A thermal type flow meter includes a first resistor (R1) is disposed along a flow path through which a fluid flows, generating heat when a current is applied, and outputting a first output signal indicating a heat generation temperature, a second resistor (R2) disposed at a position different from that of the first resistor along the flow path and outputting a second output signal indicating a temperature of the fluid, and a current application unit configured to apply a current to the first resistor so that the first output signal indicates a predetermined temperature. A parameter for converting the difference between the first output signal and the second output signal when a predetermined input is received if the current is applied into a target value is determined. The flow rate is acquired using the parameter, the difference detected after the parameter is determined, and a predetermined function.

We disclose herein a CMOS-based flow sensor comprising a substrate comprising an etched portion; a dielectric region located on the substrate, wherein the dielectric region comprises a dielectric membrane over an area of the etched portion of the substrate; a p-n junction type device formed within the dielectric membrane, wherein the p-n junction type device is configured to operate as a temperature sensing device.

A flow sensor comprises an electroactive material device. A driver controls the electroactive material device to deliver heat locally to the flowing medium for which the flow is to be sensed. Temperature sensing signals are obtained and these are used to derive a flow measurement. The way the heat is dissipated relates to the flow, and it is measurable based on the temperature sensing signals. The temperature sensing involves measuring an electrical characteristic which comprises an impedance or an impedance phase angle of the electroactive material device at at least a first frequency and at a second frequency different from the first frequency. The influences of temperature and pressure can in this way be decoupled so that the temperature can be measured at any pressure.

A mass flow sensor assembly that contains an absolute pressure sensor for compensating via electronics an output reading of mass flow of a fluid through a channel. The flow and pressure sensors may be built in close proximity to each other in the channel. The mass flow sensor assembly incorporating the absolute pressure sensor may be fabricated using MEMS techniques.

Disclosed is a method for liquid measurements including:providing a sensor including a surface arranged to receive a liquid thereupon, an electrical heating element arranged to heat the surface, and an arrangement for measuring a temperature of the surface;receiving liquid on the sensor surface;heating the surface by means of the electrical heating element at a known rate while taking a plurality of temperature measurements thereof in function of time, the heating being at an absolute temperature of at least 90% of the boiling point of the liquid under ambient pressure; andderiving a volume or a flow rate measurement related to the liquid from the electrical heating rate and the temperature measurements.

A device for detecting air flows includes an air line channeling an air flow. The line (for example a tube) includes at least one first temperature sensor and one second temperature sensor (inside the tube). At least one of the sensors is subjected to periodic temperature fluctuations controlled by at least one heating device, such as a variable-current power source dedicated to the sensor.

A method for operating a thermal flow sensor includes: bringing a measuring medium into thermal contact with a sensor element of the flow sensor and periodically heating the medium using an AC voltage introduced into the sensor element; simultaneously detecting a maximum amplitude of a temperature and/or a phase shift between a curve of the AC voltage and the curve of the temperature; adjusting the detected maximum amplitude and/or the detected phase shift using calibration data; determining an isoline using the adjusted maximum amplitude and/or the adjusted phase shift based on model of the flow sensor, wherein the isoline has a plurality of value pairs of thermal conductivity and thermal capacitance of the medium; deriving a medium information from the isoline; and performing a flow measurement by converting signal values from the sensor element into measurement values of an effective flow velocity of the medium using the medium information.

A thermal flow sensor for determining flow of a medium, comprising: a substrate; first and second temperature sensors arranged on the substrate, wherein the first and second temperature sensors are embodied as heatable temperature sensors or as a first non-heatable temperature sensor, which is associated with a first heating element, and as a second non-heatable temperature sensor, which is associated with a second heating element; a power supply unit, which by means of a first signal supplies the first heatable temperature sensor or the first heating element with a first heating power determined earlier during an adjustment operation and by means of a second signal supplies the second heatable temperature sensor or the second heating element with a second heating power determined earlier in the adjustment operation; and an evaluation unit, which in a measurement operation for determining flow of the medium ascertains a temperature difference between the first temperature sensor and the second temperature sensor and based on the temperature difference determines a measured value, which represents the flow of the medium.

A wind speed measuring device includes a constant temperature heat generating device that generates heat at a predetermined set temperature. The constant temperature heat generating device includes a power source, a heat generating element, a switching element, a comparator element, a first negative characteristic thermistor element, and a plurality of resistance elements. The heat generating element and the first negative characteristic thermistor element define a wind speed sensor. The switching element repeats turning on and off to make the heat generating element generate heat at a predetermined set temperature. A pulse voltage is applied from the power source to the heat generating element. A wind speed of a wind contacted with the wind speed sensor is calculated based on a wave form of the applied pulse voltage.

In order to measure water flow in sewer systems or other tubes, a sensor ring is inserted into a pipe with capacitive sensors at discrete levels along a circumference of the pipe. Speed is measured by heating up a resistor and measuring the rate at which heat is extracted from the resistor by the flowing liquid.