A device configured to jet one or more droplets of a viscous medium, the device comprising: a housing having an inner surface at least partially defining a jetting chamber configured to hold the viscous medium; and a flexible jetting nozzle , the flexible jetting nozzle having an inner surface at least partially exposed to the jetting chamber, the flexible jetting nozzle including a flexible conduit extending between an inlet orifice in the inner surface of the flexible jetting nozzle to an outlet orifice in an outer surface of the flexible jetting nozzle; characterized by an impacting device including an impact end surface at least partially defining the jetting chamber, the impacting device being configured to build up a rapid pressure impulse in the jetting chamber such that the pressure impulse: causes an increase of internal pressure of viscous medium in the jetting chamber to cause at least a portion of the flexible jetting nozzle to deform, to cause a cross-sectional flow area of at least a portion of the flexible conduit to dilate, and to force the one or more droplets of the viscous medium through the flexible conduit and through the outlet orifice of the flexible jetting nozzle, and causes a decrease of internal pressure of viscous medium in the jetting chamber, to cause at least the portion of the flexible jetting nozzle to relax, to cause the cross-sectional flow area of at least the portion of the flexible conduit to contract, thereby inducing break-off of the one or more droplets. a housing having an inner surface at least partially defining a jetting chamber configured to hold the viscous medium; and a flexible jetting nozzle , the flexible jetting nozzle having an inner surface at least partially exposed to the jetting chamber, the flexible jetting nozzle including a flexible conduit extending between an inlet orifice in the inner surface of the flexible jetting nozzle to an outlet orifice in an outer surface of the flexible jetting nozzle; characterized by an impacting device including an impact end surface at least partially defining the jetting chamber, the impacting device being configured to build up a rapid pressure impulse in the jetting chamber such that the pressure impulse: causes an increase of internal pressure of viscous medium in the jetting chamber to cause at least a portion of the flexible jetting nozzle to deform, to cause a cross-sectional flow area of at least a portion of the flexible conduit to dilate, and to force the one or more droplets of the viscous medium through the flexible conduit and through the outlet orifice of the flexible jetting nozzle, and causes a decrease of internal pressure of viscous medium in the jetting chamber, to cause at least the portion of the flexible jetting nozzle to relax, to cause the cross-sectional flow area of at least the portion of the flexible conduit to contract, thereby inducing break-off of the one or more droplets. causes an increase of internal pressure of viscous medium in the jetting chamber to cause at least a portion of the flexible jetting nozzle to deform, to cause a cross-sectional flow area of at least a portion of the flexible conduit to dilate, and to force the one or more droplets of the viscous medium through the flexible conduit and through the outlet orifice of the flexible jetting nozzle, and causes a decrease of internal pressure of viscous medium in the jetting chamber, to cause at least the portion of the flexible jetting nozzle to relax, to cause the cross-sectional flow area of at least the portion of the flexible conduit to contract, thereby inducing break-off of the one or more droplets. <EOS>