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Introduction to Electromechanical Filters
Published in John T. Taylor, Qiuting Huang, CRC Handbook of ELECTRICAL FILTERS, 2020
Since most electromechanical filters, which include SAW filters, use piezoelectric transducers, we will concentrate on filters of this type. A piezoelectric transducer is composed of a material that changes dimensions in the presence of an electric field and, conversely, a material that generates an electric field when mechanically stressed. The most commonly used piezoelectric materials are quartz and PZT ceramics. In most cases, electrodes are plated on opposite surfaces of the transducer, like a capacitor. In converting from electrical to mechanical energy, a voltage is applied across the plated surfaces producing an electric field and a resultant deformation of the material. Since we are using the transducer in a bandpass filter, we are also dealing with a resonant device. The transducer therefore acts as a resonator, a capacitor, and an electromechanical energy conversion device. Equivalent circuits of piezoelectric transducers are shown in Figure 2a (classical analogy) and Figure 2b (mobility analogy).
Application of ultrasounds in the extraction process for food waste valorisation
Published in Cândida Vilarinho, Fernando Castro, Margarida Gonçalves, Ana Luísa Fernando, Wastes: Solutions, Treatments and Opportunities III, 2019
D. Lopes, A. Mota, J. Araújo, J. Carvalho, C. Vilarinho, H. Puga
Ultrasounds are typically generated by piezoelectric transducers, which consist of arrays of crystals that due to the piezoelectric effect, are able to convert electrical energy in mechanical and vice-versa, thus, in response to an electrical signal, these vibrate and generate high-frequency sound waves. The first ultrasound transducers were made of natural piezoelectric crystals, such as quartz, Rochelle salts and tourmaline. Nowadays, most transducers use synthetic crystals, such as lead zirconate titanate, also called PZT (Gray, 2019). The most used equipment’s used for the processing of liquids are an ultrasonic cleaning bath, which sonicates samples that immersed in a bath, as shown in Fig. 2a, and a probe system, which is in direct contact with the samples, Fig. 2b.
High-Intensity Focused Ultrasound (HIFU)
Published in Ayman El-Baz, Gyan Pareek, Jasjit S. Suri, Prostate Cancer Imaging, 2018
The development of the modern ultrasound relies on the piezoelectric effect, which was first discovered in 1880 by Jacques and Pierre Curie. The piezoelectric effect is the ability of certain materials to generate an electric charge when mechanical stress is applied to them. This effect is also reversible—if a material generates electricity when external stress is applied, then it also has an ability to generate stress when an external electric field is applied. The piezoelectric effect was not incorporated into practical applications from its discovery until the initiation of World War I, when it was employed in the form of SONAR devices. As technology has advanced, new materials that can utilize the piezoelectric effect have been created and this phenomenon has been applied in many different industries.
Surface waves in piezoelectric semiconductor by using Eigen value approach
Published in Waves in Random and Complex Media, 2023
Adnan Jahangir, Sayed M. Abo-Dahab, Aiman Iqbal
Piezoelectric materials are materials that have the ability to create inner electrical charge from applied mechanical stress. Piezo is a Greek word used for ‘push’. A few normally happening substances in nature show the piezoelectric impact. These are DNA, Enamel, Silk, certain ceramics, crystals, Bone, Dentine and many more. The conductivity of semiconductors is in between insulators and good conductors, and it increments with expansion in temperature. A pure semiconductor, accordingly, acts as an insulator. The resistance of a semiconductor decreases with expansion in temperature. In a pure semiconductor, which carries on like an insulator under standard conditions, if modest quantity of certain metallic impurity is added, it achieves current conducting properties. The impure semiconductor is then called ‘impurity semiconductor’ or ‘outward semiconductor’. The way toward adding impurity to a semiconductor to make it extrinsic semiconductor is called Doping.
Improvement of electrical and energy harvesting properties of new lead-free BST modified 0.995BNKT–0.005LN ceramics
Published in Journal of Asian Ceramic Societies, 2023
Pimpilai Wannasut, Panupong Jaiban, Pharatree Jaita, Methee Promsawat, Orawan Khamman, Anucha Watcharapasorn
Piezoelectric materials are well-known smart materials that can convert mechanical energy to electrical energy and vice versa. With these characteristics, the piezoelectric materials have been used in a variety of technological applications such as sensor, actuator, transducer, filter, resonator, micro-electromechanical system (MEMS), electromechanical device, high energy storage capacitor, and so on [1–7]. Pb(Zr,Ti)O3 or PZT is a commercial piezoelectric material that has been selected as a material for piezoelectric applications due to its high piezoelectric performance. However, the toxicity of lead compounds released to the environment during a production process has been a concern [8–11]. This problem has led to the development of new lead-free piezoelectric materials with useable piezoelectric properties.
Self-assisted wound healing using piezoelectric and triboelectric nanogenerators
Published in Science and Technology of Advanced Materials, 2022
Fu-Cheng Kao, Hsin-Hsuan Ho, Ping-Yeh Chiu, Ming-Kai Hsieh, Jen‐Chung Liao, Po-Liang Lai, Yu-Fen Huang, Min-Yan Dong, Tsung-Ting Tsai, Zong-Hong Lin
In biomedical applications, the choice of material mainly depends on the strength of the piezoelectric effect and the material cost. The most common piezoelectric ceramics are PZT and quartz. PZT is cheap to manufacture, its piezoelectric coefficient is high, and it has broad applications as its composition can be adjusted. However, quartz is more stable over an extensive temperature range, maintaining consistent characteristics [3]. Restrictions apply as regards development of implants or technology involving direct human contact. Lead-free ceramics, such as quartz, barium titanate, and potassium sodium niobate, have higher biocompatibility [64]. In addition, many biomedical devices require flexibility to accommodate the dynamics of human movement. PVDF and its copolymers are widely used biocompatible polymers with high flexibility, low weight, low thermal conductivity, high chemical corrosion resistance, and heat resistance, and have been developed as biomechanical energy harvesting systems, sensors, and wound scaffolds [64,65].