Ceramic Sensors Research Articles

Flexible Ceramic Film Sensors for Free-Form Devices.

Recent technological innovations, such as material printing techniques and surface functionalization, have significantly accelerated the development of new free-form sensors for next-generation flexible, wearable, and three-dimensional electronic devices. Ceramic film sensors, in particular, are in high demand for the production of reliable flexible devices. Various ceramic films can now be formed on plastic substrates through the development of low temperature fabrication processes for ceramic films, such as photocrystallization and transferring methods. Among flexible sensors, strain sensors for precise motion detection and photodetectors for biomonitoring have seen the most research development, but other fundamental sensors for temperature and humidity have also begun to grow. Recently, flexible gas and electrochemical sensors have attracted a lot of attention from a new real-time monitoring application that uses human breath and perspiration to accurately diagnose presymptomatic states. The development of a low-temperature fabrication process of ceramic film sensors and related components will complete the chemically stable and reliable free-form sensing devices by satisfying the demands that can only be addressed by flexible metal and organic components.

BaZrO3 based non enzymatic single component single step ceramic electrochemical sensor for the picomolar detection of dopamine

BaZrO3 perovskite crystallites were synthesized in a single step using a calcination free room temperature co precipitation method. Crystallite size, presence of metal oxygen bond, thermal stability, defect structure, surface morphology were studied using structural, thermal and microscopic investigations. This material was used for the modification of carbon paste electrode (CPE) for the fabrication of an advanced sensor. The modified electrode exhibited lower resistance and better charge transfer compared to an unmodified electrode. The electrochemical characteristics investigated using CV and DPV showed high current sensitivity towards the detection of dopamine (DA). The modified electrode achieved a remarkable low concentration of 5 pM detection limit level for the detection of DA. Limit of detection for co existing molecules of uric acid (UA) and ascorbic acid (AA) were 500 pM and 500 nM respectively. The developed sensor could quantify the DA in the presence of uric acid (UA) and ascorbic acid (AA). Mixed sample analysis, interference studies, stability analysis etc prove the competence of the developed sensor. Real sample analysis in blood plasma and urine marked the practical utility of the developed sensor.

The influence law of concrete aggregate particle size on acoustic emission wave attenuation

Elastic waves have different attenuation laws when propagating in various materials, which is one of the important challenges in the application of non-destructive testing methods, such as acoustic emission (AE) technology in geotechnical engineering. The study presented in this paper investigated the influence mechanism of concrete composition materials and parameters on the propagation law of elastic waves using concrete specimens produced in six different particle sizes of sand or gravel. The burst AE signal was generated through the lead-breaking experiment, and ceramic piezoelectric sensors were used to record the signal waveform at different propagation distances. Through parameter analysis, spectrum analysis, and pattern recognition techniques, the influence of the concrete aggregate particle size on AE wave propagation and attenuation was revealed. The results show that the attenuation of elastic wave amplitude, energy spectral density, and frequency all were positively correlated with the aggregate particle size, and the elastic wave spectrum center of gravity generally decreased with the propagation distance. The ring count gradually decreased with the propagation distance, and the specimens with a larger aggregate particle size underwent a relatively faster ring count attenuation rate. The rise time increased rapidly with the propagation of the elastic wave, and the specimens with a larger aggregate particle size experienced a relatively rapid increase in rise time. In addition, in the feature spaces of ring count-amplitude and rise time–amplitude, the size of aggregate has an obvious influence on the distribution of these feature vector.

Flexible Stannum-Doped SrTiO3 Nanofiber Membranes for Highly Sensitive and Reliable Piezoresistive Pressure Sensors.

Mechanically flexible ceramic fiber-based electronic skins are attractive materials ascribed to the features of monitoring signals of various physical parameters in a harsh environment, but the inherent brittleness of the ceramic fibers has limited their wide applications in emerging fields, such as fire-protecting clothing. Herein, a strategy to fabricate the flexible stannum(IV)-doped SrTiO3 (SSTO) nanofiber membranes by a facile sol-gel electrospinning method is reported. The calcination temperature and Sn4+ doping content play vital roles in regulating the crystalline and pore structures that are closely relevant to the flexibility and mechanical properties of the resultant SSTO nanofiber membranes. The as-prepared SSTO nanofiber membranes exhibited exceptional flexibility with an optimum tensile strength of 0.22 MPa, an elongation rate of 1.8%, and a Young's modulus of 13.3 MPa. Significantly, the flexible SSTO nanofiber-based piezoresistive sensors exhibited intriguing sensing performance toward pressure involving high sensitivity (2.24 kPa-1) in a low-pressure range (<400 Pa), fast response time (12 ms) and recovery time (32 ms), good durability (>1000 cycles), and excellent stability at different humidity levels and elevated temperatures. Furthermore, the sensor can also accurately monitor the signals of human motion such as finger bending, throat swallowing, and radial pulse. The fabrication of flexible ceramic nanofiber-based piezoresistive sensors would pave the way to fabricate wearable devices for fire-protecting clothing, personal healthcare, real-time human activity detection.

Sandy soil moisture content measurement method based on heated fiber Bragg grating

Actively heated optical fiber method (AHFO) based on fiber Bragg grating (FBG) temperature measurement technology has been continuously applied in soil moisture monitoring due to its advantages such as good durability, quasi-distribution, and small size. The FBG alumina ceramic tube sensor with symmetrical internal heating is used to design a laboratory model. By changing the inner capillary tube, a continuous function was used to fit the calibration relationship between the temperature rise and the volumetric water content, and the influence of different heating times on the calibration relationship was analyzed. Laboratory test studies have shown that the capillary tube with a low thermal conductivity material inside can help improve the sensor’s ability to resolve volumetric water content. The calibration relationship under short-time heating also has a high correlation, and it can also reduce the impact on the soil environment. The research results are of great significance for improving the measurement accuracy of the AHFO method and the improvement of the test method.

Temperature and Pressure Wireless Ceramic Sensor (Distance = 0.5 Meter) for Extreme Environment Applications.

This paper presents a design for temperature and pressure wireless sensors made of polymer-derived ceramics for extreme environment applications. The wireless sensors were designed and fabricated with conductive carbon paste on an 18.24 mm diameter with 2.4 mm thickness polymer-derived ceramic silicon carbon nitride (PDC-SiCN) disk substrate for the temperature sensor and an 18 × 18 × 2.6 mm silicon carbide ceramic substrate for the pressure sensor. In the experiment, a horn antenna interrogated the patch antenna sensor on a standard muffle furnace and a Shimadzu AGS-J universal test machine (UTM) at a wireless sensing distance of 0.5 m. The monotonic relationship between the dielectric constant of the ceramic substrate and ambient temperature is the fundamental principle for wireless temperature sensing. The temperature measurement has been demonstrated from 600 °C to 900 °C. The result closely matches the thermocouple measurement with a mean absolute difference of 2.63 °C. For the pressure sensor, the patch antenna was designed to resonate at 4.7 GHz at the no-loading case. The sensing mechanism is based on the piezo-dielectric property of the silicon carbon nitride. The developed temperature/pressure sensing system provides a feasible solution for wireless measurement for extreme environment applications.

Application of PZT Ceramic Sensors for Composite Structure Monitoring Using Harmonic Excitation Signals and Bayesian Classification Approach.

The capabilities of ceramic PZT transducers, allowing for elastic wave excitation in a broad frequency spectrum, made them particularly suitable for the Structural Health Monitoring field. In this paper, the approach to detecting impact damage in composite structures based on harmonic excitation of PZT sensor in the so-called pitch–catch PZT network setup is studied. In particular, the repeatability of damage indication for similar configuration of two independent PZT networks is analyzed, and the possibility of damage indication for different localization of sensing paths between pairs of PZT sensors with respect to damage locations is investigated. The approach allowed for differentiation between paths sensitive to the transmission mode of elastic wave interaction and sensitive reflection mode. In addition, a new universal Bayesian approach to SHM data classification is provided in the paper. The defined Bayesian classifier is based on asymptotic properties of Maximum Likelihood estimators and Principal Component Analysis for orthogonal data transformation. Properties of the defined algorithm are compared to the standard nearest-neighbor classifier based on the acquired experimental data. It was shown in the paper that the proposed approach is characterized by lower false-positive indications in comparison with the nearest-neighbor algorithm.

Research of Low-Power MEMS-Based Micro Hotplates Gas Sensor: A Review

In this paper, the research status of low power micro hot plate gas sensor is reviewed. This type of sensor is characterized by the combination of MEMS technology and related insulation measures. Compared with the traditional ceramic tubular sensor, the power consumption of the sensor is greatly reduced, which provides the possibility of remote sensor arrangement and long term stable operation. This paper firstly collects the current sensor-related heat conduction, heat convection and heat radiation theories, and summarizes the calculation model of heat loss in different regions of the micro hot plate gas sensor. Then, the application examples of the finite element method in the analysis of thermal characteristics of the sensor and the common preparation process of the substrate and gas sensitive layer of the micro hot plate are listed. Finally, the main test methods of the stability and gas sensitivity of the micro hot plate gas sensor are summarized.

Polymer-derived ceramic thin-film temperature sensor

In-situ monitoring of machines in harsh environment remains challenging due to lack of high-performance sensors. Most of sensors cannot survive over 600 ℃ even with packaging. In this work, an ultra-thin-film temperature sensor was fabricated based on polymer-derived ceramics (PDCs) via direct-writing for aerospace applications. The sensitive film with thickness of 10 µm consists of polymer-derived SiCN filled with TiB2, ZrB2 and SiC nano-particles. The resistance-temperature dependence tests of the sensor indicates that the resistance of the PDC thin film decreases monotonically with rising temperature and exhibits good repeatability at temperatures from room temperature to 800 ℃ in the air environment. The fabricated thin-film sensor shows great potential for high temperature applications and the technological routine provides a feasible pathway for structure/function integration in aerospace manufacture.

Determining humidity of nitrogen and air atmospheres by means of a protonic ceramic sensor

• An original design of a solid-state high-temperature amperometric gas sensor. • The sensor includes two electrochemical cells based on proton-conducting electrolytes. • Sc-doped barium stannate is used for the first time as the sensor’s electrolyte. The present work describes a design, fabrication, operation principle and testing of a solid-state amperometric sensor used for humidity analysis of nitrogen and air gas atmospheres. This sensor consists of two electrochemical cells (in fact, two sensors are combined into one) based on proton-conducting electrolytes, one of the cells is made of Sc-doped calcium zirconate (CaZr 0.95 Sc 0.05 O 3–δ ; CZS), while another is made of Sc-doped barium stannate (BaSn 0.75 Sc 0.25 O 3–δ ; BSS). Using two sensors in one allowed us to compare their sensing properties. The sensor was tested at 500 °C and different water vapor partial pressures (pH 2 O). The volt-ampere ( U – I ) dependencies and calibration curves (limiting current vs pH 2 O) of the fabricated sensor were obtained and analyzed. The limiting current of the BSS-based cell is reached at a lower voltage than that of the CZS-based cell. In a nitrogen-containing atmosphere, the limiting current was reached for both electrochemical cells, and it varied linearly depending on pH 2 O. In an air atmosphere, the limiting current could not be reached only for the BSS-based cell at pH 2 O values less than 0.043 atm. A possible explanation for this is proposed.

Activation of percolation network in structural-strengthened polymer-derived ceramic for minor deformation detection

Monitoring of minor deformation in precision instruments is of great significance to guarantee the reliable operation. Polymer derived ceramic sensors with superior piezoresistive performance are promising. The traditional forming methods of the PDC sensor may cause the decline in mechanical properties. Thus, a silicon oxycarbide (SiOC) ceramic pressure sensor with diamond minimal surface structure were designed to improve the dimensional stability and ensure the uniform distribution of the stress. The percolation network comprising of electrically conductive free carbon was formed in the SiOC by the post heat treatment, which provided the structure superior piezoresistive property. The customized percolation network provided tunable sensing behavior and the resulting sensor had excellent accuracy and repeatability, possessing high sensitivity with the gauge factor of 297. More importantly, the sensor exhibited the high sensitivity with the small strains lower than 1.5%, indicating a reliable detection ability to the easily overlooked deformation. Additionally, the sensor had a high conductivity of 1.05 S/m and outstanding mechanical properties with the compressive strength and energy absorption of 15.11 MPa and 71.39 kJ•m−3. The printed sensor surmounts the limitations of current sensing materials, providing a promising way for the fabrication of high-performance and customized polymer derived ceramic pressure sensor.

Performance of two innovative stress sensors imbedded in mortar joints of new masonry elements

Many historical cities enjoy the presence of masonry buildings with inestimable historical, artistic and cultural value. Old masonry buildings often suffer structural deficiencies, design faults and materials aging process. In recent years, many researchers focused their attention on the opportunities that structural health monitoring (SHM) can ensure for the health state of existing masonry structures, where damage can be difficult to be promptly predicted, pontentially causing abrupt collapses, with high risks for the community.This paper presents an experimental study on the effectiveness of two types of stress sensor for SHM of new masonry elements. Ceramic piezoelectric sensors and capacitive sensors were installed in mortar joints of two series of specimens made of calcarenite stone masonry and clay brick masonry. All specimens were tested under uniaxial compression with displacement control, to assess the effectiveness of sensors in recording pressure variation within the different types of masonry and therefore testing their potential use for SHM applications. Even though both the ceramic and capacitive sensors were designed as stress sensors for concrete structures, their installation within mortar joints provided a good response, based on the comparison with standard measurement devices. Results demonstrate the suitability of the sensors even for SHM of masonry structures.

How to Make Ceramic Gas Sensor Films at Room Temperature - the Powder Aerosol Deposition Method

Introduction Typically, gas sensors are ceramic devices. They are manufactured in ceramic techniques like tape technology and/or conventional thick-film techniques (typically screen-printing with subsequent firing) [1]. During firing, interdiffusion processes occur between substrate and gas sensitive film. At least partly, they may deteriorate the gas sensing properties of the functional oxides. Some materials can even hardly be processed without decomposition. Therefore, room temperature deposition techniques are advantageous. The Powder Aerosol Deposition Method The Powder Aerosol Deposition Method (PAD) bases on the Room Temperature Impact Consolidation (RTIC) as the film densification mechanism. This allows producing dense ceramic films without any high-temperature processes directly from an initial ceramic powder on almost any substrate material. This contribution gives examples for PAD-applications in the field of gas sensing.Although the process is rather simple, the results are very promising. Driven by a pressure difference to a vacuum deposition chamber (evacuated only to rough vacuum), the aerosol is accelerated by a slit nozzle to several hundred m/s. This aerosol jet ejects particles into the deposition chamber. Here, the particles impact on a movable substrate and get fractured into nanometer-sized fragments that are compacted by subsequently impacting particles. Fig. 1 depicts the basic principle. Further process details can be found in the reviews [2], [3], or [4]. Results and Discussion Some examples for PAD-based sensors are surveyed here. Besides conventional conductometric gas sensors based on SnO2 and other metal oxides to detect limited components, applications for temperature independent oxygen sensors are reported, e.g. of SrTi1-x Fe x O3 [5], [6] or Alumina-doped BaFe1-x Ta x O3 (BFATx) [7]. Simultaneous powder aerosol co-deposition of inert and functional oxides to fine-tune the sensing properties may be promising [6].Figure 2 is a measurement protocol at 900 °C of the logarithm of the film conductivity of BFAT30 fabricated by PAD. The material is rapidly and reproducibly responding to stepwise changes of the oxygen partial pressure, pO2. In Figure 3, the log-log plot of the conductivity (log s vs. log pO2) of the sensor between 600 °C and 900 °C in the pO2 range from 0.01 to 1 bar is shown. Neither the sensitivity to oxygen (slope in the log-log-plot) nor the base line resistance changes with temperature. Log s depends linearly on log pO2 between 700 °C and 900 °C, showing a slope of 0.24. An improved formulation contains 1 % alumina (BFATx). Amongst the BFATx samples examined, particularly good properties were found with regard to temperature independency for BFAT25 (BaFe0.74Al0.01Ta0.25O3).Combined resistive and thermoelectric oxygen sensors with almost temperature-independent characteristics of both conductivity and Seebeck coefficient were manufactured using BFAT30 [8].Classical tin-oxide conductometric metal oxide gas sensors were deposited by PAD at room temperature on interdigital electrodes. As expected, they show a pronounced sensitivity to nitrogen oxides at around 300 °C and to hydrogen at around 450 °C [9].With PAD, solid electrolyte electrochemical gas sensors have also been successfully manufactured [10]. A nitrogen oxide sensor using the novel pulsed-polarization method, which attracted much attention recently with YSZ as solid electrolyte, can now be operated at lower temperatures due to the use of a Bismuth-based fast oxide ion conductors (Fig. 4).The powder aerosol deposition method is also suitable to produce thermistors with a negative temperature coefficient of resistance (NTCR) [11]. They may serve as sensitive detectors for pellistors. Conclusions It is possible to manufacture ceramic gas sensor films completely without any high-temperature process and directly from an initial ceramic powder on almost any substrate material. Even temperature sensors can be realized. Future research directions may focus on sensors on polymers or textiles by applying the powder aerosol deposition method.

Microwave-Based State Diagnosis for Three-Way Catalysts – A Promising Technology for Future Gasoline Exhaust Gas Aftertreatment

Microwave-Based State Diagnosis for Three-Way Catalysts – A Promising Technology for Future Gasoline Exhaust Gas Aftertreatment

Ceramic multilayer technology as a platform for miniaturized sensor arrays for water analysis

Abstract. Ion-selective electrodes (ISEs) have been proven particularly useful in water analysis. They are usually used as single-rod measuring chains in different designs, which are manufactured using precision mechanical manufacturing and assembling technologies. The paper describes a microsystem technology approach for the fabrication of miniaturized electrochemical sensors. The ceramic HTCC (high-temperature co-fired ceramic) and LTCC (low-temperature co-fired ceramic) multilayer technology enables suitable processes for the manufacturing of robust and miniaturized sensor arrays with a high functional density. Design, manufacture, and electrochemical performance of the novel ceramic multilayer-based sensor array are presented in the paper using various examples. An adapted material and process development was carried out for the sensitive functional films. Special thick-film pastes for the detection of the pH value as well as NH4+, K+, Ca2+, and Cu2+ ion concentrations in aqueous solutions were developed. Ion-sensitive thick-film membranes were deposited on a ceramic multilayer sensor platform by means of screen-printing. All ISEs, integrated in the sensor array, showed suitable electrochemical performances including a very quick response (several seconds) combined with a high sensitivity (exhibiting Nernstian behaviour) in the tested measuring range. The obtained sensitivities were around 57 mVper decade: for the pH sensor, 30 mVper decade for calcium, 53 mVper decade for potassium, and 57 mVper decade for ammonium. Depending on the application, different sensitive electrodes on the ceramic sensor array can be combined as required.

High-Temperature Properties and Applications of Si-Based Polymer-Derived Ceramics: A Review.

Ceramics derived from organic polymer precursors, which have exceptional mechanical and chemical properties that are stable up to temperatures slightly below 2000 °C, are referred to as polymer-derived ceramics (PDCs). These molecularly designed amorphous ceramics have the same high mechanical and chemical properties as conventional powder-based ceramics, but they also demonstrate improved oxidation resistance and creep resistance and low pyrolysis temperature. Since the early 1970s, PDCs have attracted widespread attention due to their unique microstructures, and the benefits of polymeric precursors for advanced manufacturing techniques. Depending on various doping elements, molecular configurations, and microstructures, PDCs may also be beneficial for electrochemical applications at elevated temperatures that exceed the applicability of other materials. However, the microstructural evolution, or the conversion, segregation, and decomposition of amorphous nanodomain structures, decreases the reliability of PDC products at temperatures above 1400 °C. This review investigates structure-related properties of PDC products at elevated temperatures close to or higher than 1000 °C, including manufacturing production, and challenges of high-temperature PDCs. Analysis and future outlook of high-temperature structural and electrical applications, such as fibers, ceramic matrix composites (CMCs), microelectromechanical systems (MEMSs), and sensors, within high-temperature regimes are also discussed.

2Pb2-2 Multiple damage detection in piezoelectric ceramic sensor using scanning point contact excitation and detection method

2Pb2-2 Multiple damage detection in piezoelectric ceramic sensor using scanning point contact excitation and detection method

A Feasibility Study on Monitoring Pile‐Soil Bonding Condition Using Piezoceramic Transducer and Horizontal Impact

The in situ evaluation of pile‐soil bonding condition plays an important role for pile safety assessment in its life cycle. However, so far, there is still no fully mature tool to analyze such couplings, since the pile‐soil coupling exhibits complex and time‐varying relationships. This paper innovatively proposes a health monitoring approach to evaluate the bonding status of the soil and pile contact area. An impact method based on a piezoelectric ceramic sensor is proposed to monitor the bond of pile and soil. A horizontal impact was introduced near the top of the pile, and the induced stress waves were detected by the piezoceramic smart aggregate (SA) sensor embedded in the pile. Different crack damage sizes were made between the soil and the pile to investigate the change of the bonding. An energy index was developed to quantitatively evaluate the quality of the bonding as a pile‐soil bonding index. The proposed approach inspired a potential way to directly judge if there is crack damage between the pile and soil and to evaluate pile safety.

Significant enhancement in microstructural and electrical properties of lead-free (1-x)Ba0.9Sr0.1Ti0.9Zr0.1O3-xLiNbO3 ceramic composites

Ferroelectric composites of compositions (1-x)Ba0.9Sr0.1Ti0.9Zr0.1O3-(x)LiNbO3 (BTSZ-LNO) were synthesized by employing a modified mechano-chemical activation technique. The results indicate that there is a significant improvement in the material density and microstructural properties of the composites with LNO substitution, which has resulted in an improvement in electrical properties of the materials. The peak dielectric constant of the material is markedly enhanced from 8,536 to 9,512 for the sample with x = 0.10 LNO concentration. LNO substitution in BTSZ has led to a transformation from classical ferroelectric to relaxor, which is a crucial requirement for energy storage materials. The electromechanical response as a function of poling temperature and poling electric field has been investigated to obtain optimum piezoelectric characteristics. The sample with x = 0.10 LNO concentration exhibited a significant improvement in breakdown strength, which is ascribed to relatively higher density, uniform grain distribution, and optimum grain size of the material. The enhancement in electrical and electromechanical properties in (1-x)BTSZ-xLNO sample with x = 0.10 concentration indicates that the material can be employed in multi-layer ceramic capacitors, electrical insulators, and piezoelectric sensors.

Design of a downlink algorithm for rotary steering (logging while drilling) systems

For logging while drilling (LWD) systems, it is necessary to adjust the working state of the downhole tools in real-time according to different operating conditions. In this paper, on the basis of the characteristics of LWD systems, a mud pressure-apperceived downlink system was examined. For the design of this system, a signal acquisition and processing board was created based on a piezoelectric ceramic sensor to acquire the mud pressure signal. The error sources of the downlink command sending process were analyzed, and an error accumulation compensation processing algorithm was proposed to improve the recognition success rate of the downhole system. Moreover, to reduce noise interference on the characteristics of the mud impulse signal, a filtering algorithm was proposed based on the empirical mode decomposition method, and the success rate of instruction issuance was determined by identifying feedback instructions. Field tests were conducted to further improve the system, the results of which suggested that the system had good mud adaptability, high recognition success rate, and a certain application value.