Sensing viscosity and density of glycerol–water mixtures utilizing a suspended plate MEMS resonator

Abstract

A sensor suitable for online monitoring of viscosity and density of glycerol-water mixtures is presented. The device is based on Lorentz force excitation and features an integrated piezoresistive readout. The core sensing element is a rectangular vibrating plate suspended by four beam springs. Two of the plate-carrying springs comprise piezoresistors. With two additional resistors on the silicon rim they form a half Wheatstone-bridge. Through the conductive layer of the beam springs a sinusoidal excitation current is driven. In the field of a permanent magnet, the Lorentz force excites plate vibrations resulting in a bridge unbalance. We recorded both the frequency response of the amplitude and the phase of the bridge output. By evaluating the properties of the resonant system, it is possible to extract the glycerol percentage and, hence, the viscosity and the mass density of the mixtures. This work is an extended version of the paper originally presented at SPIE List of symbols

A 1–8-GHz Miniaturized Spectroscopy System for Permittivity Detection and Mixture Characterization of Organic Chemicals

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3D Tunable, Multiscale, and Multistable Vibrational Micro‐Platforms Assembled by Compressive Buckling

“…Microelectromechanical systems (MEMS) exploit structural vibrations for precision mass sensing, [1–3] microscale rheology, [4–7] measurement of cell mechanics, [8–12] and energy harvesting [13–15] and other important purposes. Current MEMS devices are limited to only a few, largely two-dimensional (2D) geometries such as cantilevered beams, [16–18] doubly clamped bridges, [19] stressed wires, [20] and other constructs based on flat membranes and plates.…”

Complex Permittivity Detection of Organic Chemicals and Mixtures Using a 0.5–3-GHz Miniaturized Spectroscopy System

“…As a result, the fabrication of mixture detectors based on permittivity sensing is easier compared to other techniques employing thermal conductivity [33], mass density, and viscosity [34]. In this section, the characterization of an isopropanol-methanol binary mixture is explored as an application for the complex permittivity detection procedure presented in Section V-B.…”

“…21, the principal value of the integral of from 0 to is given by (34) The result in (34) is used in the evaluation of the integral in (25).…”