A thermal-type drop generator having a geometry that is configured so that the ejection of liquid from the chamber has the effect of separating the ejected volume into a number of small droplets. The relationship between the thickness of the liquid chamber and the area of the heat transducer used to eject the liquid is controlled to provide the separating aspect so that the resultant droplets have very small volumes, in the range of tens of femtoliters. Such small droplets are readily entrained in an aerosol and especially useful for pulmonary delivery of medicinal fluid.