An electronically actuated droplet delivery device for delivering a fluid as an ejected stream of droplets to the pulmonary system of a subject, the device comprising: a housing ; a reservoir disposed within or in fluid communication with the housing for receiving a volume of fluid; an electronically actuated ejector mechanism in fluid communication with the reservoir and configured to generate the ejected stream of droplets; at least one differential pressure sensor positioned within the housing; the at least one differential pressure sensor configured to activate the ejector mechanism upon sensing a pre-determined pressure change within the housing to thereby generate the ejected stream of droplets; the ejector mechanism comprising a piezoelectric actuator and an aperture plate , the aperture plate having a plurality of openings formed through its thickness and the piezoelectric actuator is operable to oscillate the aperture plate at a frequency and voltage to thereby generate the ejected stream of droplets; wherein the plurality of openings and the frequency and the voltage of oscillation of the aperture plate of the ejector mechanism are configured to generate the ejected stream of droplets wherein at least 50% of the droplets have an average ejected droplet mass mean aerodynamic diameter (MMAD) of less than 5 microns, characterized in that the housing comprises a mouthpiece located at an airflow exit of the housing, and an airflow laminar flow element located at an airflow entrance of the housing wherein the airflow laminar flow element is configured to facilitate laminar airflow across an exit side of the aperture plate, to provide internal airflow resistance within the device, and to provide sufficient airflow through the device during use. a housing ; a reservoir disposed within or in fluid communication with the housing for receiving a volume of fluid; an electronically actuated ejector mechanism in fluid communication with the reservoir and configured to generate the ejected stream of droplets; at least one differential pressure sensor positioned within the housing; the at least one differential pressure sensor configured to activate the ejector mechanism upon sensing a pre-determined pressure change within the housing to thereby generate the ejected stream of droplets; the ejector mechanism comprising a piezoelectric actuator and an aperture plate , the aperture plate having a plurality of openings formed through its thickness and the piezoelectric actuator is operable to oscillate the aperture plate at a frequency and voltage to thereby generate the ejected stream of droplets; wherein the plurality of openings and the frequency and the voltage of oscillation of the aperture plate of the ejector mechanism are configured to generate the ejected stream of droplets wherein at least 50% of the droplets have an average ejected droplet mass mean aerodynamic diameter (MMAD) of less than 5 microns, characterized in that the housing comprises a mouthpiece located at an airflow exit of the housing, and an airflow laminar flow element located at an airflow entrance of the housing wherein the airflow laminar flow element is configured to facilitate laminar airflow across an exit side of the aperture plate, to provide internal airflow resistance within the device, and to provide sufficient airflow through the device during use. <EOS>