J. Appl. Cryst.の発刊に際して

This review provides a detailed overview of the energy harvesting technologies associated with piezoelectric materials along with the closely related sub-classes of pyroelectrics and ferroelectrics. These properties are, in many cases, present in the same material, providing the intriguing prospect of a material that can harvest energy from multiple sources including vibration, thermal fluctuations and light. Piezoelectric materials are initially discussed in the context of harvesting mechanical energy from vibrations using inertial energy harvesting, which relies on the resistance of a mass to acceleration, and kinematic energy harvesting which directly couples the energy harvester to the relative movement of different parts of a source. Issues related to mode of operation, loss mechanisms and using non-linearity to enhance the operating frequency range are described along with the potential materials that could be employed for harvesting vibrations at elevated temperatures. In addition to inorganic piezoelectric materials, compliant piezoelectric materials are also discussed. Piezoelectric energy harvesting devices are complex multi-physics systems requiring advanced methodologies to maximise their performance. The research effort to develop optimisation methods for complex piezoelectric energy harvesters is then reviewed. The use of ferroelectric or multi-ferroic materials to convert light into chemical or electrical energy is then described in applications where the internal electric field can prevent electron–hole recombination or enhance chemical reactions at the ferroelectric surface. Finally, pyroelectric harvesting generates power from temperature fluctuations and this review covers the modes of pyroelectric harvesting such as simple resistive loading and Olsen cycles. Nano-scale pyroelectric systems and novel micro-electro-mechanical-systems designed to increase the operating frequency are discussed.

/pdf/piezoelectric-and-ferroelectric-materials-and-structures-for-39myuuqvo7.pdf

Piezoelectric and ferroelectric materials and structures for energy harvesting applications

A control circuit of a surgical device is disclosed. The control circuit includes a first circuit portion coupled to at least one switch operable between an open state and a closed state. The first circuit portion communicates with a surgical generator over a conductor pair to receive a control signal to determine a state of the at least one switch.

Surgical generator for ultrasonic and electrosurgical devices

High-Performance Piezoelectric Energy Harvesters and Their Applications

A surgical instrument. The surgical instrument may comprise a transducer and an end effector. The transducer may be configured to provide vibrations along a longitudinal axis at a predetermined frequency and may comprise a piezoelectric stack positioned along the longitudinal axis. The transducer also may comprise a first metallic end mass positioned along the longitudinal axis adjacent a first end of the piezoelectric stack and a second metallic end mass positioned along the longitudinal axis adjacent a second end of the piezoelectric stack. The length of the transducer may be greater than or equal to of one wavelength and less than ½ of one wavelength. The end effector may be coupled to the transducer and may extend along the longitudinal axis. The length of the transducer and the end effector may be a multiple of ½ of one wavelength.

Ultrasonic surgical instruments

An apparatus that passes vibrational energy across a mechanical structure lacking a perforation. The disclosed apparatus and method provide the ability to transfer work (rotary or linear motion) across pressure or thermal barriers or in a sterile environment without generating contaminants; the presence of reflectors in the solid barrier to enhance the efficiency of the energy/power transmission, and the ability to produce a bi-directional driving mechanism using a plurality of different mode resonances, such as a fundamental frequency resonance and a higher frequency resonance. In some instances, a plane within the mechanical structure lacking a perforation is a nodal plane of the vibrational energy field.

/pdf/acoustic-mechanical-feed-throughs-for-producing-work-across-3kc696oju9.pdf

Acoustic mechanical feed-throughs for producing work across a structure

To address the challenges, which are involved with the development of flow control valves that can meet high demand
requirements such as high pressure, high flow rate, limited power and limited space, the authors have conceived a novel
design configuration. This design consists of a digitalized flow control valve with multipath and multistage pressure
reduction structures. Specifically, the valve is configured as a set of parallel flow paths from the inlet to the outlet. A
choke valve controls the total flow rate by digitally opening different paths or different combination of the paths. Each
path is controlled by a poppet cap valve basically operated in on-off states. The number of flow states is 2N where N is
the number of flow paths. To avoid erosion from sand in the fluid and high speed flow, the seal area of the poppet cap
valve is located at a distance from the flow inlet away from the high speed flow and the speed is controlled to stay
below a predefined erosion safe limit. The path is a multistage structure composed of a set of serial nozzles-expansion
chambers that equally distribute the total pressure drop to each stage. The pressure drop of each stage and, therefore, the
flow speed at the nozzles and expansion chambers is controlled by the number of stages. The paths have relatively small
cross section and could be relatively long for large number of stages and still fit in a strict annular space limit. The paper
will present the design configuration, analysis and preliminary test results.

Digital valve for high pressure high flow applications

Electroactive polymers are attractive actuation materials because of their large deformation, flexibility, and lightweight A CCD camera system was constructed to record the curved shapes of bending during the activation of EAP films and image-processing software was developed to digitize the bending curves A computer program was developed to solve the invese problem of cantilever EAP beams with tip position limiter using the developed program and acquired curves without tip position limiter as well as the corresponding tip force, the EAP material properties of voltage-strain sensitivity and Young's modulus were determined

Characterization of bending EAP beams

Novel Ultrasonic Horn Designs for Extraterrestrial Applications

One of NASA priorities is the in-situ exploration of ocean worlds in the solar system where potentially there might be life under the ice shell. This requires reaching the ocean below extremely cold through significant deep ice. Jupiter’s moon, Europa, is such a challenging body, where it is estimated to have a 40 km thick ice shell. An approach for reaching the ocean has been conceived using a melting probe Cryobot concept that has been studied for a potential future mission. A lander is assumed to be the platform from which the Cryobot would be deployed. The ice penetrating vehicle concept consists of a cylindrical, narrow-body probe that encases a radioisotope heat/power source that would be used to do the penetration by melting through the icy crust. The baseline design of the probe includes a suite of science instruments to analyze the ice during descent and the liquid ocean underneath. For communication, a set of fiber optic wire as well as wireless RF in the very cold porous top layer is assumed, and then acoustic modules would be used for the communication in warmer denser ice over distance of 25 km between the modules. In addition to the acoustic communication modules, a sonar is part of the concept, for obstacle avoidance. The focus of this paper is on the use of elastic waves in the 1kHz range.

Acoustic communication in deep ice at ocean worlds

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