An accurate and continuous measurement of heat flux is needed in many long-term operation facilities in order to monitor and improve the life of its machinery. A thin film heat flux sensor is usually fabricated via sputtering, according to different spatial arrangements of thermocouple junctions. A novel thin film heat flux sensor was designed, fabricated, and calibrated, but the connection between the thin film and the leads could not be fixed quickly and steadily. For this purpose, in this paper a method to seamlessly integrate the leads and the thin film has been proposed to improve the sensor output signal. The sensor is capable of simultaneously measuring surface heat flux and temperature magnitude, to address the current situation of the single design of heat flux sensors. The novel thin film heat flux sensor is structured as follows: Thirty pairs of NiCr-NiSi thermocouple junctions are deposited in an annular pattern on a well-designed ceramic substrate. Over the annular thermopile, a 2000 nm-thick thermal insulator layer is deposited to create a temperature gradient across the layers. In addition, in this study a new calibration method was used to evaluate the static and dynamic properties of this novel thin film heat flux sensor. The analysis and experimental results show that the heat flux calculated from the sensor output was in good agreement with the value obtained from the pre-calibrated standard sensor. The sensitivity and response time of the novel sensor were measured at 0.06 mV/(kW/m2) and 475 ms, respectively. The heat flux measurements made with the sensor presented good repeatability. The heat-transfer coefficient of the Al2O3 thin film was 4.477 w/(m∙k) for the novel thin film heat flux sensor described in this paper.
Flexible pressure sensors have attracted a lot of attention in fields such as medicine and healthcare due to their ease of making wearable devices. However, the development of flexible pressure sensors is facing the challenges of a complex manufacturing process and high cost. Herein, a zinc oxide (ZnO) piezoelectric film flexible pressure sensor with a 3 × 3 sensor array presented through an extremely simple and ultralow‐cost fabrication process is reported. The 3 × 3 sensor array in series and again, in parallel. The output voltage of the 3 × 3 sensor array is significantly higher compared to the original thin‐film piezoelectric sensors at the same film thickness. The ZnO flexible pressure sensor shows good linear sensitivity and high durability over 4000 cycles of loading in the test range of 0–14 N. The response and recovery times tend to decrease as the dynamic pressure increases in the experimental range. Furthermore, a high‐precision dynamic force calibration system through a comparison between the open‐loop and closed‐loop strategies used in the dynamic force calibration experiments that are performed is presented. Potential applications of the sensor are demonstrated, including elbow flexure and finger tapping. The sensor also shows the ease of massive fabrication.
Traditional thin-film thermocouples have limitations in measuring real surface temperature changes in aircrafts because the connection between the nanofilm and the leads can easily fail. However, how to improve the weak connection has rarely been mentioned in previous studies. In this study, a lead-embedded alumina ceramic substrate is proposed to improve the durability of thin-film thermocouples. Multilayer two-dimensional nanofilms with different thin-film electrode lengths were prepared on a substrate using DC-pulsed magnetron sputtering. Furthermore, the effect of the thin-film electrode length on the sensitivity, response time, and measurement error of the sensor was investigated. The electrode length did not affect the sensitivity and response time; however, as it increased, the temperature measurement error decreased. In addition, the static and dynamic performance, repeatability, measurement accuracy, and service lifetime of the developed sensor were verified. The results showed that the sensor had high sensitivity and linearity and good repeatability, with the response time being in microseconds. The sensor can continue to operate at 500 ℃ for more than 2 h with no signal interruption. The sensor accuracy was 0.43% at 300 ℃.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.