BENZENE GAS SENSOR BASED ON SCREEN-PRINTED PZT CANTILEVERS

2011 ◽  
Vol 2011 (CICMT) ◽  
pp. 000111-000116
Author(s):  
Hélène Debéda ◽  
Rosa M. Vázquez ◽  
Riadh Lakhmi ◽  
Francisco J. Arregui ◽  
Claude Lucat ◽  
...  
Keyword(s):  
Screen Printing ◽  
Room Temperature ◽  
Tin Dioxide ◽  
Sacrificial Layer ◽  
Longitudinal Vibration ◽  
Longitudinal Mode ◽  
High Sensitivity ◽  
Layer Technique ◽  
Longitudinal Vibration Mode ◽  
Ppm Level

Benzene gas detections at ppm level are performed at room temperature with a piezoelectric resonant type sensor. For this purpose, self-actuated PZT cantilevers made of multi-layered Au/PZT/Au beam (8×2×0.1 mm3) partially released from an alumina substrate, are fabricated thanks to the association of screen-printing and sacrificial layer technique. Then, PZT cantilevers are functionalized with different organic (polypyrrole and polyaniline) and inorganic (active carbon and tin dioxide) coatings. The high sensitivity (tens of hertz/ppm) is achieved by using the unusual 31's longitudinal vibration mode of the PZT cantilever, unlike classical modes like transversal bending resonating mode. With the second “in-plane” 31-longitudinal mode of the PZT beam, benzene detection at sub-ppm level is expected with the organic and inorganic sensitive coatings. These very interesting results already demonstrate the potentialities of coated PZT cantilevers for gas detection and can be extended to species detection in liquid media.

Study of self-actuated screen-printed PZT-cantilevers

2011 ◽  
Vol 2011 (CICMT) ◽  
pp. 000105-000110
Author(s):  
Riadh LAKHMI ◽  
Christophe CASTILLE ◽  
Hélène DEBEDA ◽  
Mario MAGLIONE ◽  
Claude LUCAT
Keyword(s):  
Screen Printing ◽  
Sintering Temperature ◽  
Sacrificial Layer ◽  
Longitudinal Vibration ◽  
Ferroelectric Ceramics ◽  
Mechanical Pressure ◽  
Bending Mode ◽  
Resonance Frequencies ◽  
Cantilever Structure ◽  
Screen Printed

Usually, resonating cantilevers come from silicon technology and are generally activated with pure bending mode. In this work, we suggest to combine high sensitive cantilever structure with full self-actuated piezoelectric thick-film for high electrical-mechanical coupling. This cantilever is realized through the screen-printing deposition associated with a sacrificial layer. The beam part of the cantilever is composed of a PZT layer between two gold electrodes. Optimum performances of ferroelectric ceramics strongly rely on their composition and microstructure which imply generally the use of mechanical pressure and very high sintering temperature. These conditions are not compatible with the screen-printing process. As already shown with ceramics, addition of eutectic composition Li2CO3-CuO-Bi2O3 or borosilicate glass-frit to PZT powder and application of isostatic pressure, the sintering temperature of cantilevers may be decreased. Screen-printed piezoelectric samples are thus fired at 850°C, 900°C and 950°C. SEM analyses show the densification of the microstructure while increasing the sintering temperature. Electrical and mechanical characterizations are then achieved after poling the self-actuated cantilevers of different dimensions. In addition to the bending mode observed with a vibrometer, we pointed out other resonances related to the piezoelectric properties of the PZT cantilevers. Indeed, the three first orders of “in-plane” 31-longitudinal vibration mode and the first order “out-of-plane” 33-thickness resonance mode are revealed. The resonance frequencies deduced from analytical modeling are linked to the cantilever dimensions and thus confirm the experimental results. The piezoelectric parameters of PZT cantilevers approach those of ceramics. Quality factors of 300 to 400 associated to the unusual 31-longitudinal mode make self-actuated screen-printed PZT cantilevers good candidates for detection in liquid and gaseous media.

Design and Fabrication of a Micro-Knife for Minimally Invasive Surgery

2008 ◽  
Author(s):  
Hang Guo ◽  
Hui Yang ◽  
Liming Zou
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Minimally Invasive Surgery ◽  
Minimally Invasive ◽  
Invasive Surgery ◽  
Vibration Frequency ◽  
Vibration Mode ◽  
Longitudinal Vibration ◽  
Longitudinal Mode ◽  
Longitudinal Vibration Mode

In this paper, a micro-knife for minimally invasive surgery is proposed. It is a silicon horn shape and works in an ultrasonic longitudinal vibration mode to realize the precise incision with its sharp tip at one end. Finite element method in ANSYS is used to analyze and design the device to obtain the vibration frequency and displacement amplitude of the longitudinal mode. In the end, microfabrication of the proposed micro-knife is presented.

The Design of Piezoelectric Transducer for Structural Health Monitoring Using Longitudinal Vibration Modes

2009 ◽  
Vol 413-414 ◽  
pp. 407-414 ◽  
Author(s):  
Xing Long Liu ◽  
Zhong Wei Jiang
Keyword(s):  
Vibration Mode ◽  
Longitudinal Vibration ◽  
Longitudinal Mode ◽  
Vibration Modes ◽  
Practical Applications ◽  
Longitudinal Modes ◽  
Impedance Response ◽  
Piezoelectric Impedance ◽  
Longitudinal Vibration Mode ◽  
Fixed Beam

Longitudinal vibration mode is conveniently used for damage localization and detection in truss structure. However, a satisfactory piezoelectric impedance response due to longitudinal modes is not so easy to obtain in practical applications. The objective of this paper is to investigate how to obtain the impedance response of longitudinal modes with a piece of PZT transducer. In this case various vibration modes will be excited by unilaterally bonded PZT transducer, so the observation of longitudinal modes becomes complicated. In this paper, the effect of parameters of PZT transducer such as the length and attachment position is discussed in detail. Through selecting a suitable size and attachment position, the impedance response of expected longitudinal modes can be generated. An example for generating impedance peaks of specified longitudinal mode in fixed-fixed beam is given to demonstrate its validity.

scholarly journals Preparation and Gas Sensing Properties of PANI/SnO2 Hybrid Material

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1360
Author(s):  
Qiaohua Feng ◽  
Huanhuan Zhang ◽  
Yunbo Shi ◽  
Xiaoyu Yu ◽  
Guangdong Lan
Keyword(s):  
Hybrid Material ◽  
Room Temperature ◽  
Tin Dioxide ◽  
Gas Adsorption ◽  
Gas Sensing ◽  
Oxidative Polymerization ◽  
Environmental Pollutants ◽  
Decomposition Temperature ◽  
Benzene Vapor ◽  
Thermo Gravimetric Analyzer

A sensor operating at room temperature has low power consumption and is beneficial for the detection of environmental pollutants such as ammonia and benzene vapor. In this study, polyaniline (PANI) is made from aniline under acidic conditions by chemical oxidative polymerization and doped with tin dioxide (SnO2) at a specific percentage. The PANI/SnO2 hybrid material obtained is then ground at room temperature. The results of scanning electron microscopy show that the prepared powder comprises nanoscale particles and has good dispersibility, which is conducive to gas adsorption. The thermal decomposition temperature of the powder and its stability are measured using a differential thermo gravimetric analyzer. At 20 °C, the ammonia gas and benzene vapor gas sensing of the PANI/SnO2 hybrid material was tested at concentrations of between 1 and 7 ppm of ammonia and between 0.4 and 90 ppm of benzene vapor. The tests show that the response sensitivities to ammonia and benzene vapor are essentially linear. The sensing mechanisms of the PANI/SnO2 hybrid material to ammonia and benzene vapors were analyzed. The results demonstrate that doped SnO2 significantly affects the sensitivity, response time, and recovery time of the PANI material.

UV-assisted High-sensitivity Room-temperature Pd-gated HEMT NO2Gas Sensor

2021 ◽  
Author(s):  
Chong Xing ◽  
Dongcheng Xie ◽  
Haochen Zhang ◽  
Kang Song ◽  
Lei Yang ◽  
...  
Keyword(s):  
Room Temperature ◽  
High Sensitivity

scholarly journals Fabrication of Graphene Nanomesh FET Terahertz Detector

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 641
Author(s):  
Yuan Zhai ◽  
Yi Xiang ◽  
Weiqing Yuan ◽  
Gang Chen ◽  
Jinliang Shi ◽  
...  
Keyword(s):  
Room Temperature ◽  
Energy Gap ◽  
Coupling Efficiency ◽  
High Sensitivity ◽  
Fabrication Process ◽  
Monolayer Graphene ◽  
Terahertz Waves ◽  
Wet Process ◽  
Graphene Nanomesh ◽  
Thz Detector

High sensitivity detection of terahertz waves can be achieved with a graphene nanomesh as grating to improve the coupling efficiency of the incident terahertz waves and using a graphene nanostructure energy gap to enhance the excitation of plasmon. Herein, the fabrication process of the FET THz detector based on the rectangular GNM (r-GNM) is designed, and the THz detector is developed, including the CVD growth and the wet-process transfer of high quality monolayer graphene films, preparation of r-GNM by electron-beam lithography and oxygen plasma etching, and the fabrication of the gate electrodes on the Si3N4 dielectric layer. The problem that the conductive metal is easy to peel off during the fabrication process of the GNM THz device is mainly discussed. The photoelectric performance of the detector was tested at room temperature. The experimental results show that the sensitivity of the detector is 2.5 A/W (@ 3 THz) at room temperature.

B- and P-Doped Si0.8Ge0.2 Thin Film Deposited by Helicon Sputtering for the Micro-Thermoelectric Gas Sensor

2006 ◽  
Vol 320 ◽  
pp. 99-102 ◽  
Author(s):  
Kazuki Tajima ◽  
Woosuck Shin ◽  
Maiko Nishibori ◽  
Norimitsu Murayama ◽  
Toshio Itoh ◽  
...  
Keyword(s):  
Thin Film ◽  
Hydrogen Oxidation ◽  
Exothermic Reaction ◽  
High Sensitivity ◽  
Hydrogen Sensor ◽  
Thermoelectric Effect ◽  
Boron Doped ◽  
Reliable Monitoring ◽  
Ppm Level ◽  
Pt Catalyzed

Micro-thermoelectric hydrogen sensor (micro-THS) with the combination of the thermoelectric effect of Si0.8Ge0.2 thin film and the Pt-catalyzed exothermic reaction of hydrogen oxidation was prepared by microfabrication process. In the viewpoint of high sensitivity of micro-THS, the thermoelectric properties of the Si0.8Ge0.2 thin film could be improved by optimizing carrier concentration using helicon sputtering with an advantage of easy doping control, and sensitivity of the device with this thin film was investigated. As the result, the boron-doped Si0.8Ge0.2 thin film is considered to be the better choice ensuring the reliable monitoring of hydrogen concentration down to ppm level.

Evaluation Humidity Sensing Properties of Graphene/HS-TiO2 Nanocomposites

2021 ◽  
Vol 21 (10) ◽  
pp. 5143-5149
Author(s):  
Zhen Zhu ◽  
Wang-De Lin
Keyword(s):  
Room Temperature ◽  
Response Times ◽  
Sol Gel ◽  
Hollow Spheres ◽  
High Sensitivity ◽  
Humidity Sensing ◽  
X Ray ◽  
Transmission Electron ◽  
Recovery Times ◽  
Relative Humidity Range

This paper reports on a nanocomposite synthesized by sol–gel procedure comprising graphene sheets with hollow spheres of titanium dioxide (G/HS-TiO2) with varying weight percentages of graphene for the purpose of humidity sensors. The surface morphology of the nanocomposite was characterized using transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). The structural properties were examined using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). The response to 12–80% RH at room temperature exhibited sensitivity (S = 135). However, the relative humidity range of 12–90% at room temperature exhibited higher sensitivity (S = 557). Sensors fabricated using the proposed nanocomposite exhibited high sensitivity to humidity, high stability, rapid response times, and rapid recovery times with hysteresis error of less than 1.79%. These results demonstrate the outstanding potential of his material for the monitoring of atmospheric humidity. This study also sought to elucidate the mechanisms underlying humidity sensing performance.

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