Impedance-based detection

Jonsson MK, Wang QD, Becker B (2011) Impedance-based detection of beating rhythm and proarrhythmic effects of compounds on stem cell-derived cardiomyocytes. Assay Drug Dev Technol 9(6) 589-599. doi 10.1089/adt.2011.0396... 

A. Schroter, A. Rosen-Wolff, and G. Gerlach, Impedance-based detection of extracellular DNA in wounds, in Journal of Physics Conference Series, lOP Publishing, vol. 434, 2013, pp. 012-057. 

C.M. Li, W. Chen, and X. Yang, Impedance labelless detection-based polypyrrole protein biosensor. Front. Biosci. 10, 2518—2526 (2005). 

Part II of the book deals with lesser known aspects of US for the analytical chemists such as its use as an energy source for detection purposes. Thus, ultrasound-based detection techniques viz. US spectrometry in its various modes including ultrasound attenuation, ultrasonic velocity, resonant ultrasound, laser-generated, ultrasound reflection and acoustic wave impedance spectroscopies) are dealt with in Chapter 9. Finally, Chapter 10 is devoted to seleoted applioations of US spectrometry — mostly non-analytical applications from whioh, however, analytical chemists can derive new, interesting analytical uses for ultrasound-based deteotion techniques. 

Before we discuss the applications of US-based detection techniques, we should emphasize the difference between the measured data and the desired output parameters. In ultrasound spectrometry, the measured data can be the attenuation coefficient, the sound speed and the acoustic impedance. However, the researcher is rarely interested in these measured properties, but rather on elastic moduli of solid samples particle size distributions or rheological properties of heterogeneous samples and concentrations, rheology, stability and chemical reactivity of liquids (particularly emulsions). 

Further development of new impedance-based gas sensors is likely to allow their introduction to niche applications in the field of zirconia-based, solid-state gas sensors. Impedance spectroscopy has the potential to measure changes not detectable with simple current or voltage measurements. Although it is not practical to implement complete impedance spectroscopy in an operating sensor, an optimized frequency suitable for a specific gas sensor may be used. So far, these sensors are still more complex and expensive as compared to the potentiometric zirconia-based gas sensors. However, they have two important advantages (1) measurement of total NOx concentration, regardless of the NO/NO2 ratio in exhausts and (2) near equal sensitivity to NO and NO2 at 700°C. These are essential prerequisites to their practical implementation in vehicle exhausts. Therefore, further investigation is... 

Recently, the development of the impedance-based zirconia sensors using the specific spinel-type oxide SE for NO measurement at high temperatures allowed detecting the total NOx concentrations regardless of the NO-NO2 ratio in a gas mixture [55-57]. Development of the impedancemetric NO sensors was described in detail in Chapter... 

Rodriguez, M. C., Kawde, A-N., Wang, J. (2005). Aptamer biosensor for label-free impedance spectroscopy detection of proteins based on recognition-induced switching of the surface charge. Chem Commun 34, 4267-4269. 

Sensitive electrochemical DNA biosensors based on electrochemically fabricated PANI-NFs and methylene blue [483], as well as based on the synergistic effect between PANI-NFs and MWCNTs in chitosan film have been successfully prepared [484]. Highly sensitive electrochemical impedance spectroscopic detection of DNA hybridization based... 

N. Zhou, T. Yang, C. Jiang, M. Du, and K. Jiao, Highly sensitive electrochemical impedance spectroscopic detection of DNA hybridization based on Au ano-CNT/PAN ano films, Talanta, 77, 1021-1026 (2009). 

Geddes and Baker (1989) used the expression Detection of Physiological Events by Impedance. The physiological variable may, for instance, be blood volume or flow and air volume or flow as described in Section 10.8.1. Impedance-based transducers convert the measured variable online into a signal from which the clinical parameter can be continuously calculated. Users are often not aware of which variable is the primary (actually measured) variable. 

Keywords Wound sensor Bio-impedance DNA detection Fiber-based electrodes... 

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