A gas sensor that detects a specific gas concentration in a measurement-object gas, the gas sensor includes: a sensor element having an element body provided with a measurement-object gas flow section therein, the measurement-object gas flow section introducing the measurement-object gas, a measurement electrode disposed in the measurement-object gas flow section, a measurement-object-gas side electrode provided on the element body, a reference electrode, a reference-gas introduction section that causes a reference gas to flow to the reference electrode, and a reference-gas adjustment pump cell constituted by including the measurement-object-gas side electrode and the reference electrode; and a controller that performs a moisture-concentration decrease process of controlling the reference-gas adjustment pump cell so that oxygen is pumped out from a periphery of the reference electrode to a periphery of the measurement-object-gas side electrode to decrease a moisture concentration around the reference electrode.

A filter contamination measuring device includes: a working electrode adjacent to a first surface of a filter, the filter configured to adsorb an ionic material of a first polarity, a counter electrode disposed on the other surface of the filter, a potentiostat configured to apply a voltage of a second polarity to the working electrode for a predetermined period of time, and to measure current output from the working electrode. The potentiostat is configured to increase the voltage over the predetermined amount of time. The filter contamination measuring device further includes a controller configured to calculate a maximum current attained during the predetermined amount of time and a corresponding voltage value, and to determine the type and concentration of the ionic material based on the maximum current and the voltage value.

Methods, electrodes, and electrochemical devices using surface-modified pseudo-graphite are disclosed. In one illustrative embodiment, a method may include depositing a pseudo-graphite material onto a surface of an electrode substrate to produce a pseudo-graphite material surface. The method may also include modifying the pseudo-graphite material surface to alter electrochemical characteristics of the electrode.

Embodiments of the invention are directed to a system for detecting neurotransmitters. A non-limiting example of the system includes a porous electrode. A system can also include a pH sensor attached to the porous electrode, wherein the pH sensor includes a sensing electrode and a reference electrode. The system can also include electronic circuitry in communication with the pH sensor.

An online calibration system for an electrochemical sensor. The calibration system comprises a calibration electrode coupled with a redox species, where the redox species is configured to control a pH of a reference solution local to the calibration electrode, such that when a voltammetric signal is applied to the calibration electrode the output generated from the calibration system is determined by the local environment pH. The output signal from the calibration system is used to calibrate a reference potential generated by a reference system of the electrochemical sensor to correct for drift in the reference potential when the electrochemical sensor is being used. The calibration electrode may be disposed in a reference cell of the electrochemical sensor.

A method of using an electrochemical device includes at least first and second electrodes; a chamber for receiving a fluid sample and defining a volume partially bounded by a first portion of the first electrode and a second portion of the second electrode, the first portion having a first characteristic for influencing an electrochemical reaction at the first portion, the second portion having a second characteristic for influencing an electrochemical reaction at the second portion, the first and second characteristics having a predetermined relationship. The method also includes receiving a fluid sample in the chamber; measuring first and second electrical outputs at least one of the first and second electrodes; and determining whether the first and second electrical outputs are related according to the predetermined relationship.

Composites comprising metal-oxide-functionalized carbon nanotubes with metal nanoparticles deposited thereon are provided. These composites can be used as a working electrode in an electrochemical sensor to detect arsenite in aqueous solutions. The composite can electrochemically reduce As.sup.3+ to As.sup.0 due to increasing adsorption capability. In one embodiment, Au nanoparticles are deposited on the TiOx/CNT electrode to facilitate the adsorption of As.sup.3+ on the electrode surface for further electrochemical reduction process. Square wave voltammetry (SWV) is performed to detect the electrochemical reduction of arsenite in water.

Disclosed herein is a sensor for measuring perfluoroalkyl acids and/or polyfluoroalkyl acids. The sensor includes a working electrode, a counter electrode and optionally a reference electrode. The working electrode includes a film disposed on the surface of the working electrode and the film includes a perfluorinated anion exchange ionomer. A method of using the sensor to detect perfluoroalkyl acids and/or polyfluoroalkyl acids is also described.

The present invention discloses a portable system comprised of an electrochemical cell for batch injection analysis (BIA) coupled to a copper oxide electrode for the selective determination and quantification of monoethylene glycol (MEG) from different petrochemical samples with application in the environment laboratory and in field analyses, aiming at the quality control of these samples by portable methodology and in a short analysis time.

Provided herein is technology relating to electrochemical detection of analytes and particularly, but not exclusively, to a double junction reference electrode, methods of using a double junction reference electrode, handheld or robotically manipulable apparatuses comprising a double junction reference electrode, and systems comprising a double junction reference electrode.