In this study, we fabricated piezoelectric energy harvesters composed of lead-free (K,Na)NbO3 (KNN) thin films and compared the power generation performance with PZT-thin film energy harvesters. Both of the piezoelectric thin films were deposited on Pt/Ti/Si cantilevers by rf-sputtering. The KNN and PZT thin films had perovskite structure, and showed the relative dielectric constants of 744 and...

A series of active piezoelectric diaphragms were fabricated and patterned with several geometrically defined Inter-Circulating Electrodes "ICE" and Interdigitated Ring Electrodes “IRE”. When a voltage potential is applied to the electrodes, the result is a radially distributed electric field that mechanically strains the piezoceramic along the Z-axis (perpendicular to the applied electric field...

The present work experimentally investigates the thermal effects of a synthetic jet actuator on the heat transfer performance of single-phase flow confined in a microchannel heat sink. The heat sink consisted of a single rectangular microchannel 500 μm wide, 300 μm deep and 26 mm long. Deionized water was employed as the cooling fluid. A synthetic jet actuator with a 100 μm diameter orifice was...

A closed-loop-controlled surface perturbation technique was developed for controlling the flow-induced sound in a flow duct and acoustic resonance inside downstream cavities. The surface perturbation was created by piezo-ceramic THUNDER (THin layer composite UNimorph Driver and sEnsoR) actuators embedded underneath the surface of a test model with a semi-circular leading edge. A modified closed...

Structured, complete inflectional paradigm data exists for very few of the world’s languages, but is crucial to training morphological analysis tools. We present methods inspired by linguistic fieldwork for gathering inflectional paradigm data in a machine-readable, interoperable format from remotely-located speakers of any language. Informants are tasked with completing language-specific parad...

This paper presents novel micromachined two-dimensional array piezoelectrically actuated flextensional transducers that can be used to generate sound in air or water. Micromachining techniques to fabricate these devices are also presented. Individual unimorph array elements consist of a thin piezoelectric annular disk and a thin, fully clamped, circular plate. We manufacture the transducer in t...

Cantilevered beams with piezoceramic layers have been frequently used as piezoelectric vibration energy harvesters in the past five years. The literature includes several single degree-of-freedom models, a few approximate distributed parameter models and even some incorrect approaches for predicting the electromechanical behavior of these harvesters. In this paper, we present the exact analytic...

This paper describes a minimalist mobile robot design approach that offers a high locomotive efficiency, and is therefore well suited to mesoscale robot design. The authors have incorporated this approach into the development of a dynamically controlled piezoelectrically actuated mesoscale robot quadruped. The design described utilizes a lightly damped skeletal structure that generates locomoti...

Unimorph design consisting of a piezoceramic bonded to an elastic surface is the most common structure used to induce deformations. The analytic models developed by Park and Agrawal are extensively used to determine the induced strain on piezo-actuated surfaces. These models are based on different strain distribution hypothesis that, however, do not consider the relative thickness size between ...

Recent biological studies on water strider insects revealed the detailed mechanism of their staying and walking on water. While macro scale bodies use buoyancy to stay on water, these very light and small insects balance their weight using repulsive surface tension forces where the insect legs are covered with hydrophobic micro-hairs. Utilizing the unique scaling advantage of these insects, thi...