The Effect of Glycerol-Based Suspensions on the Characteristics of Resonators Excited by a Longitudinal Electric Field

At a Glance

Metadata	Details
Publication Date	2023-01-05
Journal	Sensors
Authors	A. P. Semyonov, Б. Д. Зайцев, A. A. Teplykh, И. А. Бородина
Institutions	Institute of Radio-Engineering and Electronics
Citations	5
Analysis	Full AI Review Included

Technical Documentation & Analysis: Diamond-Based Acoustic Sensing

This document analyzes the research paper “The Effect of Glycerol-Based Suspensions on the Characteristics of Resonators Excited by a Longitudinal Electric Field” to highlight 6CCVD’s capabilities in supplying high-performance MPCVD diamond materials for advanced acoustic and rheological sensing applications.

Executive Summary

This study successfully demonstrates a reliable method for characterizing the acoustic and rheological properties of liquid suspensions using piezoelectric resonators, leveraging synthetic diamond particles as the dispersed phase.

Core Achievement: Accurate determination of density ($\rho^s$), shear modulus ($C_{66}^s$), shear viscosity ($\eta_{66}^s$), and shear acoustic wave velocity ($v^s$) of glycerol/diamond suspensions.
Sensing Mechanism: Piezoelectric resonators (AT-cut Quartz for shear waves, X-cut Langasite for longitudinal waves) were used to measure changes in electrical impedance upon immersion in the suspension.
Material Focus: Synthetic diamond powder (1-2 µm particle size) was used across volume concentrations up to 2.86%.
Methodology Validation: Material constants were derived by fitting experimental impedance data to Mason’s electromechanical equivalent circuit. The derived shear viscosity showed excellent agreement with independent measurements from an SV-10 viscometer.
Key Finding: Changes in diamond particle concentration qualitatively correspond to changes in the resonator’s characteristics (resonant frequency, quality factor, impedance maximums).
6CCVD Relevance: This research validates the use of diamond materials in high-precision acoustic sensing, a field where 6CCVD’s high-purity Single Crystal Diamond (SCD) and Boron-Doped Diamond (BDD) substrates offer significant performance advantages over traditional piezoelectric materials.

Technical Specifications

Parameter	Value	Unit	Context
Resonator 1 Material	AT-cut Quartz	N/A	Shear acoustic mode
Resonator 2 Material	X-cut Langasite	N/A	Longitudinal acoustic mode
Quartz Plate Thickness	370	µm	Resonator 1 dimension
Langasite Plate Thickness	706	µm	Resonator 2 dimension
Electrode Diameter (Quartz)	5.8	mm	Round electrodes
Electrode Diameter (Langasite)	7.5	mm	Round electrodes
Quartz Resonant Frequency ($F_{par}$)	4.37	MHz	Approximate parallel resonance
Diamond Particle Size	1-2	µm	Synthetic powder used in suspension
Max Volume Concentration Studied	2.86	%	Diamond in Glycerol suspension
Operating Temperature	27.3 ± 0.05	°C	Thermostatted environment
Max Suspension Density ($\rho^s$)	1290.8	kg/m³	At 2.857% concentration
Max Shear Modulus ($C_{66}^s$)	3.12 x 10⁶	Pa	At 2.857% concentration
Max Shear Viscosity ($\eta_{66}^s$)	0.557	Pa·s	Resonator-derived value (2.857% conc.)
Max Shear Wave Velocity ($v^s$)	116.5	m/s	Pure Glycerol (0.0% concentration)

Key Methodologies

The experimental procedure combined precise suspension preparation with advanced electromechanical modeling to derive material constants.

Suspension Preparation: Synthetic diamond powder (1-2 µm particle size) was mixed with 30 mL of glycerol at six distinct volume concentrations (ranging from 0.098% to 2.86%) and stirred magnetically for 5 hours to ensure homogeneity.
Resonator Setup: Two disk resonators (AT-cut Quartz and X-cut Langasite) with round electrodes were mounted in a 30 mL plastic container and fully immersed in the suspension under study.
Environmental Control: The container and resonator were placed in a thermostat maintaining a stable temperature of 27.3 ± 0.05 °C, monitored using a chromel-alumel thermocouple.
Electrical Measurement: Frequency dependences of the real (R) and imaginary (X) parts of the electrical impedance were measured rapidly (< 2 seconds per measurement) using an E4990A impedance analyzer.
Modeling and Fitting: Mason’s electromechanical equivalent circuit was employed to model the loaded resonator. The least squares method was used to fit the theoretical impedance curves to the experimental data, allowing for the determination of the unknown suspension constants ($C_{66}^s$ and $\eta_{66}^s$).
Validation: The resonator-derived shear viscosity coefficient ($\eta_{66}^s$) was independently verified using an SV-10 liquid viscometer, confirming the accuracy of the acoustic sensing technique.

6CCVD Solutions & Capabilities

This research demonstrates the utility of diamond materials in high-frequency acoustic sensing, a critical area for rheology and liquid analysis. 6CCVD is uniquely positioned to supply the advanced MPCVD diamond substrates necessary to replicate, miniaturize, and enhance these resonator designs.

Applicable Materials for Advanced Acoustic Resonators

While the paper used traditional quartz and langasite resonators, the highest performance acoustic sensors utilize diamond due to its extreme stiffness and low acoustic loss.

6CCVD Material	Application Relevance	Key Advantage
Optical Grade SCD	High-Q Acoustic Resonators, High-Frequency BAW/SAW devices	Highest stiffness (Young’s Modulus), lowest acoustic damping, enabling higher operating frequencies and superior Q-factors compared to quartz.
Electronic Grade SCD	Integrated Sensor Substrates, High Thermal Conductivity Platforms	Excellent thermal management for stable operation at elevated temperatures (critical for viscosity measurements).
Boron-Doped Diamond (BDD)	Integrated Electrodes, Electrochemical Sensing	BDD is conductive and chemically inert, allowing the diamond substrate itself to function as the electrode, simplifying the resonator structure and enhancing chemical resistance.

Customization Potential for Resonator Design

6CCVD’s manufacturing capabilities directly address the dimensional and integration requirements of high-performance acoustic sensors.

Custom Dimensions: The paper used plates of 370 µm and 706 µm thickness. 6CCVD provides SCD and PCD plates with precise thickness control from 0.1 µm up to 500 µm, and custom dimensions up to 125 mm (PCD). We can supply substrates cut to the exact diameter required (e.g., 5.8 mm or 7.5 mm) or smaller for miniaturized devices.
Precision Polishing: Achieving reliable acoustic contact is crucial. 6CCVD guarantees ultra-smooth surfaces: Ra < 1 nm for SCD and Ra < 5 nm for inch-size PCD, ensuring optimal coupling between the resonator and the liquid suspension.
Integrated Metalization: The resonators require robust electrodes. 6CCVD offers in-house custom metalization services including Au, Pt, Pd, Ti, W, and Cu deposition, allowing for the creation of precise electrode patterns directly onto the diamond substrate for optimal electrical and mechanical coupling.

Engineering Support

6CCVD’s in-house PhD team specializes in optimizing MPCVD diamond properties for demanding applications. We offer consultation on:

Material Selection: Choosing the optimal diamond grade (SCD vs. PCD, doping level) and crystallographic orientation for specific acoustic wave modes (shear vs. longitudinal).
Design Optimization: Assisting engineers in transitioning from traditional materials (Quartz, Langasite) to diamond to achieve higher sensitivity and stability in similar acoustic wave sensing and rheology projects.
Integration: Providing expertise on surface preparation and metalization schemes to ensure reliable, long-term operation in harsh liquid environments.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

This study examines the effect of suspensions based on pure glycerol and diamond powder with different concentrations on the characteristics of resonators with a longitudinal electric field. We used two disk resonators made of the quartz and langasite plates with round electrodes on both sides of the plate and resonant frequencies of 4.4 and 4.1 MHz, operating in shear and longitudinal acoustic modes, respectively. Each resonator was mounted on the bottom of a 30 mL liquid container. During the experiments, the container was filled with the suspension under study in such a way that the resonator was completely immersed in the suspension, and the frequency dependences of the real and imaginary parts of the electrical impedance of the resonator were measured. As a result, the shear modulus of the elasticity and shear coefficient of the viscosity of the studied suspensions were determined. The material constants of the suspensions were found by fitting the theoretical frequency dependences of the real and imaginary parts of the electrical impedance of the resonator to the experimentally measured ones, which was calculated using Mason’s equivalent circuit. As a result, the dependencies of the density, shear modulus of elasticity, shear viscosity coefficient, and velocity of the shear acoustic wave on the volume concentration of the diamond particles were constructed.

Tech Support

Original Source

DOI: https://doi.org/10.3390/s23020608

References

1967 - Viscoelastic Relaxation of Supercooled Liquids. I
2018 - Sound Absorption and Metamaterials: A Review [Crossref]
2011 - Elastic waves in suspensions [Crossref]
2009 - Sound attenuation in a liquid containing suspended particles of micron and nanometer dimensions [Crossref]
2009 - Sound absorption by a solution of nanoparticles [Crossref]
2022 - Compact liquid analyzer based on a resonator with a lateral excitation electric field [Crossref]
2015 - Liquid Sensor Based on a Piezoelectric Lateral Electric Field -Excited Resonator [Crossref]
2022 - A new liquid sensor based on a piezoelectric resonator with a radial electric field [Crossref]
2022 - Sensor System Based on a Piezoelectric Resonator with a Lateral Electric Field for Virus Diagnostics [Crossref]