Device extrinsic

Both extrinsic- and intrinsic-type sensors incorporate a transducer element making it an active device. Extrinsic sensors have an external transducer, and the optical fiber just serves the purpose of a light carrier to and from the external transducer whereas, intrinsic sensors have the structure of the optical fiber modified to incorporate the transducer element. In both cases, the transduction mechanisms change the light properties based on interaction with chemical species. 

J.-H. Chen, C. ang, S. Xiao, M. Ishigami, M.S. Fuhrer, Intrinsic and extrinsic performance limits of graphene devices on Si02, Nature Nanotechnology, 3 (2008) 206-209. 

The properties of semiconductors are extremely sensitive to the presence of impurities at concentrations as low as 1 part in 10 °. For this reason, silicon manufactured for transistors and other devices must be very pure. The deliberate introduction of a very low concentration of certain impurities into the very pure semiconductor, however, alters the properties in a way that has proved invaluable in constructing semiconductor devices. Such semiconductors are known as doped or extrinsic semiconductors. Consider a crystal of silicon containing boron as an impurity. Boron has one fewer valence electron than silicon. Therefore, for every silicon replaced by boron, there is an electron missing from the valence band (Figure 4.10) (i.e., positive holes occur in the valence band and these enable electrons near the top of the band to conduct electricity). Therefore, the doped solid will be a better conductor than pure silicon. A semiconductor like this doped with an element with fewer valence electrons than the bulk of the material is called a p type semiconductor because its conductivity is related to the number of positive holes (or empty electronic energy levels) produced by the impurity. 

Fig. S. Matrix-addressed liquid crystal display using an FET as an extrinsic threshold device. The capacitor (dashed) is optional.

A limited amount of trapping (either intrinsically or extrinsically) is helpful in that it ensures a deep OFF state of the device during the time at which other lines are addressed that is a (properly adjusted) hysteresis can serve as a memory element over the frame time (Ast, 1982a,b, 1983). This argument is not readily accepted by those who believe that a device must be inherently stable to function in a reliable manner. However, Luo et al. (1983) arrived at an identical conclusion in their analysis of the switching performance of CdSe transistors in matrix-addressed LC displays. It is very important that the trapping be noncumulative. Since the duty cycle of a... 

Roggenkamp HG, Jung F, Kiesewetter H (1983) Em Gerat zur elektrischen Messung der Verformbarkeit von Erythro-cyten. A device for the electrical measurement of the de-formability of red blood cells. Biomed Techn 28 100-104 Seiffge D, Behr S (1986) Passage time of red blood cells in the SER their distribution and influences of various extrinsic and intrinsic factors. Clin Hemorheol 6 151-164... 

The demonstrations cited above illustrate how AW devices can be used to probe intrinsic and extrinsic fluid properties. This capability can be useful for providing in-situ probes of critical solution properties such as viscosity, density, and conductivity. This capability should prove useful in the monitoring of process streams or critical fluids (e.g., automotive oil condition monitoring [41]). 

The detection of chemical analytes can be based on changes in one or more of the physical characteristics of a thin film or layer in contact with the device surface. Some of the intrinsic film properties that can be utilized for detection include mass/area, elastic stiffness (modulus), viscoelasticity, viscosity, electrical conductivity, and permittivity. In addition, changes in extrinsic variables such as... 

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