Sensors commercial

An important part of the decision-making tool flow chart (see Fig. 1) is the redefinition of the specifications by the sensor customer after the surveying and testing of commercial sensor systems. This process almost always involves a downgrading of the expectations of the sensor customer, but it can also force a reaUstic evaluation of what sensor information really needs to be made available and at what cost. 

Zirconium oxinitride resistors (best known are Cernox) are thin-film resistors. Typical commercial sensors have resistance values of about 105fl at IK falling to 1000 at... 

Depending on the gas type and application, different gas detection and sensor principles may be suitable. Beside the price, there are other parameters like accuracy, power consumption, long-term stability, lifetime, selectivity and sensitivity which have to be taken into account. However, whether a sensor is developed into a product depends on the relation between additional functionality and additional cost. In the subsequent chapters we intend to give an overview of common sensor principles and their potential use in household appliances. In order to give some information about existing (commercialized) sensors and sensor systems each subchapter is completed by an amendment listing a selection of relevant gas sensor products. 

Development of a commercial sensor or assay requires incorporation of the sensing elements into materials appropriate for device manufacture. Some assay applications use solution-phase materials only this is more common for drug discovery assays and diagnostic testing than in environmental sensing. Polymers are less soluble than small molecules however, with appropriate choice of side chains... 

Commercial sensors suitable for automated measurements are available and can be used, for example, for field measurements of hydrogen uptake by cathodically protected steel buried in soil sediments. Other types can be mounted in process plants for monitoring purposes. 

The most thoroughly developed sensor based on a solid electrolyte is the oxygen sensor using a stabilised zirconia electrolyte. This type of sensor is one of the most successful commercial sensors to date. They are widely used in industry, especially in the analysis of exhaust gases from combustion engines. The following configuration is used in the Oj sensors ... 

The determination of iodide with ion-selective electrodes is possible with commercial sensors often based on ion conducting Ag2S—Agl solid membranes [57]. A PVC membrane-based sensor employing a silver complex with thiourea derivatives has been reported by El Aamrani et al. [202]. Interference from thiocyanate and bromide was investigated and a limit of detection in the nanomolar range was determined. A study assessing the performance... 

Nitrate ISEs have been formulated using amino acid betaines with the general formula (CH2=CHCH2)3N+CHRCOOH CT within styrene-butadiene membranes. These have been shown to give a Nernstian response from 10 10 7 M with selectivity over chloride (selectivity coefficient 0.0034), representing a significant improvement on commercial sensors with response times <1 min [23]. 

It is obvious that this method of odor measurement is a very time-consuming and expensive method. However, Stuetz et al. (2000) were able to correlate the global parameters BOD, COD and TOC of sewage samples by headspace measurements of odor using a commercial sensor array system. Thus, the electronic nose seems to have several interesting applications in wastewater treatment technologies. 

Accurate measurement of photon flux is essential in order to calculate quantum efficiency (whether based on absorbed photons flux or the flux of photons impinging on the surface). The response of commercial sensors is wavelength dependence, hence, the readout, which is in energy flux units (W cm ), is usually calibrated according to either the 365 nm line of mercury or the 254 nm line, depending on the sensor. For more details on radiation sources see de Lasa et al. (2005). A different method for measuring photon flux is actinometry. This method was very popular in the past, however, very few researchers still use it due to its complexity and the time it consumes. 

The commercial sensors BIACORE [37] and lAsys [65] offer a variety of advanced surface chemistries for attachment of the different receptor layers as can be seen in Table 5.4. 

One of the successfully commercialized sensors in the last century was the zirconia-based potentiometric oxygen sensor (A,-sensor), which has greatly improved... 

In another experiment, a sensor array was constructed with several commercial sensors to test the enhancement of sensor selectivity using pattern recognition techniques [67]. This type of sensor array was configured using two strategies ... 

There are a large number of commercial sensors. They differ either in the basic measuring principle they employ or in their construction characteristics. For more details the reader can consult the various references at the end of Part IV or the technical booklets circulated by the various manufacturers. Table 13.1 lists typical measuring devices encountered in various applications of process control. 

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