[electro- + Gr. hodos, a way]
1. An electrical terminal or lead.
2. A conductive medium.
3. In electrotherapy, an instrument with a point or surface from which to discharge current to a patient's body.
4. An electrical terminal or lead that is adapted to sense current or voltage in response to specific analytes, for purposes of quantifying the particular analyte.
An electrode that is smaller than a dispersive electrode and produces stimulation in a concentrated area.
An electrode that develops a standard electric potential and is used to provide a reference voltage in the circuit for sensing electrodes. It is composed of an amalgam of mercury and mercury (I) chloride. It is used as a standard in determining the pH of fluids.
carbon dioxide electrode
A blood gas electrode used to measure the carbon dioxide tension (symbol Pco2) in blood. Its operation is based on the diffusion of carbon dioxide from the blood sample through a semipermeable membrane into a buffer solution with a subsequent change in the pH of the buffer.
SYN: SEE: Severinghaus electrode
SEE: Oxygen electrode.
coated wire electrode
An electrode with greater resistance than the part of the body in the circuit.
A monitoring electrode implanted into tissue, e.g., into the brain or spinal cord.
fetal scalp electrode
ABBR: FSE A device to measure the health of the fetus during complicated or protracted labor and delivery.
An electrode in which a gas-permeable membrane separates the test solution fluid from an aqueous electrode solution in contact with an ion-selective electrode. Gas permeation of the membrane changes the chemical equilibrium within the electrolyte, and the ion-sensitive electrode detects this change.
In chemistry, a chemical sensor that uses a glass membrane as the sensing surface, as opposed to one that uses an organic or solid-state membrane. The glass contains materials in its structure that are sensitive to a material that is to be measured. In the case of a pH glass electrode, lithium ions are commonly used.
An electrode that absorbs and measures hydrogen gas; used as the reference for pH measurement in research laboratories.
immobilized enzyme electrode
A chemical sensor that is highly selective due to a specific enzyme incorporated into its structure.
An electrode larger than an active electrode. It produces electrical stimulation over a large area.
SYN: SEE: dispersive electrode
internal reference electrode
The metal electrode inside all chemical-sensing potentiometric electrodes. The two most common internal reference electrodes are the calomel and the silver/silver chloride.
A chemical transducer that yields a response to variations in the concentration of a given ion in solution.
liquid membrane electrode
An electrode in which the sensing membrane is made up of a hydrophobic ion-exchange neutral carrier (ionophore) dissolved in a viscous, water-insoluble solvent. The liquid membrane is physically supported by an inert porous matrix such as cellulose acetate.
multiple point electrode
Several sets of terminals providing for the use of several electrodes.
A cathode; the pole by which electric current leaves the generating source.
SEE: Oxygen electrode.
An electrode with an insulating handle at one end and a small metallic terminal at the other for use in applying static sparks.
SEE: Oxygen electrode.
polymer membrane electrode
An electrode in which the sensing membrane is an organic polymer containing a hydrophobic ion-exchange neutral carrier (ionophore).
An anode; the pole opposite a cathode.
A chemical electrode whose cell potential remains fixed and against which an indicator electrode is compared. The most common reference electrode is the silver/silver chloride (Ag/AgCl) electrode.
saturated calomel electrode
ABBR: SCE One of two practical reference electrodes, used with a mercurous chloride (calomel) paste in pH and other potentiometric instruments. The other is the silver/silver chloride electrode. The calomel electrode has been the standard secondary reference electrode used in the laboratory since the introduction of the pH electrode.
solid-state membrane electrode
An electrode in which the sensing membrane is made of a single crystal or pressed pellet containing the salt of the ion to be sensed.
standard hydrogen electrode
ABBR: SHE The standard reference electrode against which all others are measured. Its assigned electrode potential is 0.000 V.
An electrode placed beneath the skin.
An electrode placed on the surface of the skin or exposed organ.
An electrode used for introduction of medicines through the skin by ionization.