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 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 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 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.