Closed-loop systems and methods for controlling pH. The system includes a working electrode, a counter electrode, a reference electrode, a first ion-sensitive field-effect transistor (ISFET), a second ISFET, and an electronic controller. The working electrode, the counter electrode, the reference electrode, and a first sensing terminal of the first ISFET are immersible in an active solution. A second sensing terminal of the second ISFET is immersible in a reference solution. The electronic controller is configured to apply a first amount of current or voltage to the working electrode and determine a differential voltage between the first ISFET and the second ISFET. The electronic controller is also configured to set a second amount of current or voltage to reduce a difference between the differential voltage and a target voltage. The electronic controller is further configured to apply the second amount of current or voltage to the working electrode.

A water quality measurement apparatus is provided. The apparatus comprises an electrochemical cell, a pH sensor, a temperature sensor, a control circuit, a power source, a database, and a warning device. The electrochemical cell comprises a working electrode, a reference electrode, and a counter electrode. The control circuit provides predetermined adjustable potentials between the reference electrode and the working electrode and measures electrochemical currents between the working electrode and the counter electrode, to form a current diagram based on the predetermined adjustable potentials and the electrochemical currents. The database stores predetermined reference diagrams based on various pH values and temperatures, and is in communication with the control circuit. The warning device is configured to output warnings, wherein the control circuit triggers the warning device in the condition that the current diagram exceeds the predetermined reference diagram based on the same range of the pH values and the temperatures.

A microfluidic pH-stat with a specially-is designed slide and portable device can be used for point-of-care enzyme diagnostics. The slide includes a microchamber and a substrate for the enzyme being tested. The substrate is homogenized with the sample in the microchamber to form a test volume. The microchamber includes a working microelectrode that injects current to split water in the test volume to generate hydrogen ions and/or hydroxide ions and a micro-pH-electrode to measure a pH of the test volume; the slide also includes a reference microelectrode. The device includes a processor to adjust the injected current based on the pH of the test volume and determine an activity of the enzyme based on an amount the injected current is adjusted.

Device and methods for use in a biosensor comprising a multisite array of test sites, the device and methods being useful for modulating the binding interactions between a (biomolecular) probe or detection agent and an analyte of interest by modulating the pH or ionic gradient near the electrodes in such biosensor. An electrochemically active agent that is suitable for use in biological buffers for changing the pH of the biological buffers. Method for changing the pH of biological buffers using the electrochemically active agents. The methods of modulating the binding interactions provided in a biosensor, analytic methods for more accurately controlling and measuring the pH or ionic gradient near the electrodes in such biosensor, and analytic methods for more accurately measuring an analyte of interest in a biological sample.

An embodiment provides a method for measuring an analyte of a sample, including: introducing a sample to a sample region of a measurement device; the measurement device comprising: a measurement electrode and a ground electrode contacting the sample; a low-slope reference electrode in a reference electrode assembly having an electrolyte solution, wherein the electrolyte solution is in contact with the low-slope reference electrode; wherein the electrolyte solution is electrically coupled to the sample via at least one junction; and measuring a first potential between the measurement electrode and the ground electrode; measuring a second potential between the low-slope reference electrode and the ground electrode; determining an analyte in the sample by comparing the first potential and the second potential. Other aspects are described and claimed.

A measuring element is disclosed for an ion-sensitive solid-contact electrode for measuring ion activity in a measurement medium. An ion-sensitive solid-contact electrode having such a measuring element and an electrochemical sensor having such a solid-contact electrode are also disclosed. The measuring element can include an ion-sensitive layer arranged to contact a measurement medium when in operation, and conductive to lithium ions; and a single-phase electrically conductive layer, which includes metallic lithium or a lithium-(0)-alloy. A solid-state electrolyte layer can be arranged between the ion-sensitive layer and the electrically conductive layer.

Various apparatus, systems, and methods for measuring a solution characteristic of a sample comprising microorganisms are disclosed. In one embodiment, a sensor apparatus is disclosed comprising a sample container comprising a sample chamber configured to receive the sample and a reference sensor component comprising a reference conduit having a reference conduit cavity defined therein. The reference conduit cavity can be at least partially filled with a reference buffer gel, buffer solution, or wicking component. A segment of the reference conduit can extend into the sample chamber. A reference electrode material can be positioned at a proximal end of the wicking component or extend partially into the reference conduit cavity. The sensor apparatus can also comprise an active sensor component having an active electrode in fluid contact with the sample. The sample in the sample chamber can be aerated through an aeration port defined along a surface of the sample container.

A half cell for an electrochemical sensor includes: a housing having a chamber, wherein the chamber includes an electrolyte; an electrically conductive lead in contact with the electrolyte; and a closure element connecting the lead to the housing, wherein the lead has a coating, and the coating includes molecules including a first functional group, which enables the molecule to interact chemically with the lead, and a second functional group different from the first functional group, which enables the molecule to interact chemically with the closure element, wherein a first portion of the molecules with the first functional group are in an intermolecular connection with the lead and the first portion of the molecules and/or a second portion of the molecules with the second functional group are in an intermolecular connection with the closure element.

A water pH detection sensor and a use of a ruthenium-iridium electrode as a PH sensing material. The water pH detection sensor includes a ruthenium-iridium electrode and a reference electrode, and the pH value of a solution to be detected is obtained by means of a voltage between the ruthenium-iridium electrode and the reference electrode. The ruthenium-iridium electrode is used as the pH sensing material, the electrode potential of the material in a solution has a good linear correspondingly relationship with a hydrogen ion concentration, and the material has the features of a wide pH value response range, a high response speed, a stable response performance and repeated measurement and use, and is suitable for different practical application scenarios.

An electrochemical detection electrode includes: a plurality of electrode structures; and a plurality of groups of detection structures on the plurality of electrode structures; wherein: the plurality of groups of detection structures include a first group of detection structures and a second group of detection structures, each of the first group of detection structures on one of the plurality of electrode structures having a first shape in a plane parallel to a surface of one of the plurality of electrode structures is configured to combine with a first detection object, each of the second group of detection structures on one of the plurality of electrode structures having a second shape in a plane parallel to a surface of one of the plurality of electrode structures is configured to combine with a second detection object; and wherein the first shape is different from the second shape.