Multi-frequency reduction of fluid droplet

Apparatus comprising:

• a signal generator having a generator output, the signal generator configured to generate first and second signals at the generator output, the first signal having a first frequency, and the second signal having a second frequency;
• switching circuitry having a circuitry input and a circuitry output, the circuitry input coupled to the generator output, the circuitry output adapted to be coupled to an ultrasonic transducer mechanically coupled with a surface, and the switching circuitry configured to:
• provide the first signal to the ultrasonic transducer at the first frequency to reduce a fluid droplet on the surface from a first size to a second size;
• and provide the second signal to the ultrasonic transducer at the second frequency to reduce the fluid droplet from the second size to a third size;
• and
• an ultrasonic transducer current sensor coupled to the ultrasonic transducer wherein the ultrasonic transducer current sensor senses a current transient of the ultrasonic transducer;
• wherein the ultrasonic transducer is deactivated based on the current transient of the ultrasonic transducer.