Optimized liquid droplet spray device for an inhaler suitable for respiratory therapies

This application claims priority of European patent application 122 751.5 filed Dec. 1, 1998 and European patent application 107 553.2 filed Apr. 15, 1999. The entire disclosure of the above patent applications is incorporated by reference herein. The liquid droplet spray device () comprises a housing formed of a superposition of a first and a second substrate () and a space () within the housing for containing a liquid substance (), vibrating means () for applying a frequency vibration to the substance () thereby generating the liquid droplet spray, and outlet means () for ejecting the liquid droplet spray. The outlet means comprise a cavity (), output nozzles () and output channels () connecting the cavity () to the outlet nozzles (). According to the invention, the vibrating means () creates a standing wave pattern within the liquid substance (), and the outlet means are arranged such that said outlet nozzles () are superposed on the vibration mode peaks of the standing wave pattern. Advantageously, the first and second substrates have similar geometrical shapes. Minimal retention and optimal flow of the substance are obtained.