Piezoelectricity is the electric charge that accumulates in certain solid materials—such as crystals, certain ceramics, and biological matter such as bone, DNA, and various proteins—in response to applied mechanical stress. The word piezoelectricity means electricity resulting from pressure and latent heat. It is derived from the Greek word πιέζειν; piezein, which means to squeeze or press, and ἤλεκτρον ēlektron, which means amber, an ancient source of electric charge.
A mechanical or physical shock is a sudden acceleration caused, for example, by impact, drop, kick, earthquake, or explosion. Shock is a transient physical excitation.
An actuator is a component of a machine that is responsible for moving and controlling a mechanism or system, for example by opening a valve. In simple terms, it is a "mover".
An accelerometer is a tool that measures proper acceleration. Proper acceleration is the acceleration of a body in its own instantaneous rest frame; this is different from coordinate acceleration, which is acceleration in a fixed coordinate system. For example, an accelerometer at rest on the surface of the Earth will measure an acceleration due to Earth's gravity, straight upwards of g ≈ 9.81 m/s2. By contrast, accelerometers in free fall will measure zero.
Microphonics, microphony, or microphonism describes the phenomenon wherein certain components in electronic devices transform mechanical vibrations into an undesired electrical signal (noise). The term comes from analogy with a microphone, which is intentionally designed to convert vibrations to electrical signals.
Smart materials, also called intelligent or responsive materials, are designed materials that have one or more properties that can be significantly changed in a controlled fashion by external stimuli, such as stress, moisture, electric or magnetic fields, light, temperature, pH, or chemical compounds. Smart materials are the basis of many applications, including sensors and actuators, or artificial muscles, particularly as electroactive polymers (EAPs).
A pickup is a transducer that captures or senses mechanical vibrations produced by musical instruments, particularly stringed instruments such as the electric guitar, and converts these to an electrical signal that is amplified using an instrument amplifier to produce musical sounds through a loudspeaker in a speaker enclosure. The signal from a pickup can also be recorded directly.
Energy harvesting is the process by which energy is derived from external sources, captured, and stored for small, wireless autonomous devices, like those used in wearable electronics and wireless sensor networks.
An ultrasonic motor is a type of piezoelectric motor powered by the ultrasonic vibration of a component, the stator, placed against another component, the rotor or slider depending on the scheme of operation. Ultrasonic motors differ from other piezoelectric motors in several ways, though both typically use some form of piezoelectric material, most often lead zirconate titanate and occasionally lithium niobate or other single-crystal materials. The most obvious difference is the use of resonance to amplify the vibration of the stator in contact with the rotor in ultrasonic motors. Ultrasonic motors also offer arbitrarily large rotation or sliding distances, while piezoelectric actuators are limited by the static strain that may be induced in the piezoelectric element.
A piezoelectric sensor is a device that uses the piezoelectric effect to measure changes in pressure, acceleration, temperature, strain, or force by converting them to an electrical charge. The prefix piezo- is Greek for 'press' or 'squeeze'.
A charge amplifier is an electronic current integrator that produces a voltage output proportional to the integrated value of the input current, or the total charge injected.
A thin-film bulk acoustic resonator is a device consisting of a piezoelectric material manufactured by thin film methods between two conductive – typically metallic – electrodes and acoustically isolated from the surrounding medium. The operation is based on the piezoelectricity of the piezolayer between the electrodes.
Vibration isolation is the process of isolating an object, such as a piece of equipment, from the source of vibrations.
Mercedes Reaves is a Puerto Rican research engineer and scientist. She is responsible for the design of a viable full-scale solar sail and the development and testing of a scale model solar sail at NASA Langley Research Center in Virginia.
A piezoelectric accelerometer is an accelerometer that employs the piezoelectric effect of certain materials to measure dynamic changes in mechanical variables.
Pyroshock, also known as pyrotechnic shock, is the dynamic structural shock that occurs when an explosion or impact occurs on a structure. Davie and Bateman describe it as: "Pyroshock is the response of a structure to high frequency, high-magnitude stress waves that propagate throughout the structure as a result of an explosive event such as an explosive charge to separate two stages of a multistage rocket." It is of particular relevance to the defense and aerospace industries in that they utilize many vehicles and/or components that use explosive devices to accomplish mission tasks. Examples include rocket stage separation, missile payload deployment, pilot ejection, automobile airbag inflators, etc. Of significance is the survival and integrity of the equipment after the explosive device has activated so that the vehicle can accomplish its task. There are examples of flight vehicles Boeing-The Aerospace Corp which have crashed after a routine explosive device deployment, the cause of the crash being determined as be a result of a computer failure due to the explosive device. The resultant energies are often high g-force and high frequency which can cause problems for electronic components which have small items with resonant frequencies near those induced by the pyroshock.
KCF Technologies is a technology company that develops and commercializes products for industry and the military. The company was founded in November, 2000 by three researchers from Penn State University and is located in State College, Pennsylvania. It specializes in energy harvesting, wireless sensors, underwater navigation and smart material devices.
Artificial muscles, also known as muscle-like actuators, are materials or devices that mimic natural muscle and can change their stiffness, reversibly contract, expand, or rotate within one component due to an external stimulus. The three basic actuation responses– contraction, expansion, and rotation can be combined within a single component to produce other types of motions. Conventional motors and pneumatic linear or rotary actuators do not qualify as artificial muscles, because there is more than one component involved in the actuation.
Alper Erturk is a mechanical engineer and the Woodruff Professor in the George W. Woodruff School of Mechanical Engineering at Georgia Institute of Technology.
Dr. James E. Hubbard, Jr is a mechanical engineer who has made significant contributions to the field of aerospace engineering throughout a career spanning more than four decades in academia and industry.
