The present inventive concept relates to a battery-free gas sensor or humidity sensor comprising a metal-organic framework and a method of manufacturing the same. In a photodiode-type battery-free gas sensor or humidity sensor according to the present inventive concept, since photoelectron collection electrodes are formed at certain intervals between P-N junction layers, when gas is adsorbed thereon, the gas can be detected without an extra power source by change of photocurrent. Due to fine pores of the metal-organic framework, gas sensitivity may be increased and stability of catalysts may be improved. When catalysts are not provided, humidity may be detected. Therefore, a system that used the photodiode-type battery-free gas sensor and the photodiode-type battery-free humidity sensor together may be performed humidity correction to accurately measure an amount of a gas.

A first gas sensor having a first sensor element includes a first protective cover that protects the first sensor element, and a second gas sensor having a second sensor element includes a second protective cover that protects the second sensor element. The first protective cover is coated with an oxidation catalyst for one target component from among a plurality of target components, and the second protective cover is coated with an inert catalyst for the one target component.

In examples, there is a method comprising receiving an esophageal gas sample at a nitric oxide sensor, the nitric oxide sensor generating a signal indicative of the amount of nitric oxide in the esophageal gas sample, the nitric oxide sensor outputting the signal, and, based on the signal, determining the amount of nitric oxide in the esophageal gas sample.

A method for determining the level of contamination in cities comprising the steps of providing a server, transmitting information from users which report contamination issues by means of a mobile electronic device to the server, providing a wireless sensor network (WSN) for measuring level of contamination, obtaining measured data tagged with a geo-reference tag and a time stamp, and configured for supporting delay-tolerant communications transmitting data measured from sensors to the server, processing data measured and information from users by using big data and machine learning algorithms, and providing reports on contamination levels; and a system for collecting and processing environmental information comprising at least one mobile electronic device, including at least one environmental sensor, at least one wireless communication interface, a geo-location unit, and a storage unit; at least one communication gateway and at least a server for storing and processing the information obtained.

A method and system for measuring an amount of a gas dissolved in a liquid is described, in which the liquid is transferred to an equilibrator and in which the amount of the various gases is measured in the gas phase of the equilibrator and that a calculation of the amount of gas which is dissolved in the liquid is carried out.

A photonic gas sensor and a method for producing a photonic gas sensor are disclosed. In an embodiment a photonic gas sensor includes a component housing with at least one cavity, a radiation-emitting semiconductor chip arranged in the cavity and configured to transmit electromagnetic radiation in a first wavelength range, a radiation-detecting semiconductor chip arranged in the cavity and configured to detect electromagnetic radiation in a second wavelength range and an active sensor element having a fluorescent dye configured to emit electromagnetic radiation in the second wavelength range upon being excited by electromagnetic radiation in the first wavelength range, wherein an intensity of the emitted electromagnetic radiation in the second wavelength range changes reversibly in presence of a gas to be detected.

A deterioration determination apparatus is usable with an ammonia sensor that includes an ammonia element portion that includes, a solid electrolyte, an ammonia electrode, and a reference electrode. The deterioration determining apparatus compares a first evaluation value and a second evaluation value, and determines whether deterioration has occurred in the ammonia element portion of the ammonia sensor at an evaluation time or subsequent to the evaluation time. The first evaluation value is based on a first sensor current obtained when a DC voltage is applied between the ammonia electrode and the reference electrode of the ammonia element portion at an initial time that is during an initial use period of the ammonia sensor. The second evaluation value is based on a second sensor current obtained when the DC voltage is applied between the ammonia electrode and the reference electrode subsequent to the initial period of use of the ammonia sensor.

The present disclosure provides an ammonia sensor and method of use. The sensor includes: at least one thermal indicator component independently selected from an electronic thermal sensor, an irreversible temperature indicator, and a heat-shrinkable film; an acid-functional porous sorbent in thermal contact with the at least one thermal indicator component; and an acid having a boiling point above 120° C. and a pKa of no greater than 2.5. The acid is impregnated in or covalently attached to the porous sorbent. The method includes: placing an ammonia sensor in contact with a container holding a volume of ammonia; and monitoring the ammonia sensor for a detectable response from the at least one thermal indicator component due to contact of ammonia with the acid that generates thermal energy sufficient to cause the response.

Provided is a urea solution sensor that can accurately measure a concentration of urea. The ammonia concentration sensor (1) includes: a light source (10) that emits measurement light toward a measurement subject, the measurement light including near-infrared light; a light reception unit (20) that receives transmitted light or reflected light from the measurement subject; and an analysis unit (30) that analyzes a concentration of urea contained in the measurement subject based on a spectrum of light which has been received by the light reception unit (20).

Apparatus and method for detecting a dissolved gaseous impurity in an aqueous environment, comprises a tube for isolating liquid surface, or a sampler for obtaining a liquid sample from the aqueous environment, a vacuum pump located to exert a vacuum, leaving the surface to evaporate into the vacuum; and a holding compartment for holding evaporated gas which may then be analyzed using electrochemical or spectroscopic methods. The apparatus is useful for detecting levels of ammonia in fish ponds or indeed any impurity that may be dissolved in the water.