Sensor for measuring a PH value

Patent metadata

Field	Value
Publication number	US-12546740-B2
Application number	US-202218047833-A
Country	US
Kind code	B2
Filing date	Oct 19, 2022
Priority date	Oct 20, 2021
Publication date	Feb 10, 2026
Grant date	Feb 10, 2026

Abstract

A sensor for measuring a pH value of a measuring liquid includes: a sensor element including a surface adapted to the measuring liquid; a radiation source configured to emit electromagnetic transmission radiation to the sensor element, wherein at least a portion of the transmission radiation is converted into measurement radiation by reflection and/or scattering in a region of the surface; a radiation receiver configured to receive the measurement radiation and convert it into electrical signals; and a measuring circuit configured to determine the pH value from signals, wherein a wavelength of at least a portion of the transmission radiation generates charge carriers in at least a surface region or a near-surface region of the surface of the sensor element as to effect a photoelectrochemical reaction with formation of hydrogen at the surface.

First claim

The invention claimed is:

1 . A sensor for measuring a pH value of a measuring liquid, the senor comprising:
a sensor element, which includes a first surface adapted to contact the measuring liquid; at least one radiation source configured to emit electromagnetic transmission radiation incident on the sensor element, wherein at least a portion of the transmission radiation is converted into measurement radiation in a region of the first surface by reflection and/or scattering; at least one radiation receiver configured to receive the measurement radiation and convert the measurement radiation into electrical signals; and a measuring circuit connected to the radiation receiver, the measuring circuit configured to determine a measured value representing the pH value of the measuring liquid based on the electrical signals of the radiation receiver, wherein the sensor element is configured such that a wavelength of at least a portion of the transmission radiation generates charge carriers in at least one surface region or a near-surface region of the first surface adapted to contact the measuring liquid to effect a photoelectrochemical reaction with formation of hydrogen in the measuring liquid adjacent the first surface adapted to contact the measuring liquid.

2 . The sensor of claim 1 , wherein the surface region comprises a metal or a metal alloy that binds atomic hydrogen and/or molecular hydrogen to form a metal hydride.

3 . The sensor of claim 2 , wherein the metal or metal alloy comprises at least one element of the group 8-10 (VIIIB) or the group 11 (IB) of the periodic table of the elements.

4 . The sensor of claim 2 , wherein:
the sensor element comprises a first layer, comprising the metal or the metal alloy, and a second layer disposed directly adjacent the first layer; the first layer defines the first surface adapted to contact the measuring liquid; and the second layer comprises a first semiconductor material.

5 . The sensor of claim 4 , wherein the semiconductor material is a metal oxide selected from d 0 -metal oxides, d 10 -metal oxides, complex metal oxides, perovskites, silicon oxide, germanium oxide, and III/IV or II/VI semiconductors, either intrinsically or doped.

6 . The sensor of claim 4 , wherein the first semiconductor material includes a doping, and wherein the sensor element further comprises a third layer formed of a doped second semiconductor material disposed between the first layer and the second layer such that a p-n junction is formed between the second layer and the third layer.

7 . The sensor of claim 4 , wherein the first semiconductor material includes a doping, and wherein the sensor element further comprises a third layer formed of a doped second semiconductor material disposed on a side of the second layer, the side facing away from the first layer, such that a p-n junction is formed between the second layer and the third layer.

8 . The sensor of claim 7 , wherein the first semiconductor material and the second semiconductor material are the same type of semiconductor material but with different doping.

9 . The sensor of claim 2 , wherein the sensor element comprises a plurality of semiconductor nanoparticles, which are doped and form quantum dots, and wherein the semiconductor nanoparticles are at least partially surrounded by the metal or the metal alloy.

10 . The sensor of claim 9 , wherein the plurality of semiconductor nanoparticles each form a core of a core-shell structure that includes a shell, wherein the shell comprises the metal or the metal alloy.

11 . The sensor of claim 10 , wherein the plurality of semiconductor nanoparticles are configured as nanorods, each including a first end and a second end opposite the first end,
wherein a portion of the nanorods comprising the first end is enveloped by a first layer comprising the metal or metal alloy, and the second end is covered by a second layer comprising a doped semiconductor material such that a p-n junction is formed between the second end of the nanorods and the second layer.

12 . The sensor of claim 2 , wherein the sensor element comprises at least first semiconductor nanostructures and second semiconductor nanostructures, each of which is at least partially covered by a layer comprising the metal or metal alloy such that the layer defines the first surface adapted to contact the measuring liquid, and
wherein the first semiconductor nanostructures have a different geometry and/or chemical composition and a different bandgap than the second semiconductor nanostructures.

13 . The sensor of claim 12 , wherein the at least one radiation source is configured to emit transmission radiation of different wavelengths, and
wherein the at least one radiation source is further configured to emit transmission radiation of:
a first wavelength selected to excite the first semiconductor nanostructures as to generating free charge carriers, and
a second wavelength different from the first wavelength and selected to excite the second semiconductor nanostructures as to generate free charge carriers.

14 . The sensor of claim 2 , wherein the sensor element comprises a first layer, comprising the metal or the metal alloy, and a second layer disposed directly adjacent the first layer,
wherein the second layer includes individual regions, comprising at least one doped semiconductor material, which are electrically insulated from each other by intervening regions comprising an electrically-insulating material.

15 . The sensor of claim 14 , wherein the individual regions of the second layer each comprise a first partial layer, directly adjoining the first layer and comprising a first doped semiconductor material, and a second partial layer, comprising a second doped semiconductor and disposed on a side of the first partial layer, which side faces away from the first layer, such that a p-n junction is formed between the first partial layer and the second partial layer.

16 . The sensor of claim 2 , wherein the sensor element includes a top first layer, comprising the metal or the metal alloy, and a coating which is disposed below the first layer and is transparent at least to a portion of the transmission radiation and/or at least to a portion of the measurement radiation, wherein the transparent coating comprises an electrically-conductive material.

17 . The sensor of claim 16 , wherein the transparent coating comprises a transparent and conductive oxide.

18 . The sensor of claim 16 , further comprising:
an auxiliary electrode adapted to contact the measuring liquid; and a voltage source configured to apply a voltage between the transparent coating and the auxiliary electrode.

19 . The sensor of claim 2 , wherein the sensor element comprises a top first layer of the metal or the metal alloy, and a second layer disposed directly below the first layer, wherein the second layer comprises a material switchable between a state transparent to the transmission radiation and a state reflective to the transmission radiation.

20 . The sensor of claim 1 , wherein the sensor element in the surface region includes a photosensitizer operative for formation of electron hole pairs in semiconductor materials, the band gaps of which are too large for direct excitation with the transmission radiation.

21 . The sensor of claim 20 , wherein the photosensitizer is selected from metal porphyrins, metal phthalocyanines, BODIPY, thiazines, phenazines, xanthenes, acridines and triphenylmethy

Assignees

• Endress Hauser Conducta Gmbh Co Kg

Inventors

• Wilhelm Thomas
• Löbbert Andreas
• Speck Matthäus

Classifications

• G01N27/302

  pH sensitive, e.g. quinhydron, antimony or hydrogen electrodes (ion selective electrodes G01N27/333, glass electrodes G01N27/36) · CPC title

• G01N27/4167

  pH (electrodes therefor G01N27/302, G01N27/36) · CPC title

• G01N27/305 Primary

  optically transparent or photoresponsive electrodes · CPC title