The present invention provides antibodies that bind to the growth differentiation factor-7. The selection element includes a first junction portion, having a first type of conductivity, and a second junction portion, having a second type of conductivity and forming a rectifying junction with the first junction portion. The droplet ejection surface is curved corresponding to a curved surface onto which the nozzles ejecting droplets. The gasket material is preferably a flexible polymeric sheet, which is biocompatible and compatible with the reservoir contents. A noise dissipater for suppressing noises caused by pulsating vibrations generated in the ejector is disposed in the sucking passage at a position close to the sucking portion of the ejector.