Project of the Russian Science Foundation – NSFC (China) No. 21-49-00062 (2021-2023) “Investigation of the characteristics of liquid suspensions using acoustoelectronic technologies and the development of a new generation of sensors.”
Head: Doctor of Physico-mathematical Sciences Kuznetsova I.E.
Report 2022
In 2022, work was carried out on a theoretical analysis and experimental study of the influence of an external electric field on the characteristics of acoustic waves propagating in piezoelectric materials and structures adjacent to suspensions containing dielectric microparticles. As is known, electrorheological suspensions are a colloidal system consisting of a non-polar or weakly polar organic liquid (transformer and castor oil, dibutyl sebacate, cyclohexane, oleic acid, silicone oils) with embedded dielectric or semiconductor particles. Under the influence of an electric field, the rheological properties of such suspensions can change significantly. This is due to the fact that when an external electric field is applied, the filler particles acquire surface charges of different polarities, which cause them to line up in chains along the lines of the applied electric field. In this case, the effective viscosity of the suspension changes. As a result of the calculations, the dependences of the phase velocity and attenuation per wavelength were obtained for a transverse-horizontal zero-order wave in YX lithium niobate and YX potassium niobate, bordering on a suspension based on polydimethylsiloxane, filled with detonation synthesis nanodiamonds with a concentration of 1%, at a frequency of 3.3 MHz . It was found that the appearance of an external electric field leads to an insignificant change in the phase velocity of the wave, while its attenuation changes for thin plates (hf = 100 m/s) from 0.47 to 0.67 dB/l for lithium niobate and from 0.41 to 0.61 for potassium niobate (l is the wavelength). The effect of an external electric field on the electrical and acoustic properties of suspensions created at the first stage, including suspensions of glycerin and vaseline oil with ZnO nanoparticles and submicron BaTiO3 particles, was experimentally studied at frequencies of 1 kHz and 1 MHz. It is shown that, as expected, for suspensions based on polar liquids, an increase in frequency from 1 kHz to 1 MHz leads to a decrease in the permittivity. As for suspensions based on non-polar liquids, their permittivity practically does not change in the frequency range of 1 kHz – 1 MHz. It should also be noted that for suspensions based on non-polar liquids, the dielectric constant did not change when an electric voltage was applied from -40 V to +40 V. However, for suspensions based on polar liquids, a decrease in the dielectric constant was found, both at positive and at negative values applied voltage. This can be explained by the fact that the dipole moment of the particles of the suspension is screened by the ions of the polar liquid, and this leads to a decrease in the electrical susceptibility of the suspension as a whole. An analysis of the influence of an external electric field on the characteristics of an acoustic wave at a frequency of 14 MHz in the YX lithium niobate-suspension plate structure at various values of the external electric voltage from 0 to 2 kV showed that for the selected suspensions, the external electric field does not lead to a significant change in the attenuation of this acoustic wave. This can be caused both by the weak electrorheological effect of the considered suspensions and by the low sensitivity of the acoustic wave used to record the effect. This issue needs further elaboration. At this stage of the work, it was theoretically and experimentally shown that reverse acoustic waves, characterized by oppositely directed phase and group velocities, remain reverse when the piezoelectric plate contacts the liquid. The possibility of using backward waves for the implementation of liquid sensors is shown. An experimental study of the characteristics of suspensions of various types was carried out using a piezoelectric resonator with a longitudinal electric excitation field created at the first stage. Suspensions of glycerol and ASM 2/1 diamond powder with a particle size of 1–2 µm and various volume concentrations (0.098%, 0.147%, 0.73%, 1.45%, 1.92%, and 2.86%) were prepared. The density of the obtained samples, their transverse and longitudinal moduli of elasticity and viscosity coefficients were determined. It was found that with an increase in the volume concentration of diamond nanoparticles, the transverse modulus of elasticity of the suspension slightly decreases when going from pure glycerol to the minimum concentration (beta = 0.098%) and then monotonically increases. In this case, the velocity of the transverse acoustic wave and the transverse viscosity coefficient have a minimum at a concentration beta = 0.147%. As for the longitudinal modulus of elasticity of suspensions, it increases with an increase in the volume concentration of diamond particles, while the velocity of the longitudinal acoustic wave decreases. This is due to an increase in the density of the suspension with an increase in the concentration of diamond particles. The dependence of the coefficient of longitudinal viscosity on the concentration of diamond, as well as in the case of transverse viscosity, has a minimum at the same concentration beta = 0.147%. The physical reason for the existence of such a minimum is still unclear and requires further research. At this stage of the project, work has begun on studying the influence of an external magnetic field on the characteristics of acoustic waves propagating in a piezoelectric structure adjacent to a magnetic fluid. A typical magnetorheological fluid is a suspension of magnetic microparticles, a fluid (oil, water or glycol) and anti-settling additives. In the absence of a magnetic field, the liquid particles are distributed randomly, and when the field is applied, they line up in chains along the lines of force, while the viscosity in the direction perpendicular to the field increases sharply. To analyze the magneto-acoustic interaction and determine the corresponding nonlinear material constants, the theory of magneto-acoustic interaction was developed, based on equations describing the magneto-acoustic interaction in a scalar form, by analogy with the electro-acoustic interaction. Using this approach, the linear and nonlinear constants of the magnetoacoustic interaction of magnetoelastic elastomers based on a high-pressure polyethylene matrix with embedded carbonyl iron nanoparticles with a size of 3-5 μm were determined. As a result of joint theoretical and experimental work of the Russian and Chinese groups, modified Lamb waves and acoustic plate waves with SH polarization with increased sensitivity to fluid viscosity along with reduced sensitivity to fluid conductivity and temperature were found in quartz plates with a thickness of about a wavelength. The modes are characterized by a small or zero displacement along the normal to the surface, which makes it possible to avoid radiation of the modes into the neighboring liquid, and large displacements in the plane, which enhance the viscous coupling of the wave and the liquid deposited on the plate. Based on waves with polarization in the plane of the plate, selective viscosity sensors have been developed: the sensitivity of the sensors to viscosity is 0.3 dB/cP for 1–20 cP, 0.12 dB/cP for 20–100 cP, and 0.015 dB/cP for 100 cP. -1500 cP; responses to conductivity (from 0 to 2 S/m) are two orders of magnitude smaller. The temperature responses of these waves are practically zero in air, but when the plate is covered with a liquid, they increase depending on the properties of the liquid. The temperature dependence of the viscosity of glycerin, measured by the sensor, is consistent with the data published in the reference books.
Published articles:
- Zaitsev B.D., Borodina I.A., Teplykh A.A. Compact liquid analyzer based on a resonator with a lateral excitation electric field. Ultrasonics (2022) WOS SCOPUS Q1 RSCI RSCI
- Anisimkin V., Shamsutdinova E., Li P., Zhu F., Qian Zh., Kuznetsova I. Selective Detection of Liquid Viscosity Using Acoustic Plate Waves with In-Plane Polarization. Sensors (2022) WOS SCOPUS Q1 RSCI RSCI
- Shamsutdinova E.S., Anisimkin V.I., Fionov A.S., Smirnov A.V., Kolesov V.V., Kuznetsova I.E. Improvement of methods for studying the electrophysical and viscous properties of liquids. Acoustic journal (2023) WOS SCOPUS Q2 RSCI RSCI
- Shamsutdinova E.S., Anisimkin V.I., Fionov A.S., Smirnov A.V., Kolesov V.V., Kuznetsova I.E. Study of the physical properties of suspensions by electrophysical and acoustoelectric methods. Microwave engineering and telecommunication technologies (2022) RSCI
- Zaitsev B.D., Semenov A.P., Teplykh A.A., Borodina I.A. Study of a longitudinal acoustic wave in a suspension “glycerin – microparticles of synthetic diamond” Microwave engineering and telecommunication technologies (2022) RSCI