The free response is considered of piezoelectric crystals (lithium niobate) with various polarities (including longitudinal only, shear only, and combined longitudinal and shear), which are stacked (mechanically and electrically in series) or are parallel (electrically parallel and mechanically uncoupled). Measurements of impedance magnitude from an impedance analyzer are compared with results ...

Piezoelectricity allows precise and robust conversion between electricity and mechanical force, and arises from the broken inversion symmetry in the atomic structure. Reducing the dimensionality of bulk materials has been suggested to enhance piezoelectricity. However, when the thickness of a material approaches a single molecular layer, the large surface energy can cause piezoelectric structur...

A study of the optoelectronic properties of strained 40 nm Ga1-xInxN layers on GaN films is presented. The fact of pseudomorphic strain leads to a new interpretation of the film composition when derived from x-ray scattering. In addition we directly confirm that strain induces huge piezoelectric fields in this uniaxial system by the observation of Franz-Keldysh oscillations in photoreflection. ...

The development of micro-/nano-scaled energy harvesters and the self-powered sensor system has attracted great attention due to the miniaturization and integration of the micro-device. In this work, lead-free NaNbO₃ piezoelectric nanofibers with a monoclinic perovskite structure were synthesized by the far-field electrospinning method. The flexible active humidity sensors were fabricated by tra...

Functionally Graded Materials (FGMs) possess continuously graded material properties and are characterized by spatially varying microstructures. The smooth variation of properties may offer advantages such as reduction of stress concentration and increased bonding strength. Recently, this concept has been explored in piezoelectric materials to improve properties and to increase the lifetime of ...

A high-performance flexible piezoelectric nanogenerator (PNG) is fabricated by a direct writing method, which acquires both patterned piezoelectric structure and aligned piezoelectric nanowires simultaneously. The voltage output of the as-prepared PNG is nearly 400% compared with that of the traditional spin-coated device due to the effective utilization of stress. This facile printing approach...

This paper presents the design and fabrication of a novel piezoelectric actuator for a gas micro pump with check valve having the advantages of miniature size, light weight and low power consumption. The micro pump is designed to have eight major components, namely a stainless steel upper cover layer, a piezoelectric actuator, a stainless steel diaphragm, a PDMS chamber layer, two stainless ste...

The design of a rotary ultrasonic motor for space applications is considered. First the working principle of such device is examined. The dynamics of the stator and the rotor is then studied by means of modelling approaches proposed in tW recent literature. A special attention is devoted to geometry of the piezoelectric actuating layers and the relevant electrodes pattern. A preliminary design ...

We present the fabrication of parylene-based hollow nanomechanical resonators, following a simple two step fabrication process with a thermal budget of less than 120°C. This process is ideal for fast prototyping and compatible with most materials used in microand nano-fabrication. In particular, the example we present here shows a hybrid structure with silicon nitride and parylene, but we have ...