A jetting device comprising: a fluid chamber connected to a nozzle and containing a fluid to be jetted, and an electrically conductive medium; a magnetic field source arranged to create a magnetic field in the electrically conductive medium; a pair of electrodes contacting the electrically conductive medium; and a controller arranged to control a flow of an electric current through the electrodes and the electrically conductive medium, characterized in that the pair of electrodes is configured to constitute a sonode for generating an ultrasonic acoustic wave in the electrically conductive medium, and the controller is arranged to activate the sonode during a time at which the jetting device does not perform a jetting operation.