# US 11,307,163 B2 · Carbon nanotube based reference electrodes and all-carbon electrode assemblies for sensing and electrochemical characterization

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- Number: US 11,307,163 B2
- Document ID: US11307163B2
- Status: Granted
- Kind: B2
- Application number: 15/625,249
- Filed: 2017-06-16
- Published: 2017-12-21
- Granted: 2022-04-19
- Earliest claimed: 2016-06-16
- Assignees: University of Cincinnati
- Applicants: University of Cincinnati
- Inventors: Noe Alvarez; Daoli Zhao, I; William Heineman; Vesselin Shanov; David Siebold
- Web page: https://patentgrep.com/patent/US11307163B2

## CPC

- G01N 27/308: {at least partially made of carbon}
- C01B 32/158: Carbon nanotubes
- C01B 32/162: characterised by catalysts
- C23C 14/0694: {Halides}
- C23C 16/08: from metal halides
- D01F 9/12: Carbon filaments; Apparatus specially adapted for the manufacture thereof
- G01N 27/42: Measuring deposition or liberation of materials from an electrolyte; Coulometry, i.e. measuring coulomb-equivalent of material in an electrolyte
- C01B 2202/36: Diameter
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- D01F: CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS

## Abstract

A carbon nanotube-based reference electrode and an all-carbon nanotube microelectrode assembly for electrochemical sensing and specialized analytics are disclosed, along with methods of manufacture, and applications including detection of ionic species including heavy metals in municipal and environmental water, monitoring of steel corrosion in steel-reinforced concrete, and analysis of biological fluids.

## Claims

### Claim 1

An electrode assembly for electrochemical sensing, the electrode assembly comprising:
a reference electrode comprising a core portion and a plating on an exterior of the core portion,
the core portion comprising an aligned assembly of carbon nanotube fibers;
each carbon nanotube fiber having a diameter of at least 10 micrometers and comprising a plurality of carbon nanotubes spun together;
the core portion being metal free and binder free; and
the plating being an Ag/AgCl plating.

### Claim 2 (depends on 1)

The electrode assembly of claim 1, further comprising a working electrode, an auxiliary electrode, or both a working electrode and an auxiliary electrode, wherein the working electrode when present and the auxiliary electrode when present comprise a core consisting of substantially pure carbon nanotubes.

### Claim 3 (depends on 2)

The electrode assembly of claim 2, wherein the working electrode comprises an insulating coating on the core.

### Claim 4 (depends on 3)

The electrode assembly of claim 3, wherein the insulating coating comprises a polymer coating.

### Claim 5 (depends on 4)

The electrode assembly of claim 4, wherein the polymer coating comprises a polystyrene coating.

### Claim 6 (depends on 1)

The electrode assembly of claim 1, wherein the Ag/AgCl plating is applied to the CNT core by electrochemical deposition, Physical Vapor Deposition (PVD) or Chemical Vapor Deposition (CVD).

### Claim 7 (depends on 1)

The electrode assembly of claim 1, wherein each carbon nanotube fiber has a diameter from 30 micrometers to 40 micrometers.

### Claim 8 (depends on 1)

A method for detection and/or quantitative determination of one or more ionic species in a sample, the method comprising use of the electrode assembly according to claim 1 in an anodic stripping voltammetry (ASV) analysis of the sample.

### Claim 9 (depends on 1)

The method according to claim 1, wherein the one or more ionic species comprises heavy metal ionic species selected from one or more of Hg2+, Cu2+ and Pb2+, Cd2+, and Zn2+ and detection and/or quantitative determination comprises individual or simultaneous analysis.

### Claim 10 (depends on 8)

The method according to claim 8, wherein the sample comprises municipal water, environmental water, or is derived from a hard surface.