Weight mass sensor

Weight (mass) sensors are of various types, such as bending plate, capacitance pad, capacitance strip, piezo-electric cable, load cell or strain gauge mounted to an existing road structure such a culvert (Culway system). 

The major advantages of mass sensors are the simplicity of their construction and operation, low weight, and small power requirements. In addition, their operating principle depends on a highly reliable phenomenon. The measurement of the frequency shift is one of the simplest and most accurate physical measurements. 

Fig. 1 The numerical example [6,11-13]. (a) True mass chromatogram w%V), uniform broadening g(V), and resulting measured chromatogram w(V). (b) Molecular-weight calibration logM(V), rotated calibration according to Method IV [8,9] log M V) jy, and calibrations assuming ideal molar mass sensors log M (V) and log MJV). (c-f) Comparison between the true MWD w (log M) and the MWD estimates H "(log M) obtained from Methods I[4], II[5], III[6], IV[8,9], and V[10].

Provided that a mass added to electrode surfaces is (i) small compared to the weight of the crystal, (ii) rigidly adsorbed, and (iii) evenly distributed over the active area of the ciy stal, the Sauerbrey relationship has been classically used for quantitative determination of mass deposited on the sensor surface in terms of the following equation (Sauerbrey 1959). 

In aflBnity sensors, the analyte is usually a high-molecular-weight protein, since its binding to the surface results in a large, easily detectable change in mass and/or in refractive index of the surface-bound layer. 

Metal oxide semiconductor chemical sensors in combination with MDA have been shown to be useful to estimate the oxidative stability of polypropylene during processing instead of traditional melt flow index analysis (50). An array of sensors was used to receive a detailed analysis of volatiles. At quality measurements of different poly(butylene adipate)s the use of indicator products has been proven better than analyses of the decrease in molecular weight or mass loss for early degradation detection. Adipic acid, quantified using gas chromatography, was then used as the indicator product [51]. 

Toxic foodborne proteins are typically secreted from infectious bacteria. These proteins are typically toxic in extremely low doses. Because of the molecular weight of the proteins (ranging from 5 kDa to 150 kDa), diffusion to the surface is not problematic. Their mass allows for sensor responses from direct binding at higher concentrations. For lower analyte concentrations, a sandwich assay is typically used to improve the lower detection limits for various analytes. 

The use of piezoelectric (PZ) devices as potential analytical chemistry sensors was not realized until Sauerbrey (3) described the relationship between the resonant frequency of an oscillating piezoelectric crystal and the mass deposited on the crystal surface. The relationship between the weight of an evenly distributed film of a metal and the resonant frequency of an AT cut crystal vibrating in the thickness shear mode can be expressed by ... 

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