Actuation piezoelectric

We have to make a distinction here between electric controllers (e.g. PID controllers) with a proportional valve as actuator and mechanical diaphragm controllers. In a regulation system w/ith electric controllers the coordination between controller and actuator (piezoelectric gas inlet valve, inlet valve A/ith motor drive, butterfly control valve, throttle valve) is difficult because of the very different boundary conditions (volume of the vessel, effective pumping speed at the vessel, pressure control range). Such control circuits tend to vibrate easily when process malfunctions occur. It is virtually impossible to specify generally valid standard values. 

The most common macroscopic actuators are motors. Electromagnetic motors do not operate efficiently at the microscale, but alternative actuation mechanisms become favorable. In conventional MEMS, other types of actuators have been used to generate movement, such as electrostatic actuators, thermal actuators, piezoelectric crystals, SMAs, and magnetic actuators. 

Multilayer-type piezoelectric or electrostrictive actuators are used for several apphcations including the composite smart stmcture shown in Figure 9... 

Another important class of titanates that can be produced by hydrothermal synthesis processes are those in the lead zirconate—lead titanate (PZT) family. These piezoelectric materials are widely used in manufacture of ultrasonic transducers, sensors, and minia ture actuators. The electrical properties of these materials are derived from the formation of a homogeneous soHd solution of the oxide end members. The process consists of preparing a coprecipitated titanium—zirconium hydroxide gel. The gel reacts with lead oxide in water to form crystalline PZT particles having an average size of about 1 ]lni (Eig. 3b). A process has been developed at BatteUe (Columbus, Ohio) to the pilot-scale level (5-kg/h). 

Zirconate compounds exhibit several interesting properties. Lead zirconate—titanate [12626-81 -2] compositions display piezoelectric properties which are utilized in the production of EM-coupled mode filters, resonators in microprocessor clocks, photoflash actuators, phonograph cartridges, gas... 

Sonic Methods A fixed-point level detector based on sonic-propagation characteristics is available for detection of a liquid-vapor interface. This device uses a piezoelectric transmitter and receiver, separated by a short gap. When the gap is filled with liquid, ultrasonic energy is transmitted across the gap, and the receiver actuates a relay. With a vapor filling the gap, the transmission of ultrasonic energy is insufficient to actuate the receiver. 

The major piezoelectric applications are sensors (pickups, keyboards, microphones, etc.), electromechanical transducers (actuators, vibrators, etc ), signal devices, and surface acoustic wave devices (resonators, traps, filters, etc ). Typical materials are ZnO, AIN, PbTiOg, LiTaOg, and Pb(Zr.Ti)03 (PZT). 

Ferroelectrics Poly(vynidilene fluoride) undergoes electrostriction when subjected to high ac fields, thus can be made into actuators applied pressure produces a piezoelectric response useful in sensors. 

When the development of a scientific field expands, the need for handbooks arises, wherein the information that appeared earlier in journals and conference proceedings is systematically and selectively presented. The sensor and actuator Held is now in this position. For this reason, Elsevier Science took the initiative to develop a series of handbooks with the name "Handbook of Sensors and Actuators" which will contain the most meaningful background material that is important for the sensor and actuator field. Titles like Fundamentals of Transducers, Thick Film Sensors, Magnetic Sensors, Micromachining, Piezoelectric Crystal Sensors, Robot Sensors and Intelligent Sensors will be part of this series. 

J. Pribyl, M. Hepel, J. Halameka, and P. Skladal, Development of piezoelectric immunosensors for competitive and direct determination of atrazine. Sens. Actuat. B 91, 333-341 (2003). 

In his work, Wallace [12] formed inkjet printheads from the rectangular blocks made of piezoelectric material. A diamond saw is used to create fluid channel grooves and channel actuator structures. These grooves are approximately 1 pm apart, 360 pm deep and 170 pm wide. Next, a cover plate is attached to the top of the grooves to form an enclosed rectangle channel for the working fluids. A polymer orifice plate (see Fig. 11.3) with many 40 pm diameter orifices is attached to the other end of the grooves. 

Cui, T. Markus, D. Zurn, S. Polla, D. L. 2004. Piezoelectric thin films formed by MOD on cantilever beams for microsensors and actuators. Microsystem Tech. 10 1432-1858. 

Barrow, D. A. Noteboom, R. Sayer, M. 1995. Design and fabrication of macroscopic piezoelectric actuators based on thick PZT films. Int. Ferro. 8 1-11. 

Percin, G. Levin, L. Khuri-Yakub, B. 1997. Piezoelectrically actuated droplet ejector. Rev. Sci. Instr. 68 4561—4563. 

Piezochromism, 6 606-607, 612-613 negative piezosolvatochromism, 6 611 Piezoelectric actuation, for lab-on-a-chip valves, 26 975... 

Ayhan, A.E. 2002. Design of a piezoelectrically actuated microvalve for flow control in fuel cells. M.S. Thesis, University of Pittsburgh, School of Engineering, Pittsburgh, PA. 

The actuator part may also be a smart material, such as a piezoelectric bar, placed in a wind foil that changes orientation according to a current imputed by the computer center allowing a machine such as an automobile to handle better and be more fuel efficient. 

Benes E, Groschl M, Burger W, Schmid M. Sensors based on piezoelectric resonators. Sens Actuat A 1995 48 1-21. 

Fig. 1.41. Micropositioning assembly in the MIM tunneling experiment. In an aluminum block (1), two gold electrode.s (2) are contained. The right electrode is attached to a pair of membranes (3), and actuated by a stack of piezoelectric plates (4). The left electrode is actuated by a differential screw (5) for coarse positioning. The entire assembly is enclosed in a thermostat and then a vacuum chamber. (After Teague, 1978.)...

In the early years of STM instrumentation, tripod piezoelectric scanners were the predominant choice, as shown in Fig. 9.6. The displacements along the X, y, and z directions are actuated by three independent PZT transducers. Each of them is made of a rectangular piece of PZT, metallized on two sides. Those three PZT transducers are often called x piezo, y piezo, and z piezo, respectively. By applying a voltage on the two metallized surfaces of a piezo, for example, the x piezo, the displacement is... 

The piezoelectric stepper, nicknamed the louse, was the first successful stepper used in UHV STM (Binnig and Rohrer, 1982). A schematic of the louse is shown in Fig. 12.1. As shown, the actuating element of the louse is a piezoelectric plate (PP), which can be expanded or contracted by applying a voltage (100 to 1000 V). It is resting on three metal feet (MF), separated by high-dielectric-constant insulators (I) from the metal ground plate (GP). 

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