Electrochemical transducers

Electrochemical immunoassays include a wide variety of devices based on the coupling of immunological reactions with electrochemical transduction. All of them involve the immobilization of an immunoreagent component on the surface of the electrode transducer. Electrochemical detection is based on the direct intrinsic redox behavior either of an analyte species or of some reporter molecule. For the detection no expensive equipment is needed, with the measurement of either a simple current or a voltage charge. Different electrochemical detection strategies are used, but ampero-metric detection is most widely used. Potentiometric and conductometric detection are applied in different assays as well. 

Transducers Optical, Optoelectronic Transducers Piezoelectric Transducers Electrochemical Transducers... 

The term biosensor now applies to any combination of transducer (electrochemical, optical, piezoelectric, thermoelectric)... 

Furthermore they are relatively simple in the most elementary case, the transducer (electrochemical cell) consists of nothing more than two electrodes immersed in a suitable electrolyte. A more complex arrangement might involve the use of a three-electrode cell mentioned above, with the advantages that the reference half-cell is not disturbed (polarized) by the current flowing... 

Through the examples presented above, MIPs appear to be very pronusing novel bioelements. They are more stable and more reproducible than natural antibodies. They can be used in combination with various transducers (electrochemical, optical, itnmunosensors, etc.). The synthesis can be set up so that the MIPs are directly synthesized on the transducer. A large diversity of functional monomers and cross-linking polymers as well as synthesis methods is available. An easy fabrication and characterization of the MIP could give them the potential to be widely used in an industrial fabrication of the sensors. 

Operating principle Electrochemical transducer Electrochemical transducer Electrochemical transducer... 

Operating principle Electrochemical motion transducer Electrochemical motion transducer Electrochemical motion transducer Electrochemical motion transducer... 

Ping, J., Y. Wang, J. Wu, and Y. Ying. 2011. Development of an all-solid-state potassium ion-selective electrode using graphene as the solid-contact transducer. Electrochem. Common. 13 1529-1532. 

Two major sources of ultrasound are employed, namely ultrasonic baths and ultrasonic immersion hom probes [79, 71]- The fonuer consists of fixed-frequency transducers beneath the exterior of the bath unit filled with water in which the electrochemical cell is then fixed. Alternatively, the metal bath is coated and directly employed as electrochemical cell, but m both cases the results strongly depend on the position and design of the set-up. The ultrasonic horn transducer, on the other hand, is a transducer provided with an electrically conducting tip (often Ti6A14V), which is inuuersed in a three-electrode thenuostatted cell to a depth of 1-2 cm directly facing the electrode surface. 

Fig. 1. Schematic representation of a battery system also known as an electrochemical transducer where the anode, also known as electron state 1, may be comprised of lithium, magnesium, zinc, cadmium, lead, or hydrogen, and the cathode, or electron state 11, depending on the composition of the anode, may be lead dioxide, manganese dioxide, nickel oxide, iron disulfide, oxygen, silver oxide, or iodine.

The optimization of the biorecognition layer by the modification of a transducer used. Nanostmctured poly aniline composite comprising Prussian Blue or poly-ionic polymers has been synthesized and successfully used in the assembly of cholinesterase sensors. In comparison with non-modified sensors, this improved signal selectivity toward electrochemically active species and decreased the detection limits of Chloropyrifos-Methyl and Methyl-Pai athion down to 10 and 3 ppb, respectively. 

Junge, W., Lill, H., and Engelbrecht, S., 1997. ATP. syntlia.se An electrochemical transducer with rotatory mechanics. Trends in Biochemical Sciences 22 420-423. 

Other useful sensors rely on the coupling of microorganisms and electrochemical transducers. Changes in the respiration activity of the microorganism, induced by the target analyte, result in decreased surface concentration of electroactive metabolites (e.g., oxygen), which can be detected by the transducer. 

Instead of immobilizing the antibody onto the transducer, it is possible to use a bare (amperometric or potentiometric) electrode for probing enzyme immunoassay reactions (42). In this case, the content of the immunoassay reaction vessel is injected to an appropriate flow system containing an electrochemical detector, or the electrode can be inserted into the reaction vessel. Remarkably low (femtomolar) detection limits have been reported in connection with the use of the alkaline phosphatase label (43,44). This enzyme catalyzes the hydrolysis of phosphate esters to liberate easily oxidizable phenolic products. 

The presence of polymer, solvent, and ionic components in conducting polymers reminds one of the composition of the materials chosen by nature to produce muscles, neurons, and skin in living creatures. We will describe here some devices ready for commercial applications, such as artificial muscles, smart windows, or smart membranes other industrial products such as polymeric batteries or smart mirrors and processes and devices under development, such as biocompatible nervous system interfaces, smart membranes, and electron-ion transducers, all of them based on the electrochemical behavior of electrodes that are three dimensional at the molecular level. During the discussion we will emphasize the analogies between these electrochemical systems and analogous biological systems. Our aim is to introduce an electrochemistry for conducting polymers, and by extension, for any electrodic process where the structure of the electrode is taken into account. 

Indicator electrodes are used both for analytical purposes (in determining the concentrations of different substances from values of the open-circuit potential or from characteristic features of the polarization curves) and for the detection and quantitative characterization of various phenomena and processes (as electrochemical sensors or signal transducers). One variety of indicator electrode are the reference electrodes, which have stable and reproducible values of potential and thus can be used to measure the potentials of other electrodes. 

Electrochemical information transducers can be grouped according to their functions ... 

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