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Molecular Electronic Transducers
Molecular electronic transducers (MET) are a class of inertial sensors (which include accelerometers, gyroscopes, tilt meters, seismometers, and related devices) based on an electrochemical mechanism. METs capture the physical and chemical phenomena that occur at the surface of electrodes in electrochemical cells as the result of hydrodynamic motion. They are a specialized kind of electrolytic cell designed so that motion of the MET, which causes movement (convection) in the liquid electrolyte, can be converted to an electronic signal proportional to acceleration or velocity. MET sensors have inherently low noise and high amplification of signal (on the order of 106). History of molecular electronic transducers MET technology had its origins in the 1950s, when it was discovered that very sensitive, low-power, low-noise detectors and control devices could be made based on specially designed electrochemical cells (which were referred to as “solions”, derived from the words so ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inertial Sensor
An inertial measurement unit (IMU) is an electronic device that measures and reports a body's specific force, angular rate, and sometimes the orientation of the body, using a combination of accelerometers, gyroscopes, and sometimes magnetometers. When the magnetometer is included, IMUs are referred to as IMMUs. IMUs are typically used to maneuver modern vehicles including motorcycles, missiles, aircraft (an attitude and heading reference system), including unmanned aerial vehicles (UAVs), among many others, and spacecraft, including satellites and landers. Recent developments allow for the production of IMU-enabled GPS devices. An IMU allows a GPS receiver to work when GPS-signals are unavailable, such as in tunnels, inside buildings, or when electronic interference is present. Operational principles An inertial measurement unit works by detecting linear acceleration using one or more accelerometers and rotational rate using one or more gyroscopes. Some also include a magnetom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrolytic Cell
An electrolytic cell is an electrochemical cell that utilizes an external source of electrical energy to force a chemical reaction that would not otherwise occur. The external energy source is a voltage applied between the cell′s two electrodes; an anode (positively charged electrode) and a cathode (negatively charged electrode), which are immersed in an electrolyte solution. This is in contrast to a galvanic cell, which itself is a source of electrical energy and the foundation of a battery. The net reaction taking place in a galvanic cell is a spontaneous reaction, i.e, the Gibbs free energy remains -ve, while the net reaction taking place in an electrolytic cell is the reverse of this spontaneous reaction, i.e, the Gibbs free energy is +ve.Skoog, Douglas A.; West, Donald M.; Holler, F. James; Crouch, Stanley R. (2014). ''Fundamentals of Analytical Chemistry.'' (9th ed.)''.'' Belmont: Brooks/Cole, Cengage Learning. p. 446-449. Principles In an electrolytic cell, a curren ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fiber Optic Gyroscope
A fibre-optic gyroscope (FOG) senses changes in orientation using the Sagnac effect, thus performing the function of a mechanical gyroscope. However its principle of operation is instead based on the interference of light which has passed through a coil of optical fibre, which can be as long as . Operation Two beams from a laser are injected into the same fibre but in opposite directions. Due to the Sagnac effect, the beam travelling against the rotation experiences a slightly shorter path delay than the other beam. The resulting differential phase shift is measured through interferometry, thus translating one component of the angular velocity into a shift of the interference pattern which is measured photometrically. Beam splitting optics split light from a laser diode (or other laser light source) into two waves propagating in both clockwise and anticlockwise directions through a coil consisting of many turns of optical fibre. The strength of the Sagnac effect is dependent on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microelectromechanical Systems
Microelectromechanical systems (MEMS), also written as micro-electro-mechanical systems (or microelectronic and microelectromechanical systems) and the related micromechatronics and microsystems constitute the technology of microscopic devices, particularly those with moving parts. They merge at the nanoscale into nanoelectromechanical systems (NEMS) and nanotechnology. MEMS are also referred to as micromachines in Japan and microsystem technology (MST) in Europe. MEMS are made up of components between 1 and 100 micrometers in size (i.e., 0.001 to 0.1 mm), and MEMS devices generally range in size from 20 micrometres to a millimetre (i.e., 0.02 to 1.0 mm), although components arranged in arrays (e.g., digital micromirror devices) can be more than 1000 mm2. They usually consist of a central unit that processes data (an integrated circuit chip such as microprocessor) and several components that interact with the surroundings (such as microsensors). Because of the la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Accelerometer
An accelerometer is a tool that measures proper acceleration. Proper acceleration is the acceleration (the rate of change of velocity) 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 (by definition) of g ≈ 9.81 m/s2. By contrast, accelerometers in free fall (falling toward the center of the Earth at a rate of about 9.81 m/s2) will measure zero. Accelerometers have many uses in industry and science. Highly sensitive accelerometers are used in inertial navigation systems for aircraft and missiles. Vibration in rotating machines is monitored by accelerometers. They are used in tablet computers and digital cameras so that images on screens are always displayed upright. In unmanned aerial vehicles, accelerometers help to stabilise flight. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seismometer
A seismometer is an instrument that responds to ground noises and shaking such as caused by earthquakes, volcanic eruptions, and explosions. They are usually combined with a timing device and a recording device to form a seismograph. The output of such a device—formerly recorded on paper (see picture) or film, now recorded and processed digitally—is a seismogram. Such data is used to locate and characterize earthquakes, and to study the Earth's internal structure. Basic principles A simple seismometer, sensitive to up-down motions of the Earth, is like a weight hanging from a spring, both suspended from a frame that moves along with any motion detected. The relative motion between the weight (called the mass) and the frame provides a measurement of the vertical ground motion. A rotating drum is attached to the frame and a pen is attached to the weight, thus recording any ground motion in a seismogram. Any movement from the ground moves the frame. The mass tends not to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gyroscope
A gyroscope (from Ancient Greek γῦρος ''gŷros'', "round" and σκοπέω ''skopéō'', "to look") is a device used for measuring or maintaining orientation and angular velocity. It is a spinning wheel or disc in which the axis of rotation (spin axis) is free to assume any orientation by itself. When rotating, the orientation of this axis is unaffected by tilting or rotation of the mounting, according to the conservation of angular momentum. Gyroscopes based on other operating principles also exist, such as the microchip-packaged MEMS gyroscopes found in electronic devices (sometimes called gyrometers), solid-state ring lasers, fibre optic gyroscopes, and the extremely sensitive quantum gyroscope. Applications of gyroscopes include inertial navigation systems, such as in the Hubble Space Telescope, or inside the steel hull of a submerged submarine. Due to their precision, gyroscopes are also used in gyrotheodolites to maintain direction in tunnel mining. Gyroscopes ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tiltmeter
A tiltmeter is a sensitive inclinometer designed to measure very small changes from the vertical level, either on the ground or in structures. Tiltmeters are used extensively for monitoring volcanoes, the response of dams to filling, the small movements of potential landslides, the orientation and volume of hydraulic fractures, and the response of structures to various influences such as loading and foundation settlement. Tiltmeters may be purely mechanical or incorporate vibrating-wire or electrolytic sensors for electronic measurement. A sensitive instrument can detect changes of as little as one arc second. Tiltmeters have a long history, somewhat parallel to the history of the seismometer. The very first tiltmeter was a long-length stationary pendulum. These were used in the very first large concrete dams, and are still in use today, augmented with newer technology such as laser reflectors. Although they had been used for other applications such as volcano monitoring, they ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pressure Transducer
A pressure sensor is a device for pressure measurement of gases or liquids. Pressure is an expression of the force required to stop a fluid from expanding, and is usually stated in terms of force per unit area. A pressure sensor usually acts as a transducer; it generates a signal as a function of the pressure imposed. For the purposes of this article, such a signal is electrical. Pressure sensors are used for control and monitoring in thousands of everyday applications. Pressure sensors can also be used to indirectly measure other variables such as fluid/gas flow, speed, water level, and altitude. Pressure sensors can alternatively be called pressure transducers, pressure transmitters, pressure senders, pressure indicators, piezometers and manometers, among other names. Pressure sensors can vary drastically in technology, design, performance, application suitability and cost. A conservative estimate would be that there may be over 50 technologies and at least 300 companies ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
