Electronic devices piezoelectric transducer

Defectoscope AUGUR)) is a complex device including Notebook PC with additional electronic boards, small-size automatic two-coordinate scanner, set of piezoelectric transducers, up to 25 m communication line (Fig. 1). 

The simplest application of a piezoelectric transducer is its use as a strain indicator, since the strains applied to a piezoelectric element can be quantified simply by measuring the electrical field which is created across the boundaries of that element. In the case of photoacoustic detectors, pressure pulses, created by the absorption of light from a chopped beam, deform a thin plate and are transformed into a series of voltage pulses. In such applications the electrical signals created are either dc or low-frequency, so that the design of the device and interface electronics is straightforward. 

This chapter presents a brief overview on sensor and transducer applications of piezoelectric and electrostrictive polymers. Piezoelectric and electrostrictive polymers are smart electromechanical materials which have already found commercial applications in various transducer configurations. Novel applications may arise in the emerging fields of autonomous robots, electronic skin, and flexible energy generators. This chapter focuses on recent device demonstrations of piezoelectric and electrostrictive polymers in these novel fields of research to stimulate and to facilitate the exchange of ideas between disciplines. The applications considered include piezoelectric sensors for electronic skin, piezoelectric loudspeakers and transducers for mechanically flexible energy harvesters, as well as electrostrictive transducers for haptic feedback in displays. 

The type of molecular recognition reaction determines the form of the transducer used (Table 5.3). Enzymatic reactions often involve an electron transfer. This electrical activity can be measured with amperometric, potentiometric or conductometric sensors. If the bioreaction includes the generation of H+ or OH ions, then a pH sensitive dye in combination with an optical device can be used. For antibody-antigen binding, the mass change on the surface of the transducer can be detected with a piezoelectric device. Exothermic or endothermic reactions can be followed with a temperature sensor. 

The most efficient and widely used means of generating and detecting surface elastic waves for electronic applications is the interdigital transducer shown in Fig. 2. In its simplest form it consists of a series of parallel metal plate electrodes periodically spaced on the surface of a piezoelectric substrate. The transducer is a three-port device one electrical and two acoustic. When an alternating voltage is applied to its electrical port, time varying electric fields are set up within the substrate, and these excite alternating stress pattern via the piezoelectric effect. The electric field... 

A transducer converts the biochemical signal to an electronic signal. The biochemical transducer or biocomponent gives the biosensor selectivity or specificity. The transducer of an electrical device responds in such a way that a signal can be electronically amplified and displayed. The physical transducers vary from electrochemical, spectroscopic, thermal, piezoelectric and surface acoustic wave technology [24, 25]. The most common electrochemical transducers being utilised are based on amperometric and potentiometric techniques [26-28]. 

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