Qiulin Tan

A wireless passive pressure microsensor fabricated in HTCC MEMS technology for harsh environments.

A wireless passive high-temperature pressure sensor without evacuation channel fabricated in high-temperature co-fired ceramics (HTCC) technology is proposed. The properties of the HTCC material ensure the sensor can be applied in harsh environments. The sensor without evacuation channel can be completely gastight. The wireless data is obtained with a reader antenna by mutual inductance coupling. Experimental systems are designed to obtain the frequency-pressure characteristic, frequency-temperature characteristic and coupling distance. Experimental results show that the sensor can be coupled with an antenna at 600 °C and max distance of 2.8 cm at room temperature. The senor sensitivity is about 860 Hz/bar and hysteresis error and repeatability error are quite low.

A Harsh Environment-Oriented Wireless Passive Temperature Sensor Realized by LTCC Technology

To meet measurement needs in harsh environments, such as high temperature and rotating applications, a wireless passive Low Temperature Co-fired Ceramics (LTCC) temperature sensor based on ferroelectric dielectric material is presented in this paper. As a LC circuit which consists of electrically connected temperature sensitive capacitor and invariable planar spiral inductor, the sensor has its resonant frequency shift with the variation in temperature. Within near-filed coupling distance, the variation in resonant frequency of the sensor can be detected contactlessly by extracting the impedance parameters of an external antenna. Ferroelectric ceramic, which has temperature sensitive permittivity, is used as the dielectric. The fabrication process of the sensor, which differs from conventional LTCC technology, is described in detail. The sensor is tested three times from room temperature to 700 °C, and considerable repeatability and sensitivity are shown, thus the feasibility of high performance wireless passive temperature sensor realized by LTCC technology is demonstrated.

A High Temperature Capacitive Pressure Sensor Based on Alumina Ceramic for in Situ Measurement at 600 °C

In response to the growing demand for in situ measurement of pressure in high-temperature environments, a high temperature capacitive pressure sensor is presented in this paper. A high-temperature ceramic material-alumina is used for the fabrication of the sensor, and the prototype sensor consists of an inductance, a variable capacitance, and a sealed cavity integrated in the alumina ceramic substrate using a thick-film integrated technology. The experimental results show that the proposed sensor has stability at 850 °C for more than 20 min. The characterization in high-temperature and pressure environments successfully demonstrated sensing capabilities for pressure from 1 to 5 bar up to 600 °C, limited by the sensor test setup. At 600 °C, the sensor achieves a linear characteristic response, and the repeatability error, hysteresis error and zero-point drift of the sensor are 8.3%, 5.05% and 1%, respectively.

Wireless Passive Temperature Sensor Realized on Multilayer HTCC Tapes for Harsh Environment

A wireless passive temperature sensor is designed on the basis of a resonant circuit, fabricated on multilayer high temperature cofired ceramic (HTCC) tapes, and measured with an antenna in the wireless coupling way. Alumina ceramic used as the substrate of the sensor is fabricated by lamination and sintering techniques, and the passive resonant circuit composed of a planar spiral inductor and a parallel plate capacitor is printed and formed on the substrate by screen-printing and postfiring processes. Since the permittivity of the ceramic becomes higher as temperature rises, the resonant frequency of the sensor decreases due to the increasing capacitance of the circuit. Measurements on the input impedance versus the resonant frequency of the sensor are achieved based on the principle, and discussions are made according to the exacted relative permittivity of the ceramic and quality factor () of the sensor within the temperature range from 19°C (room temperature) to 900°C. The results show that the sensor demonstrates good high-temperature characteristics and wide temperature range. The average sensitivity of the sensor with good repeatability and reliability is up to 5.22 KHz/°C. It can be applied to detect high temperature in harsh environment.

An Embedded Passive Resonant Sensor Using Frequency Diversity Technology for High-Temperature Wireless Measurement

This paper presents an embedded wireless passive temperature sensor for measurements in high-temperature applications, such as compressors and turbine engines. The performance of the sensor was improved by optimizing its performance parameters. A high-temperature-resistant material was used, and an embedded structure design was introduced to enable the sensor to operate in high-temperature environments. A series LC resonant circuit containing a fixed inductance coil and variable capacitance that varies with temperature was embedded in an alumina ceramic substrate using high-temperature cofired ceramic technology. The temperature in the high-temperature environment was detected wirelessly via the frequency diversity of the sensor. Furthermore, the experimental results showed that the sensor can measure temperatures ranging from room temperature to 1000 °C, and the average sensitivity of the sensor is ~2 KHz/°C.

An Insertable Passive LC Pressure Sensor Based on an Alumina Ceramic for In Situ Pressure Sensing in High-Temperature Environments

Pressure measurements in high-temperature applications, including compressors, turbines, and others, have become increasingly critical. This paper proposes an implantable passive LC pressure sensor based on an alumina ceramic material for in situ pressure sensing in high-temperature environments. The inductance and capacitance elements of the sensor were designed independently and separated by a thermally insulating material, which is conducive to reducing the influence of the temperature on the inductance element and improving the quality factor of the sensor. In addition, the sensor was fabricated using thick film integrated technology from high-temperature materials that ensure stable operation of the sensor in high-temperature environments. Experimental results showed that the sensor accurately monitored pressures from 0 bar to 2 bar at temperatures up to 800 °C. The sensitivity, linearity, repeatability error, and hysteretic error of the sensor were 0.225 MHz/bar, 95.3%, 5.5%, and 6.2%, respectively.

Rapid characterization of the biomechanical properties of drug-treated cells in a microfluidic device

Cell mechanics is closely related to many cell functions. Recent studies have suggested that the deformability of cells can be an effective biomarker to indicate the onset and progression of diseases. In this paper, a microfluidic chip is designed for rapid characterization of the mechanics of drug-treated cells through stretching with dielectrophoresis (DEP) force. This chip was fabricated using PDMS and micro-electrodes were integrated and patterned on the ITO layer of the chip. Leukemia NB4 cells were considered and the effect of all-trans retinoic acid (ATRA) drug on NB4 cells were examined via the microfluidic chip. To induce a DEP force onto the cell, a relatively weak ac voltage was utilized to immobilize a cell at one side of the electrodes. The applied voltage was then increased to 3.5 V pp and the cell started to be stretched along the applied electric field lines. The elongation of the cell was observed using an optical microscope and the results showed that both types of cells were deformed by the induced DEP force. The strain of the NB4 cell without the drug treatment was recorded to be about 0.08 (time t = 180 s) and the drug-treated NB4 cell was about 0.21 (time t = 180 s), indicating a decrease in the stiffness after drug treatment. The elastic modulus of the cell was also evaluated and the modulus changed from 140 Pa to 41 Pa after drug treatment. This microfluidic chip can provide a simple and rapid platform for measuring the change in the biomechanical properties of cells and can potentially be used as the tool to determine the biomechanical effects of different drug treatments for drug discovery and development applications.

Review of Research Status and Development Trends of Wireless Passive LC Resonant Sensors for Harsh Environments

Measurement technology for various key parameters in harsh environments (e.g., high-temperature and biomedical applications) continues to be limited. Wireless passive LC resonant sensors offer long service life and can be suitable for harsh environments because they can transmit signals without battery power or wired connections. Consequently, these devices have become the focus of many current research studies. This paper addresses recent research, key technologies, and practical applications relative to passive LC sensors used to monitor temperature, pressure, humidity, and harmful gases in harsh environments. The advantages and disadvantages of various sensor types are discussed, and prospects and challenges for future development of these sensors are presented.

Development of an Optical Gas Leak Sensor for Detecting Ethylene, Dimethyl Ether and Methane

In this paper, we present an approach to develop an optical gas leak sensor that can be used to measure ethylene, dimethyl ether, and methane. The sensor is designed based on the principles of IR absorption spectrum detection, and comprises two crossed elliptical surfaces with a folded reflection-type optical path. We first analyze the optical path and the use of this structure to design a miniature gas sensor. The proposed sensor includes two detectors (one to acquire the reference signal and the other for the response signal), the light source, and the filter, all of which are integrated in a miniature gold-plated chamber. We also designed a signal detection device to extract the sensor signal and a microprocessor to calculate and control the entire process. The produced sensor prototype had an accuracy of ±0.05%. Experiments which simulate the transportation of hazardous chemicals demonstrated that the developed sensor exhibited a good dynamic response and adequately met technical requirements.

Microfabrication of a Novel Ceramic Pressure Sensor with High Sensitivity Based on Low-Temperature Co-Fired Ceramic (LTCC) Technology

In this paper, a novel capacitance pressure sensor based on Low-Temperature Co-Fired Ceramic (LTCC) technology is proposed for pressure measurement. This approach differs from the traditional fabrication process for a LTCC pressure sensor because a 4J33 iron-nickel-cobalt alloy is applied to avoid the collapse of the cavity and to improve the performance of the sensor. Unlike the traditional LTCC sensor, the sensitive membrane of the proposed sensor is very flat, and the deformation of the sensitivity membrane is smaller. The proposed sensor also demonstrates a greater responsivity, which reaches as high as 13 kHz/kPa in range of 0–100 kPa. During experiments, the newly fabricated sensor, which is only about 6.5 cm2, demonstrated very good performance: the repeatability error, hysteresis error, and nonlinearity of the sensor are about 4.25%, 2.13%, and 1.77%, respectively.