A spiral spring resonator for mass density and viscosity measurements

Most recently introduced viscosity and mass density sensors utilize vibrating resonant mechanical structures interacting with the sample fluid where the resonance frequency and the quality factor are affected by both, the fluid’s viscosity and its mass density. Unlike singly clamped beams, straight, doubly clamped structures are advantageous when using electromagnetic excitation and read-out based on Lorentz forces which allow high excitation forces and read-out signals. However, classical straight beams such as bridges are subjected to high cross-sensitivities of their resonance frequencies to ambient temperature. To overcome high spurious temperature dependencies but to benefit from the straight doubly clamped approach, a spiral spring resonator applicable as viscosity and mass density sensor has been designed.