Embedded wire electrodes

Resistor shaped test samples with two embedded wire electrodes, see Figure 10.13, are used to perform these experiments. These test samples were prepared at a mould temperature of 180°C and a compression time of two minutes. Subsequently, the samples were post-cured during four hours at 180°C. 

Helix-electrodes contact peripheral nerves on a small area due to their open structure. They consist of a silicone rubber substrate with one or two embedded platinum wire electrodes (Fig. 1). They were developed at the Huntington Medical Research Institute (HMRI) in a monopolar and a bipolar version [17]. The latest versions have been applied in paralyzed people at the sacral spinal roots for micturition control and incontinence. Their advantage can be seen in the self-sizing properties due to the spiral structures when the nerve is affected by edematous swelling after the implantation trauma. 

A schemahc diagram of the DEMS apparatus is shown in Fig. 5. The electrochemistry compartment corrsists of a circular block of passivated htanirrm (a) that rests above a stainless-steel support (1) cormected to the mass spectrometer. The space between the cell body and the snpport is a Teflon membrane (j) embedded on a steel mesh (k) the membrane is 75 pm thick, has 50% porosity and pore width of 0.02 pm. The single-crystal disk (h) is the working electrode its face is in contact with the electrolyte solution and separated from the cell body by another Teflon membrane (i) that functions as a spacer to form a ca 100-pm thick electrolyte layer (j). Stop-flow or continnons-flow electrolysis can be performed with this arrangement. For the latter, flow rates have to be minimal, ca 1 pL/s, to allow ample time (ca 2 s) for the electrogenerated products to diffuse to the upper Teflon membrane. Two capillaries positioned at opposite sides of the cell body (b, e) serve as electrolyte inlet and outlet as well as connection ports to the reference (f) and two auxiliary Pt-wire electrodes (d, f). 

Figure 4. Experimental chamber for recording from the 6th abdominal ganglion of the cockroach. The ganglion (black) is placed in a wax chamber (shaded) and the nerve cord is embedded in vaseline, thus isolating the cut end of the nerve cord from the ganglion. A stimulus pulse (p) was applied to the cereal nerve via a suction electrode (s). Recordings from the nerve cord were made via silver wire electrodes (e), and chemicals were added to the left side of the saline-filled chamber Copyright 1986 American Cyanamid Co. Reprinted with permission.

The electrode area and distance are approximated by considering only the two opposing surfaces of the embedded wires as electrodes. Substitution of the known values for V, A and d results then in ... 

For actuators designed to act like an artificial muscle, EAPs were synthesized with at least one embedded electrode. If the material is particularly electroactive, the material would move so quickly that the embedded wire would disengage, causing the actuator to lose its electric impulse (Figs. 4.18 and 4.19). 

FfCURE 13.54 Semiconductor gas sensors (o) tubular, (b) thick film, (e) bulk-type one-electrode sensor where a thin Pt wire spiral is embedded Inside a sintered oxide semiconductor button. ... 

The pressed disc (or pellet) type of crystalline membrane electrode is illustrated by silver sulphide, in which substance silver ions can migrate. The pellet is sealed into the base of a plastic container as in the case of the lanthanum fluoride electrode, and contact is made by means of a silver wire with its lower end embedded in the pellet this wire establishes equilibrium with silver ions in the pellet and thus functions as an internal reference electrode. Placed in a solution containing silver ions the electrode acquires a potential which is dictated by the activity of the silver ions in the test solution. Placed in a solution containing sulphide ions, the electrode acquires a potential which is governed by the silver ion activity in the solution, and this is itself dictated by the activity of the sulphide ions in the test solution and the solubility product of silver sulphide — i.e. it is an electrode of the second kind (Section 15.1). 

The Cottrell equation, as written here, relates to an electrode in the form of a cylindrical wire. One end of the wire will be embedded in a non-conductive sleeve (e.g. glass), so that only one end of the wire will ever be in contact with the analyte solution. If the wire has a length h and a diameter r, then the surface area A of the wire is given by ... 

Lipid membranes were fitted on a multichannel electrode. Figure 5 shows a front view and a cross section of the electrode. The electrode was made from Ag wires, which were 1.5 mm in diameter, embedded in a basal acrylic board. The lipid membranes cut into rectangle pieces were put on the Ag wires, and then the electrode was dried in air for 1 hour and dipped in 1 mM KC1 solution. 

The used multichannel electrode was basically the same as that reported before, but was improved in a few respects. The detecting electrode of each channel was made up of Ag wires whose surface was plated with Ag/AgCl, which were embedded in a basal acrylic board of 2 mm thickness. Another acrylic board of 1 cm thickness which had eight cone-shaped holes was affixed to this board. The holes were filled with 100 mM KC1 solution, and the eight membranes were fitted on the board to cover the holes. 

This section described the fabrication of ITO electrodes modified with porphyrin-terminated M(tpy)2 complex wires by the stepwise coordination method, and it is demonstrated that the electronic nature of the molecular wire is critical to the photoelectron transfer from the porphyrin to ITO. These results suggest that the new facile fabrication method of molecular assemblies is effective in the construction of photoelectron transfer systems. The system could be upgraded by extending the wire length, embedding the redox potential step in the wire, increasing the photoreceptors in the wire, and/or incorporating donors and acceptors. 

There are reports on the preparation of lithium electrodes in which Li wires [17,23-25] and Li rods have been embedded in glass or plastic materials, and fresh Li surfaces have been prepared in solutions by shearing off the edges of the metal [17,23,24], An example of such an approach was noted in the discussion on the construction of various cells. It should be mentioned that the plastics that can be used with metals such as lithium are highly pure (low plasticizer content) polyethylene and propylene. 

A glass electrode contains a reference solution of dilute hydrochloric acid in contact with a thin glass membrane, in which a silver wire coated with silver chloride has been embedded. When the electrode is dipped into a solution containing ET ions, the electrode potential is determined by the difference in [H+] between the two solutions. 

Indeed, tlie assembly of the thiol-functionalized molecular wire on an Au-electrode followed by the association of the protein to the inhibiting diethylaniline units, led to an electrically contacted protein where the TPQ moiety embedded in the protein revealed quasi-reversible electrochemical properties. 

Heart Valves and Pacemakers. Pacemakers, which regulate the heart beat by electrical stimulation, have been used on humans since 1952, and implantable models have been used since 1958. The wires and electrodes are usually plastic coated for purposes of insulation, and the entire device is usually embedded in a plastic for protection from the body fluids. Over 60,000 of these pacemakers are placed in people each year. 

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