Generation of Linear Traveling Waves in Piezoelectric Plates in Air and Liquid

Abstract

A micro- to milli-sized linear traveling wave (TW) actuator fabricated with microelectromechanical systems (MEMS) technology is demonstrated. The device is a silicon cantilever actuated by piezoelectric aluminum nitride. Specifically designed top electrodes allow the generation of TWs at different frequencies, in air and liquid, by combining two neighboring resonant modes. This approach was supported by analytical calculations, and different TWs were measured on the same plate by laser Doppler vibrometry. Numerical simulations were also carried out and compared with the measurements in air, validating the wave features. A standing wave ratio as low as 1.45 was achieved in air, with a phase velocity of 652 m/s and a peak horizontal velocity on the device surface of 124 μm/s for a driving signal of 1 V at 921.9 kHz. The results show the potential of this kind of actuator for locomotion applications in contact with surfaces or under immersion in liquid.

Bidirectional Linear Motion by Travelling Waves on Legged Piezoelectric Microfabricated Plates

“…Figure 1 depicts the layout, while the electromechanical properties assumed for the device design are summarised in Table 2. The generation of linear TW in beams by the combination of two flexural vibration modes was already reported, using two symmetrically placed piezoelectric patches [16,18,29,34]. Here, we followed the same approach.…”

“…In the following sections, the flexural resonant modes were named using two numbers, based on Leissa nomenclature for bending modes [35]. Each number was used to designate the amount of nodal lines along the two orthogonal directions on the plane: the first one indicated the number of nodal lines in the longitudinal direction, while the second one indicated the The generation of linear TW in beams by the combination of two flexural vibration modes was already reported, using two symmetrically placed piezoelectric patches [16,18,29,34]. Here, we followed the same approach.…”

“…In our case, such a procedure was discarded due to the suspended nature of the devices and the micrometric thickness. Besides, we must also deal with built-in stresses that result in a static deformation of hundreds of nm [29]. In order to circumvent such difficulties, the inclusion of millimetre-long legs was carried out, following the procedure reported already for mobile miniature robots [18].…”

“…Tellers et al [28] proposed a different approach, where an array of PZT-actuated micro-hammers worked as a linear conveyor, capable of transporting 2 mg masses at 1 mm/s with 5 V excitation and positional errors as low as 2%, without speed control. Towards the goal of miniaturization, recent research [29] proved the feasibility of linear TW generation in AlN-actuated devices in the mili-to-micro scale. However, the practical motion of objects on top of the device was not implemented due to difficulties associated with both the static deformation produced by built-in stress and the fragility of the suspended structure.…”

Performance Analysis of a Travelling-Wave Ultrasonic Motor under Impact Load

“…There are many industrial applications, including micro-machine, information technology, surgery devices, ecological/energy areas, absolute gravimeter and nano-positioning stages [ 1 , 2 , 3 , 4 , 5 ]. There are numerous merits of USMs over electromagnetic motors, including low speed with high torque, a quick response, a wide velocity range and a high power/weight ratio [ 2 , 3 , 4 , 6 ]. The unique properties of USMs make it have a bright application prospect in extreme environments, such as space exploration [ 7 , 8 ].…”