Sensor for determining the oscillating frequency in a fluidic oscillating nozzle and a method using the sensor

A method for monitoring a dispensed fluid jet, comprising the steps of:

• providing an oscillating nozzle comprising:
• a fluidic oscillator with inlet and outlet and a main channel and at least one control passage surrounding the main channel;
• and
• a splitter comprising at least two splitter channels merging to an outlet of the splitter, and forming at least two unrestricted fluid flow paths, wherein the splitter is attached to the outlet of the fluidic oscillator and arranged downstream from the fluidic oscillator, wherein at least one of the at least two splitter channels comprises a sleeve having a flexible foil configured to be position in direct communication with a fluid in the at least two splitter channels and in between the outlet of the fluidic oscillator and the outlet of the splitter, wherein the flexible foil is configured to measurably deform concavely or convexly in response to pressure changes in the at least one of the at least two splitter channels;
• and
• injecting a fluid jet and in parallel determining the oscillation frequency by determining the deformation changes of the flexible foil.