Applications of Piezoelectrics

As electromechanical transducers, piezoelectrics find many uses in ultrasonics such as sonar transmitters and receivers, ultrasoimd imaging, and nondestructive testing. They are also used in microphones and speakers. Their extreme sensitivity to small changes in pressure makes them useful in strain gages, pressure gages, and accelerometers. Coating metal strips with a piezoelectric makes a very sensitive temperature gage used in thermostats. 

Organic piezo-polymers such as polyvinylidene fluoride along with trifluoroethylene and their copolymers can be made ferroelectric by poling the crystalline regions of these polymers. Because the density of these materials is close to that of human tissue, they have foimd use as transducers for ultrasound imaging with no acoustic mismatch. 

Although the expansion of piezoelectric crystals is small, the force they can exert is large and, when stacked together, they can serve as linear actuators. Also they can provide very small movements with extreme precision which makes them ideal for positioning atomic force microscopes. 

Quartz, since it is a piezoelectric and not a ferroelectric, has no hysteresis loss when it oscillates, thus quartz crystal oscillators are widely used as frequency control devices in radios, computers, and watches. Since the frequency is a function of the mass of the crystal, they can serve as deposition monitors (quartz crystal microbalances) with sensitivities of less than 1 ng. By functionalizing the surface to absorb specific gases, they can also act as chemical sensors. The temperature sensitivity of a quartz crystal oscillator can be minimized by choosing the cut of the crystal relative to the optical axis, which is necessary for its use as a frequency standard. On the other hand, a cut can be chosen to maximize the frequency dependence on temperature and quartz crystal thermometers with millikelvin resolution are available. 

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In Applications of Piezoelectric Quartz Crystal Microbalances Lu, C. Czanderna, A., Eds. Elsevier New York, 1984. 

J.H.T. LUONG and G.G. GUILBAULT, "Analytical applications of piezoelectric crystal biosensors", in "Biosensors Principles and Applications", M. Dekker, Inc., New York, 1991. 

Application of Piezoelectric Quatz Crystal Microbalances (Vol.7 of Methodes and Phenomena, Their Applications in Sience and Technology) Elesvier, Amsterdam, Oxford, New York, Tokio, 1984... 

The first application of piezoelectricity to measure the pressure developed on expln was done by Sir J.J,Thomson in 1917 (Ref 36, pl6A) and this was followed by D.A.Keys in 1921 and by J.C.Karcher in 1922. The device constructed by Karcher at the US Bureau of Standards used quartz and proved to be successfulto obtain the indicator diagram of a gun discharge (Ref 3)... 

C. Lu, A. Czanderna (eds.), Applications of Piezoelectric Quartz Crystal Microbalances, Elsevier, Amsterdam, 1984. 

The nonlinearity and hysteresis have a profound influence on application of piezoelectric sensors and actuators, particularly in high precision devices. Details and additional references can be found in [4],... 

Spin coated copolymer films show a decrease in remanent polarisation if the film thickness [504, 505] decreases. The application of piezoelectric materials in micro-electro-mechanical systems (MEMS) or sensors makes it often necessary to decrease the lateral dimensions of the elements. Recently, Alexe et al. [506, 507] fabricated freestanding microcells with lateral dimensions down to 100 nm and heights of 110 nm from a ferroelectric PZT by direct... 

Refs. [i] Vives AA (2004) Piezoelectric transducers and applications. Springer, Berlin [ii] Lu C, Czanderna AW (eds) (1984) Applications of piezoelectric quartz crystal microbalances (Methods and phenomena, their applications in science and technology). Elsevier, New York... 

Refs. [i] Lu C, CzandernaAW (eds) (1984) Applications of piezoelectric quartz crystal microbalances. Elsevier New York [ii] Buttry DA (1991) Applications of the quartz crystal microbalance to electrochemistry. In Bard AJ (ed) Electro analytical chemistry, vol. 17. Marcel Dekker, New York, pp 1-85 [Hi] Buck RP, Lindner E, Kutner W, Inzelt G (2004) Pure Appl Chem 76 1139 [iv] Sauerbrey G (1959) Z Phys 155 206 [v] Buttry DA, WardMD (1992) Chem Rev 92 1355 [vi] O Sullivan CK, Guil-bault (1999) Biosens Bioelectron 14 663 [vii] Bacskai J, Lang G, Inzelt G (1991) J Electroanal Chem 319 55... 

Applicability of piezoelectric acoustic emission sensors to end-point determination has been studied since the beginning of this century.F l The technique is very promising, especially because it is non-invasive, sensitive, and relatively inexpensive. Granulation process signatures obtained with acoustic transducer can be used to monitor changes in particle size, flow, and... 

SECM involves the measurement of the current through an ultramicroelectrode (UME) (an electrode with a radius, a, of the order of a few nm to 25 (zm) when it is held or moved in a solution in the vicinity of a substrate. Substrates, which can be solid surfaces of different types (e.g., glass, metal, polymer, biological material) or liquids (e.g., mercury, immiscible oil), perturb the electrochemical response of the tip, and this perturbation provides information about the nature and properties of the substrate. The development of SECM depended on previous work on the use of ultramicroelectrodes in electrochemistry and the application of piezoelectric elements to position a tip, as in scanning tunneling microscopy (STM). Certain aspects of SECM behavior also have analogies in electrochemical thin-layer cells and arrays of interdigitated electrodes. 

Lu C, Czanderna AW (1984) Applications of piezoelectric quartz crystal microhal-ances. Elsevier, Amsterdam... 

Abstract This chapter reviews the basic theory and applications of piezoelectric immunosensors. The immunosensor assay formats most often used are introduced as well as a brief explanation of the typical methods of measurement. Immobilisation is discussed, the importance of each characteristic, the basic techniques employed and a comparison of their performance as investigated by many researchers. The main historical developments of piezoelectric sensors and how these have led to early piezoelectric immunosensors are reviewed. Immunosensor applications and a comparison of sensor performance, for various analytes are summarised. The potential future of this field is also discussed. 

Luong JHT, Guilbault GG (1991) Analytical applications of piezoelectric crystal biosensors. In Blum LJ, Goulet PR (eds) Biosensors, principles and applications. Dekker, New York... 

Piezoelectricity links the fields of electricity and acoustics. Piezoelectric materials are key components in acoustic transducers such as microphones, loudspeakers, transmitters, burglar alarms and submarine detectors. The Curie brothers [7] in 1880 first observed the phenomenon in quartz crystals. Langevin [8] in 1916 first reported the application of piezoelectrics to acoustics. He used piezoelectric quartz crystals in an ultrasonic sending and detection system - a forerunner to present day sonar systems. Subsequently, other materials with piezoelectric properties were discovered. These included the crystal Rochelle salt [9], the ceramics lead barium titanate/zirconate (pzt) and barium titanate [10] and the polymer poly(vinylidene fluoride) [11]. Other polymers such as nylon 11 [12], poly(vinyl chloride) [13] and poly (vinyl fluoride) [14] exhibit piezoelectric behavior, but to a much smaller extent. Strain constants characterize the piezoelectric response. These relate a vector quantity, the electrical field, to a tensor quantity, the mechanical stress (or strain). In this convention, the film orientation direction is denoted by 1, the width by 2 and the thickness by 3. Thus, the piezoelectric strain constant dl3 refers to a polymer film held in the orientation direction with the electrical field applied parallel to the thickness or 3 direction. The requirements for observing piezoelectricity in materials are a non-symmetric unit cell and a net dipole movement in the structure. There are 32-point groups, but only 30 of these have non-symmetric unit cells and are therefore capable of exhibiting piezoelectricity. Further, only 10 out of these twenty point groups exhibit both piezoelectricity and pyroelectricity. The piezoelectric strain constant, d, is related to the piezoelectric stress coefficient, g, by... 

F. Duan, C. Fang Z. Ding and H. Zhu, Properties and Applications of Piezoelectric Glass-Crystalline Phase Composite in the Ba0-Sr0-Ti02-Si02 Sytem, Mat. Lett. 34, 184-187 (1998). 

Thin sheets of piezoelectric materials are used in sensors, buzzers, and actuators. In addition to the conventional vibrators, pressure and acceleration sensors are now also being manufactured from these materials. Lead zirconate titanate (PZT) is one of the most common materials used for these applications. The trend is to produce thinner and thinner and smaller and smaller parts. Therefore tape casting has become the manufacturing route of choice. One of the basic applications of piezoelectric ceramics is as a gas igniter where a spark is generated by the piezoelectric under an applied mechanical stress. Microphone discs are also prepared from thin... 

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