Wireless High Temperature Sensing Chipless Tag Based on a Diamond Ring Resonator

At a Glance

Metadata	Details
Publication Date	2023-03-25
Journal	Micromachines
Authors	Bo Wang, Youwei Li, Tingting Gu, Ke Wang
Institutions	Xi’an University of Posts and Telecommunications
Citations	3
Analysis	Full AI Review Included

Technical Documentation and Analysis: High-Temperature Wireless Sensing

Executive Summary

This research demonstrates a highly effective passive wireless temperature sensor utilizing a Double Diamond Split Rings Resonator (DDS RR) structure on a ceramic substrate, achieving robust performance in harsh environments.

Application Focus: Real-time, passive wireless temperature monitoring for high-stress, high-temperature applications (e.g., aerospace, turbine engines).
Sensing Mechanism: Relies on the temperature-dependent change in the dielectric constant ($\epsilon_r$) of the substrate material, causing a measurable shift in the resonant frequency ($f$).
Performance Range: Successfully simulated operation across a wide temperature span of 200 °C to 1000 °C.
High Sensitivity: Achieved a maximum sensitivity of 0.6 MHz/°C, demonstrating superior performance compared to existing ceramic-based sensors cited in the literature.
Miniaturization: Compact design with overall dimensions of 23 x 23 x 0.5 mm³, enabling integration into constrained spaces.
Fabrication: Simple manufacturing process using Platinum (Pt) metalization via screen printing on an alumina ceramic substrate.
6CCVD Value Proposition: Diamond (SCD/PCD) offers a superior platform for replicating and extending this research, providing unmatched thermal stability, mechanical strength, and Q-factor performance for next-generation harsh environment sensors.

Technical Specifications

The following key data points were extracted from the simulation and comparison analysis of the DDS RR sensor:

Parameter	Value	Unit	Context
Operating Temperature Range	200 - 1000	°C	Simulated range for sensing.
Resonant Frequency Shift	300	MHz	Total shift across the 800 °C range.
Resonant Frequency Range	6.79 - 6.49	GHz	Corresponds to 200 °C to 1000 °C.
Maximum Sensitivity (S)	0.6	MHz/°C	Achieved at the lower end of the range (200 °C).
Minimum Sensitivity (S)	0.375	MHz/°C	Achieved at the upper end of the range (1000 °C).
Substrate Material	Alumina Ceramic	N/A	Selected for high temperature resistance.
Resonator Material	Platinum (Pt)	N/A	Printed metalization layer.
Overall Sensor Dimensions	23 x 23 x 0.5	mm³	Miniaturized design.
Substrate Dielectric Constant ($\epsilon_r$) Range	9.8 - 11.0	N/A	Change corresponding to 200 °C to 1000 °C.

Key Methodologies

The sensor design and validation relied on specific material selection, structural geometry, and simulation techniques:

Substrate Selection: Alumina ceramic was chosen as the temperature-sensitive dielectric substrate, leveraging its inherent property that the relative dielectric constant ($\epsilon_r$) changes monotonically with temperature.
Resonator Structure: A Double Diamond Split Rings Resonator (DDS RR) was implemented due to its high Radar Cross Section (RCS) frequency response, high Q value, and simple, symmetrical design.
Fabrication Technique: The Platinum (Pt) resonator structure was realized using screen printing technology on the alumina ceramic surface.
Structural Parameters: Key dimensions included a substrate size of 23 mm x 23 mm x 0.5 mm, a diamond width (W) of 1 mm, and specific inner and outer ring split lengths (0.34 mm and 4.14 mm, respectively).
Simulation Environment: High-Frequency Structure Simulator (HFSS) software was utilized to model the electromagnetic wave propagation and simulate the resonant frequency shift as the substrate’s dielectric constant was varied (simulating temperature change).
Performance Characterization: The relationship between temperature (T) and resonant frequency ($f$) was established as inversely proportional (T $\uparrow$ $\rightarrow$ $\epsilon_r$ $\uparrow$ $\rightarrow$ $f$ $\downarrow$), and fitting formulas were derived for two distinct frequency ranges.

6CCVD Solutions & Capabilities

The research highlights the critical need for materials with exceptional thermal stability, mechanical robustness, and precise dielectric properties for high-temperature wireless sensing. 6CCVD’s MPCVD diamond materials offer significant advantages over traditional ceramics like alumina, enabling superior sensor performance and longevity.

Applicable Materials: Enhancing Sensor Performance

While alumina ceramic is functional up to 1000 °C, diamond provides a path to higher performance, especially concerning thermal management and Q-factor stability.

Research Requirement	6CCVD Material Solution	Technical Advantage
High Thermal Stability	Optical Grade SCD or High Purity PCD	Diamond is chemically inert and stable far beyond 1000 °C, ensuring structural integrity in extreme environments.
Superior Thermal Management	SCD (Single Crystal Diamond)	Diamond possesses the highest known thermal conductivity, ensuring rapid and uniform temperature response across the sensor surface, improving measurement accuracy.
High Q-Factor Resonators	Optical Grade SCD	SCD offers extremely low dielectric loss (tan $\delta$), crucial for maximizing the Q-factor of the DDS RR structure, leading to sharper resonance peaks and higher measurement precision.
Conductive Elements (If required)	Boron-Doped Diamond (BDD)	BDD substrates can be utilized for integrated heating elements or highly stable conductive paths, offering superior chemical resistance compared to metals.

Customization Potential: Precision Fabrication for Resonators

6CCVD’s advanced fabrication capabilities ensure that the precise dimensions and metalization requirements of the DDS RR structure can be met or exceeded, offering greater flexibility than screen printing.

Custom Dimensions: The paper used a 23 x 23 x 0.5 mm³ substrate. 6CCVD routinely supplies PCD plates up to 125mm in diameter and SCD/PCD thicknesses ranging from 0.1µm to 500µm, allowing for scaling or miniaturization of the sensor design.
Precision Metalization: The research utilized Platinum (Pt). 6CCVD offers in-house, high-precision metalization using advanced deposition techniques (e.g., sputtering, evaporation) for superior adhesion and uniformity compared to screen printing. Available metals include: Pt, Au, Ti, Pd, W, and Cu.
Surface Finish: For optimal resonator performance and minimal scattering loss, 6CCVD provides ultra-smooth polishing, achieving surface roughness (Ra) of < 1nm for SCD and < 5nm for inch-size PCD.

Engineering Support

6CCVD’s in-house PhD team specializes in the application of MPCVD diamond in extreme environments, including microwave electronics and harsh environment sensing. We can assist researchers in transitioning from ceramic substrates to diamond to leverage its superior thermal, mechanical, and dielectric properties for similar Wireless High Temperature Sensing projects.

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

View Original Abstract

A passive wireless sensor is designed for real-time monitoring of a high temperature environment. The sensor is composed of a double diamond split rings resonant structure and an alumina ceramic substrate with a size of 23 × 23 × 0.5 mm3. The alumina ceramic substrate is selected as the temperature sensing material. The principle is that the permittivity of the alumina ceramic changes with the temperature and the resonant frequency of the sensor shifts accordingly. Its permittivity bridges the relation between the temperature and resonant frequency. Therefore, real time temperatures can be measured by monitoring the resonant frequency. The simulation results show that the designed sensor can monitor temperatures in the range 200~~1000 °C corresponding to a resonant frequency of 6.79~~6.49 GHz with shifting 300 MHz and a sensitivity of 0.375 MHz/°C, and demonstrate the quasi-linear relation between resonant frequency and temperature. The sensor has the advantages of wide temperature range, good sensitivity, low cost and small size, which gives it superiority in high temperature applications.

Tech Support

Original Source

DOI: https://doi.org/10.3390/mi14040731

References

2021 - All-Ceramic LC Resonator for Chipless Temperature Sensing Within High Temperature Systems [Crossref]
2014 - Photoresponse of an electrically tunable ambipolar graphene infrared thermocouple [Crossref]
2019 - An experimental method for improving temperature measurement accuracy of infrared thermal imager [Crossref]
2014 - Technologies for printing sensors and electronics over large flexible substrates: A review [Crossref]
2013 - SAW-RFID enabled temperature sensor [Crossref]