Light addressable potentiometric sensors LAPS

Several other approaches for detecting nucleic acids are reported in the literature, based, for example, on the light-addressable potentiometric sensor (LAPS) (Kung et al. 1990) or on acoustic wave devices (Su et al. 1996). 

The concept of light addressable potentiometric sensors (LAPS) was introduced in 1988 [67], LAPS is a semiconductor-based sensor with either electrolyte-insulator-semiconductor (EIS) or metal-insulator-semiconductor (MIS) structure, respectively. Figure 4.13 illustrates a schematic representation of a typical LAPS with EIS structure. A semiconductor substrate (silicone) is covered with an insulator (Si02). A sensing ion-selective layer, for instance, pH-sensitive S3N4, is deposited on top of the insulator. The whole assembly is placed in contact with the sample solution. 

FIGURE 4.13 Schematic representation of a light-addressable potentiometric sensor (LAPS). 

Y. Mourzina, Y. Ermolenko, T. Yoshinobu, Y. Vlasov, H. lwasaki, and MJ. Schoning, Anion-selective light-addressable potentiometric sensors (LAPS) for the determination of nitrate and sulphate ions. Sens Actuators, B 91, 32—38 (2003). 

T. Yoshinobu, M.J. Schoning, R. Otto, K. Furuichi, Y. Mourzina, Y. Ermolenko, and H. lwasaki, Portable light-addressable potentiometric sensor (LAPS) for multisensor applications. Sens. Actuators, B 95, 352-356 (2003). 

FIGURE 1.3 Schematic drawing of a light addressable potentiometric sensor (LAPS) for pathogen detection. (Adapted from reference Gehring et al., 1998). 

Tu, S. 1., Uknalis, J., Gore, M., and Irwin, P. (2002). The capture of Escherichia coli 0157 H7 for light addressable potentiometric sensor (LAPS) using two different types of magnetic beads. /. Rapid Methods Automat. Microbiol. 10,185-195. 

Light-addressable potentiometric sensors (LAPS) recent trends and applications... 

M. Sartore, M. Adami, C. Nicolini, L. Bousse, S. Mostarshed and D. Hafeman, Minority carrier diffusion length effects on light-addressable potentiometric sensor (LAPS) devices, Sens. Actuators A Phys., 32(1-3) (1992) 431-436. 

W. Parak, M. George, J. Domke, M. Radmacher, J. Behrends, M. Denyer, and H. Gaub, Can the light-addressable potentiometric sensor (LAPS) detect extracellular potentials of cardiac myocytes IEEE Trans. Bio-med. Eng., 47 (2000) 1106-1113. 

B. Stein, M. George, H.E. Gaub and W.J. Parak, Extracellular measurements of averaged ionic currents with the light-addressable potentiometric sensor (LAPS), Sens. Actuators B Chem., 98(2-3) (2004) 299-304. 

Y. Mourzina, T. Yoshinobu, J. Schubert, H. Liith, H. Iwasaki and M.J. Schoning, Ion-selective light-addressable potentiometric sensor (LAPS) with chalcogenide thin film prepared by pulsed laser deposition, Sens. Actuators B Chem., 80(2) (2001) 136-140. 

The objective of this protocol is the fabrication of a light-addressable potentiometric sensor (LAPS) for the detection of the pH value and the cadmium-ion concentration in aqueous solutions. For the pH-sensitive LAPS, use, e.g., Ta205 as a sensor membrane, and for the cadmium-selective LAPS, use a Cd2+-selective chalcogenide glass thin film as a heavy metal-sensitive material. The electrochemical sensor characterisation of the LAPS structure perform current vs. voltage (I/V) and constant current (CC) measurements. 

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