Coated wire type

The multiple coated wire type catheters developed at General Electric have also been evaluated in vivo. For example, the pH-sensing device was implanted in the femoral artery of beagle dogs for up to 6 hours (L3). Over that time span, the pH of the blood as measured by the in vivo coated wire electrode was nearly identical to that measured in vitro with conventional glass electrode instrumentation. In addition, the same catheter also has been used percutaneously to measure the muscle pH of dogs in shock (K14). The... 

L.A. A1 Shatti, H.M. Marafie, A.E Shoukry, Plastic membrane electrodes of coated wire type for micro determination of quininium cation in pharmaceutical tablets, American Journal of Applied Sciences, 8 (2), 116-123,2011. 

The proposed electrodes resemble the coated-wire type of electrodes. 

Vytras K (1984) Determination of some pharmaceuticals using simple potentiometric sensors of coated-wire type. Mikrochim Acta 3 139-148... 

What type of extrusion die is used to coat wire with polyvinyl chloride ... 

There are all sorts of commercial supports available. Quick and easy to use are the galvanized metal or plastic circles with a grid, or L-shaped plastic-coated wires that hook into each other. Suitable candidates for this type of staking are clump-forming perennials such as heleniums, phloxes, and chrysanthemums. 

Ion-selective membranes can be used in two basic configurations. If the solution is placed on either side of the membrane, the arrangement (e.g., Fig. 6.16a) is symmetrical. It is found in conventional ion-selective electrodes in which the internal contact is realized by the solution in which the internal reference electrode is immersed. In the nonsymmetrical arrangement (Fig. 6.16b), one side of the membrane is contacted by the sample (usually aqueous), and the other side is interfaced with some solid material. Examples of this type are coated wire electrodes and Ion-Sensitive Field-Effect Transistors (ISFETs). 

In our laboratory, these disadvantages have been overcome with the development of the coated wire electrode (CWE). This sensor, having response characteristics equal to and occasionally better than conventional types, is only 1-2 mm in diameter (further size reduction can be easily achieved), can be used at any angle, and costs only a few pennies to make. Indeed, they can be considered "disposable", though with proper handling lifetimes of over six... 

Establish electrical contact for the disposable electrodes via an Ag/AgCl coated wire that was previously soldered to a Lemo connector. The galvanic cell experimental setup is shown in Fig. 2.1. Connect electrodes via a high-impedance interface (World Precision Instruments) to a 16-channel BNC block (National Instruments) coupled to a 16-bit PCI-type data acquisition board (National Instruments). Take potentials at 1-s intervals and average them (N = 250). 

Dancer Roll These can be used as a tension-sensing device in film, sheet, and coating (wire, film, etc.) lines. They provide an even controlled rate of material movement. Type roll can have an influence on the roll s performance. As an example, chrome plated steel casting drums would seem to be very durable dancers. If used in the absence of a nip roll, should last many years. However, these rolls are in fact very soft due to the annealing which good rolls receive for stress relieving the steel. 

Coated-wire electrode (CWE)-type devices for in vivo monitoring have also been described. For example, workers at General Electric Inc. (N3), have patented a catheter for in vivo pH measurements which was based on the approach used by the Miles workers to prepare the previously mentioned K CWE. The ISE portion of the pH catheter consisted of a Ag/AgCl wire coated first with a hydrophilic polymer containing bufifer components and chloride ions and then with a polymer membrane containing a H" carrier molecule. A second tube with appropriate Ag/AgCl wire and electrolyte served as the external reference element. Once again, stable potentials can only be obtained if the osmolarity of the hydrophilic polymer layer matches that of whole blood. 

Figure 19.3 Measurement set-up of ion-specific electrodes. Schematic of a measuring cell with a ISE targeted for the fluoride ion using a double junction reference electrode. From the two sides of the membrane two equilibria are produced, LaF, - LaF -F F . To avoid osmosis of KCI into the solution, the reference electrode is surrounded by a separate chamber which contains an auxiliary non-interfering electrolyte. KNO, IM difficult to oxidize or to reduce, is often used for F , CP, P, CN , or Ag+. The measurement requires a high impedance mihivoltmeter (type pH-meter). Right, two examples of simple to construct coated wire electrodes . A wire forms an ohmic contact with the membrane (ISE for fluorine with a LaF, crystal and ISE for chloride with frit).

Many researchers have used fine wire thermocouples (T/Cs), with and without coatings. Costa et al. [77] used a bare 300 pm diameter wire uncoated Pt/Ptl3%Rh thermocouple to measure gas temperatures inside an industrial glass-melting furnace. Mital et al. [78] used three different diameter (76,125, and 200 pm) fine wire Type R thermocouples to measure the gas temperature inside porous ceramic radiant burners by extrapolating the measurements to zero diameter. 

Brominated flame retardants (BFRs) are a structurally diverse group of compounds including aromatics, cyclic aliphatics, phenolic derivatives, ahphatics, and phthahc anhydride derivatives (Figure 31.3). The most common BFRs are tetrabromobisphenol A (TBBPA), polybrominated diphenyl ethers (PBDE), hexabromocyclododecane (HBCD), and polybrominated biphenyls (PBB). The primary use of TBBPA is as reactive additive in epoxy resin circuit boards, while decabromodiphenyloxide (DBDO) is primarily used in high impact polystyrene for electronic enclosures. PBDEs are typically used as the additive type of flame retardant in high impact polystyrene, acrylonitrile butadiene styrene, flexible polyurethane foam, textile coatings, wire and cable insulation and electrical connectors. 

Building onto the concept of molecularly wired sensors for signal amplification, Swager reported in 1998 the synthesis of a series of porous PPE derivatives in which pentiptycene modules are incorporated into the PPE main chain. The incorporation of the pentypticene moieties makes 29 and 30a (Chart 5) efficient solid-state emitters unaffected by aggregation i.e., their emission spectra in solution and in the solid state are almost identical. The authors found that thin films of these highly fluorescent PPEs are excellent sensors for the detection of trinitrotoluene and dinitrotoluene. Both aromatics suppress the fluorescence of 29 or 30a effectively but reversibly. The headspace, i.e., the atmospheric volume above land mines, contains measurable quantities of dinitrotoluene. As a consequence, polymers 29 and 30 coated on top of a fiber optic sensor will allow their simple detection by these very sensitive molecular wire-type materials. This elegant concept should be extendable and applicable to any other analyte, (a) which has the ability to quench fluorescence and (b) for which a receptor can be attached to PPEs. 

Figure 2. Schematic diagrams of resistive SThM probes a) Wollaston wire type [34,35], b) micro-machined coated Si cantilever [37] and c) data storage doped Si probe [55].

Figure 2 Basic types of ISE (A) glass electrode (B) electrode with a solid homogeneous or heterogeneous membrane (C) classical liquid membrane electrode (D) electrode without internal solution (all-solid-state electrode) (E) coated-wire electrode. 1, Internal standard solution 2, internal reference electrode (Ag/AgCI) 3, membrane 4, glass or plastic body of the electrode 5, reservoir of the electroactive substance solution 6, solid-state contact and 7, metal wire.

The general trend to miniaturize chemical sensors and to make them cheap and easier for handling has led to the development of potentiometric sensors with solid internal contact. This class of sensors includes different types of solid-state electrodes, solid-state contact, and coated wire electrodes as well as ion-selective field-effect transistors (FETs). 

As a membrane matrix, PVC is most frequently used [16]. This type of selective membrane is also suitable for preparing a coated-wire i.s.e. and ion-selective MISFET (ISFET) sensors (see next subparts of this chapter). 

Coated wire electrodes, CWE Coated-wire ion-selective electrodes, CWISE (CWE), have been developed to overcome some of the disadvantages of i.s.e.s, namely their large size, the need for an upright position in some types, and their high cost. 

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