This study proposes an innovative method to wirelessly measure the ultra-high temperatures of rotational parts in aero-engines/turbines. The upper measurement limit of this proposed sensor is $1100 ^\circ \text{C}$ . Based on the thick film integration process, the inductor and capacitor are integrated in-situ on the ceramic turntable and ceramic blade. The inductor and capacitor operate in the high temperature and ultra-high temperature areas, respectively, and the temperature signal is transmitted through the electromagnetic coupling between the inductor coil and the antenna. The design of the structure separating the capacitor and inductors is important and can improve the sensor’s high temperature signal reading performance. The designed sensor is tested in the temperature range of 25– $1100 ^\circ \text{C}$ and the rotational speed range of 0–400 rpm. The results show that the minimum sensitivity of the sensor at different rotational speeds is 7.66 kHz/ $^\circ \text{C}$ , and the minimum sensitivity of the sensor at different rotational speeds is 7.83 kHz/ $^\circ \text{C}$ . The maximum standard deviation and repeatability of the sensor measured across different temperatures and rotational speeds are 0.11(400 rpm, 900 °C)and 0.389%(400 rpm, 900 °C), respectively. The interference of the rotational speed on the temperature test of the sensor is negligible. The experimental results show that the sensor has strong signal strength in ultra-high temperature rotational environments and is suitable for ultra-high temperature testing.

As the key component of aero-engines and industrial gas turbines, a bearing’s working temperature at high speed is close to $300℃$. The measurement of an engine bearing’s temperature is of great significance to ensure flight safety. In this study, we present a wireless LC conformal temperature sensor for bearing temperatures, which integrates silver on the bearing surface in situ through a screen-printing process. This process makes Ag film (9912-K FL) firmly adhere to the bearing surface and realizes wireless measurements for bearing temperatures in situ. A high-temperature holding experiment of the prepared sensor was conducted, and the results showed that the sensor can work stably for $10$ h at $300℃$. We tested the designed wireless LC conformal temperature sensor at $20–270℃$. The results showed that the proposed temperature sensor attained as good accuracy and stability in the temperature range $20–270℃$. The sensitivity of the temperature measurements was $20.81\mathrm{KHz}/℃$ when the bearing rotateds, the maximum repeatability was $0.039\%$, the maximum uncertainty was $0.081\%$, and the relative error was stable within $0.08\%$.

In this study, a 4-channel high-precision pressure test system was designed. It implements high-precision measurement of pressure parameters at multiple test points in situ and synchronously in irregularly variable high-temperature environments. The test system consists of a pressure–temperature double-parameter composite sensor along with signal acquisition, temperature compensation algorithm processing, and real-time online display modules. The temperature-sensitive chip of the sensor was integrated on the surface of the differential pressure-sensitive chip for in-situ temperature compensation. The collected pressure-temperature parameters were calculated and displayed using the temperature compensation algorithm processing and real-time online display modules. Finally, a high-precision pressure test was conducted. The proposed test system realizes the pressure test in high-temperature environments with irregular variations in the range of 24–400 °C, with a test error of less than 0.95% and a sensitivity of 6.378 mV/kPa. The study results can be used for real-time monitoring of high-precision pressure of key components operating in irregularly variable high-temperature environments, which provides a significant guarantee for the normal operation of equipment.

Roller bearings are important rotating components of engines and have been widely used in the commercial, aerospace, railway transportation, and military fields. The inner race of a bearing that operates at high speeds can attain a temperature of almost 200 °C. Therefore, accurately measuring the speed of bearing inner race under a high-temperature thermal load is vital to ensure that engine is working properly. Herein, we propose a wireless method for measuring the bearing speed. The proposed method has a higher temperature application range and better accuracy than previous used methods. It measures the bearing’s inner race speed based on the eddy current effect and impedance matching. Adding a silver/copper layer to the surface of the bearing substrate changes its conductivity, magnetic permeability, and the equivalent impedance of the antenna. After passing through the coupler and detection circuit, the signal is output to the oscilloscope as a periodic voltage. The rotational speed of the bearing’s inner ring is measured by calculating the periodicity of the waveform. A bearing speed test platform is built and used for multiple groups of bearing speed measurements at 20, 100, and 200 °C on the platform. The results indicate that the method provides excellent stability and accuracy in the range of 0–1000 rpm, with a stable relative error of less than 1.64 % and maximum hysteresis of 1.72 %. The maximum repeatability is 1.63658 % (1000 rpm, 200 °C) and the maximum uncertainty is 0.66782 (1000 rpm, 200 °C).

In this study, we designed an absolute pressure micro-pressure sensor, with its testing method based on the requirements of high-temperature resistance, self-compensation, and micro-pressure test. The substrate of the sensor is made of raw porcelain through high-temperature sintering, and the functional layer is integrated on the surface of the substrate by silver paste through a screen-printing process. Therefore, the sensor has high temperature resistance. The ceramic base of the sensor is prepared based on the principle of film stress and strain measurement of micro pressure by filling carbon film in raw porcelain layer and using a high-temperature sintering process to obtain an air-tight cavity structure. In the preparation of the functional layer, a unique differential capacitance structure is constructed on the surface of the substrate using the screen-printing process. This hardware temperature self-compensation structure enables the high-precision measurement of the sensor. Finally, the high temperature and absolute pressure micro-pressure sensor is combined with a C-V conversion circuit to complete the test on the high-temperature-micro pressure composite test platform. The experimental results show the sensor can measure the absolute pressure from 3 to 100 kpa in the temperature range of 23 to 300 °C, and the repeatability error of the pressure test is less than 3.3% at 300 °C.

In this study, a high-performance surface acoustic wave (SAW) device based on a multi-layer graphene amplifier is proposed, which is mainly composed of a zinc-oxide (ZnO) substrate, an interdigital transducer (IDT) input, a graphene sensing layer, metal electrodes and a fork finger transducer output. The sensor uses graphene’s unique band structure and the electron transport properties of the high mobility of the carrier with extremely small temperature influence to amplify the signal of the SAW caused by the sensing signal, thereby improving the sensitivity of the SAW sensor. The influence of graphene variable conductivity controlled by the uniform electric field on SAW amplifier devices in the near field is studied and analyzed. A small size surface acoustic wave device is fabricated with microelectromechanical system (MEMS) technology. The results show that the resonant frequency of the sensor is about 72 MHz, and the maximum amplification performance is 36 dB/cm. It is found that the SAW amplifier proposed in ZnO piezoelectric crystals exhibits superior performance in graphene-based SAW amplifiers.