Abstract:
A nebulizer (1, 102) has a liquid reservoir (3, 112) for supply of liquid to be aerosolized to a first surface of a vibratable aperture plate (41) with apertures having a size in the range of 1µm to 10µm. A drive has a piezoelectric annular element on an aperture plate support to cause the aperture plate to vibrate at a drive frequency of 128kHz to cause droplets to separate from a side of the aperture plate opposed to the reservoir. An outlet conduit (6, 114) is for flow of droplets from the aperture plate. A sensor is arranged with an acoustic transducer in contact with the conduit outer surface to pick up an acoustic signal which is representative of a droplet plume in the conduit, and a processor analyses the signal to provide an output representative of a plume. The monitored acoustic signal frequency band is centred around half of the drive frequency because it takes on average more than one aperture plate cycle to separate a droplet.
Abstract:
An aperture plate (1) is attached at its rim (203) to a support washer (3) by adhesive. Anchor grooves (204) having a zig-zag pattern in plan are machined in the lower surface of the rim (203 of the aperture plate before application of the adhesive. The grooves (204) extend out to the edge of the aperture plate (1). The anchor grooves have a depth in the range of 10µm to 40µm, and a width in the range of 20µm to 150µm, and an angular pitch in the range of 2.5° to 12.5°. Excellent bonding strength is achieved for long term reliable attachment in an environment of high frequency vibration and moisture and chemical corrosion.
Abstract:
An aerosol delivery system has an aerosol generator with a vibrating aperture plate (10) and an actuator (11, 16, 17, 19), a controller (18, 19). The controller in real time monitors (201) the aerosol generator as it is driven for vibration of the aperture plate, and detects (202) a change in an electrical characteristic in response to a transition from a wet state to a dry state of the aperture plate. It automatically modifies (203, 205, 206), during the transition, operation of the aerosol generator in response to the detected change. The modification includes reducing applied power (203). The controller continues (204) to monitor during the transition, including monitoring the aperture plate for presence of residual liquid on the aperture plate first surface. The controller monitors at a number of drive frequencies and maintains data representing trends in a combination of the electrical characteristic signals at the different frequencies, and identifies a start of a transition if a calculated value rises above a threshold. There is one threshold for triggering a check scan for residual volume and a higher threshold to trigger an immediate shut down.
Abstract:
A high flow nasal therapy system (1) has a gas supply (2), a nebulizer (12), and a nasal interface (7). There are two branches (11, 10) and a valve (6) linked with the controller, the branches including a first branch (11) for delivery of aerosol and a second branch (10) for delivery of non-aerosolized gas. The controller controls delivery into the branches (11, 10), in which flow is unidirectional in the first and second branches, from the gas supply towards the nasal interface. The first branch (11) includes the nebulizer (12) and a line configured to store a bolus of aerosol during flow through the second branch (10). The valve (6) comprises a Y-junction between the gas inlet on one side and the branches on the other side.
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.
Abstract:
An aerosol delivery system (1) has a nebulizer (2) and a humidifier (7) providing a gas flow to the nebulizer. A controller varies humidity level of the gas flow to the nebulizer (2) so that if the nebulizer is not operating it has about 100% humidity and it is operating the value is less to allow for the humidification effect of the nebulizer. The control may be achieved by dynamically varying proportions of flow through a dry branch (10, 11) and a humidification branch (8, 7).
Abstract:
An aperture plate is manufactured by plating metal around a mask of resist columns (2) having a desired size, pitch, and profile, which yields a wafer about 60µm thickness. This is approximately the full desired target aperture plate thickness. The plating is continued so that the metal (3) overlies the top surfaces of the columns until the desired apertures (4) are achieved. This needs only one masking/plating cycle to achieve the desired plate thickness. Also, the plate has passageways (24) formed beneath the apertures (32), formed as an integral part of the method, by mask material removal. These are suitable for entrainment of aerosolized droplets exiting the apertures (32).