Viscosity measurements of viscous liquids using magnetoelastic thick-film sensors

Abstract

A ribbon-like magnetoelastic thick-film sensor can be considered the magnetic analog of an acoustic bell. In response to an externally applied magnetic field impulse the magnetoelastic sensor magnetically rings, in a bell-like fashion, emitting magnetic flux with a characteristic resonant frequency that is determined from a fast Fourier transform of the transient response captured using a pickup coil. The resonant frequency of the sensor changes in response to mass loading and, when immersed in liquid, interfacial shear forces associated with viscosity. We report on the use of magnetoelastic sensors to measure the viscosity and density of highly viscous liquids. When characterizing highly viscous liquids, to avoid over damping of the sensor due to the liquid mass load the sensor is suspended from a boat-like structure with one end of the sensor immersed a fixed distance into the liquid. Using this method liquid viscosities ranging from 1.3 to 12 P are measured.

Wireless Magnetoelastic Resonance Sensors: A Critical Review

“…Through the inverse magnetoelastic effect, the vibration of the sensor in turn generates a time varying magnetic flux, which can be measured with a set of pick-up coils. The time-domain signal is then converted into the frequency domain by performing a Fast Fourier Transform (FFT), and the resonant frequency is determined [9]. The resonant frequency of the transiently excited sensor can also be determined by counting the zero crossings of the sensor response for a given time period.…”

“…Magnetoelastic sensors have attracted considerable interest within the sensor community as they form an excellent sensor platform that can be used to measure a wide range of environmental parameters including pressure [1][2][3], humidity [3][4][5], temperature [5][6], liquid viscosity and density [7][8][9][10], thin-film elasticity [11], and chemicals such as carbon dioxide [12][13], ammonia [14], and pH [15]. Magnetoelastic sensors are typically made of amorphous ferromagnetic ribbons or wires, mostly iron-rich alloys such as Fe 40 Ni 38 Mo 4 B 18 (Metglas brand 2826MB) and Fe 81 B 13.5 Si 3.5 C 2 (Metglas 2605SC) ribbons [15] that have a high mechanical tensile strength (~1000-1700 MPa), and a low material cost allowing them to be used on a disposable basis.…”

Synthesis and Characterization of a Composite Zeolite-Metglas Carbon Dioxide Sensor

“…Changes in environmental parameters that alter material properties, such as temperature and humidity, cause a measurable shift in the resonance frequency. It has already been demonstrated that magnetoelastic materials can be used to sense pH, [14] temperature, [15] viscosity, [16] pressure, [17] glucose, [18] and ammonia. [19] The main goal of the present work is to present a new approach for utilizing zeolite properties in sensing applications.…”

Simultaneous measurement of liquid density and viscosity using remote query magnetoelastic sensors

“…A common problem in almost all viscosity measurements [1][2][3][4][5][6][7] is that the extracted information depends on both the density l and the viscosity of the fluid. A ( l ) 0.5 factor is found in most of the theoretical calculations that consider viscosity measurements, [7][8][9][10][11] including those that describe the response of surface acoustic wave sensors 8-10 and magnetoelastic sensors 6,7 upon immersion in liquid.…”