Sensors dynamic

Some attempts to exploit sensor dynamics for concentration prediction were carried out in the past. Davide et al. approached the problem using dynamic system theory, applying non-linear Volterra series to the modelling of Thickness Shear Mode Resonator (TSMR) sensors [4], This approach gave rise to non-linear models where the difficulty to discriminate the intrinsic sensor properties from those of the gas delivery systems limited the efficiency of the approach. 

The increase of the sensor size comes with a decrease in sensor label sensitivity, that is, the sensor response for a single magnetic label is smaller. On the other hand, the sensor dynamic range is larger as the sensor is able to detect a larger number of particles. In order to be sensitive to single labels 106 the sensor size can be reduced to match the label size [121], but in this case the assay biological sensitivity is smaller. 

Wang, D.Y. and Detwiler, E. (2006) Exhaust oxygen sensor dynamic study. Sens. Actuators B. 120, 200-6. 

A property that is particularly important for model formation is the linearity or nonlinearity of the reaction kinetics. Linear reaction rates permit models with parabolic differential equations having linear terms. This in turn allows the derivation of explicit solution formulas which are substantially better suited to the simulation of the sensor dynamics than numerical calculations. Since, for the enzyme elec-... 

Deterioration of the sensor dynamics changes the control state, especially if the response times lean/rich and rich/lean are asymmetrically increased. Adsorption of CO and HC and plugging of the protective layer will slow down the rich/lean response, while electrode poisoning (lead poisoning), which leads to reduced catalytic activity, does the same with the lean/rich response. Symmetrically delayed response times have no effect on the control state, but on the emissions by increasing the control amplitude, which diminishes the conversion rate of the catalyst [1]. 

The curves shown in Fig. 5 not only involve the sensor dynamics, but also the dynamics of the gas mixing apparatus, the pipes, and the measurement chamber. After the control signal to increase the propane concentration, it takes some time (less than one minute) until a concentration step (smoothed by mixing and gas flow) reaches the sensor. The associated dead times are, however, much smaller than the settling times visible in Fig. 5. Therefore, the sensor investigated exhibits the slow dynamics typical of chemical sensors in general. 

Reliable measurements of the periodically changing outputs are not always available, as they are highly dependent on the sensor dynamic characteristics. 

Fig. 11.44 Bode plot of sensor dynamics (a). Step and impulse response (b)...

Assuming a magnetic volume of 5.4 x 1(P nm, the fluctuations have an amplitude of 80 70 degrees A significant fraction of the sensor dynamic... 

The closed-loop frequency response can be calculated analytically from the open-loop frequency response. Again, consider Fig. J.l, and assume that the sensor dynamics are negligible so that G s) = From Fig. J.l... 

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