring G01S; {generating seismic energy G01V1/02}; control of mechanical vibrations in general G05D; sound-producing devices, e.g. bells, sirens, whistles G10K, {e.g. methods or devices for transmitting, conducting, or directing sound in general G10K11/00}; generation of electrical oscillations H03B; electromechanical resonators in general H03H; electromechanical transducers {for communication techniques, e.g. microphones, speakers} H04R) ## Abstract A digital processor of a nebulizer controller controls and monitors drive current (I) applied to an aperture plate. The drive current is detected as a series of discrete values at each of multiple measuring points, each having a particular drive frequency The processor in real time calculates a slope or rate of change of drive current with frequency and additionally determines a minimum value for drive current leading up to the peak value. The processor uses both the value of the minimum drive current during the scan and also the maximum slope value to achieve reliable prediction of end of dose, when the aperture plate becomes dry. ## Claims ### Claim 1 A nebulizer, comprising: a vibrating aperture plate; an actuator; and an aperture plate drive circuit having a controller, wherein the controller is configured to: measure drive current to the aperture plate; detect end-of-dose based on a minimum value of the drive current and a maximum rate of change of the drive current; and upon detection of end-of-dose, automatically stop operation of the actuator, and wherein the controller is further configured to detect the end-of-dose based on a ratio of the maximum rate of change and the minimum value of the drive current. ### Claim 2 (depends on 1) The nebulizer of claim 1, wherein the controller is configured to measure the drive current during a scan across a plurality of drive frequencies. ### Claim 3 (depends on 2) The nebulizer of claim 2, wherein the plurality of drive frequencies includes a drive frequency range of 128 kHz to 165 kHz. ### Claim 4 (depends on 2) The nebulizer of claim 2, wherein the controller is configured to initiate the scan in response to a trigger of possible end-of-dose. ### Claim 5 (depends on 4) The nebulizer of claim 4, wherein the trigger is a short scan with a smaller number of measuring points and which detects a change of drive current above a threshold. ### Claim 6 (depends on 5) The nebulizer of claim 5, wherein the threshold is above 5 mA. ### Claim 7 (depends on 1) The nebulizer of claim 1, wherein the minimum value of the drive current for end-of-dose corresponds to approximately less than 30% of a minimum value of the drive current for a wet state of the aperture plate. ### Claim 8 A method of operation of a controller of a nebulizer comprising a vibrating aperture plate, an actuator, and an aperture plate drive circuit, the method comprising: measuring drive current to the aperture plate at multiple discrete measuring points, each measuring point associated with a particular drive frequency; detecting end-of-dose based on a ratio of a maximum rate of change of the drive current and a minimum value of the drive current; and upon detection of end-of-dose, automatically stopping operation of the actuator. ### Claim 9 (depends on 8) The method of claim 8, wherein the plurality of drive frequencies includes a drive frequency range of 128 kHz to 165 kHz. ### Claim 10 (depends on 8) The method of claim 8, further comprising initiating a scan in response to a trigger of possible end-of-dose. ### Claim 11 (depends on 10) The method of claim 10, wherein the trigger is a short scan with a smaller number of measuring points and which detects a change of drive current above a threshold. ### Claim 12 (depends on 11) The method of claim 11, wherein the threshold is above 5 mA. ### Claim 13 (depends on 8) The method of claim 8, wherein the minimum value of the drive current for end-of-dose corresponds to approximately less than 30% of a minimum value of the drive current for a wet state of the aperture plate. ### Claim 14 A non-transitory computer readable medium comprising software code to perform a method of operation of a controller of a nebulizer comprising a vibrating aperture plate, an actuator, and an aperture plate drive circuit, when executing on a digital processor, the method comprising: measuring drive current to the aperture plate at multiple discrete measuring points, each measuring point associated with a particular drive frequency; detecting end-of-dose based on a ratio of a maximum rate of change of the drive current and a minimum value of the drive current; and upon detection of end-of-dose, automatically stopping operation of the actuator.