Transducers, configurations

In fact, this last configuration (a sonochemical cell where the electrodes and the ultrasound transducer tip are directly dipped into the working solution) is the most used experimental configuration [38], see Fig. 4.2a, which we will name electrode-apart-transducer configuration. The relative orientation between the transducer tip and electrode surfaces has been taken into account when the electrode is placed so... 

Fig. 4.2 (a) Electrode-apart-transducer configuration (Acknowledge [21]. Reproduced by permission of The Electrochemical Society), (b) Sonotrode configuration with sleeve (Reprinted from [42], Copyright (2008) with the permission from Elsevier), (c) Sonotrode configuration without sleeve (Reprinted from [43], Copyright (2006) with the permission from Elsevier)... 

Fig. 4.3 Electrode-apart-transducer configuration (a) small volume cell (b) preparative cell for bulk electrolysis in the presence of high intensity ultrasound. (Acknowledge [46]. Reproduced by permission of The Royal Society of Chemistry)...

When ultrasound emitter and electrode are different elements in the system, electrode-apart-transducer configuration, Fig. 4.2a, ultrasound removes the nanoparticles from the cathode to form suspended seeds. The ultrasonic agitation maintains a suspension of these preformed nanoparticles, which move continuously around, hit the electrodes, and these charged particles attach to one another and grow in suspension [90]. In this case, ultrasound keeps the larger structures from agglomeration. 

Our work deals with only a few examples (i) the immunosensor for the forest-spring encephalitis diagnosis (a metal label is used for signal generation), (ii) the enzyme-free urea sensor and (iii) the platinum sensor for antioxidant activity determination. What they all have in common is a screen-printed transducer consisting of graphite or Pt nanoparticles. Transducer configuration is shown in Fig. 27.1. 

Fig. 27.1. Transducer configuration (45 x 4.0 mm). (1) Substrate. (2) Graphite or metal containing layer. (3) Insulator. (4) Working area (7.5 mm2).

Figure 21.2. Characterization of margarine using ultrasound. (A) In-line ultrasound configuration using a single transducer to monitor the solid fat content of margarine. (B) and (C) Multiple transducer configuration for following the evolution of solid fat content and (D) Time evolution of solid fat content measured by NMR of ultrasound velocity.

The following sections give examples of dielectric elastomer generators in several categories of energy source, size, transducer configuration, coupling type, and purpose. 

A variety of transducer configurations that has been employed in photometric sensor devices fall into two sensor types extrinsic sensors and intrinsic sensors. While in the former sensor type the optical fiber merely acts as a light guide, conveying the optical information between the optical source and the chemical transducer and between the chemical transducer and the detector, in the latter sensor type the optical fiber, probably in some modified form, would become a part of the transducer. 

Optical sensors Optical transducer configurations Applications... 

The basic element shown in Figure 20.1 can be incorporated into a wide variety of transducer configurations. For example, the film and electrodes can be formed into a tube, rolled into a scroll, stretched onto a frame or laminated to a flexible substrate to produce bending. Several examples of actuator configurations are shown in Figure 20.3. Which configuration is best depends on the application and properties of the film. 

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 fitud category to be rfiscuased n a general one which will be denoted measurement instrumentation. Included within this is accelerometers, strain and stress gauges, acoustic emission sensors, fiber optic phase nwdulators. gas emission detectors, and external pressure field flow detection by use of surfsce acoustic wave (SAW) ferroelectric polymer transducer configurations. 

Imaging of human tissues and nooinvasive assessment of their lesions is the most important diagnostic area of ultrasonics, and PVDF devices have also been exploited in m ical ultrasound imaging. Different transducer configurations have been adopted in the realization of the PVDF-based devices. 

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