Sensors detector device

Fuel cell polymer battery photoelectric cell capacitor Storage element liquid crystal display device electrochromic display device electrochemiluminescence device photoelectric transducer Biosensor ion sensor detector in HPLC and FIA gas sensor voltam-metric indicator electrode reference electrode... 

Fig. 5) This figure shows a sketch of the investigated detector concept. An irradiated high mobility two-dimensional electron gas device is subjected to a constant magnetic field Bo, where Bo is chosen to correspond to a fixed point (marked as a dot on the top inset) of the resistance oscillations for incident radiation at a frequency f. The detector device function is realized by superimposing on the static magnetic field, a small time varying component, which has been shown here in blue. Then, a high harmonic, tuned band Terahertz sensor is realized by detecting the device resistance at a odd-harmonic multiple of the field modulation frequency, as the detector is illuminated by Terahertz radiation.

Of- and /f-ionization detector devices (pressure gauges, gas flow metering, smoke sensors, electron capture detectors). 

The detector is a concentration sensor appropriate to the analysis in question. As in the case of all sensors, detectors do not react immediately, but instead have a time constant. Thus, they contribute to band broadening through both their cell volume and their response time. The cell-volume contribution can be handled in the same way as the volume of the injection device. The response-time contribution is given by Equation 46, and it is proportional to the square of the mobile-phase velocity. The response time should be less than one-tenth of the standard deviation of a Gaussian peak in order to have a negligible effect on the retention time and profile of the peak [31]. 

Sensor array detection also is needed because these devices can be micro-fabricated with very low dead volumes they require no support gases for their operation, and they can be fabricated with a variety of selectivities, which can be used for vapor recognition and for the deconvolution of overlapping peaks. This can reduce the resolution requirements for the colunm. Sensor detectors usually have lower sensitivity than do detectors incorporated in laboratory gas chromatographic instruments. Low detector sensitivity, coupled with the very low concentrations often associated with air monitoring, requires the use of a sorption preconcentrator for sample enrichment prior to separation and detection. 

Safety sensors sensing devices of mechanical and non-mechanical presence that send signal to interrupt or prevent the onset of dangerous functions, as light curtains, optoelectronic motion detectors, laser multi-beam, optical barriers, area monitors, or scanners, stops, carpets and position sensors ... 

Many commercial bioprocesses for food, pharmaceutical, chemical and agricultural apphcations require immobilization ofbiocatalysts (Moo-Young, 1988 Cass, 1998). Similarly, environmental, industrial and clinical sensors, detectors or diagnostic devices, as well as DNA and protein arrays, all depend on precisely immobilized biomolecules on a solid support. 

Cadmium sulphide (CdS) is an II-VI semiconductor material with a direct band gap of 2.42 eV at room temperature with many outstanding physical and chemical properties, which has promising applications in photochemical catalysis, gas sensors, detectors for laser and infrared, solar cells, nonlinear optical materials, luminescence devices and optoelectronic devices [36-39]. CdS also exhibited excellent visible light detecting properties [40]. In the last decades, many techniques have been reported on synthesis of CdS nanoparticles [41-43]. 

The detector setup consists of four 256 x 256 pixel amorphous silicon technology sensor flat panels with 0.75 x 0.75 mm pixel size, having an active area of 192 x 192 mm [5j. These sensors are radiation sensitive up to 25 MeV and therefor well suited for detecting the LINAC radiation. The four devices are mounted onto a steel Irame each having the distance of one active area size from the other. With two vertical and two horizontal movements of the frame it is possible to scan a total area of about 0.8 x 0.8 m with 1024 x 1024 pixel during four independent measurements. 

Fig. 4. Some electronic device applications using amorphous silicon (a) solar cell, (b) thin-fiLm transistor, (c) image sensor, and (d) nuclear particle detector.

Acoustic Wave Sensors. Another emerging physical transduction technique involves the use of acoustic waves to detect the accumulation of species in or on a chemically sensitive film. This technique originated with the use of quartz resonators excited into thickness-shear resonance to monitor vacuum deposition of metals (11). The device is operated in an oscillator configuration. Changes in resonant frequency are simply related to the areal mass density accumulated on the crystal face. These sensors, often referred to as quartz crystal microbalances (QCMs), have been coated with chemically sensitive films to produce gas and vapor detectors (12), and have been operated in solution as Hquid-phase microbalances (13). A dual QCM that has one smooth surface and one textured surface can be used to measure both the density and viscosity of many Hquids in real time (14). 

Thermal Methods Level-measuring systems may be based on the difference in thermal characteristics oetween the fluids, such as temperature or thermal conductivity. A fixed-point level sensor based on the difference in thermal conductivity between two fluids consists of an electrically heated thermistor inserted into the vessel. The temperature of the thermistor and consequently its electrical resistance increase as the thermal conductivity of the fluid in which it is immersed decreases. Since the thermal conductivity of liquids is markedly higher than that of vapors, such a device can be used as a point level detector for liquid-vapor interface. 

Verifying temperature is the second most important aspect of any compressor operation. As with pressure, the basic form of measurement is a simple temperature gauge. The construction of the gauges is quite varied, ranging from a bimetallic device to the filled systems. When transmis sion is involved, the sensor becomes quite simple, taking the form v)l a thermocouple or a resistance temperature detector (RTD). The monitor does the translation from the native signal to a temperature readout ()r signal proportional to temperature. 

The fuse is a level detector and is both the sensor and the interrupting device. It is installed in series with the equipment being protected, and it operates by nieltiiig a fusible eleliieiit in response to the current flow. 

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