In an embodiment, a hydrogen monitoring system comprises a plurality of sensing elements that individually comprise a working electrode, a counter electrode, an insulating layer located in between the working electrode and the counter electrode, a catalyst located on an end of both the working electrode and the counter electrode, an electrolyte located on the end of the sensing elements on both the working electrode and the counter electrode, between the working electrode and the counter electrode, and in contact with the catalyst, and an electrical circuit located on an opposite end of the sensing element that connects the working electrode and the counter electrode.

An electrochemical hydrogen cyanide sensor (1) comprises a housing (10) comprising an opening (2) allowing gas to enter the sensor (1); an electrolyte disposed within the housing (10); a plurality of electrodes in contact with the electrolyte within the housing (10), wherein the plurality of electrodes comprise a working electrode (5) and a counter electrode (7), and wherein the electrodes comprise a metal catalytic material; and a filter (3) operable to cover the opening (2) of the housing (10), and prevent hydrogen sulfide from reaching the electrodes, wherein the filter (3) comprises silver sulfate layered onto a polytetrafluoroethylene support material.

A gas detector includes a measurement control section that controls a voltage application section, obtains an output current flowing between a first electrode and a second electrode of an electrochemical cell, and detects a concentration of sulfur oxides in exhaust gas based on the output current. The measurement control section uses a minimum value of the output current obtained by using a current detection section in a period in which lowering sweep is executed and in which an applied voltage is a voltage within a detection voltage range that is equal to or lower than a decomposition initiation voltage of sulfur oxides as a parameter used for detection of the concentration of sulfur oxides.

A method of exposing a sample to an electrical effect for electrochemical analysis of the sample in an electrolyte solution is disclosed. The method comprises causing an external electrical conductor of an electrode head to apply the electrical effect, the external electrical conductor of the electrode head being external to the electrode head and on an external side of the sample exposed to the electrolyte solution. Apparatuses are also disclosed.

A gas sensor includes a sensor element having electrode pads, metal terminal members connected to the respective electrode pads, separators, and lead wires connected to the rear ends of the metal terminal members. Each metal terminal member has a forward locking portion and a rear locking portion provided at the forward and rear ends, respectively. The separator is composed of a forward separator and a rear separator connected to each other. The forward separator includes a first locking portion having a rearward-facing surface, and the rear separator includes a second locking portion having a forward-facing surface. The metal terminal member is held between the forward separator and the rear separator in a state in which the forward locking portion is in locking engagement with the rearward-facing surface and the rear locking portion is in locking engagement with the forward-facing surface.

Provided is a gas sensor element or the like in which the diffusion mode of NO.sub.x that reaches a measurement electrode is changed from molecular diffusion to a mode of diffusing while repeatedly colliding with a wall face of a sufficiently narrow flow path. In a gas sensor element according to one aspect of the invention, a porous diffusion layer, which accounts for 70% or more of a cross-section of a flow path of a measurement target gas that is orthogonal to a flow direction of the measurement target gas, has a porosity of 5% or more and 25% or less, and is located at a position that is upstream of the measurement electrode and where the distance to the measurement electrode is 0.15 mm or less.

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 HVAC system is provided having an air supply system, a refrigerant circuit configured to condition air in the air supply system, and an electrochemical sensor configured to detect a refrigerant leak from the refrigerant circuit.

A sensing electrode, and an electrochemical system and method utilizing same for detecting peroxide-containing compounds in a sample, are provided. The sensing electrode is a carbon electrode having ions of a metal that promotes decomposition of a peroxide absorbed to its surface, optionally along with a solid electrolyte membrane.

An insulating separator of a gas sensor is formed to be dividable into a forward separator having a terminal disposition hole, and a rear separator having four terminal disposition holes. The insulating separator has a ventilation path formed between the forward separator and the rear separator. As a result, moisture and the like which enter the insulating separator from a forward side of the forward separator through the terminal disposition hole can be discharged outward of the insulating separator through the ventilation path. As a result, corrosion of metal terminals caused by entry of moisture can be reduced, whereby transmission of a sensor signal and application of current or voltage through the metal terminals can be appropriately implemented.