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High temperature measurement of the rotating parts in aero-engine system requires wireless passive sensors. Surface acoustic wave (SAW) devices capable of measuring high temperature wirelessly are therefore ideal for these extreme scenarios where wired sensors are not applicable. In this article, SAW sensors built on the LiNbO3 substrate which can measure up to 1100 °C with a good repeatability and endurance are reported. The platinum IDT and LiNbO3 substrate were effectively protected by a SiO2 passivation layer to ensure the functionality and stability of the SAW devices under extremely high temperature. Distinct linearity of f0 vs. temperature, together with the temperature durability of the SAW sensors were verified by conducting various high-temperature RF tests. Such a SAW sensor attached with an embedded near-field antenna was also formulated to enhance the wireless transmission quality for future high-temperature remote sensing system.

Integrated thin-film sensors to measure the vane’s surface temperature are necessary for more efficient and smarter aeroengines. In this paper, a thin-film platinum/rhodioplatinum sensor array was ...

Intelligent aeroengine requires high temperature sensors, especially MEMS thin film sensors directly fabricated on the surface of turbine blade. For this purpose, an electrical insulation layer is needed on blade substrate metals. However, the electrical insulation of ceramic materials will degrade at high temperatures, thereby affecting the characteristics of the sensor. In this paper, ceramic material of YSZ thermal barrier coating (TBC) formulation was modified by adding a certain amount of Al2O3 to improve its insulation at high temperatures. Micro processing was carried out on the surface of the TBC, including the fabrication of platinum-point thermocouples and thermal resistor on TBC surface, and high temperature electrical insulation properties of the modified TBC were studied. Results show that electrical insulation can be improved several orders of magnitude with adding Al2O3 which meets the requirement to build reliable thin film sensors on the top of TBC surface coated on turbine blade metals. Several verification experiments were carried out to ensure the working ability of TBC layer, including robustness test, thermal shock test and high temperature retention test.

The surface acoustic wave (SAW) device can be used to measure temperature wirelessly, which is highly adaptable to the use in aero-engines high-temperature test scenarios where wired-sensors is not suitable for its difficulty in signal transfers. Herein, this paper presents a SAW sensor capable of achieving high-temperature measurement up to 800 °C with a good repeatability. The sensor is built on 41°Y LiNbO3 substrate with a SiO2 passivation. With the protection of SiO2 layer, the volatilization of platinum is effectively prevented to ensure SAW’s stability at a higher temperature. At the same time, SiO2 layer also protects the lithium niobate substrate, according to our verification result of XRD and EDS. Both crystal orientation and chemical composition of LiNbO3 substrate have been maintained after high-temperature testing. The temperature coefficient factor TCF is −2.98KHz/°C for our passivated SAW devices with a good linearity and repeatability.

Summary Coronavirus disease 2019 (COVID-19) has highlighted the need for the timely collection and sharing of public health data. It is important that data sharing is balanced with protecting confidentiality. Here we discuss an innovative mechanism to protect health data, called differential privacy. Differential privacy is a mathematically rigorous definition of privacy that aims to protect against all possible adversaries. In layperson's terms, statistical noise is applied to the data so that overall patterns can be described, but data on individuals are unlikely to be extracted. One of the first use cases for health data in Australia is the development of the COVID-19 Real-Time Information System for Preparedness and Epidemic Response (CRISPER), which provides proof of concept for the use of this technology in the health sector. If successful, this will benefit future sharing of public health data., The bigger picture Differential privacy is an innovative technique that can be applied to data to protect confidentiality. This has been used primarily to protect private sector data, but has significant implications for public health. We describe the methods of differential privacy in terms understandable to a non-computer-science audience. To our knowledge, this is the first article describing differential privacy in language and context appropriate for a health audience. The case study described shows the feasibility of the use of differential privacy for public health surveillance data to optimize information sharing while protecting data confidentiality. This method allows for data to be released in more granular detail in terms of time, place, and person without compromising privacy and confidentiality. Future research needs to consider other use cases, including a range of surveillance systems and applications in other types of health data., Differential privacy is a novel technique applied to data to provide additional privacy. To date, this has been used primarily in the private sector. This technique may have applications in the release of public health data. Here we describe differential privacy in language appropriate for a health audience, using a public health case study as an example.

Thin film bulk acoustic resonator (FBAR) plays a very important role in radio frequency (RF) filters used in cell phone and other wireless systems. Although FBAR is commercialized, the design/process interactions on the frequency response variation in FBAR device are still lacking. Design and fabrication are two crucial aspects affecting FBAR device performance. In this report, various solidly mounted resonators (SMR) were designed, fabricated and analyzed to study wafer-level site-to-site RF variation on design and fabrication process. As a key process step for SMR FBAR, the optimization process of Mg-doped ZnO piezoelectric thin film deposition was studied by varying thin film sputtering conditions using various sputtering targets and by post annealing treatment after the deposition. The quality of this crucial layer was verified by XRD on its (0 0 2) crystallization and wafer-level FBAR RF characterization. FBAR devices with high quality were fabricated with an excellent resonant behavior near 2 GHz and a maximum return loss of −15 to 25 dB. Quality factor Q ranges from 400 to 800, with a coupling coefficient keff2 of 1.5–3%. Wafer-level and wafer-to-wafer variation of central frequency are within 1.8–2.1 GHz. Computer simulation verified that this frequency variation correlates to the piezoelectric film variation of 1.6–1.9 μm. Process control on this piezoelectric thin film is essential to maintaining the resonator frequency-controlled value when building duplexer RF circuits. The dependency of RF performance on FBAR size, density and orientation is not obvious, compared to that of the wafer-level FBAR device variation on fabrication process. Regarding to the Mg-doping effect in MgxZn1-xO piezoelectric film, the amount of Mg in MgxZn1-xO film during the sputtering process must be properly controlled within 30% to keep the piezoelectric quality. The average acoustic speed of the Mg-doped ZnO film is 6870 m/s with the estimated range of 5760–7980 m/s, which is better than that of pure ZnO film (6330 m/s).

Thermal barrier coating (TBC) is an important material for aero-engine as a good thermal and electrical insulator. However this ceramic layer becomes electrically conductive at elevated temperatures above 600°C. By making use of its thermal resistance sensitivity to ambient temperature a smart thermal sensor can also be formulated to monitor the surface temperature on aero-engine turbine blade. In this paper the fabrication of this new sensor is reported together with comprehensive high-temperature characterizations such as repeatability, responsiveness and measurement error evaluation under various high temperature cycling and aero-engine onsite combustion test. Results show this sensor is capable to test the surface temperature in 500–1 000°C range or higher. YSZ-based (yttria-stabilized zirconia) TBC thermistor sensor shows a reliable and repeatable resistor vs temperature behavior and comparable responsiveness as conventional thermalcouple device with the measurement errors in 3%. Sensor fabrication is fairly simpels just involving a platinum soldering on TBC surface for wiring connection to outside meters. A new test array based on the YSZ thermal resistor is proposed as a temperature distribution monitor and verified by the aid of thermal-electrical interactive simulations. This simple methodology can be used for quick checking of surface temperature on turbine guide vane used in combustion chamber and other relevant parts.