Abstract: In accordance with an embodiment, a gas-sensitive device includes a substrate structure, and a gas sensitive capacitor. The gas sensitive capacitor a first capacitor electrode in form of a gas-sensitive layer on a first main surface region of an insulation layer, and a second capacitor electrode in form of a buried conductive region below the insulation layer, so that the insulation layer is arranged between the first and second capacitor electrode. The gas-sensitive layer comprises a sheet impedance which changes in response to the adsorption or desorption of gas molecules.

Abstract: In various embodiments, rapid, sensitive detection of molecular hydrogen is achieved by receiving sample gas that includes ambient water vapor and hydrogen, passing the sample gas through a gas dryer, chemically converting hydrogen in the sample gas to water vapor to produce converted sample gas, measuring water vapor in the converted sample gas to produce a water vapor signal, separating the water vapor signal in the time domain into an ambient water vapor signal and a hydrogen-derived water vapor signal, wherein the gas dryer dampens variation in the ambient water vapor signal, and outputting a hydrogen signal that describes molecular hydrogen in the sample gas that is based on the hydrogen-derived water vapor signal.

Abstract: Provided is a reducing gas detection sensor which has sensitivity improved as compared to that of the related art, and in which power consumption is decreased. The reducing gas detection sensor includes: a reducing gas detection material including a palladium compound and a carbon compound, and having reactivity with a reducing gas; and a unit configured to measure a conductivity of the reducing gas detection material.

Abstract: A surveillance device according to the present invention includes: a memory; and at least one processor coupled to the memory. The processor performs operations. The operations includes: calculating, based on a value of a parameter that is contained in a received data frame and represents a state of an apparatus, a change in the state of the apparatus; and determining whether the change is included in an allowable range determined in accordance with the state of the apparatus before the change.

Abstract: A gas monitor apparatus includes a sorbent material that adsorbs a target gas based on a concentration of the target gas in a monitored environment and a reference material that does not respond to the target gas. The gas monitor also includes a first thermistor disposed within the sorbent material and a second thermistor disposed within the reference material, the first thermistor to provide a first indication of a first temperature of the sorbent material and the second thermistor to provide a second indication of a second temperature of the reference material. A processing device determines a concentration of the target gas based at least in part on a differential measurement between the first temperature and the second temperature.

Abstract: A detection device for detecting characteristics of a mixed fluid containing different types of substances with different thermal properties within a prescribed range, includes: one or a plurality of heaters for heating the mixed fluid; a plurality of temperature detectors for detecting the temperature of the mixed fluid heated; a flow rate calculation unit for calculating the flow rate of the mixed fluid using the output from at least a portion of the plurality of temperature detectors; a correspondence relation storage unit that stores the correspondence relation between the output from the temperature detectors for a prescribed flow rate and the mixture ratio of the substances in the mixed fluid; and a mixture ratio calculation unit for calculating the mixture ratio of the substances in the mixed fluid on the basis of the output from the temperature detectors and the correspondence relation.

Abstract: A system and process for the recovery of at least one halogenated hydrocarbon from a gas stream. The recovery includes adsorption by exposing the gas stream to an adsorbent with a lattice structure having pore diameters with an average pore opening of between about 5 and about 50 angstroms. The adsorbent is then regenerated by exposing the adsorbent to a purge gas under conditions which efficiently desorb the at least one adsorbed halogenated hydrocarbon from the adsorbent. The at least one halogenated hydrocarbon (and impurities or reaction products) can be condensed from the purge gas and subjected to fractional distillation to provide a recovered halogenated hydrocarbon.

Abstract: In a gas sensor having a gas-sensitive layer and a heating element to heat the gas-sensitive layer, the heating element comprises a heater track having first and second outer electric terminals and at least one inner electric terminal located between the outer electric terminals. The gas sensor includes a control unit configured to control the electric potentials that are applied to the electric terminals during use, and the control unit is configured to be capable of varying the set of electric potentials applied to the electric terminals. In certain applications the control unit may select the terminals to which power is applied, in order to assure the gas-sensitive layer is heated to a specified temperature. In certain applications the gas sensor has multiple measurement electrodes and the control unit selects the set of electric potentials so that different temperatures are attained at locations where different measurement electrodes are located.

Abstract: A Thermal Conductivity Detector (“TCD”) including: a gas flow switching mechanism that switches between a first state where a measured gas is introduced into a first flow path and a reference gas is introduced into a second flow path, and a second state where the reference gas is introduced into the first flow path and the measured gas is introduced into the second flow path; a first filament unit connected to the first flow path and including a first filament; a second filament unit connected to the second flow path and including a second filament; and a detection circuit unit for detecting an electric signal in accordance with a change in voltage applied to or current through the first filament and the second filament. The first filament unit and the second filament unit have different detection characteristics of thermal conductivity of gas.

Abstract: Provided is a thermal conductivity detector including a detection channel through which a gas to be measured flows as a fluid, a heat conducting part that includes at least a filament provided at a position in the detection channel at which the filament is in direct contact with the fluid flowing through the detection channel, the filament being folded at least once in a direction substantially parallel to a flow direction of the fluid flowing through the detection channel, and that conducts heat via the fluid flowing through the detection channel, and a detection circuit that detects an electric signal in accordance with a change in current or voltage of the filament. The filament is folded by being holed on a folding pin provided substantially perpendicular to the flow direction in the detection channel, and the folding pin has a position shift prevention structure for preventing a fold of the filament hooked on the folding pin from shifting in a longitudinal direction of the folding pin.

Abstract: A measurement device ascertains the thermal conductivity of a fluid. The device has a fluid volume holding the fluid, a controller, and a sensor module disposed in the fluid volume. The sensor module has a supporting body and a plurality of sensor wires that extend freely between in each case two contact positions of the supporting body. One of the sensor wires serves as a heat source and is able to be energized for this purpose by the controller. The controller is set up to capture, via at least two of the sensor wires that serve as temperature sensors and are arranged at different distances from the heat source, temperature measurement values that depend on the temperature at the respective temperature sensor, and to ascertain the thermal conductivity in dependence on the temperature measurement values.

Abstract: A sensor and method for measuring respiratory gas properties are presented. A thermal conductivity sensor is used to measure the thermal conductivity of a gas with unknown composition and/or mass flow rate at different temperatures. The measured thermal conductivities at different temperatures are compared with known thermal conductivities of gases at different temperatures. In an exemplary application the sensor and method are installed in a tube to determine a mass of respiratory air flowing through the tube and a concentration of CO2 therein.

Abstract: A system and method of predicting impending failure of a pressure vessel include a pressure vessel, a fluid source, a line coupled to the pressure vessel and to the fluid source, an apparatus, a sensor and a controller. The apparatus includes a conduit and a containment structure. The containment structure includes a cavity separated from an interior of the conduit by a portion of a conduit wall of the conduit. The sensor is configured to determine a value of a physical property in the cavity. The controller is in signal communication with the sensor and configured to detect a change in the value. The method includes determining a first value of a physical property in the cavity, experiencing a failure of the conduit wall, determining a second value of the physical property in the cavity, and detecting a difference between the first and second values.

Abstract: The purpose of the present invention is to provide a gas sensor device with which highly accurate measurement performance can be achieved even if there are changes in the environmental temperature. The present invention is provided with: a detection heater (3) formed in a thin film part; a temperature compensation heater (4) formed so as to surround the detection heater; a detection heater heating control circuit for controlling the heating temperature of the detection heater (3); and a temperature compensation heater heating control circuit for controlling the heating temperature of the temperature compensation heater to a heating temperature lower than the heating temperature of the detection heater.

Abstract: A method comprises suspending a measuring element within a fluid and applying measuring power to the measuring element. Radiation loss compensation power is applied to a heating element. The radiation loss compensation power is selected to compensate parasitic radiative heat loss from the measuring element. Heat transfer from the measuring element into the fluid is evaluated and a property of the fluid is derived. A sensor which implements the method uses a resistive measuring element which is electrically connected to an evaluation circuit. The heating element is electrically connected to a power source. A processor receives an input from the evaluation circuit and calculates a property of the fluid while the power source provides radiation loss compensation power to the first heating element.

Abstract: The present invention relates to a sensor for sensing hydrogen. The sensor of the present invention comprises: a core which reacts with hydrogen to change a resistance value; at least two electrodes connected to the core; and a variable resistor which is connected to at least one of the two electrodes and of which the resistance value changes in response to a control signal, wherein the core includes palladium having a thin film shape, and graphene which is applied on the palladium and has a thin film shape.

Abstract: A detector arrangement to be scaled or adapted in a simple manner depending on the application includes n·m (n?2, m?2) thermal conductivity detectors that are each arranged in a mounting on a detector block having a high thermal conductivity, wherein each case m detector block is secured radially symmetrically and spaced apart from one another on a carrier having a central opening, forming a detector module, and n detector modules are located on a common axis by the central openings of the carriers.

Abstract: Certain embodiments described herein are directed to devices that can be used to control fluid flow through one or more detectors. In some configurations, the device can be configured as a manifold that can receive a positive pressure to decouple the flow of fluid through a chromatography column from fluid flow through a detector. In certain configurations, sample flow can be accelerated into a detector cell comprising one or more filaments.

Abstract: A CMOS-based process for manufacturing a semiconductor gas sensor includes the steps of: I) providing a semi-product, II) etching a substrate to remove a portion of the substrate and a portion of a first insulation layer so as to form a gas-sensing cavity, thereby to expose at least one sensing electrode; and III) depositing a gas-sensitive layer to cover the at least one sensing electrode.

Abstract: A metal oxide semiconductor-based toxic gas detector is provided. The metal oxide semiconductor-based detector includes a metal oxide semiconductor-based gas sensor that has an electrical characteristic that varies with concentration of a toxic gas. Measurement circuitry is coupled to the metal oxide semiconductor-based gas sensor and is configured to measure the electrical characteristic and provide a digital indication of the measured electrical characteristic. A controller is coupled to the measurement circuitry and is configured to provide a toxic gas output based on the digital indication. The controller is also configured to provide a diagnostic output relative to the metal oxide semiconductor-based sensor based on fluctuations of the measured electrical characteristic over time.

Abstract: A device for measuring thermal conductivity of gas components of a gas mixture in order to determine fractions of the gas components includes a plurality of thermal conductivity sensors, each thermal conductivity sensor being a component of a resistance bridge circuit and being connected to an evaluation unit associated with the device. Each thermal conductivity sensor has a heating element and an integrated temperature measuring element, which elements generate two measuring voltages (UM3, UM2) when the temperature of the thermal conductivity sensor changes as a result of heat dissipation by the gas mixture. Voltages are compared in the evaluation unit in order to detect measuring errors.

Abstract: A thermal conductivity detector includes at least four detector components that are arranged in receptacles of a thermal conduction block in a circle around a center axis of the thermal conduction block. The thermal conduction block comprises a central portion along the axis, the cross-axial dimensions of the central portion being less than the diameter of the circle. There are at least four equal peripheral portions that are connected solely to the central portion and are separated from each other, each of the peripheral portions carrying one of the detector components.

Abstract: An apparatus and a method for identifying a CO2 content of a fluid. The apparatus includes: an absorber device having a porous material, the absorber device being capable of being brought into contact with the fluid; pores of the porous material having at least one hydrophilic first chemically functional group; the first chemically functional group being joined to the porous material; the first chemically functional group having the property of reacting in alkaline fashion with water; an electrode device that is disposed on the absorber device for electrical contacting of the absorber device; and an evaluation device that is electrically connected to the electrode device and by which an electrical property of the absorber device is measurable to identify the CO2 content of the fluid.

Abstract: A multi-channel contaminant sensor includes a first contamination test platform including an exposed first base metal portion that react in a first manner when exposed to one or more airborne contaminates. A second contamination test platform includes an exposed second base metal portion that reacts in a second manner when exposed to the one or more airborne contaminants.

Abstract: A method is provided for calibrating a thermal conductivity sensor in a first medium A from measurements in a second medium B. The method includes maintaining the sensor at a substantially fixed temperature T1, and measuring a heat flux IB(T1) from the thermal element in the second medium B. A corresponding heat flux IA(T1) in the first medium A is calculated using known thermal conductivities of the first medium A and the second medium B.

Abstract: A light emitting diode (LED) lighting system having a gas detection function may be used not only for lighting but also for detection of volatile organic compounds (VOCs) causing the sick house syndrome at home and other odorless and colorless non-combustible gas harmful to a human body. The LED lighting system may be used as an optical sensor showing with the fast response time and high sensitivity with respect to an environment harmful to a human body. In addition, since the presence of gas can be easily detected through a change of color in comparison to sound alarms for fire and gas contamination, emergency situations can be effectively handled.

Abstract: The present invention relates to a thermal conductivity detector, comprising a sensor block having two cavities for the purpose of accommodating gases, wherein one of the cavities is open and the other cavity is sealed and in each of the cavities there is disposed a thermistor and also sealing elements for the purpose of sealing the cavities, which sealing elements comprise electric current feed through elements, which are electrically connected to the respective thermistor disposed in the respective cavity. At least the sealing element in the sealed cavity is a glass to metal feed through element, which is welded to the sensor block to form a gas-tight joint. The present invention further relates to a method for the production of the thermal conductivity detector.

Abstract: The present invention provides a thermal conductivity detector capable of realizing high detection performance even with the use of a miniaturized heating element, and expanding an effective applicable temperature range of a heating element, and to provide a gas chromatograph using the same. The thermal conductivity detector comprises a flow-path through which a measurement gas is caused to flow, a heating element disposed inside the flow-path, the heating element being formed on the substrate, for detecting thermal conductivity of the measurement gas according to magnitude of an amount of heat taken away from the heating element by the measurement gas, wherein said heating element is provided with a beam including a part where the beam is folded at a predetermined angle, the part being formed at the central part of the beam.

Abstract: A method for determining physical properties of combustion including: flowing a gas a critical nozzle and past a microthermal sensor wherein the mass flow of the gas through the critical nozzle is the same as the mass flow through the microthermal sensor; measuring the pressure drop in a reservoir of gas flowing to the nozzle; determining a first gas property factor based on the measured pressure drop; determining a second gas property factor based on a flow signal generated by the microthermal sensor; determining a thermal conductivity of the gas using the microthermal sensor; and determining a physical property of the combustion based on a correlation of the first and/or second gas property factors and the thermal conductivity.

Abstract: A gas detector for use in, for example, measuring the concentration of flammable gas or detecting leakage of flammable gas. The gas detector has a gas detection element in which at least a heat-generating resistor and an insulation layer are laminated on a semiconductor substrate made of silicon while the insulation layer encloses the heat-generating resistor. The gas detector detects flammable gas on the basis of temperature and resistance of the heat-generating resistor which vary according to flammable gas. In the gas detection element, a protection layer in the form of a gas impermeable oxide film is provided on its outermost surface which comes into contact with an environmental atmosphere that contains flammable gas. Thus, alkali resistance is ensured. Since the protection layer is impermeable to gas, entry of impurities (organic silicon) contained in the environmental atmosphere into the protection layer is restrained, whereby output is stabilized and becomes accurate.

Abstract: A particle sensor including a diaphragm, a diaphragm heater, and at least two measuring electrodes situated on the diaphragm, for electrical conductivity measurement, the diaphragm having a thickness of less than or equal to 50 ?m, in order to allow a calorimetric particle quantity determination.

Abstract: A simple gas sensor for detecting a concentration of a detected gas with high accuracy, in which a thermal interference can hardly occur between a normal detection element pair and a reference detection element pair, is provided.

Abstract: An integrated circuit and a method of making the same. The integrated circuit includes a semiconductor substrate. The integrated circuit also includes a relative humidity sensor on the substrate. The relative humidity sensor includes a first sensor electrode, a second sensor electrode, and a humidity sensitive layer covering the first and second electrodes. The integrated circuit further includes a thermal conductivity based gas sensor on the substrate. The thermal conductivity based gas sensor has an electrically resistive sensor element located above the humidity sensitive layer.

Abstract: The gas sensor includes: a cylindrical member which includes a gas detection chamber therein and extends along an axial thereof; a base member which closes an opening of a first axial end of the cylindrical member; a status sensor which is disposed at a substantially central portion of the base member, and detects at least the temperature or the humidity in the gas detection chamber; a gas detection element disposed around the status sensor on the base member; a lid member which closes an opening of a second axial end of the cylindrical member; and a gas inlet port which penetrates the lid member at a location not coinciding with the status sensor and the gas detection element when seen from the axial direction, and enables the introduction of an inspection target gas from an outside into the gas detection chamber.

Abstract: The present invention provides a high-responsiveness and high-accuracy thermal gas sensor configured to enable gas to be analyzed based on a variation in heat conductivity. The thermal gas sensor includes a substrate 2 with a cavity portion 5, a thin-film support 6 stacked in the cavity portion and comprising a plurality of insulating layers 8a and 8b, and a first heating member 3 and a second heating member 4 both sandwiched between the insulating layers in the thin-film support. The second heating member is located around a periphery of the first heating member. The first heating member is controlled to a temperature higher than a temperature to which the second heating member is controlled. The concentration of ambient gas is measured based on power applied to the first heating member.

Abstract: A measurement head is provided for a device for measuring the concentration of at least one gas, in particular oxygen. A gas sample a measurement element (1) is arranged in the region of an opening on a circuit board (11). To convey gas a duct (16, 17) is formed in each of two metal bodies, which surround the measurement element (1) and serve as magnetic poles. During operation of the measurement head the gas sample flows substantially perpendicularly, first through one of the metal bodies (12, 13), and then through the opening (18) on a side of the measurement element (1) facing the opening and emerges again through the other metal body (14, 15).

Abstract: An improved Pirani sensor uses a measuring element disposed within a fluid between a base plate and a cover. The measuring element is held by suspension members that are connected to the base plate. A heating element is thermally conductively connected to the suspension members. Using the sensor the characteristic of the fluid is determined by evaluating the heat transfer from the thermal element through the fluid into the cover when heating power is applied to measuring element. Parasitic conductive heat loss from the measuring element into the suspension members is compensated by applying power to the heating element.

Abstract: The invention relates to a leak detector comprising a first sensor for detecting a gas component (helium) in a gas taken in. Because the sensor is susceptible to saturation or contamination, a second sensor is provided. The sensor is a thermal conductivity sensor. The thermal conductivity sensor has a lower detection sensitivity, yet, at a high concentration of the gas component, it does not risk being contaminated. The two sensors together allow for a large detection range, from extremely sensitive measurements to instances with high concentrations of the gas components as those which can occur with gross leaks.

Abstract: A gas sensor includes a substrate having a low thermal conductivity. Localized heating can be produced using a serpentined heater carried by the substrate. The low thermal conductivity of the substrate substantially confines the generated heat to a region local to the heater thereby reducing required power to operate the sensor. Multiple sensing elements can be deposited onto the substrate adjacent to respective heaters and relatively close together because of the thermal isolation provided by the substrate. In one embodiment, the sensor can include the ceramic substrate, the heater, catalytic material overlying the heater with a gas impermeable layer overlying, at least in part the catalytic material.

Abstract: The invention relates to a method for the real-time determination of the filling level of a cryogenic tank intended to house a two-phase liquid/gas mixture, in which at least one of the the level, volume or mass contained in the tank is calculated for the liquid or the gas at each time step. The method includes the use of a thermal model at each time step to calculate the average temperatures of the liquid and the gas in the tank on the basis of the measured pressure differential and at least one of the pressures of said differential; calculation of the change over time in at least the density of the liquid on the basis of the average temperature of the liquid and the pressures in the tank.

Abstract: An apparatus for measuring a flow velocity and a flow rate of groundwater leaking from the earth surface includes: a storage tank that is fixed to close a side surface and a top surface of an earth surface region from which the groundwater leaks and that stores the groundwater leaking from the earth surface; a liquid column tube that causes the groundwater stored in the storage tank to introduce thereto and causes a water column to rise; and a pressure-type measuring unit that is formed in a top opening of the liquid column tube and that senses a differential pressure. Accordingly, it is possible to easily and rapidly measure a flow velocity and a flow rate of groundwater leaking from the earth surface by the use of a user's terminal in real time, or by time zones, or on the user's request.

Abstract: A system and related method are provided for measuring conductivity/resistivity of water having high purity, including a temperature sensor and a conductivity/resistivity sensor exposed to a water source. The system further includes a computing assembly configured to receive measurement signals from the sensors and to determine change in resistivity over a change in temperature (a collected R/T slope) from the collected temperature measurements and the collected resistivity measurements. The system compares the collected R/T slope to a standardized R/T slope at a temperature value corresponding to a midpoint temperature of the temperature measurements over the prescribed time interval. Based on the comparing, the system provides providing a compensated measurement for resistivity or conductivity of the water source. As a result, the system can calibrate the sensor continually during use, in real time, resulting in highly improved accuracy.

Abstract: A device for sensing a gas comprises a plastics housing (106, 107) moulded in situ around at least one portion of a conducting lead frame (100), the housing defining an enclosure (113) and being provided with means for enabling gas flow into the enclosure. A gas sensitive element (114) within the enclosure (113) is mounted to the conducting lead frame (100). The conducting lead frame (100) comprises connection leads which are accessible through, and at least partially encapsulated by, the wall of the housing.

Abstract: The measurement sensitivity is improved by suppressing the surrounding temperature influence as much as possible, while realizing scale reduction, and by enlarging the detection signal, while reducing the production errors in enclosing a reference gas. Provided is a thermal conductivity sensor that detects thermal conductivity of a sample gas by using a Wheatstone Bridge circuit constructed in such a manner that measurement resistors that are brought into contact with the sample gas are disposed on a first side, and reference resistors that are brought into contact with a reference gas are disposed on a second side, and comparing the potential difference between connection points of the reference resistors and the measurement resistors. The measurement resistors disposed on the first side are assembled in one measurement space, and the reference resistors disposed on the second side are assembled in one reference space.

Abstract: A system and process for the recovery of at least one halogenated hydrocarbon from a gas stream. The recovery includes adsorption by exposing the gas stream to an adsorbent with a lattice structure having pore diameters with an average pore opening of between about 5 and about 50 angstroms. The adsorbent is then regenerated by exposing the adsorbent to a purge gas under conditions which efficiently desorb the at least one adsorbed halogenated hydrocarbon from the adsorbent. The at least one halogenated hydrocarbon (and impurities or reaction products) can be condensed from the purge gas and subjected to fractional distillation to provide a recovered halogenated hydrocarbon.

Abstract: A gas detector for use in, for example, measuring the concentration of flammable gas or detecting leakage of flammable gas. The gas detector has a gas detection element in which at least a heat-generating resistor and an insulation layer are laminated on a semiconductor substrate made of silicon while the insulation layer encloses the heat-generating resistor. The gas detector detects flammable gas on the basis of temperature and resistance of the heat-generating resistor which vary according to flammable gas. In the gas detection element, a protection layer in the form of a gas impermeable oxide film is provided on its outermost surface which comes into contact with an environmental atmosphere that contains flammable gas. Thus, alkali resistance is ensured. Since the protection layer is impermeable to gas, entry of impurities (organic silicon) contained in the environmental atmosphere into the protection layer is restrained, whereby output is stabilized and becomes accurate.

Abstract: A physical gas sensor of thermal type capable of determining the concentrations of a gas mixture even in the presence of humidity by measuring the thermal diffusivity and conductivity includes a cell with thermal conductivity whose frequency response to the gases is known, in particular in respect of humidity, delivering a signal Vm representative of the concentration of the gas. This cell is excited by a pulsed signal so that a processing can be carried out at different analysis frequencies: at low frequency and at higher frequency. The output signals from the two processing chains are combined in the circuit (60) so as to provide the levels of concentration of the gas and the concentration of the water vapour. The signals obtained may also be re-combined together with components of the signal Vm of various passbands.

Abstract: A metal compound (50) able to trap a sulfur component in exhaust gas is arranged in a flow path of the exhaust gas, a property of the metal compound (50) changing along with an increase of the amount of sulfur component trapped at the metal compound (50) is measured, and the cumulative value of the amount of SOX actually contained in the exhaust gas is calculated from the measured property. On the other hand, the assumed cumulative value of the amount of SOX, assumed to be contained in the exhaust gas when assuming that fuel or oil of a sulfur concentration assumed in advance is used, is calculated. It is judged if fuel or oil with a high sulfur concentration is being used from the actual cumulative value of the amount of SOX and the assumed cumulative value of the amount of SOX.

Abstract: A method for the determination of gas concentrations xi in a gas mixture using a thermal conductivity detector with a Wheatstone bridge. It comprises the following method steps: measuring the bridge voltage Xa; correcting the measured values for the bridge voltage Xa, in particular with respect to drift; determination of the thermal conductivity of the gas mixture; and determination of at least one gas concentration xi. Preferably, an automatic zero-point correction and an automatic measuring range end value correction occur within the framework of the correction.

Abstract: The present invention provides a thermal conductivity detector capable of realizing high detection performance even with the use of a miniaturized heating element, and expanding an effective applicable temperature range of a heating element, and to provide a gas chromatograph using the same. The thermal conductivity detector comprises a flow-path through which a measurement gas is caused to flow, a heating element disposed inside the flow-path, the heating element being formed on the substrate, for detecting thermal conductivity of the measurement gas according to magnitude of an amount of heat taken away from the heating element by the measurement gas, wherein said heating element is provided with a beam including a part where the beam is folded at a predetermined angle, the part being formed at the central part of the beam.