Abstract: We disclose herein a flow and thermal conductivity sensor comprising a semiconductor substrate comprising an etched portion, a dielectric region located on the semiconductor substrate, wherein the dielectric region comprises at least one dielectric membrane located over the etched portion of the semiconductor substrate and a heating element located within the dielectric membrane. The dielectric membrane comprises one or more discontinuities located between the heating element and an edge of the dielectric membrane.

Abstract: A method for controlling a fluid-flow sensor in the presence of a flowing fluid, the method comprising: determining an initial estimate of a parameter corresponding to a flow rate of the flowing fluid, comparing the initial estimate to a threshold parameter, and based on the comparison, determining the parameter corresponding to the flow rate of the flowing fluid based on: a signal from a temperature sensor of the fluid-flow sensor; a signal from a heater of the fluid-flow sensor; or a combination of the signal from the temperature sensor and the heater of the fluid-flow sensor. A controller for a fluid-flow sensor is also described.

Abstract: A thermal sensor comprising: a supply voltage input configured to receive a supply voltage; a differential circuit, the differential circuit comprising a first element configured to provide a first sensing signal, and a first reference element configured to provide a first reference signal; and a controller configured to: obtain a measured supply voltage value, the measured supply voltage value corresponding to a measurement of the supply voltage received by the supply voltage input; obtain a differential measurement between the first sensing signal and the first reference signal; and determine a sensor output value based on the measured supply voltage value and the differential measurement. A method for operating a thermal sensor is also described.

Abstract: A thermal conductivity fluid sensor for detecting a first component of a mixture, the thermal conductivity fluid sensor comprising: a first heating element; and a controller, the controller configured to: control a temperature of the first heating element such that the temperature of the first heating element changes from a first temperature to a second temperature over a first transient time period; obtain a first reading indicative of a first thermal transport property of the mixture during the first transient time period; obtain a second reading indicative of second thermal transport property of the mixture when the first heating element is at the second temperature; and determine, based on the first reading and the second reading, a concentration of the first component of the mixture. A method for determining a concentration of a component of a mixture is also described.

Abstract: A flow sensor assembly comprising a first substrate, a flow sensor located over the first substrate, a lid located over the first substrate and the flow sensor, a flow inlet channel, a flow outlet channel, and an overmold laterally encircling the flow sensor. The overmold is in contact with the side walls of the flow sensor, and extends between the flow sensor and the lid such that the overmold, the flow sensor, and the lid define a flow sensing channel between the flow inlet channel and the flow outlet channel. the lid and the encapsulation cooperate to define the flow inlet channel and the flow outlet channel.

Abstract: A thermal conductivity sensor for measuring a concentration of a gas, the sensor comprising: a substrate portion; an intermediate layer disposed on the substrate portion; a semiconductor layer disposed on the intermediate layer, and a dielectric layer comprising a dielectric membrane, the dielectric membrane provided with a heater; wherein the dielectric membrane is located over a gap, the gap being located in the semiconductor layer. Methods for manufacturing a thermal conductivity sensor are also described.

Abstract: A thermal conductivity sensor for measuring a concentration of a gas, the sensor comprising: a substrate portion; a dielectric layer comprising a dielectric membrane, wherein the dielectric membrane is provided with a heater; a first gap between the substrate portion and the dielectric membrane wherein the primary dielectric membrane is located above the first primary gap; and a micro-machined cap layer; a second gap located between the cap layer and the dielectric membrane. A method of manufacturing a thermal conductivity sensor is also described.

Abstract: We disclose herein a fluid sensor for sensing a concentration or composition of a fluid, the sensor comprising a semiconductor substrate comprising a first etched portion, a dielectric region located on the semiconductor substrate, wherein the dielectric region comprises a first dielectric membrane located over the first etched portion of the semiconductor substrate, a heating element located within the first dielectric membrane, and a first temperature sensing element spatially separated from the heating element. The fluid sensor further comprises a second temperature sensing element within the dielectric membrane, or the heating element may be further configured to operate as a second temperature sensing element.

Abstract: A method for controlling a fluid-flow sensor in the presence of a flowing fluid, the method comprising: determining an initial estimate of a parameter corresponding to a flow rate of the flowing fluid, comparing the initial estimate to a threshold parameter, and based on the comparison, determining the parameter corresponding to the flow rate of the flowing fluid based on: a signal from a temperature sensor of the fluid-flow sensor; a signal from a heater of the fluid-flow sensor; or a combination of the signal from the temperature sensor and the heater of the fluid-flow sensor. A controller for a fluid-flow sensor is also described.

Abstract: We disclose herein a sensing device comprising a semiconductor substrate having a first etched portion, a dielectric layer located on or over the semiconductor substrate, wherein the dielectric layer comprises a first dielectric membrane located adjacent to the first etched portion of the semiconductor substrate, a pressure sensing element and/or a flow sensing element within the first dielectric membrane, and a first structure configured to reinforce the dielectric membrane. A first portion of the first structure is located within the first dielectric membrane, the first structure has a higher stiffness than the first dielectric membrane, and the first portion of the first structure is located between a perimeter of the dielectric membrane and the pressure sensing element or flow sensing element.

Abstract: A fluid sensor for sensing a concentration or composition of a fluid, the sensor comprising: a semiconductor substrate comprising a first etched portion; a dielectric region located on the semiconductor substrate, wherein the dielectric region comprises a first dielectric membrane located over the first etched portion of the semiconductor substrate; a first heating element located within the first dielectric membrane; and a second heating element; wherein the first heating element is arranged to thermally shield the second heating element from ambient temperature changes; wherein the first heating element or the second heating element is configured to operate as a temperature sensing element; wherein the first heating element is configured to operate in a constant temperature or constant resistance mode; wherein the second heating element is configured to operate in a constant current or constant voltage mode or constant power mode; and wherein the sensor is configured to determine a thermal conductivity of t

Abstract: A method for controlling a fluid-flow sensor in the presence of a flowing fluid, the method comprising: applying an electrical bias to the heater element of the fluid-flow sensor, determining a phase of the flowing fluid, and modifying the electrical bias according to the phase of the flowing fluid. A controller for a fluid-flow sensor is also described.

Abstract: A sensor for sensing direction of fluid-flow, the sensor comprising: a heating element; a first active temperature sensing element; and a processor; wherein the processor is configured to: receive a first signal corresponding to a first sensed temperature from the first active temperature sensing element; and determine a direction of fluid-flow based on a difference between the first sensed temperature and a threshold value. A method for sensing direction of fluid-flow and a method for manufacturing a sensor are also described.

Abstract: A fluid sensor for sensing a concentration or composition of a fluid, the sensor comprising a first temperature sensing element located on or within a first dielectric membrane and a second temperature sensing element located on or within a second dielectric membrane. An output circuit is configured to measure a differential signal between the first temperature sensing element and the second temperature sensing element. The fluid sensor comprises a first region configured to be exposed to the fluid, and a second region configured to be isolated from the fluid, where the first dielectric membrane is located in the first region, such that in use, the first dielectric membrane is exposed to the fluid, and wherein the second dielectric membrane is located in the second region such that in use, the second dielectric membrane is isolated from the fluid.

Abstract: We disclose herein a flow sensor comprising: a first substrate comprising an etched portion, a dielectric region located on a first side of the first substrate, wherein the dielectric region comprises at least one dielectric membrane located over the etched portion of the first substrate, a sensing element located on or within the dielectric membrane, and a second substrate adjoining a second side of the first substrate. The first side of the first substrate and the second side of the first substrate are opposite sides. The first substrate and the second substrate cooperate to form a sensing channel through the flow sensor.

Abstract: A fluid sensor for sensing a concentration or composition of a fluid, the sensor comprising: a semiconductor substrate comprising a first etched portion and a second etched portion; a dielectric region located on the semiconductor substrate, wherein the dielectric region comprises a first dielectric membrane located over the first etched portion of the semiconductor substrate, and a second dielectric membrane located over the second etched portion of the semiconductor substrate; two temperature sensing elements on or within the first dielectric membrane and two temperature sensing elements on or within the second dielectric membrane; an output circuit configured to measure a differential signal between the two temperature sensing elements of the first dielectric membrane and the two temperature sensing elements of the second dielectric membrane; wherein the first dielectric membrane is exposed to the fluid and the second dielectric membrane is isolated from the fluid.

Abstract: There is disclosed herein a flow sensor comprising: a first substrate comprising an etched portion; a dielectric layer located on the first substrate, where the dielectric layer comprises at least one dielectric membrane located over the etched portion of the first substrate; a first heating element and a second heating element located on or within the dielectric membrane; and a controller coupled with the first heating element and the second heating element. The first heating element and the second heating element are arranged to intersect one another within or over an area of the dielectric membrane. The controller is configured to: take a measurement from the second heating element; determine a calibration parameter using the measurement from the second heating element; take a measurement from the first heating element; and determine a flow rate through the flow sensor using the determined calibration parameter and the measurement from the first heating element.

Abstract: We disclose herein a flow sensor assembly comprising a first substrate, a flow sensor located over the first substrate, a lid located over the flow sensor, a flow inlet channel, and a flow outlet channel. A surface of the flow sensor and a surface of the lid cooperate to form a flow sensing channel between the flow inlet channel and the flow outlet channel, and a surface of the flow sensing channel is substantially flat throughout the length of the flow sensing channel.

Abstract: We disclose herein a flow and thermal conductivity sensor comprising a semiconductor substrate comprising an etched portion, a dielectric region located on the semiconductor substrate, wherein the dielectric region comprises at least one dielectric membrane located over the etched portion of the semiconductor substrate and a heating element located within the dielectric membrane. The dielectric membrane comprises one or more discontinuities located between the heating element and an edge of the dielectric membrane.