Principle of a non-contact liquid level sensor using electromagnetic-acoustic resonators

摘要: Liquid level measurement is a key aspect for many applications in the processing industry, chemistry, and pharmaceutical industry to determine, e.g., exact liquid volume reaction chamber. A large variety of principles exist these applications, ranging from mechanical, electrical, optical methods ultrasonic radar measurements. However, are not suitable sensing very small amounts levels. Ultrasonic transducers allow precise measurements, where sensitivity can be improved by increasing operating frequency. In this contribution we introduce concept electromagnetic-acoustic resonators as transducer. Here, measure changed frequency shifts damping characteristics due interference effects instead time-of-flight measurements usually employed. Our experiments show, that using continuous, resonant excitation achievable resolution limited wavelengths waves radiated into liquid. We an experimental setup consisting simple resonating element placed inside fluidic chamber, which remotely excited planar coil. present analytical model operation devices based on finite simulations mode shapes. The ability easily generate different modes vibration also advantage simultaneously other properties.