Abstract: A flow sensor is provided having a substrate with a sensing element and flow channel over the sensing element. The sensing element senses at least one property of a fluid. The flow channel is configured such that tilting the flow sensor does not have a significant effect on the measured signal. A device for measuring tilt in a system having a fluid flow path is also provided.

Abstract: A thermal type flow sensor includes a base portion provided along the direction of a fluid flowing through a main passage, and a sensor element mounted on the base portion and having an exothermic resistor formed on a substrate for detecting the fluid flow rate. The base portion has a rectangular recessed portion in which the sensor element fixed so that the surface of the detecting portion of the sensor element is positioned lower than an upper edge of the recessed portion. A wall portion of the measuring passage facing the sensor element is constricted. The exothermic resistor is disposed along the fluid passage and spaced away from the upstream side upper edge of the recessed portion and cannot be substantially affected by a fluid flow disturbance due to a step portion formed between the upper edge of the recessed portion and the detecting portion surface.

Abstract: The coupling capacitance of the wiring portions of a thermal type flow rate measuring apparatus is reduced so as to prevent a drop in the response characteristics. A detection element of the thermal type flow rate measuring apparatus includes a planar substrate made of silicon, ceramic, or the like, in which a diaphragm is formed. On the surface of the diaphragm, there are disposed a heat-generating resistor as a heat-generating element that is heated to a predetermined temperature difference from the temperature of air flow to be measured, a heat-generating element temperature-detecting resistor for detecting the temperature of the heat-generating resistor, and temperature-detecting resistors disposed on both sides of the heat-generating resistor. The detection element also includes wiring portions which have connecting terminals electrically connected to the heat-generating resistor and a wiring pattern electrically connected with the surface of the planar substrate.

Abstract: A flow sensor transducer can measure fluid flow rates as a fluid flows though a channel and under an air bridge. Resistive thermal devices (RTDs) and a heater are on top of the air bridge with two RTDs upstream of the heater and two downstream. The RTDs can be connected in a Wheatstone bridge configuration. A magnetoresistive material that changes its electrical resistance based on its temperature can be used to form the RTDs. The temperature response of magnetoresistive materials, however, can change due to magnetic fields and to the material's magnetic history. Forming the RTDs into a dual spiral structure minimizes the effect of magnetic fields. As such, a magnetoresistive material such as permalloy can be used instead of an expensive material such a platinum. The resulting flow sensor transducer can be formed using standard semiconductor processing techniques and is less expensive than sensors containing platinum.

Abstract: Detection accuracy of flow rates is higher even when the temperature of fluid is varied or when there is any difference between temperature of fluid and that around a thermosensible flow sensor. A thermosensible detector element comprises an insulating support film formed on the surface of a plate-like substrate, a heat resistor and a fluid temperature-measuring resistor made of thermosensible resistive films formed on this support film, an insulating protective film formed on this thermosensible resistive film, and cavities and formed under respective thermosensible resistive films by removing partially the plate-like substrate, and in which flow velocity of fluid is measured on heat transfer phenomenon from the portion heated by the heat resistor to fluid, and top surface of the cavity located under the fluid temperature-measuring resistor is formed within the part where the fluid temperature-measuring resistor is located.

Abstract: Sensor equipment includes: a sensor device having a sensing portion; and an electric connection portion coated with an electric insulation member. The electric connection portion electrically connects an external circuit and the sensor device. The electric insulation member is a thin film disposed on the electric connection portion. In the sensor equipment, the insulation member is made of the deposition film, which is not deteriorated with time. Therefore, the insulation member does not flow out from the connection portion. Accordingly, detection sensitivity of the sensor equipment is prevented from reducing.

Abstract: The present invention relates to a method for energy conversion by gas flow over solid materials and also to a method for measurement of velocity of a gas flow over solid material such as doped semiconductors, graphite, and the like as a function of the 5 electricity generated in the solid material due to the flow of the gas along the surface thereof using a combination of the Seebeck effect and Bernoulli's principle.

Abstract: A system is provided for controlling boundary layer shear stress adjacent a surface over which a fluid stream has been established. The system comprises a boundary layer control device adapted for altering at least one flow characteristic within a boundary layer in a selected region of the surface. The system further comprises a shear stress measurement system comprising a hot film sensor arrangement having at least one hot film sensor element appliable to the surface in the selected region. The at least one hot film sensor element is connected to an anemometer circuit configured to provide a sensor signal corresponding to heat transfer from the associated hot film sensor to the fluid stream. The system also comprises a control module in communication with the anemometer arrangement and the boundary layer control device. The control module is adapted for receiving and processing sensor signals signal from the anemometer circuit and for providing input signals to the boundary layer control device.

Abstract: IN a thermal type flow measurement apparatus, a heating element is disposed in a fluid passage and generates heat by a passage of a current through itself. A first thermal sensitive element is disposed adjacent upstream of the heating element in a direction of fluid flow to be measured. A second thermal sensitive element is disposed adjacent downstream of the heating element in the direction of fluid flow to be measured. The fluid passage is provided with the heating element, the first thermal sensitive element, and the second thermal sensitive element. The fluid passage has an asymmetric structure with respect to the direction of fluid flow. Means for measuring a difference of temperatures is sensed by the first and the second thermal sensitive elements to produce a voltage according to a fluid flow rate.

Abstract: A thermal air flow rate measuring apparatus of great precision wherein sensitivity is enhanced by sensors having different output characteristics and an operating device employing a digitized signal. The sensitivity and temperature can be corrected easily depending on the flow direction of fluid. The measuring apparatus includes at least one heating resistor disposed in a gas fluid, temperature detecting resistors formed at an upstream part and a downstream part of the heating resistor in the flow direction of the fluid, a device for outputting at least two signals relating to the flow rate of the fluid, a quantizing device for quantizing the output values, and an operating device for operating the flow rate based on the quantized signals.

Abstract: A flow sensor system includes a plurality of flow sensor chips, wherein each flow sensor chip among the plurality of flow sensor chips comprises a substrate, a heater element, a heater control circuit, and flow sensor component formed on the substrate, wherein the heater element is disposed separately from the heater control circuit on the substrate, wherein the heater control circuit is thermally isolated from the heater element and the flow sensor component. Additionally, an air gap can be formed between each sensor chip among the plurality of flow sensor chips, wherein the plurality of flow sensor chips comprises a flow sensor system in which each of the flow sensor chips are separated from one another by the air gap formed therebetween in order to reduce output distortion, response time, warm-up time, drift and noise associated with the plurality of flow sensor chips.

Abstract: A sensor apparatus includes a heating element comprising an upstream side and a downstream side. A first heat sensing set is generally configured adjacent to the upstream side of the heating element and comprises a first sensing element and a second sensing element, the first and second sensing elements configured in a serpentine, interdigitated pattern. A second heat sensing set can be configured adjacent to the downstream side of the heating element and comprises a third sensing element and a fourth sensing element, the third and fourth sensing elements configured in a serpentine, interdigitated pattern.

Abstract: A thermal gas-flow measuring instrument has a first heating resistor placed in the gas to be measured. A temperature sensing resistor is positioned upstream or downstream of the first heating resistor and generates signals relating to the flow rate. Between the first heating resistor and the support for supporting the first heating resistor is a second heating resistor that is electrically insulated from the first heating resistor. The second heating resistor suppresses the heat being transferred from the first heating resistor to the support. A control circuit controls the temperatures of the first heating resistor and the second heating resistor so that the operational temperature range of the second heating resistor or the temperature range at the joint section between the first heating resistor and the second heating resistor is at or above the temperature at which water droplets evaporates to disappear by film boiling.

Abstract: A Thermal type fluid flow sensor comprises a heating resistor formed on a thin film of a substrate, and plural thermal sensitive resistors configuring a bridge circuit. The thermal sensitive resistors are disposed on the thin film of the substrate so as to be located on an adjacent upstream side and an adjacent downstream side of the heating resistor in a stream direction of fluid to be measured. Resistor traces for the thermal sensitive resistors are formed so that the respective thermal sensitive resistors exhibit substantially equal changes in resistance with each other to distortion caused in the thin film.

Abstract: A fluid system installed on a vehicle and a method for assessing a property of a fluid flowing in the fluid system. The fluid system and method entail flowing at least a portion of the fluid through a passage within a freestanding portion of a micromachined tube supported above a substrate so as to define a gap therebetween, vibrating the freestanding portion of the micromachined tube at a resonant frequency thereof, sensing the movement of the freestanding portion of the micromachined tube so as to measure at least one of the vibration frequency and deflection of the freestanding portion relative to the substrate and produce therefrom at least one output corresponding to at least one of the mass flow rate, specific gravity, and density of the portion of the fluid flowing through the passage, and then using the output to compute the property of the fluid.

Abstract: A flow sensor is provided having a substrate with a sensing element and flow channel aligned over the sensing element. The sensing element senses at least one property of a fluid. The flow channel is aligned by one or more guide elements formed in an alignment layer. The flow channel across the sensing area is accurately and precisely aligned due to the guide elements provided at the wafer-level, facilitating reliable, low-cost, and consistent results among multiple flow sensors. The flow sensor is adapted for use in harsh environments.

Abstract: A thermal fluid flow sensor and method of forming same. The flow sensor has an integrated circuit substrate, such as a silicon substrate, and a region of low thermal conductivity material carried on the top surface of the integrated circuit substrate. One or more pairs of temperature sensing elements are disposed on the low thermal conductivity region together with a heating element so that a robust flow sensor can be provided at low cost. Signal conditioning circuitry is disposed on the same surface as the temperature sensing elements and connected to the sensing elements thereby further reducing costs and improving the flow sensor sensitivity.

Abstract: An apparatus and corresponding method measure physical parameters using a plurality of low-cost sensors coupled in series is provided. These sensors can be thermal sensors for measuring the temperature of a heating pad. Different types of sensors to measure temperature, moisture, pressure, or state change of a switch may be employed. Such sensors may be distributed throughout a building to concurrently monitor multiple physical parameters at numerous locations. The sensors are easily manufactured, thus reducing sensor cost. Costs are further reduce by the user of two wires to connect the series of sensors. Moreover, the wires can be run easily through conduit or cable troughs.

Abstract: Two heat generating resistors are formed on a substrate in the upstream side with respect to an air flow direction and two other heat generating resistors are formed in the downstream side. A thermometer resistor for detecting a temperature in the intake manifold is formed on the substrate. A bridge circuit is formed of the heat generating resistors. A temperature of the four heat generating resistors is controlled to be at a predetermined temperature by balancing a bridge circuit constituted of the thermometer resistor or the like with a differential amplifier and a transistor. When air flows, electric potentials of the intermediate terminals in the bridge circuit change. A flow quantity and a flow direction of the air are calculated by detecting the electric potential difference.

Abstract: According to an embodiment, the present invention pertains to a system for detecting airflow in a room. The system includes an airflow indicating device having a movable component whose movement substantially corresponds to airflow in a vicinity of the airflow indicating device. The system also includes cooling system components and a computer system configured to control the cooling system components substantially based upon movement of the movable component.

Abstract: In a method for producing a protective cover for a device formed in a substrate, at first a sacrificial structure is produced on the substrate, wherein the sacrificial structure comprises a first portion covering a first area of the substrate including the device and a second portion extending from the first portion into a second area of the substrate including no device. Then a first cover layer is deposited that encloses the sacrificial structure such that the second portion of the sacrificial structure is at least partially exposed. Then the sacrificial structure is removed, and the structure formed by the removal of the sacrificial structure is closed.

Abstract: A micromachined fluid sensing device and a method for its fabrication. The sensing device incorporates a bypass passage, preferably an integral bypass passage within the device, that enables a volume of fluid to be delivered to the device, with a limited portion of the fluid passing through a passage within the device in which one or more properties of the fluid are sensed, such as but not limited to density, specific gravity, and chemical concentrations. The device is suitable for monitoring the fuel concentration in a fuel mixture for a fuel cell.

Abstract: In a thermal-type flow rate sensor, a mold material is formed to integrally cover a predetermined range including a circuit chip, connecting parts of connecting wires with a flow rate detecting chip and the circuit chip, and connecting parts of connecting wires with the circuit chip and a lead portion, to expose a part of the flow rate detecting chip to a measured fluid. The flow rate detecting chip is located in a groove portion of a support member to have a clearance with the groove portion and to form a cavity part inside a thin wall portion of the detecting chip. The cavity part communicates with an outside through a communicating portion that includes the clearance, and the clearance is blocked by a filler at least at a portion positioned in the predetermined range. Therefore, the filler prevents the mold material from entering the clearance in the mold forming.

Abstract: A sensor device for use in an automobile as an airflow sensor is composed of a silicon substrate in which a cavity is formed and a base plate bonded to the silicon substrate. An upper end of the cavity is closed with a thin membrane including a sensor element such as a temperature sensor element, while a lower end of the cavity is closed with the base plate. An air passage having a small cross-section is formed through the base plate, so that the cavity communicates with the outside air through the air passage. The thin membrane is prevented from being damaged by collision with foreign particles included in the airflow because the air in the cavity functions as a damper. The air passage may be made in the silicon substrate in parallel to its surface without using the base plate.

Abstract: An analytical chip is provided with a flow channel (5), whose section is in a closed shape and through which a fluid sample (Fs) is made to flow, for carrying out analysis regarding the fluid sample (Fs) based on interaction between a predetermined substance and a specific substance (61), which is placed facing said flow channel (5). The chip further has a projection member (9b) attached to said flow channel (5). With this arrangement, it becomes possible to analyze the fluid sample (Fs) efficiently with high precision.

Abstract: A measuring device for a flow sensor is provided, in which the drift is minimized.

Abstract: A sensor and carrier device are provided in combination with a pipeline for either placing a sensor element within the flow stream of the pipeline or a device to divert flow outside of the pipeline to measure a parameter of the conditions within the pipeline or of the gas flowing through the pipeline. The configuration of the probe comprising the carrier and sensor is such as to reduce the possibility of structural failure of the probe.

Abstract: For measuring the flow and the thermal conductivity of a fluid, a sensor is used, which has a first temperature detector for measuring a first temperature and a second temperature detector for measuring a second temperature. A heating is arranged between the temperature detectors. Two measured quantities are determined by means of the temperature detectors, a first of which is e.g. a difference between the temperatures and a second one of which is one of the temperatures. By comparing the two measured quantities, the flow and the thermal conductivity of the fluid can be determined.

Abstract: A thermal flow sensor which is fabricated at a low cost and has improved reliability. Over a cavity (7) formed in a semiconductor substrate (2), at least a heating resistance (4) is formed near the center of the cavity with an electrical insulation film interposed between the heating resistance and the cavity. The temperature (Th) of the heating resistance (4) is controlled to be higher than the medium temperature (Ta) by a constant temperature (?Th=Th?Ta). A distance (Ws) in the direction of airflow from an upstream end of the heating resistance (4) to an upstream end of the electrical insulation film lying over the cavity and the constant temperature (?Th) satisfy the following relationship: ?Th/Ws?800 (° C./mm) Thus, a thermal flow sensor is provided which can prevent deposition of floating fine particles, such as carbon particles, caused by the thermophoretic effect, can be fabricated at a low cost, and has high reliability.

Abstract: A thermal flow sensor has a first, second and third substrate, each having a first side and a second opposite side. The first substrate is connected to the second substrate such that the second side of the first substrate abuts the first side of the second substrate. The third substrate is connected to the second substrate such that the second side of the second substrate abuts the first side of the third substrate. The first, second and third substrate form a multi-layer body structure having at least one edge extending between a first side of the first substrate and the second side of the third substrate. The second substrate has a groove formed therein so as to form a conduit bounded by the second substrate and the second side of the first substrate and the first side of the third substrate. The conduit has an inlet opening and an outlet opening that are formed in the at least one edge.

Abstract: A sensor element (10) and sensor supporting body (30) are fixed on a jig (80) by adhesive (48) so that a surface (10A) of the sensor element (10) and a surface (30A) of the sensor supporting body (30) agree with each other. Therefore, it is possible to eliminate a step portion between the surface (10A) of the sensor element (10) of the thermal-process-type air-flow-rate sensor and the surface (30A) of the sensor supporting body (30). Accordingly, it is possible to reduce fluctuations in the characteristic of the thermal-process-type air-flow sensor.

Abstract: A thermal air flowmeter which improves air flow rate measurement sensitivity, reduces power consumption of a heating element and broadens the measuring range. A heating resistor is provided on insulating film in a thermal insulating area as a rectangular space on a flat substrate; and two resistance temperature detectors are provided upstream and downstream of the heating resistor. The sides of the rectangular thermal insulating area which are parallel to the axis of air flow are longer than its sides which are perpendicular to the axis of air flow.

Abstract: A flow rate sensor has a problem that a resistance value of a heat generating resistor itself varies and sensor characteristics are changed during use of the sensor for a long term. Also, the temperature of the heat generating resistor must be adjusted on a circuit substrate with a resistance constituting one side of a fixed temperature difference control circuit, and this has been one of factors pushing up the production cost. All resistances used for fixed temperature difference control are formed on the same substrate as temperature sensitive resistors of the same material. This enables all the resistances for the fixed temperature difference control to be exposed to the same environmental conditions. Hence, even when the resistances change over time, the changes over time occur substantially at the same tendency. Since the resistances for the fixed temperature difference control change over time essentially at the same rate, a resulting output error is very small.

Abstract: A disposable fluid flow sensor is disclosed herein, which generally includes a flow channel assembly comprising a flow channel tube in association with a disposable flow channel portion. A sensor die is located approximate to a thin interface or membrane formed from the disposable flow channel portion, such that the sensor die measures a flow of fluid flowing through the flow channel tube and the disposable flow channel portion of the flow channel assembly. Additionally, a substrate can be provided upon which the sensor die is formed and located. A seal can also be provided for sealing the disposable flow channel portion to the flow channel tube. Such a flow sensor can be implemented in the context of a “non-isolated” sensor die approach in which the sensor die, substrate and flow tube are assembled together into a complete disposable assembly, in which a thin interface does not cover the sensor die.

Abstract: In a semiconductor sensor having a membrane structure, the destruction of the membrane caused by the expansion or contraction of a fluid within a hollow part formed under the membrane while the sensor is in use is prevented. A semiconductor sensor 10 comprising a substrate 30 and a membrane 20 formed on the top surface thereof, in which the bottom of the substrate 30 and a mounting surface 50 on which the sensor 10 is mounted are bonded, has pressure difference adjusting means 22a to 22c for eliminating the difference in pressure of a fluid between an inside and an outside of a hollow part 34 while the sensor is in use.

Abstract: A device for measuring the flow rate of a fluid confined by a wall member, and wherein the device comprises contacting apparatus for contacting the wall member, the contacting apparatus being formed of a material having a first heat transfer coefficient so that heat may be exchanged between the wall member and the contacting apparatus. The device further comprises heating apparatus for supplying heat to and draining heat from the contacting apparatus so that heat is being supplied to the wall member when heat is being supplied to the contacting apparatus and so that heat is being drained from the wall member when heat is being drained from the contacting apparatus. Bridging apparatus for providing thermal contact between the heating apparatus and the contacting apparatus are provided.

Abstract: A thermal flow sensor has a first substrate, second substrate and a third substrate, each of which has a first side and a second opposite side. The first substrate is connected to the second substrate such that the second side of the first substrate abuts the first side of the second substrate. The third substrate is connected to the second substrate such that the second side of the second substrate abuts the first side of the third substrate. The second substrate has a groove formed therein so as to form a conduit bounded by the second substrate and the second side of the first substrate and the first side of the third substrate. A heater is disposed on the first side of the first substrate opposed to the conduit. A first temperature sensor is disposed on the first side of the first substrate opposed to the conduit.

Abstract: An integrated flow sensor for determining a fluid flow is described.

Abstract: Firstly, a supporting frame is produced, whose opening is spanned by an auxiliary layer flush on one side. Following the production of microstructures, flat parts or membranes on the common plane defined by the auxiliary layer and the supporting frame, the auxiliary layer is removed, preferably by etching. In a preferred application, the self-supporting microstructures produced in accordance with the method of the invention are used as electrically heatable resistance grids in a device for measuring weak gas flows.

Abstract: A flow sensor is described, in particular for analysis of gas flows, having a substrate and at least one sensor component which is sensitive to a flow of a medium, the sensor component being separated from the substrate in at least some areas by a region that is a poor heat conductor compared to the substrate. In addition, the region having poor heat conductivity is a porous silicon region or a porous silicon oxide region, or the region having poor heat conductivity is a recess in the surface of the substrate above which the sensor element (15) is situated on at least one web which bridges the recess and is at least mostly unsupported. The flow sensor described here is particularly suitable for angle-dependent detection of a gas flow.

Abstract: A thermal flow sensor has a first, second and third substrate, each having a first side and a second opposite side. The first substrate is connected to the second substrate such that the second side of the first substrate abuts the first side of the second substrate. The third substrate is connected to the second substrate such that the second side of the second substrate abuts the first side of the third substrate. The second substrate has a groove formed therein so as to form a conduit bounded by the second substrate and the second side of the first substrate and the first side of the third substrate. A heater is disposed on the first side of the first substrate opposed to the conduit. A first temperature sensor is disposed on the first side of the first substrate opposed to the conduit. A second temperature sensor is disposed on the first side of the first substrate opposed to the conduit.

Abstract: A mass flow meter employs discrete chip-type temperature sensors to sense a fluid flow rate. The sensor can be a semiconductor chip such as SiC or silicon, or thin film tungsten on an AlN substrate. The sensors can be distributed symmetrically with respect to the conduit through which the fluid flows, and can be connected in a four-sensor bridge circuit for accurate flow rate monitoring. An output from the mass flow meter can be used to control the fluid flow.

Abstract: A heating resistor type flow-measuring device is capable of adjusting heating temperature of a heating resistor according to the ambient temperature as well as making the initial adjustment. A heating resistor, a thermoresistance, a group of the resistors, and an amplifier constitute a bridge circuit, and leading terminals of the group of resistors are connected to one of input terminals of an amplifier for amplifying an error voltage through MOS transistors. The heating temperature of the heating resistor can be changed by selecting one of the MOS transistors and turning it on.

Abstract: A method and a control unit for operating an internal combustion engine of a motor vehicle are provided, in particular for controlling/regulating the internal combustion engine as a function of an air-mass sensor signal from a first air-mass sensor. A first auxiliary signal, which is obtained arithmetically from an additional sensory system or from models of the internal combustion engine, allows a plausibility control or the substitution of the air-mass sensor signal in the case of signal interference of the air-mass sensor signal, and thereby ensures that the internal combustion engine is able to continue working in the optimal operating point.

Abstract: It is an object of the present invention to provide a simple-structure physical quantity detecting device whose resistance does not vary irrespective of use for long periods, a method for manufacturing thereof and a motor vehicle control system using the physical quantity detecting sensor to improve its reliability. An airflow sensor (20) is equipped with a heat generating resistor (12H) and a temperature measuring resistor (12C), formed on a semiconductor substrate (11). The heat generating resistor (12H) is formed in a thin-wall portion (11A). Both end portions of the heat generating resistor (12H) are connected through first lead conductors (13H1, 13H2) to electrodes (14H1, 14H2), respectively. A second lead conductor (15H1) connected to the electrode (14H1) extends to an outer circumferential portion of the airflow sensor (10).

Abstract: A flow sensor for detecting flow of fluid includes a thin film portion. The thin film portion has a heater and a detector for detecting temperature around the heater. The heater is made of semiconductor. This flow sensor has high sensor sensitivity with low energy consumption. Further, the sensor has high detection accuracy, and the thin film portion has high endurance. Furthermore, the flow sensor with a passivation film has appropriate thickness so as to improve strength of a thin film portion.

Abstract: A measuring element for a flow rate sensor is described, in which the number of terminals is minimized to reduce the dimensions of the measuring element.

Abstract: A flow sensor includes a substrate, an electrical insulating film, and a flow velocity detection mechanism. In the substrate, a diaphragm portion having a first surface in contact with a measurement target fluid and a thick fixing portion surrounding the diaphragm portion are integrally formed. The electrical insulating film is formed on a second surface of the diaphragm portion which is on a side opposite to the first surface. The flow velocity detection mechanism is arranged on the electrical insulating film. A method of manufacturing a flow sensor is also disclosed.

Abstract: Cavities are formed so as to extend from a rear surface side of a base material to a protective film, an electrically-insulating film is formed on a rear surface of the base material, wall surfaces of the cavities, and exposed surfaces of the protective film, and a heating resistor portion and a fluid temperature resistance thermometer portion are formed on portions of the electrically-insulating film on the exposed surfaces of the protective film inside the cavities. In addition, leader patterns are formed on the electrically-insulating film so as to extend from end portions of the heating resistor portion and the fluid temperature resistance thermometer portion along the wall surfaces of the cavities onto the rear surface of the base material.

Abstract: A flow rate detection device has a flow rate detection chip that is partially exposed to the flowing material to be measured and a casing that accommodates the flow rate detection chip. The casing has a bottom plate portion on which the flow rate detection chip is mounted, and a top plate portion that is disposed over the bottom plate portion and partially covers the flow rate detection chip. The space between the bottom plate portion and the top plate portion is filled with a sealant.