Planar Miniaturized Rotational Drive - PlateDrive
Synthesis and Properties of Functional Materials
Final Report Abstract
This project aimed to develop and characterize a planar, miniaturized, piezoelectric rotary actuator based on a metallic sheet structure and named “PlateDrive”. The motor concept relies on a stator manufactured from a metal sheet and comprised of piezoelectric bending tongues. Upon application of an electrical field, the bending tongues are excited to structural vibrations. The generated force is to be transmitted to the rotor through an intermediate layer consisting of carbon fiber arrays fixed at the bending tongues free end. The objective of the project was to build a demonstrator with a diameter of 20 to 30 mm and a total thickness in the range of 1 to 5 mm. The first aspect of the project focuses on the manufacturing and the modelling of the carbon fiber arrays. Based on an existing process, the manufacturing of the carbon fibers has been improved. An automated winding mechanism has been designed and built to embed the fibers with chemical adhesives, producing highly parallel carbon fiber arrays. These arrays are then fixed onto substrates and the fibers freed from adhesive to be freestanding. The reproducibility of carbon fiber arrays manufacturing was improved through the project. As part of the project, the friction interaction of the bending fibers tips with the rotor has been modeled. However, the established model and experimental results revealed that the arrays are not efficient to transfer the power from the stator to the rotor at the accessible bending tongues deflection amplitude, as constrained by the PlateDrive motor desired geometry. Therefore, the concept of the PlateDrive motor does not provide any significant advantage over existing concepts and no demonstrator was produced. The objectives of the project have been refocused on the modelling and manufacturing of ferroelectric bending tongues on stainless steel substrates. The project second aspect treats of the modelling and deposition of ferroelectric thin films on bending tongues with metallic substrates. A model has been developed, bridging the gap in literature between the modelling of ferroelectric switching and the mechanical approach for linear piezoelectric structures. The proposed model allows to optimize the bending tongue geometry and materials selection by analyzing the impact of the different parameters onto the bending tongue vertical deflection. The model confirms the applicability of PZT thin films deposited on stainless steel substrates for piezoelectric MEMS applications as sufficient vertical deflection is generated under an applied electrical field. Through this project, it has been established that tetragonal {001}-oriented lead zirconate titanate thin films can be grown directly on stainless steel substrates by pulsed laser deposition. Their crystallographic orientation can be tailored with selected buffer layers and appropriate substrate preparation, improving their piezoelectric properties. The thin films deposited, in particular with 2 mol.% Nb-doping, are promising candidates for future piezoelectric MEMS applications requiring non-brittle substrates. Further research can be considered to improve the thin films piezoelectric properties and to further their characterization towards MEMS applications. This project demonstrates the possibility to integrate a piezoelectric lead zirconate titanate thin film by pulsed laser deposition on a stainless steel substrate without the need for gluing the components together, opening the road towards miniaturization. Both undoped PZT and 2 mol.% Nb-doped PZT thin films display ferroelectric properties suitable for sensing MEMS applications. The ferroelectric properties of the deposited thin make them more suitable for sensing purposes rather than actuation applications.
Publications
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"Rotary Planar Actuator Using Mechanical Anisotropy of Tilted Carbon Fiber Arrays," Innovative Small Drives and Micro-Motor Systems; 11th GMM/ETG-Symposium, Saarbruecken, Germany, 2017, pp. 1-5
D. B. Thiem, A. Carrasco, J. Cardoletti, L. Alff and H. F. Schlaak
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“Air-coupled ultrasonic bending plate transducer with piezoelectric end electrostatic transduction element combination”, 2019 IEEE International Ultrasonics Symposium (IUS), Glasgow, United Kingdom, 2019, pp. 147-150
M. Rutsch, O. Ben Dali, A. Jäger, G. Allevato, K. Beerstecher, J. Cardoletti, A. Radetinac, L. Alff, and M. Kupnik
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“Modelling of the vertical deflection of ferroelectric bending tongues loaded at their free end”, AIP Advances 9, 025017 (2019)
J. Cardoletti, A. Radetinac, D. Thiem, J. Walker, P. Komissinskiy, B.-X. Xu, H. Schlaak, S. Trolier-McKinstry, and L. Alff
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“{001}-textured Pb(Zr, Ti)O3 thin films on stainless steel by pulsed laser deposition”, Journal of Applied Physics 128, 104103 (2020)
J. Cardoletti , P. Komissinskiy , E. Bruder , C. Morandi , and L. Alff
