Flow-through sensors features

The most salient feature of flow-through sensors is the way in which the sample is brought into contact with the sensitive microzone (see Fig. 1.14), which distinguishes them from probe and drop-planar sensors. In fact, the liquid (or gaseous) sample is passed over the microzone rather than dropped onto it or used to immerse the probe [1]. 

At this point it is worth setting a clear distinction between continuous-flow analytical systems (occasionally referred to as "sensor systems") and flow-through sensors, two terms that are often confused in the analytical literature. The primary difference between them lies in whether or not detection is performed simultaneously with other steps in the continuous system. Figures 2.1 and 2.2 illustrate the differential features of the two types of system. 

An automated electronic tongue consisting of an array of potentiometric sensors and an artificial neural network (ANN) was developed to resolve mixtures of anionic surfactants. The sensor array was formed by five different flow-through sensors for anionic surfactants, based on polyvinyl chloride membranes having cross-sensitivity features. 

A number of descriptions of this instrument have already appeared in the literature (14,15), including a full description of its main features by Cannon (16). Sayer (17) also provides a general block diagram. The instrument comes in a number of different configurations a flow-through cell (the PPL-80 sensor) and a dip-type probe (SPP-80). The... 

Fig. 1 (a) Cross-view of a MAMP cell chamber. Cells are cultured on a polycarbonate insert that is placed in the sensor cup. A spacer and additional insert are placed on top of the cells, and the sensor head is lowered over the assembly. The sensor head features inlet and outlet tubes to allow for 100 pL/min flow through the 3 pL chamber, as well as the Pt wires for amperometric detection and a stainless steel counter electrode for the LAPS circuit. A Ag/AgCl (2 M KCl) reference electrodes is placed downstream of the chamber, (b) Raw amperometric signals of cells during 80 s 100 pL flow periods and 40 s stop-flow periods black bar)... 

Branchial neuroepithelial cells are currently the best candidates for the O2 chemoreceptor cells that mediate the reflex responses to hypoxia in fish. In the gills, these cells are located in the primary epithelium of the giU filaments and he on the basal lamina between the inhalant water flowing over the gill and blood flow through the gill in an ideal anatomical location to function as O2 sensors. Branchial neuroepithelial cells share many of the characteristic anatomical features of mammalian O2 sensors (glomus and pulmonary neuroepithehal ceUs). Like mammalian cells, branchial neuroepithehal cells are innervated and possess a well-developed Golgi complex and numerous mitochondria and dense-cored... 

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