The ExOsense™ sensor incorporates proprietary transducer technology employing piezoelectric material. When piezoelectric material is excited, it creates an acoustic signal as a function of the natural resonance of the material. ExOsense sensors generate this acoustic signal, direct it through the bottle wall and sense the reflection pulse.
The amount of energy that is reflected is determined by the "acoustic impedance mismatch" of the materials in use. For example, if sound passes through two materials with similar acoustic impedances , very little energy will be reflected. If sound passes through two materials with dissimilar impedance values, the majority of the acoustic energy will be reflected. The acoustic impedance mismatch provides the basis for the detection of liquid level.