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June 2007
Piezo Film: Unique Sensor Material
Given the unique properties and almost unlimited applications of piezoelectric PVDF – "piezo film" for short – summarizing its capabilities can be challenging. Measurement Specialties is the world's largest producer of piezo film.
Imagine a single sensor that offers decades of bandwidth, nine decades of dynamic range, and is available in a choice of package footprints covering nine orders of magnitude, and you begin to get a feeling for the wide open spaces in which piezo
film can operate.
Although individual sensors don't tend to require anything more than a fraction of this continuum, the fact is that there are few hard limits on the detection capability of piezo film. Sensor cable installed underground can detect subsonic signals of approaching footsteps or vehicles at one end of the frequency spectrum, while immersed ultrasonic probes can to function beyond 100 MHz. Almost any piezo film sensor can generate over a thousand volts potential difference across its electrodes, yet useful information content can often be found in the nV/√Hz spectral density range.
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Measurement Specialties Introduces Automotive-Qualified Temperature Sensor
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The new Ni1000 SOT sensor is a miniature, low cost, high precision temperature sensor suitable for use in harsh environments, including hot oil.
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Measurement Specialties (MEAS) is pleased to introduce a new temperature sensor for use in harsh environments - the Ni1000SOT. This nickel thin film resistance temperature detector (RTD) is suitable for use in contact temperature sensing. The characteristics of this temperature sensor comply with DIN 43760. The Ni1000SOT sensor is qualified for the most demanding automotive applications, including exposure to hot oil. This RTD is also suitable for many industrial applications with harsh conditions.
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Fiber Optic EZ Treadle™ Simplifies Toll Road Sensor Installation
The new lightweight EZ-Treadle premounted sensor block makes fiber-optic toll sensors even easier to install, regardless of the weather condition. Once fitted, benefits for toll applications include improved accuracy and reliability.
Toll roads are the roads of the future. They are the most effective method of allocating road costs directly to road users. Advances in technology allow for better collection of tolls, especially the ability to gather information about vehicles to ensure the correct tolls are paid. Most tolls are axle based, since this is a good indicator of the size of the vehicle.
Traditional toll treadles are contact closure based, using metal strips embedded in rubber. When a load is applied to the treadle, electrical contact is made between the strips. These can be difficult to use because they are very heavy (>200kg) and not proven for higher speeds (100 kph). Furthermore durability can be an issue; for instance, they are susceptible to water leakage which will ruin signal output.
The Fiber Optic Solution
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The fiber optic element in the SPZ toll sensor by SensorLine is wrapped around a pentagonal core, causing microbending and loss of light proportional to the load applied.
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Fiber optic sensors solve these problems. A fiber optic sensor uses light attenuation in lieu of the electrical connection to count the axles. A optical fiber element consists of an ultra pure glass fiber with a dielectric cladding on the outside. Under normal data transmission, the cladding serves as a wave guide, propagating the transmission of light along the fiber core through the internal reflection of light within the fiber. To use an optical fiber as a sensor, a loss of light must be induced in a controlled manner. Bending the fiber will cause a change in the index of refraction between the core and the cladding, allowing for the loss of light. This action is called microbending, and it is the principle used for fiber optic sensors.
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