Mechanical sensors

Pressure. Pressure so defined is sometimes called absolute pressure. The differential pressure is the difference between two absolute pressures. The most common types of pressure-measuring sensors are silicon pressure sensors, mechanical strain gauges, and electromechanical transducers. 

It is well known that survival and proliferation of microbial cells in the environment depend on the expression of advantageous phenotypes controlled by the genotype expression. It is becoming clear that such evolutionary pressure has resulted in a network of sensor mechanisms that transduce environmental stimuli into gene expression and hence a phenotype complementary to the prevail-... 

The model analytes, which were used to show the sensor performance of the microsystems include carbon monoxide, CO, and methane, CH4. The sensor microsystems were designed for practical applications, such as environmental monitoring, industrial safety applications or household surveillance, which implies that oxygen and water vapors are present under normal operating conditions. In the following, a brief overview of the relevant gas sensor mechanisms focused on nano crystalline tin-oxide thick-film layers will be given. 

The Fido technology is currently under evaluation for use by U.S. military forces. The Fido X and Fido XT are available as commercial off-the-shelf (COTS) items. Consequently, the technology is adequately mature for commercial deployment. However, as a platform technology, the AFP sensor and Fido detection system support broad application to meet explosives detection needs. Further, Nomadics has incorporated the amplification features of AFP into other sensor mechanisms aimed at the detection of analytes that are not explosives related, including other chemicals and compounds of interest in the biomedical and food safety fields. Thus, while the technology is mature enough for commercialization, its potential is far from fully exploited. 

Otterbein LR, Kordowska J, Witte-Hoffmann C, Wang CL, Dominguez R. 2002. Crystal structures of S100A6 in the Ca(2+)-free and Ca(2+)-bound states the calcium sensor mechanism of S100 proteins revealed at atomic resolution. Structure 10(4) 557-567. 

G. Paula, Crime-fighting sensors, Mechanical Engineering, 120 (1998) 1. 

Figure 13.2 Mixed potential sensor mechanism, (a) Mixed...

The vision of braking and steering by wire will demand new, extremely reliable sensors. Even in early implementations of steer-by-wire systems, in which manual control can override any system failure, more than one sensor is normally used for the sake of redundancy. Many of the sensor principles required are already established in the market, including steering-angle sensors (e.g., for vehicle dynamics control) and pedal-position sensors. Mechanical action or feedback control, however, will drive the emergence of torque and force sensors. 

Chang S-C and Ko W H 1994 Capacitive sensors Mechanical Sensors (Sensors ... 

Much of the art of the sensor is in the synthesis of the desired material. Characteristics such as homogeneity, grain size, and crystalline phase, which can be controlled to varying degrees during the synthesis process, greatly influence the ultimate sensor mechanisms [52]. Iterative experimentation with metal oxide particle size, prefired compositions, catalysts, and process variables is necessary to optimize porosity, resistance, sensitivity, and other sensor characteristics. 

A very similar sensor mechanism is used Nonetheless, there is strong similarity... 

The large and flexible backplanes available via OFET technologies can also benefit image sensing applications, many of which can benefit from large area (e.g. X-ray sensors), mechanical flexibility (contact scanners for non-planar objects) or both characteristics. 

This chapter describes a broad range of optical biosensor technologies, based on interchromophore interactions and the super-quenching phenomenon. Several specific biosensor schemes are described that are able to sense the activity of kinase, protease, lipase, and cellulase enzymes. Although the systems are disparate, the underlying sensor mechanisms are related, in that they all... 

In OECT-based sensors, it is the conjugated polymer layer which acts as a transducer upon exposure to analytes. However, it is not essential that the conjugated polymer layer be the one which responds directly to the presence of the analyte. Therefore, OECTs can be broadly divided into four types based on their mechanism of detection of the analyte. These sensor mechanism types are listed in Table 8.1. 

Active layer Analytes Sensor mechanism typea... 

It has to be remarked that in spite of the widely accepted term electronic nose, current devices are still far from the structure and functions of natural olfaction sense. The unique common feature between artificial and natural system is that both are largely based on arrays of nonselective sensors. The concept underlying electronic nose systems has been demonstrated to be independent on the particular sensor mechanism indeed during the last two decades almost all the available sensor technologies have been utilized as electronic noses. Clearly, all these sensors are very different from the natural receptors. These dissimilarities make the perception of electronic nose very different from that of natural olfaction, so that the instrumental perception of the composition of air cannot be called odor measurement because odor is the sensation of smell as perceived by human olfaction. Nonetheless, the term odor analysis with electronic noses is now largely adopted, but it is important to keep in mind, especially in medical applications, that the electronic nose measurement may be very distant from the human perception. 

As exemplified above, the application-specific performance of a sensor is thus influenced by adsorption, reactions between adsorbed species and desorption characteristics of the individual substances present in the gas mixture. These characteristics depend on the materials interacting with the substances, the structure of the materials and the operation temperature therefore, the selectivity and sensitivity to the gases of interest can be influenced by the choice of gate materials, their structure and the temperature. For the development of sensors for new applications, it is therefore important to gain knowledge about gas solid interactions and sensor mechanisms to be able to tailor devices with good selectivity and sensitivity to the target substance(s). 

The sensitivity of planar TiOj-based IDE sensors to hydrocarbons and humidity was successfully demonstrated. It was shown that the response of the sensor to the analyte gas depends on frequency, which suggests the use of impedance spectroscopy to investigate the sensor mechanism at work. 

Fig. 11.37 Piezoelectric sensor, mechanical components, and amplification circuit...

Fig. 11.40 Sensor mechanical section and equivalent bond graph model...

In the days of linear, continuous electronics non-linearity was a major problem. Such compensation techniques as were available were based on diode networks having reciprocal characteristics, but by their nature these were relatively crude. As a result all non-linear primary sensor mechanisms tended to be ignored. Now, linearisation processes such as look-up tables or polynomials are easily realisable with digital electronics. 

Most gas sensors that use solid electrolytes are operated potentiometrically. Configurations for potentiometric gas sensors have been reported (Yamazoe and Miura 1998 Miura et al. 2000). The simplest scheme for such sensors is represented in Table 6.1 as Type I. In this diagram illustrating the potentiometric sensor mechanism, A is the analyte with variable activity/concentration, is the constant activity of analyte A on the reference side of the solid electrolyte membrane, AB is a solid electrolyte membrane (A+ ion conductor), and the electrodes facilitate the reaction A +e =A when the activity of A is different on each side of the membrane, a potential, V, is observed. The voltage produced is from the concentration dependence of the chemical potential, which at equilibrium is represented by the Nemst equation ... 

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