We present our experimental results on ultrasound transducers based on Photonic Integrated Circuits. We have fabricated and tested devices based on Mach Zehnder Interferometers and Ring Resonators, in the thick-Silicon on Insulator platform (VTT, Finland) and Si3N4 platform (Ligentec, Switzerland). We have obtained a Noise Equivalent Pressure which is two orders of magnitude lower than conventional State-Of-The-Art transducers, clearly demonstrating the huge potential of this concept.