A calibration liquid (1) is used for calibrating a water quality measurement device (100). The water quality measurement device (100) includes a plurality of sensors to be brought into contact with a measurement target liquid so as to measure concentrations of a plurality of types of target components contained in the measurement target liquid, and measures the concentrations of the plurality of types of target components. The calibration liquid (1) includes a solution which contains the plurality of types of target components at respective concentrations determined for the target components, and the solution has a pH within a predetermined pH range.

A pH measuring device is disclosed. One aspect includes a body unit including a hollow portion and a through-portion formed in a first region so that the hollow portion communicates with the outside; an electrode unit including a reference electrode and a sensing electrode including different materials and configured to measure the pH in a living body by allowing a first end to be located in the hollow portion and a second end opposite to the first end to be exposed to the outside of the body unit through the through-portion; and a wireless communication unit configured to transmit a pH measurement value sensed by the electrode unit to the outside.

An electrochemical sensor for potentiometric measurements in a measurement medium has a sensor head (201) at an end of a longitudinal sensor body (203). A sensing electrode (210) and a reference electrode (220) are disposed within the longitudinal sensor body. A liquid junction (223) is established between the reference electrode and the sensing electrode. The sensor is characterized by a protective outer shaft (250) into which a polymeric tube-like structure (230) is disposed, electrically isolating the protective outer shaft from a reference electrolyte.

A device for measuring pH levels and contaminant concentration includes an electrode assembly that is electrically coupled to a control unit. The electrode assembly includes a FLUID first contact electrically coupled to a reference electrode, a second contact electrically coupled to a working electrode, and a third contact electrically coupled to a counter electrode. The working electrode may be modified to include a cysteine functionalized graphene oxide with polypyrrole nanocomposite. In operation, the control unit may apply a complex signal to the working electrode via the second contact in order to adhere and subsequently strip contaminant ions from the fluid sample to the working electrode. During this process, a current may be measured across the reference electrode and the counter electrode to measure contaminant ion concentration. The pH of the fluid sample may also be determined by a current measured across the reference electrode and the counter electrode. In some examples, the pH may be used to calibrate the measured levels of the contaminant ions.

A printed flexible PH sensor is provided. The printed flexible PH sensor includes a flexible substrate. A working electrode is disposed on the flexible substrate, and the working electrode includes a first silver layer formed on the flexible substrate by an ink-jet printing process, a second silver layer formed on the first silver layer by a silver mirror reaction, and a metal oxide layer disposed on the second silver layer of an end portion of the working electrode. A reference electrode is disposed on the flexible substrate, and the reference electrode includes the first silver layer and the second silver layer formed on the first silver layer, and a silver chloride layer totally covering the second silver layer. A method for fabricating the printed flexible PH sensor is also provided.

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 pH sensor comprising a metal oxide-polymer composite, comprising: a continuous polymer resin matrix;, and a solid particulate, component dispersed in the polymer resin matrix comprising (i) metal oxides and (ii) a particulate carbon-based conductor wherein the metal oxides comprise Ta.sub.2O.sub.5 and RuO.sub.2 in a weight ratio of Ta.sub.2O.sub.5: RuO.sub.2 (on the basis of weight of metal component) in the range of from 90:10 to 10:90.

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.

Systems and methods may provide for automation of how fluids are monitored. These systems and methods may provide a battery-operated, wireless automated configurable solution to enable insight into various parameters of importance, through a plurality of sensors. By embedding sensors in the fluid tanks, data may be automatically collected at chosen intervals and wirelessly sent to status display screens that can be located anywhere within a facility. This may eliminate the manual time-consuming and expensive process of traditional fluid checks. Thus, fluid condition checks may be wirelessly automated to allow consistent monitoring of accurate fluid readings to control costs, including reduction in part yield, quality reduction and decreased re-work, decrease in required additives to stabilize fluids (biocides, stabilizers and defoaming agents) and high fluid waste (using more than is needed because no awareness of amount used) and disposal costs.

The disclosed invention relates to novel materials and associated methods for conducting protons, such materials comprising cephalopod proton-conducting proteins such as reflectins. The protonic conductivity of such cephalopod proton-conducting proteins may be modulated by the application of an electric field. The invention further encompasses protonic transistors comprising a cephalopod proton-conducting protein channel. The transistors and related devices of the invention are amenable to use in biological systems for the sensing or manipulation of protonic flows within the biological system.