This paper provides a detailed overview of developments in transducer materials technology relating to their current and future applications in micro-scale devices. Recent advances in piezoelectric, magnetostrictive and shape-memory alloy systems are discussed and emerging transducer materials such as magnetic nanoparticles, expandable micro-spheres and conductive polymers are introduced. Materials properties, transducer mechanisms and end applications are described and the potential for integration of the materials with ancillary systems components is viewed as an essential consideration. The review concludes with a short discussion of structural polymers that are extending the range of micro-fabrication techniques available to designers and production engineers beyond the limitations of silicon fabrication technology.

/pdf/new-materials-for-micro-scale-sensors-and-actuators-an-21qnaonn0l.pdf

New materials for micro-scale sensors and actuators An engineering review

Relaxor-based ferroelectric single crystals: growth, domain engineering, characterization and applications.

Ganong's review of medical physiology , Ganong's review of medical physiology , کتابخانه دیجیتال جندی شاپور اهواز

Ganong's review of medical physiology

Recent progress in flexible and stretchable piezoelectric devices for mechanical energy harvesting, sensing and actuation

A modified deep convolutional neural network for detecting COVID-19 and pneumonia from chest X-ray images based on the concatenation of Xception and ResNet50V2.

Comprehensive electrocardiographic diagnosis based on deep learning.

Thick film piezoelectric ceramic sensors have been successfully deposited on different metallic substrates with different shapes by a sol?gel spray technique. The ball-milled bismuth titanate fine powders were dispersed into PZT solution to achieve the gel. The films with desired thickness up to 200??m have been obtained through the multilayer coating approach. These thick films were also effectively coated onto thin sheet metals of thickness down to 25??m. Self-support films with flat and shell geometries were made. Piezoelectricity was achieved using the corona discharge poling method. The area of the top silver paste electrode was also optimized. The center frequencies of ultrasonic signals generated by these films ranged from 3.6 to 30?MHz and their bandwidth was broad as well. The ultrasonic signals generated and received by these ultrasonic transducers (UTs) operated in the pulse/echo mode had a signal to noise ratio more than 30?dB. The main advantages of such sensors are that they (1) do not need couplant, (2) can serve as piezoelectric and UT, (3) can be coated onto curved surfaces and (4) can operate up to 440??C. The capability of these thick film UTs for non-destructive evaluation of materials at 440??C has been demonstrated.

/pdf/piezoelectric-thick-bismuth-titanate-lead-zirconate-titanate-45e4rvd5rd.pdf

Piezoelectric thick bismuth titanate/lead zirconate titanate composite film transducers for smart NDE of metals

Integrated ultrasonic transducers (IUTs) and flexible ultrasonic transducers (FUTs) are presented for nondestructive testing at high temperatures. These transducers are made of sol–gel-sprayed piezoelectric thick (>40 μm) ceramic films. The ceramic materials are lead-zirconate-titanate, bismuth titanate and lithium niobate which are for thickness measurements up to 150, 400 and 800 °C, respectively. The IUT can also be deposited onto one end of a long ultrasonic delay line to perform nondestructive testing at the other end at even higher temperatures. FUTs made of bismuth titanate films onto thin stainless steel foils are also used for thickness measurements at 300 °C with a high-temperature couplant sandwiched between the FUT and a steel substrate. All experiments at high temperatures were performed in pulse-echo mode and ultrasonic echoes with signal-to-noise ratios above 20 dB were obtained. The center operation frequencies of both IUTs and FUTs range from 4.4 to 10.7 MHz.

High-temperature integrated and flexible ultrasonic transducers for nondestructive testing

Classification of heart sound signals using a novel deep WaveNet model.

Flexible ultrasonic transducers (UTs) consisting of a metal foil, a piezoelectric ceramic film, and a top electrode have been developed. The flexibility is realized owing to the porosity of piezoelectric film and the thinness of metal foil. In this paper, the stainless steel (SS), lead-zirconate-titanate (PZT)/PZT composite and silver paste were chosen as metal foil, piezoelectric film, and top electrode materials, respectively. The SS foil serves as both substrate and bottom electrode. The PZT/PZT piezoelectric composite film is made by the sol-gel spray technique. PZT/PZT films of thicknesses from 40 to 70 mum were fabricated onto SS foils. The capability of these flexible sensors operated in the pulse-echo mode for nondestructive testing on flat and curved surfaces of different materials at room temperature and 160degC has been demonstrated. Numerical simulations of the effects of the metal foil thickness on the ultrasonic performance of flexible UTs also were carried out, and the results are in reasonable agreement with experimental data. In addition, a PZT/PZT flexible transducer showed a signal strength comparable with that obtained by a commercial room temperature broad bandwidth transducer

/pdf/flexible-ultrasonic-transducers-2a6vb96eb4.pdf

Makiko Kobayashi

Papers

Comprehensive electrocardiographic diagnosis based on deep learning.

Piezoelectric thick bismuth titanate/lead zirconate titanate composite film transducers for smart NDE of metals

High-temperature integrated and flexible ultrasonic transducers for nondestructive testing

Classification of heart sound signals using a novel deep WaveNet model.

Flexible ultrasonic transducers