Electrostatic transduction

Polymer electret and ferroelectrets have unique characteristics such as electrostatic transduction wifliout external voltage, light weight, flexibility, and so on. Their most successful apphcations are microphones and air Alters, but various other types of devices have also been proposed. In this chapter, after giving overview of their apphcations, developments of acoustic devices and power generators/energy harvesters arc discussed. 

Owing to their unique (tunable-electronic) properties, semiconductor (quantum dots) nanocrystals have generated considerable interest for optical DNA detection [12], Recent activity has demonstrated the utility of quantum dot nanoparticles for enhanced electrical DNA detection [33, 34, 50], Willner et al. reported on a photoelectrochemical transduction of DNA sensing events in connection with DNA cross-linked CdS nanoparticle arrays [50], The electrostatic binding of the Ru(NH3)63+ electron acceptor to the dsDNA... 

Katz, E., WiHner, B., and Willner, I. Light-controlled electron transfer reactions at photo isomerizable monolayer electrodes by means of electrostatic interactions Active interfaces for the amperometric transduction of recorded optical signals. Biosens. Bioelectron. 1997, 22, 703-719. 

An additional advantage of the integrated circuit technology is the ability to integrate the various components, such as the transducer, reactor, valve, pump etc., within the electronic system, forming refined flow-analysis systems on silicon wafers. Several approaches, such as electrostatic, electromagnetic, piezoelectric, thermopneumatic and thermoelectric can be employed for force transduction in the microvalves, these are also applicable to micropumps. Based on these approaches, two versions of micropumps have been developed. These are connected in parallel the first pump (dual pump) is activated with periodic two-phase voltage, while the second pump (the buffer pump) is driven by two piezoelectric actuators. Microsensors of two kinds are described below a thermopile based- and a thermistor based microbiosensor. 

Specific proteins mediate distinctive membrane functions such as transport, communication, and energy transduction. Many integral membrane proteins span the lipid bilayer, whereas others are only partly embedded in the membrane. Peripheral membrane proteins are bound to membrane surfaces by electrostatic and hydrogen-bond... 

Artificial BLMs offer opportunities for development of chemically selective biosensors [6,7], The essential idea is that a receptor (such as a protein molecule) which can selectively bind to a specific organic or biochemical species (stimulant or analyte) can be incorporated into an ordered lipid membrane assembly such that selective binding events between receptor and stimulant will lead to alterations of the phase structure or electrostatic fields of the membrane (transduction). These perturbations can be monitored electrochemically as changes of transmembrane ion conductivity or as alterations in membrane capacitance. 

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