Membranes chemical sensors

J.-S. Shih, Y.-C. Chao, M.-F. Sung, G.-J.Gau, C.-S. Chiou, Piezoelectric crystal membrane chemical sensors based on fullerene C60, Sensors and Actuators B 76 (2001) pp. 347-353. 

Shih J-S, Chao Y-C, Sung M-F, Gau G-J, Chiou C-S (2001) Piezoelectric crystal membrane chemical sensors based on fullerene C. Sens Actuators B 76 347-353... 

One important application of amperometry is in the construction of chemical sensors. One of the first amperometric sensors to be developed was for dissolved O2 in blood, which was developed in 1956 by L. C. Clark. The design of the amperometric sensor is shown in Figure 11.38 and is similar to potentiometric membrane electrodes. A gas-permeable membrane is stretched across the end of the sensor and is separated from the working and counter electrodes by a thin solution of KCl. The working electrode is a Pt disk cathode, and an Ag ring anode is the... 

There are three advantages to study molecular recognition on surfaces and interfaces (monolayers, films, membranes or soHds) (175) (/) rigid receptor sites can be designed (2) the synthetic chemistry may be simplified (J) the surface can be attached to transducers which makes analysis easier and may transform the molecular recognition interface to a chemical sensor. And, which is also a typical fact, this kind of molecular recognition involves outside directed interaction sites, ie, exo-receptor function (9) (see Fig. 5b). 

Vassilev VS, Boycheva SV (2005) Chemical sensors with chalcogenide glassy membranes. Talanta 67 20-27... 

The history of ion-selective electrodes (ISEs) [1] starts from the discovery of the pH response of thin film glass membranes by Cremer in 1906, thus making ISEs the oldest class of chemical sensors. They still are superior over other sensor types in a variety... 

R. Eugster, T. Rosatzin, B. Rusterholz, B. Aebersold, U. Pedrazza, D. Ruegg, A. Schmid, U.E. Spichiger, and W. Simon, Plasticizers for liquid polymeric membranes of ion-selective chemical sensors. Anal. Chim. Acta 289, 1-13 (1994). 

S. Ryu, J. Shin, G. Cha, R. Hower, and R. Brown, Polymer membrane matrices for fabricating potentio-metric ion sensors, in Technical Digest 5th Int. Mtg. on Chemical Sensors, vol. 2, pp. 961-964. Rome, Italy, July 11-14 (1994). 

Figure 3 Schematic diagram of a solid-phase N02 sensor. The sensor consists of a small cell supporting the polymer-coated, glass substrate behind a glass window in full view of a PMT. The CL reagent is immobilized on the hydrogel substrate. The gel is sandwiched between the glass window and a Teflon PTFE membrane. The purpose of the Teflon membrane is to permit the diffusion of N02 from the airstream into the gel while preventing the loss of water from the hydrogel. Inlet and outlet tubes (PTFE) allow a vacuum pump to sample air (2 L/min) directly across the surface of the chemical sensor. (Adapted with permission from Ref. 12.)...

A schematic diagram of a bulk acoustic wave (BAW) chemical sensor is composed of a BAW piezoelectric resonator with one or both surfaces covered by a membrane (CIM) (fig. 14). 

Figure 1. Stylised chemical sensor comprising a conducting cable or track to convey the electronic signal to the outside world, a transducer to sense the chemical signal and convert it into an electronic form, and a chemically sensitive film or membrane at which the molecular binding event occurs.

Figure 3. Components of an ion-selective electrode chemical sensor (left) and photographs of electrode body (right) showing electrode barrel with silver-silver chloride electrode, and screw-on electrode tip with end-clip for attaching the PVC membrane containing immobilised molecular receptors that will selectively bind specific target species.

Fluorinated polymers, especially polytetrafluoroethylene (PTFE) and copolymers of tetrafluoroethylene (TFE) with hexafluoropropylene (HFP) and perfluorinated alkyl vinyl ethers (PFAVE) as well as other fluorine-containing polymers are well known as materials with unique inertness. However, fluorinated polymers with functional groups are of much more interest because they combine the merits of pefluorinated materials and functional polymers (the terms functional monomer/ polymer will be used in this chapter to mean monomer/polymer containing functional groups, respectively). Such materials can be used, e.g., as ion exchange membranes for chlorine-alkali and fuel cells, gas separation membranes, solid polymeric superacid catalysts and polymeric reagents for various organic reactions, and chemical sensors. Of course, fully fluorinated materials are exceptionally inert, but at the same time are the most complicated to produce. 

Fig. 6.15. Photo of a packaged sensor chip. The partial epoxy cover enables free analyte access to the chemical sensor area. The metal cap with the gas-permeable membrane provides mechanical and dust protection...

Dr. Hui has worked on various projects, including chemical sensors, solid oxide fuel cells, magnetic materials, gas separation membranes, nanostruc-tured materials, thin film fabrication, and protective coatings for metals. He has more than 80 research publications, one worldwide patent, and one U.S. patent (pending). He is currently leading and involved in several projects for the development of metal-supported solid oxide fuel cells (SOFCs), ceramic nanomaterials as catalyst supports for high-temperature PEM fuel cells, protective ceramic coatings on metallic substrates, ceramic electrode materials for batteries, and ceramic proton conductors. Dr. Hui is also an active member of the Electrochemical Society and the American Ceramic Society. 

Space available in porous glass [487], ultrafine Nafion [488, 489], and metallic membranes [490, 491] has also been utilized for the development of smal particles. Cylindrical micropores in alumina membranes have been used, for example, as templates for the electrodeposition of parallel arrays of gold particles (0.26 pm in diameter, 0.3 pm to 3 pm in length) which were infrared transparent [491] and could be used as chemical sensors [490],... 

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