A calibration electrode for calibrating a reference system of an electrochemical sensor, such as a potentiometric sensor or an ion selective electrode. The calibration electrode has an active surface comprising redox functionalities. The redox functionalities set the pH of a reference solution proximal to the calibration electrode. A voltammetric signal is applied to the calibration electrode to produce a response that is determined by the set pH. The response of the calibration electrode to the voltammetric signal is used to calibrate/adjust a reference potential produced by a reference electrode of the reference system of the electrochemical sensor. This calibration corrects the detrimental effect of reference electrode drift.

Disclosed herein are devices, wound dressings and methods for determining the pH of fluid or a wound exudate at a wound. Example devices include a device comprising a surface configured to contact the fluid or wound and a pH indicator covalently bound thereto or applied to the surface, wherein the pH indicator has a first colour prior to contact with the fluid or the wound exudate and changes colour as a function of the pH of the fluid or wound exudate. Example devices include a device which indicates wound exudate loading within a wound dressing and wound dressing comprising an absorbent layer and a moisture indicator which indicates would exudate loading within the dressing, wherein the visibility of the moisture indictor changes as a result of a physical transformation of a first material within the dressing. Systems, devices, and methods are provided for monitoring wound status and progression by measuring pH levels indicated by pH-sensitive wound dressings. In some implementations, a wound is monitored by capturing an image of the pH-sensitive wound dressing and processing the captured image to determine the color of a pH indicator included on the wound dressing. The color of the indicator is determined in terms of RGB values from the image, and a pH value for the wound dressing is calculated from the dressing RGB values. The calculated pH value is then relayed to a user to be used as an indicator of wound status or health.

The invention relates to a comparison unit (130) configured for determining if a first pH measuring device of a first tank (104; 106) is affected by a pH-measuring problem, the comparison unit being configured for: —receiving a first CO2 concentration and a first pH value, the first CO2 concentration being a CO2 concentration of a first gas volume above a medium in a first tank, the first CO2 concentration and the first pH value being measured at a first time when the medium in the first tank is in pH-CO2 equilibrium state with the first gas volume and before said equilibrium state is modified by the metabolism of a cell culture in the first tank, the first pH value being a measured value provided by a first pH measuring device operatively coupled to the first tank (102); —receiving a second CO2 concentration and a second pH value, the second CO2 concentration being a CO2 concentration of a second gas volume above a medium in a second tank, the second CO2 concentration and the second pH value being measured at a second time when the medium in the second tank is in pH-CO2 equilibrium state with the second gas volume and before said equilibrium state is modified by the metabolism of a cell culture, the second pH value being a measured value provided by a second pH measuring device; —comparing the first and second pH values and CO2 concentrations for determining if comparing (206), by the comparison unit, the first and second pH values and comparing the first and second CO2 concentrations for determining if the first pH measuring device is affected by the pH-measuring problem.

A sensor may include a sensing element retained within a storage compartment filled with a storage medium, which may also be used as a calibration medium. The sensing element can include a sensing surface located away from the distal end of the sensing element, such that an inactive section of the sensing element can cooperate with a sealing member such as an O-ring to form part of the seal retaining the storage/calibration medium. The sensing element can be extended and retracted from the storage compartment to expose the sensing surface to a process medium, while preserving the storage medium within the storage compartment for post-measurement validation.

An embodiment a pressure compensated pH sensor apparatus, including: a pH sensing component comprising a sensing portion that is exposed to a fluid source when in use; a pressure chamber located in a position under the sensing portion and that surrounds all of the sensing portion not exposed to the fluid source when in use; and a pressure compensation mechanism located within the pressure chamber, wherein the pressure compensation mechanism reacts to pressure from an environment outside the apparatus, thereby support the sensing portion.

A sensor may include a sensing element retained within a storage compartment filled with a storage medium, which may also be used as a calibration medium. The sensing element can be moved from a first position in which the sensing element is exposed to the storage compartment, and a second position in which the sensing element can be exposed to a process medium. An actuator mechanism may be configured to engage a portion of the sensor to move the sensing element between the first position and the second position. The actuator mechanism may be controlled by an external system, and may include a rotary actuator such as a servomotor or a stepper motor to move the sensing element between the first position and the second position.

Disclosed is a food wash sensor system that includes a sensor disposed along a fluid flow path that can circulate a wash fluid through the food wash sensor system. The sensor can detect a concentration of an analyte in the wash fluid. The system also includes a reference fluid reservoir including a reference fluid, the reference fluid including a predetermined concentration of the analyte in solution, a delivery system fluidly coupled to the fluid flow path and operable to supply the reference fluid to the fluid flow path upstream from the sensor while maintaining the sensor in place along the fluid flow path, and a control and monitoring system configured to receive a signal from the sensor, the signal indicating the concentration of the analyte in the reference fluid at a first time, and control calibrating the sensor and validating the sensor over time based on the received signal.

An online calibration system for an electrochemical sensor. The calibration system comprises a calibration electrode coupled with a redox species, where the redox species is configured to control a pH of a reference solution local to the calibration electrode, such that when a voltammetric signal is applied to the calibration electrode the output generated from the calibration system is determined by the local environment pH. The output signal from the calibration system is used to calibrate a reference potential generated by a reference system of the electrochemical sensor to correct for drift in the reference potential when the electrochemical sensor is being used. The calibration electrode may be disposed in a reference cell of the electrochemical sensor.

A method, computer program product, and system are provided to calibrate a sensor array with a plurality of sensors. The method can include sweeping a voltage of a reference electrode from a first voltage to a second voltage, where the reference electrode is in fluid communication with the sensor array. The output voltage of each of the plurality of sensors can be monitored at one or more voltages within the first and second voltages. An overall average gain of the plurality of sensors can be calculated at each of the one or more voltages. Further, an acquisition window for the sensor array can be determined. The acquisition window can include a maximum distribution of sensors that provides a maximal overall average gain at a particular reference electrode voltage.

A self-vibrating pH probe comprise a housing containing an electronic assembly to which is coupled a vibration source element so that at least a portion of vibrations caused by the vibration source element propagate to the electronic assembly, the vibration source element being controllable for at least on/off operation. The self-vibrating pH probe further comprising a pH probe member having a probe tip at a first end, the probe member extending from the housing and mechanically and electrically coupled by a second end to the electronic assembly so that at least a portion of vibrations propagating to the electronic assembly further propagate to the probe tip; and further including a processor coupled to the electronic assembly for coordinating operation of the vibration source element and operation of the pH probe member.