A differential pressure sensor comprises a cavity having a base including a base electrode and a membrane suspended above the base which includes a membrane electrode, wherein the first membrane is sealed with the cavity defined beneath the first membrane. A first pressure input port is coupled to the space above the sealed first membrane. A capacitive read out system is used to measure the capacitance between the base electrode and membrane electrode. An interconnecting channel is between the cavity and a second pressure input port, so that the sensor is responsive to the differential pressure applied to opposite sides of the membrane by the two input ports.

A sensor interface circuit includes a continuous-time capacitance-to-voltage (C/V) converter having C/V input and output ends, the C/V input end being configured for electrical connection with first and second sense nodes of a capacitive sensor. A filter circuit is electrically coupled to the C/V output ends. The filter circuit has first and second resistors at corresponding first and second filter input ends of the filter circuit, a capacitor connected between first and second filter output ends of the filter circuit, and a chopper circuit interposed between the first and second filter input ends and the first and second filter output ends. A buffer circuit is electrically coupled with the first and second filter output ends of the filter circuit. The filter circuit applies low pass filtering of sense signals from the capacitive sensor before sampling and demodulation operations to reduce high-frequency interference in the sense signals.

Disclosed are an environment information sensor circuit and an environment information measurement device which can sense various kinds of environment information, such as pressure, humidity, acceleration and the like, and simply reduce quantization noise by employing a dual quantization capacitance-to-digital converter structure. The environment information sensor circuit comprises: a switch capacitor that outputs one among pressure information, humidity information, and acceleration information on the basis of a first clock signal and a second clock signal that do not overlap; a single-bit first order delta-sigma converter that includes an integrator which integrates the output from the switch capacitor and outputs the integrated output as an analog value, and a single-bit quantizer which compares the output from the integrator and a preset threshold voltage and outputs a single-bit digital signal corresponding to a comparison result; and a multi-bit quantizer that is connected to an output end of the integrator via a sampling switch, and quantizes the output from the integrator at the moment the sampling switch is turned on according to a sampling signal.

An apparatus for calibrating a pressure sensing device having a pressure sensor and a temperature compensation device includes: a chamber for applying a variable temperature and a variable pressure to the pressure sensing device; a temperature regulation device for regulating the temperature in the chamber designed such that the temperature in the chamber respectively increases in a strictly monotonous manner or falls in a strictly monotonous manner during one or more time intervals; a pressure regulation device for regulating the pressure in the chamber designed such that the pressure in the chamber respectively monotonously increases or respectively monotonously falls in at least one of the time intervals during a plurality of sub-intervals of the one-time interval; a reference pressure sensor for sensing the pressure in the chamber during the time interval(s); and a data record generation device for generating corresponding data records.

A method of driving a pump is used in a pressure-applying apparatus, the apparatus including a flow passage, a pump configured to impart pressure into the flow passage, an opening and closing valve configured to open and close the flow passage, a pressure detector configured to detect pressure in the flow passage, and an atmospheric air open valve configured to open an interior of the flow passage to atmospheric air. The method includes driving the pump after closing the opening and closing valve and opening the atmospheric air open valve, and evaluating a state of the pump, based on one of: the pressure detected by the pressure detector at a time at which a predetermined time period has elapsed after closing the atmospheric air open valve, and a time from closing of the atmospheric air open valve until detection of a predetermined pressure by the pressure detector.

The invention relates to a method for monitoring the function of a capacitive pressure measuring cell (10) comprising a measuring capacitor (C.sub.M) and a reference capacitor (C.sub.R) as well as a temperature element, wherein in an evaluation unit the pressure measurement value p is obtained by forming the quotient Q from the capacitance values of the reference capacitor (C.sub.R) and the measuring capacitor (C.sub.M). The method is characterized by the following method steps: in a matching procedure the characteristic curve of the quotient Q and the capacitance values of the measuring capacitor (C.sub.M) are each stored in a lookup table versus the pressure and at different temperature scenarios; then the corresponding absolute value of the quotient Q and of the capacitance value of the measuring capacitor (C.sub.M) from the lookup table are continuously assigned respectively to the determined pressure measurement value p at the temperature detected at this moment by the temperature element; the behavior of the course of the two absolute values of the quotient Q as well as of the capacitance value of the measuring capacitor (C.sub.M) is compared with each other; in the case of a significant deviation from an expected behavior, the evaluation unit is temporarily switched into a safety mode and meanwhile the gradient of the temperature element is detected and evaluated; in the case of a significant increase of the gradient of the temperature element, a temperature compensation is initiated; or in the case of an unchanged gradient of the temperature element, an error signal is generated.

The invention relates to various means for implementing a method for compensating measured values in capacitive pressure measuring cells using a measuring capacity and at least one reference capacity, comprising the following steps: determination of a pressure-induced capacitance change of the reference capacitance as a function of a pressure-induced capacitance change of the measuring capacitance, determination of a thermal shock-induced capacitance change of the reference capacitance as a function of a thermal shock-induced capacitance change of the measuring capacitance, measurement of the measuring capacitance and of the at least one reference capacitance, determination of the thermal shock-induced capacitance change of the measuring capacitance from a combination of the above dependencies, compensation of the measured measuring capacitance by the thermal shock induced capacitance change of the measuring capacitance, and determination and output of the pressure-induced capacitance change or a quantity derived therefrom.

A polymeric fluid sensor includes an inlet configured to receive fluid and an outlet. A polymeric tube is fluidically interposed between the inlet and the outlet and has a first sensing location with a first sidewall thickness and a second sensing location, spaced from the first sensing location, with a second sidewall thickness. A sleeve is disposed about the polymeric tube. The first sidewall thickness is less than the second sidewall thickness and a first sensing element is disposed at the first location and a second sensing element is disposed at the second location. In another example, the first and second sidewall thicknesses are the same and a fluid restriction is disposed within the polymeric tube between the first and second sensing locations.

A sensing device is provided. The sensing device includes a processing circuit and a multi-sensor integrated single chip. The multi-sensor integrated single chip includes a substrate and a temperature sensor, a pressure sensor, and an environmental sensor disposed on the substrate. The temperature sensor senses temperature. The pressure sensor senses pressure. The environmental sensor senses an environmental state. The processing circuit obtains a first sensed temperature value from the temperature sensor when the environmental sensor does not operate, and it obtains a second sensed temperature value from the temperature sensor when the environmental sensor operates. The processing circuit obtains a sensed pressure value from the pressure sensor. The processing circuit obtains at least one temperature calibration reference of the pressure sensor according to the first and second sensed temperature values and calibrates the sensed pressure value according to the temperature calibration reference.

Various embodiments include a capacitive pressure transducer for measuring the pressure of a medium adjacent to the transducer comprising: a measurement diaphragm including a first surface in contact with the medium and a second surface facing away from the medium; a measurement electrode integrated with the measurement diaphragm; a base body arranged opposite the second surface, the base body comprising a counter electrode forming a measurement capacitance with the measurement electrode; and an electrically insulating chamber bounded by the base body and the measurement diaphragm. The counter electrode is in contact with the electrically insulating chamber. At least one of the measurement electrode or the counter electrode comprises a meandering pattern layer in direct contact with the electrically insulating chamber.