Ion-Selective Water Sensor Patents: Who Leads, Where the Gaps Are 2026
- Filing has cooled sharply. from 12 families in the 2021 peak to 1 in 2024, a 92% drop over that span, though 2025-26 counts are still filling in due to publication lag.
- The field is moderately concentrated. the top 5 assignees hold 30.3% of all 261 records and the top 10 hold 44.8%, leaving a long tail of single- and few-filing entrants.
- Almost everything sits under one IPC class. G01N material analysis & testing covers 95.4% of records, while water/wastewater treatment (C02F) and body-fluid devices (A61M) each sit under 4%.
Filing growth compares 2021 (12 records) with 2024 (1) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 261 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
This dataset tracks 261 patent records published between 2015 and mid-2026 that combine ion-selective electrode or electrochemical water sensor claims with technical qualifiers such as membrane selectivity, reference electrode drift, temperature compensation and matrix interference. That combination narrows the field to sensor engineering problems rather than the broader universe of electrochemistry patents, so the records here concentrate on the practical failure modes — drift, response time, electrode lifetime — that determine whether a sensor design survives field deployment.
Filings peaked in 2021 and have declined since, a pattern consistent with a technology whose core claim space has already been staked out by an earlier generation of instrument and clinical-diagnostics companies. Japan, the United States and Europe are the dominant receiving offices, reflecting where the founding assignees are based rather than where deployment is concentrated today.
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Filing trend and technology composition
Two views of the same 261 records: how filing activity has moved year over year, and which IPC subclasses the claims fall into.
Filing trend, 2017-2026
Filings ran near 9-12 per year through the late 2010s and into the 2021 peak, then fell to 1 by 2024 — a -92% move over that three-year span. Treat 2025 and 2026 as incomplete: publication typically lags filing by about 18 months, so the true recent trend is understated.
IPC subclass composition
G01N (material analysis & testing) covers 95.4% of the 261 records, confirming this is fundamentally a measurement-and-testing landscape. Smaller but recurring clusters sit in diagnosis/surgery (A61B, 6.1%), separation processes (B01D, 4.6%) and body-fluid devices (A61M, 3.8%) — each a possible adjacent-use angle rather than a core claim area.
Shares are the percentage of the 261 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Ion-Selective and Electrochemical Water Sensors with Eureka
This page is one run against one query. Ask Eureka your own question about ion-selective and electrochemical water sensors and every answer comes back with the patent numbers behind it.
Try EurekaMost-cited records in the corpus
Metal-free buffer for ion selective electrode-based assays (US5174872A)
A heavy metal-free composition and its method of use in an ion selective electrode-based assay are disclosed. The composition includes a borate compound and an alkalinity adjusting compound, and is used to dilute and buffer a test sample while substantially reducing the effects of interferents on the ion selective electrode-based assay. It is especially useful for carbonate ion concentration testing in blood serum, blood plasma, urine or cerebrospinal fluid.Filed by Technicon Instruments Corporation, granted 1992 — one of the corpus's most-cited records and a useful lens on how buffer-composition claims were staked out around ion-selective assays.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US5001417A | Apparatus for measuring electrolytes utilizing optical signals related to the concentration of the electrolyt… | 165 |
| 2 | US4340457A | Ion selective electrodes | 85 |
| 3 | US6780307B2 | Ion selective electrodes for direct organic drug analysis in saliva, sweat, and surface wipes | 50 |
| 4 | US5174872A | Metal-free buffer for ion selective electrode-based assays | 50 |
| 5 | JP1977142584A | Ion selective electrode | 36 |
| 6 | US5629212A | Chloride monitoring apparatus | 33 |
| 7 | US20030121779A1 | Ion selective electrodes for direct organic drug analysis in saliva, sweat, and surface wipes | 32 |
| 8 | US5344547A | Polycrystalline ion selective electrode | 32 |
| 9 | US20070045128A1 | Chlorine dioxide sensor | 31 |
| 10 | US5102527A | Calcium ion selective electrode | 31 |
Citation counts favour older records simply by virtue of having had longer to accumulate citations inside this corpus; read them as a signal of influence on later filings, not as a measure of current importance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Three read-throughs from the filing trend, the concentration figures and the IPC composition.
The peak has passed, on the data available so far
Filings fell from 12 in 2021 to 1 in 2024. That is the most recent year that can be read as complete; 2025 and 2026 will fill in as publications catch up, so this should be read as a marked slowdown from peak rather than a final verdict on where the field is headed.
Moderate concentration, long tail beneath it
The top 5 ranked assignees hold 30.3% of all 261 records and the top 10 hold 44.8%, with the leader at 22 records. That leaves well over half the field spread across a long tail of smaller filers — room for a new entrant to build a position without displacing an entrenched leader.
One IPC class dominates; the rest are thin adjacencies
G01N (material analysis & testing) appears on 95.4% of the 261 records. Water/wastewater treatment (C02F) and instrument-detail claims (G12B) each sit near 3-4%, suggesting the field's growth options lie in these smaller adjacent classes rather than in G01N itself, which is already densely claimed.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to ion-selective and electrochemical water sensors, with the prior art for and against each one.
Who is filing, and where the gaps sit
The ranked assignee list spans instrument makers, clinical-diagnostics firms and a handful of water-treatment and defence-affiliated filers. Recent-year momentum across the leading names is flat.
A diagnostics-instrument incumbent sits at the top
The leading assignee holds 22 of the 261 records, well ahead of fifth place at 10 and tenth place at 7 — a gap consistent with an early, sustained filing programme rather than a recent surge.
The historic leaders have gone quiet recently
Every one of the top-named assignees shows zero filings in the latest tracked year. That is partly a publication-lag artefact, but it also matches the broader filing decline and suggests the incumbents are not currently pressing new claims in this space.
Collaboration is limited and largely intra-group
Only 8 co-assignee pairs appear in the corpus, and the strongest ones link a parent company to its own subsidiaries or affiliated labs rather than cross-company joint filings. This points to a field where most development happens inside a single organisation rather than through formal partnerships.
| Assignee | Recent year | YoY |
|---|---|---|
| FUJIFILM Holdings Corporation | 0 | — |
| Toshiba Corporation | 0 | — |
| Hitachi, Ltd. | 0 | — |
| Beckman Coulter, Inc. | 0 | — |
| EcoWater Systems LLC | 0 | — |
| TECHNICON INSTRUMENTS CORP | 0 | — |
| Abbott Laboratories | 0 | — |
| BetzDearborn Inc. | 0 | — |
Where to take this analysis
The trend and concentration figures point to where claim space is crowded and where it is thin. The next step is usually a closer read of the specific claims in the busiest classes.
Map the white space precisely
Run the under-claimed sub-areas — membrane formulation, drift compensation, matrix-interference correction — against the full claim text of the leading assignees' portfolios to confirm where a first claim would actually be novel.
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Zero recent filings from the historic leaders does not mean zero activity; it may mean filings are still working through publication lag. Set up monitoring on the leading assignees to catch new filings as they publish.
Set up assignee tracking in Eureka →Common questions about this landscape
The leading assignee in this 261-record dataset holds 22 records, noticeably ahead of the fifth-ranked filer at 10 and the tenth-ranked filer at 7. The names at the top are dominated by diagnostic-instrument and analytical-equipment companies rather than water-utility or environmental firms, reflecting the field's roots in clinical and laboratory electrochemistry. The top 5 assignees together account for 30.3% of all 261 records, and the top 10 account for 44.8%, so more than half the field is spread across a long tail of smaller filers.
Filings peaked in 2021 at 12 records and had fallen to 1 by 2024, a drop of 92% over that three-year span. That decline is real, but 2025 and 2026 figures should not yet be read as confirming a continued fall, since publication typically lags actual filing by about 18 months and those recent years are still filling in. The honest read is a marked slowdown from a 2021 peak rather than a technology in active decline today.
The overwhelming majority — 95.4% of the 261 records in scope — carry the G01N classification for material analysis and testing, which is the natural home for sensor and measurement claims. Smaller but recurring secondary classes include A61B (diagnosis and surgery, 6.1%), B01D (separation processes, 4.6%) and A61M (devices for body fluids, 3.8%), reflecting how ion-selective electrode technology crosses into clinical and filtration applications. Because a single record can carry several IPC codes, these shares add up to more than 100% and should not be summed.
US5174872A covers a heavy metal-free buffer composition — a borate compound plus an alkalinity adjusting compound — used to dilute and buffer test samples while reducing interferent effects in ion-selective electrode assays, with particular reference to carbonate ion testing in biological fluids. It is one of the most-cited records in this corpus, which signals strong influence on later buffer-composition filings rather than current market dominance, since the patent dates to 1992 and its core term has long since expired. Anyone designing a buffer system for ISE assays should still review its claim language closely, because later filings in the space frequently reference it as prior art.
The clearest gaps sit in adjacent, thinly claimed IPC classes rather than in the dominant G01N core: water and wastewater treatment applications (C02F, 3.4% of records), polymer membrane formulation work (C08J, 3.1%), and instrument-detail refinements (G12B, 3.4%) are all represented well below the core measurement claims. Reference electrode drift compensation and matrix-interference correction are specific technical problems named in the search criteria that remain candidates for narrower, defensible claims. A freedom-to-operate search focused on these smaller classes is more likely to surface open space than one aimed at G01N itself.
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Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.