Apparatus and associated methods relate to monitoring health of a hydraulic system. A method includes monitoring pressure within the system and determining when a potential fatigue condition may occur based on counting the number of times pressure in the system has exceeded the at least one threshold. In some embodiments, strain cycle data is calculated based on a time sequence of signals generated by a hydraulic fitting, which is indicative of strain of the hydraulic fitting. An output signal indicative of the fatigue condition determined is generated. In some embodiments, the strain data includes a number of strain cycles that the time sequence of signals crosses from below a strain threshold to above the strain threshold.

A pressure sensor includes a sensor chip. The sensor chip has two diaphragms, recessed portions that serve as first pressure inlet chambers disposed so as to respectively adjoin top surfaces of the diaphragms, and recessed portions that serve as second pressure inlet chambers disposed so as to respectively adjoin bottom surfaces of the diaphragms. A cavity is provided in the sensor chip such that, when a difference between pressures respectively applied to a top surface and bottom surface of the diaphragm is zero, an output voltage of a Wheatstone bridge circuit made up of strain gauges provided in the diaphragm is zero.

A pressure sensor includes a sensor chip. The sensor chip has two diaphragms, recessed portions that serve as first pressure inlet chambers disposed so as to respectively adjoin top surfaces of the diaphragms, and recessed portions that serve as second pressure inlet chambers disposed so as to respectively adjoin bottom surfaces of the diaphragms. A cavity is provided in the sensor chip such that, when a difference between pressures respectively applied to a top surface and bottom surface of the diaphragm is zero, an output voltage of a Wheatstone bridge circuit made up of strain gauges provided in the diaphragm is zero.

A method for detecting an error in a bridge sensor which is adapted for measuring a physical parameter. The method comprises biasing a first contact pair of the bridge sensor at least two times in a first direction and at least one time in a second direction opposite to the first direction; while biasing the first contact pair, measuring an output signal on a different contact pair of the bridge sensor, thus obtaining at least three output measurements which are representative for the physical parameter and which are separated by time intervals; combining the output measurements to obtain an output value which is indicative for an error in the bridge sensor, wherein the output measurements which are combined are only those output measurements which are measured when biasing the first contact pair.

A method for detecting an error in a bridge sensor which is adapted for measuring a physical parameter. The method comprises biasing a first contact pair of the bridge sensor at least two times in a first direction and at least one time in a second direction opposite to the first direction; while biasing the first contact pair, measuring an output signal on a different contact pair of the bridge sensor, thus obtaining at least three output measurements which are representative for the physical parameter and which are separated by time intervals; combining the output measurements to obtain an output value which is indicative for an error in the bridge sensor, wherein the output measurements which are combined are only those output measurements which are measured when biasing the first contact pair.

[Problem] To provide a pressure sensor that has a plurality of detection parts in a lamination direction, and moreover has improved detection accuracy. [Solution] A pressure sensor 10 has a membrane 22 in which deformation corresponding to pressure occurs, a first gauge layer 40 which is formed on the membrane 22, an intermediate insulation layer 50 which is formed on the first gauge layer 40, and a second gauge layer 60 which is formed on the intermediate insulation layer 50. The first gauge layer 40 and the second gauge layer 60 respectively include a first detection part 42 and a second detection part 62 which detect the deformation of the membrane. The distance from the surface of the membrane 22 to the second detection part 62 is no more than 30 μm.

An apparatus includes a casing defining a fluid flow channel, the casing including one or more diaphragms each defining a portion of the fluid flow channel, a strain gauge disposed on one of the one or more diaphragms, the strain gauge having a characteristic responsive to a pressure of fluid in the fluid flow channel, a temperature-sensitive circuit element disposed on one of the one or more diaphragms, the temperature-sensitive circuit element having a characteristic responsive to a temperature of the fluid in the fluid flow channel, and temperature compensation circuitry electrically coupled to the strain gauge and to the temperature-sensitive circuit element.

Provided is a pressure sensor including: a housing portion including a housing part housing a pressure sensor module, a concave portion facing the housing part across an inner wall, and a through hole part formed in the inner wall; a filter covering the through hole part; and a cover mounted on the housing portion while covering the concave portion and including cutout parts. The concave portion includes a bottom surface that is one surface of the inner wall, and two side surfaces perpendicular to the bottom surface and opposed to each other. The cover is formed with a rectangular upper plate and two rectangular side plates continuous with edges of the upper plate in a vertical direction and opposed to each other. The upper plate is arranged to face the bottom surface. The two side plates are arranged between the two side surfaces opposed to each other.

Provided is a pressure sensor including: a housing portion including a housing part housing a pressure sensor module, a concave portion facing the housing part across an inner wall, and a through hole part formed in the inner wall; a filter covering the through hole part; and a cover mounted on the housing portion while covering the concave portion and including cutout parts. The concave portion includes a bottom surface that is one surface of the inner wall, and two side surfaces perpendicular to the bottom surface and opposed to each other. The cover is formed with a rectangular upper plate and two rectangular side plates continuous with edges of the upper plate in a vertical direction and opposed to each other. The upper plate is arranged to face the bottom surface. The two side plates are arranged between the two side surfaces opposed to each other.

Methods, systems, and apparatuses are provided for detecting and determining conditions of and conditions within a fluid conduit.