Comparison of Piezoelectric and Carbon Nanotube-Based Actuators
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0922-U07-01
Comparison of Piezoelectric and Carbon Nanotube-Based Actuators Hossein Golnabi, Mahmod Ghorannevis, and Masoud Golnabi Islamic Azad University, Tehran, Iran
ABSTRACT The goal of this study is to compare operation and performance of the piezoelectric and carbon nanotube actuators, by focusing on the conditions that such piezoelectric device can be replaced by carbon nanotube actuators in a near future. For many years piezoelectric (PZT) and electrostrictors devices have been the key elements for the construction of actuator systems such as positioners, miniature ultrasonic motors, and adaptive mechanical motors. However, in recent years major advances and accomplishments have been reported in the field of nanotube materials, which promise a breakthrough in the field of nanosensors and nanoactuators. The aim here is to make a comparison between the PZT- and CNT-based actuator/sensor devices in terms of the actuator materials, designs, and device control techniques. First, a model is established for the operation of a typical PZT actuator and the related electromechanical coupling relations and equations governing the actuation process are described. In the second study actuation behavior of carbon nanotube materials is modeled and the results concerning a similar parameter to that of PZT are reported. INTRODUCTION First consider the suitable materials functioning as transduction elements in sensor/actuator designs. Proper materials for transduction purposes must have the following requirements. High sensitivity, mechanical strength, rigidity (modulus of elasticity), high electric insulation resistance (at high temperatures), minimal hygroscopic, linear relation between mechanical stress and elastic polarization, absence of hystresis, high stability of all properties, low temperature dependence of all properties within a wide temperature range, low anisotropy of mechanical properties (such as thermal expansion coefficients and elastic constants), good machinability, and finally low production cost [1,2]. Quartz is one of the most important single crystals serving as transduction element in PZT sensing devices for many years. Tourmaline crystal is another material that can be used as sensing element. Gallium orthophosphate crystals belonging to CGG group are other suitable materials for the PZT sensors. Beside mentioned group of single crystals, lithium-niobate and lithium-tantalate, which are both ferroelectric materials, are used in PZT sensor designs. PZT ceramics are of particular importance for PZT sensors. In addition PZT effect has been observed in polymers and biological materials. Therefore, PZT thin films can be used for microelectromechanical systems (MEMS). Deposition and patterning of PZT thin films on substrate (silicon) is achieved for sensor applications. ZnO and AIN have been deposited as single crystalline films due to their non-ferroelectric behavior, while PZT can be deposited as polycrystalline film with subsequent poling process. In recent years research and development in Micro-Elet
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