Application of a microwave acoustoelectronic sensor on a diamond substrate to determine the properties of solutions of substances
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2025-10-21 |
| Journal | Radioelectronics Nanosystems Information Technologies |
| Authors | B. P. Sorokin, Dmitry Yashin, Nikita O. Asafiev |
| Analysis | Full AI Review Included |
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Executive Summary
Section titled âExecutive Summaryâ- Presents a microwave acoustoelectronic sensor based on a High overtone Bulk Acoustic Resonator (HBAR) using longitudinal bulk acoustic waves for liquid property determination.
- Sensor utilizes a multilayer piezoelectric structure: Al/Al0.72Sc0.28N/Mo/(100) diamond.
- Diamond substrate provides high chemical tolerance and abrasion resistance, enabling reuse with aggressive liquids.
- Sensor measures acoustic impedance of liquids using reflection coefficient measurements.
- Tested with aqueous solutions of NaCl, glycerol, and isopropyl alcohol.
- Demonstrates a linear relationship between the sensorâs electrical reflection coefficients and the acoustic impedance of the liquids.
- Potential applications in medicine, pharmacology, and chemical industries for rapid liquid property analysis.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Operating Frequencies | 4.8, 5.6 | GHz | Two control overtones used in measurements |
| Al Layer Thickness (Outer) | 177 | nm | Outer electrode |
| Al0.72Sc0.28N Layer Thickness | 1900 | nm | Piezoelectric film |
| Mo Layer Thickness (Inner) | 122 | nm | Inner electrode |
| Diamond Substrate Thickness | 503 | ”m | (100) orientation, IIa type |
| Temperature | 23 ± 0.5 | °C | Fixed ambient temperature during experiments |
| Initial Q-factor (4.8 GHz) | 7600 | - | Sensor in initial state |
| Initial Reflection Coeff. (4.8 GHz) | 0.64 | % | Sensor in initial state |
| Initial Q-factor (5.6 GHz) | 11400 | - | Sensor in initial state |
| Initial Reflection Coeff. (5.6 GHz) | 0.56 | % | Sensor in initial state |
Key Methodologies
Section titled âKey Methodologiesâ- Substrate Preparation: A single-crystal diamond substrate with (100) orientation and IIa type was used.
- TFPT Deposition: A thin-film piezoelectric transducer (TFPT) consisting of Al/Al0.72Sc0.28N/Mo was deposited on the diamond substrate using magnetron sputtering.
- Sensor Housing: The sensor was housed in a metal casing with SMA connectors and an RG405 microwave cable for signal transmission.
- VCA Measurement: An Agilent E5071C ENA vector circuit analyzer (VCA) was used to measure the complex reflection coefficient S11(f).
- Calibration: Background measurements were taken to extract the electrical impedance.
- Liquid Application: Several milligrams of test fluids (distilled water, NaCl solutions, glycerol mixtures, 2-propanol mixtures) were applied to the diamond surface.
- Data Acquisition: The reflection coefficient S11(f) was measured for each fluid.
- Data Processing: The âextractedâ electrical reflection coefficient was calculated, and the relationship between the reflection coefficient and acoustic impedance was analyzed.
- Temperature Control: All experiments were performed at a fixed ambient temperature of 23 ± 0.5 °C.
Commercial Applications
Section titled âCommercial Applicationsâ- Pharmaceuticals: Quality control and rapid analysis of liquid formulations.
- Chemical Industry: Monitoring and control of chemical processes involving liquids.
- Food and Beverage: Quality assessment of liquid products.
- Environmental Monitoring: Detection of contaminants in water samples.
- Medical Diagnostics: Development of point-of-care diagnostic devices for analyzing bodily fluids.
- High Power RF: Could be used for thermal management of high power RF devices.
View Original Abstract
Rapid determination of liquid properties is essential for various fields of human endeavor, such as medicine, pharmacology, and various chemical industries. To this end, we have developed an acoustoelectronic liquid sensor based on a High overtone Bulk Acoustic Resonator using microwave longitudinal bulk acoustic waves. Sensor is designed to measure the acoustic impedance of liquids. The sensor is built on a multilayer piezoelectric structure composed of âAl/Al0.72Sc0.28N/Mo/(100) diamondâ. To protect the sensitive element from potential chemical damage from the analytes being tested, a metal housing is used, with the thin-film piezoelectric transducer âAl/Al0.72Sc0.28Nâ located within the housing. The analytes are placed on the opposite free side of the diamond substrate, and the sensor has been tested on aqueous solutions of NaCl, glycerol, and isopropyl alcohol at various concentrations. The samples weighed several milligrams. The relationship between the electrical reflection coefficients of the sensor and the acoustic impedance of liquids and solutions was found to be linear. Thanks to the high chemical tolerance and abrasion resistance of a diamond substrate, this sensor can be reused for studying a wide range of substances, including aggressive liquids, without any loss of performance.