An analyte-sensitive substance is provided that has an optical property related to the concentration of an analyte. The analyte-sensitive substance includes an ionophore or other substance configured to provide a local pH, within the analyte-sensitive substance, that is related to the concentration of the analyte proximate the analyte-sensitive substance. The analyte-sensitive substance further includes a pH-sensitive fluorophore that increases or decreases its intrinsic fluorescence intensity with the local pH across a specified range of pH values. The analyte-sensitive substance further includes a pH-sensitive quencher configured to increase the slope of the change of fluorescence intensity of the pH-sensitive fluorophore across the specified range of pH values. The analyte-sensitive substance may further include an ionic additive configured to adjust the local pH such that the specified range of pH values corresponds to a range of analyte concentration values of interest.

In a sensor unit, a sensor element having an optical behavior that depends on at least one analyte is in diffusive contact with an auxiliary medium, which is present in a reservoir in the sensor unit, via a membrane. The reservoir and the membrane, on the one hand, and sensor element, on the other hand, can be removed from one another in order to place the sensor unit in a measurement state. The auxiliary medium can serve to wet the sensor element during storage of the sensor unit or also for calibrating the sensor element.

A sensor for measuring a pH value of a measuring liquid includes: a sensor element comprising a surface adapted to contact the measuring liquid; a radiation source configured to emit electromagnetic transmission radiation reaching the sensor element, wherein at least a portion of the transmission radiation is converted into measuring radiation by reflection and/or scattering in the region of the surface; a radiation receiver configured to receive the measuring radiation and convert it into electrical signals; and a measuring circuit connected to the radiation receiver and configured to determine a measured value representing the pH value of the measuring liquid from signals of the radiation receiver, wherein the surface adapted to contact the measuring liquid includes a pH-sensitive component and a SERS-active component.

A sensor for measuring a pH value of a measuring liquid includes: a sensor element comprising a surface adapted to contact the measuring liquid; a radiation source configured to emit electromagnetic transmission radiation reaching the sensor element, wherein at least a portion of the transmission radiation is converted into measuring radiation by reflection and/or scattering in the region of the surface; a radiation receiver configured to receive the measuring radiation and convert it into electrical signals; and a measuring circuit connected to the radiation receiver and configured to determine a measured value representing the pH value of the measuring liquid from signals of the radiation receiver, wherein the surface adapted to contact the measuring liquid includes a pH-sensitive component and a SERS-active component.

The present disclosure relates to a pH sensor for determining the pH of an aqueous medium at least comprising a polymeric matrix comprising embedded phosphorescent nanoparticles and one or more embedded fluorescent dyes, wherein the phosphorescent nanoparticles comprise transition metal complexes having central atoms selected from the group consisting of Ru, Re, Os, Rh, Ir, Pt and the fluorescent dye comprises fluorescein derivatives according to the following formula I

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or charged structures thereof, wherein n is greater than or equal to 5 and less than or equal to 20, X═—O—, —OH, —OR.sup.4, —NH.sub.2, —NH— or NHR.sup.4, wherein R.sup.4 is selected from the group consisting of C1-C20 alkyl and the R.sup.1, R.sup.1′, R.sup.2, R.sup.3 are independently selected from the group consisting of H, D, substituted or unsubstituted C1-C20 alkyl and halogen. Furthermore, the present disclosure comprises a method and a system for determining pH.

A system for detecting COVID-19 infection, including a colorimetric sensor, an image-capturing device, and a processing unit connected to the image-capturing device. The colorimetric sensor includes an injection zone and a detection zone patterned on a paper, where the injection zone covers the detection zone by folding the paper. The injection zone is configured to inject a saliva sample acquired from a person thereon. The detection zone includes an array of chemical receptors configured to interact with the injected saliva penetrating into the detection zone. The processing unit is configured to perform a method of capturing a first image from the detection zone before injection of the saliva sample, capturing a second image from the detection zone after injection of the saliva sample, and detecting COVID-19 infection status of the person by analyzing color changes of the array of chemical receptors in the second image respective to the first image.

Disclosed herein is a more sensitive and accurate method of monitoring the pH of a solution, wherein the pH of the solution is quantified as a function of the electrochemical response of the solution in a two or three-electrode electrochemical cell, wherein the solution comprises a compound capable of undergoing a change in its oxidation state and/or structural conformation as a function of the pH of the solution. Also disclosed are highly accelerated methods and processes enabling analysis of specific polynucleotide sequences in a sample, e.g. a biological sample. The methods disclosed herein are, for example, useful for rapid screening of a large amount of samples in a point-of-care setting.

Disclosed herein is a more sensitive and accurate method of monitoring the pH of a solution, wherein the pH of the solution is quantified as a function of the electrochemical response of the solution in a two or three-electrode electrochemical cell, wherein the solution comprises a compound capable of undergoing a change in its oxidation state and/or structural conformation as a function of the pH of the solution. Also disclosed are highly accelerated methods and processes enabling analysis of specific polynucleotide sequences in a sample, e.g. a biological sample. The methods disclosed herein are, for example, useful for rapid screening of a large amount of samples in a point-of-care setting.

A pH photothermal spectrometer includes a container that receives an analyte medium and pH-sensitive chromophore. An excitation fiber and optical thermometer are disposed in the container. The optical thermometer include a light receiver disposed on a temperature detector fiber.

A pH photothermal spectrometer includes a container that receives an analyte medium and pH-sensitive chromophore. An excitation fiber and optical thermometer are disposed in the container. The optical thermometer include a light receiver disposed on a temperature detector fiber.