Multi-chamber therapeutic delivery device

A mist delivery device for delivering a mist for inhalation by a user, the mist delivery device comprising:

• a mist generator including:
• an air inlet port;
• a mouthpiece including a mist outlet port;
• a gas flow path from the air inlet port to the mist outlet port;
• a first liquid chamber containing a first liquid including a therapeutic;
• a second liquid chamber containing a second liquid;
• a first ultrasonic transducer including a first atomisation surface;
• a first capillary in contact with at least a portion of the first atomisation surface, the first capillary being absorbent and extending from the first liquid chamber to the first ultrasonic transducer;
• a second ultrasonic transducer including a second atomisation surface;
• and
• a second capillary in contact with at least a portion of the second atomisation surface, the second capillary being absorbent and extending from the second liquid chamber to the second ultrasonic transducer,
• wherein the device further comprises:
• a driver configured to generate a first AC drive signal and a second AC drive signal concurrently, the driver being coupled electrically to the first ultrasonic transducer and the second ultrasonic transducer, wherein:
• the first AC drive signal drives the first ultrasonic transducer to generate and transmit ultrasonic waves, the driver selecting a frequency of the first AC drive signal in a first frequency range of 2.9 MHz to 3.1 MHz to generate a first portion of the mist from the first liquid at the interface between the first capillary and the first ultrasonic transducer, the first portion of the mist having a first liquid particle size of less than 4 microns;
• and
• the second AC drive signal drives the second ultrasonic transducer to generate and transmit ultrasonic waves, the driver selecting a frequency of the second AC drive signal in a second frequency range of 0.5 MHz to 1.5 MHz to generate a second portion of the mist from the second liquid at the interface between the second capillary and the second ultrasonic transducer, the second portion of the mist having a second liquid particle size of 4 microns or greater,
• wherein the first portion of the mist and the second portion of the mist combine to form the mist which flows through the mist outlet port to the user when the user draws on the mouthpiece.