Determination of particle distributions from sedimentation measurements using a piezoelectric tuning fork sensor

In this work, a resonant quartz tuning fork sensor based measurement system is employed to study the settlement of small particles in suspension as they pass the sensing element. The resonator features varying sensitivity to fluid parameter changes along its length, with the tip being most sensitive. The spatial averaging effect is analyzed theoretically and measured by passing the sensor through a fluid-fluid interface. Subsequently, the averaging function is used for particle distribution determination from recorded resonance frequency and quality factor measurements. The associated inverse problem is of Fredholm type and is solved numerically. Based on the system specifications, detection limits, required temperature stability and expected precision are assessed and particle distribution functions of defined test dispersions are measured.