Piezoresistivity

Piezoresistive Sensors. The distinction between strain-gauge sensors and pie2oresistive (integrated-circuit) sensors is minor. Both function by measuring the strain on an elastic element as it is subjected to pressure. A pie2oresistive transducer is a variation of the strain gauge that uses bonded... 

Dynamic explosion detectors use a piezoresistive pressure sensor installed behind the large-area, gas-tight, welded membrane. To ensure optimum pressure transference from the membrane to the active sensor element, the space between the membrane and the sensor is filled with a special, highly elastic oil. The construc tion is such that the dynamic explosion detec tor can withstand overpressures of 10 bar without any damage or effect on its setup characteristic. The operational range is adjustable between 0 and 5 bar abs. Dynamic explo-... 

Measurements from stress gauges, assuming equal accuracy and time resolution, are equivalent to measurements from particle velocity gauges in exploring a material s equation of state. Both piezoresistive and piezoelectric techniques have been used extensively in shock-compression science. 

Another important method of determining the Gruneisen ratio in the shock state is the measurement of sound speed behind the shock front. The techniques employing optical analyzers (McQueen et al., 1982) piezoresistive (Chap-... 

Chui, B.W., Stowe, T.D., Kenny, T.W., Mamin, H.J., Terris, B.D. and Rugar, D., Lowstiffness silicon cantilevers for thermal writing and piezoresistive readback with the atomic force microscope. Appl. Phys. Leu., 69(18), 2767-2769 (1996). 

Fig. 3.7. The time periods over which significant developments are reported in the literature for the various piezoelectric and piezoresistant gauges are shown. It should be noted that the development period for development of such detectors is a minimum of 10 yr and possibly more typically 15 yr.

Detectors that have been widely used for materials studies can be conveniently categorized by the physical phenomena utilized in the measurement as piezoelectric, piezoresistant, electromagnetic, or optical. In each, the phenomena are capable of providing a signal in a time short compared to changes in characteristics of wave profiles. Given the desired time resolution of one nanosecond, the detectors must be massless. ... 

The development of piezoresistant gauges provides a counterexample in that early work was based on empirical study of responses based on simple... 

A quite important parameter for the operation of washing machines is their load. There are several ways to measure the wash load, e.g the force required to rotate the drum/tub/pulsator could be measured and the required amount of water worked out accordingly, or the machine load could be measured by a remote pressure-sensing device with piezoresistive transducers and wireless communication... 

Piezoresistive sensors, 20 655-656 Piezo technology, in commercial printing, 14 327... 

Fig. 8.4 Plots of relative change in electrical resistance against tensile deformation of a CNT/epoxy composite (a) shows the various characteristics of the piezoresistivity of nanocarbon networks linear resistance change in the elastic regime, nonlinear region after inelastic deformation and the permanent electrical resistance drop due to plastic deformation (image adapted from [30]) ...

In addition to mechanical reinforcement, the presence of nanocarbons in these hierarchical composites can also be used for piezoresistive structural health monitoring or damage evaluation by thermal imaging. Other functions of the nanocarbon, for example in structural supercapacitors, are likely to emerge in the near future. 

Wichmann MHG, Buschhorn ST, Gehrmann, Schulte K. Piezoresistive response of epoxy composites with carbon nanoparticles under tensile load. Physical Review B. 2009 Dec 80(24). 

Cantilevers are usually microfabricated from silicon by using conventional pho-tomasking and etching techniques. Typical dimensions of a cantilever are 100 pm in length, 20 pm in width, and 1 pm in thickness. Silicon and silicon nitride cantilevers and cantilever arrays that utilize optical beam deflection for signal transduction are commercially available. Piezoresistive cantilever arrays are also commercially available. Piezoresistive cantilevers are 120 pm in length, 1 pm in thickness, and 40 pm in width. 

There exists a number of readout techniques based on optical beam deflection, variation in capacitance, piezoresistance, and piezoelectricity. Piezoelectricity is... 

Deflagration experiments were conducted only for TNT vapors. For deflagration experiments we have used a piezoresistive microcantilever the piezoresistive... 

Figure 12.5 Relationship between the area under the curve obtained from the peaks shown in Figure 12.2 and the mass of adsorbed TNT calculated from the observed changes in resonance frequency of the piezoresistive cantilever.

Electric sensing devices (strain gauges, piezoresistive transducers, and piezoelectric transducers)... 

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