Hydrogen Leak Sensor Patents: Top Companies & Filing Trends 2026
Filing growth compares 2021 (109 records) with 2024 (103) — 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 1,600 records in scope (CR5), not by the ranked leaders only.
What the hydrogen leak sensor patent record actually covers
Hydrogen leak detection sits at the intersection of gas-storage safety, fuel cell system control and general sensor engineering. The 1,600 records in this dataset span methods for detecting hydrogen escape from tanks, supply lines and fuel cell stacks, plus the pressure, electrochemical and material-analysis techniques used to verify a leak once suspected. Filing is concentrated in testing and analytical method claims rather than in the sensor hardware itself, which tells a reader where the crowded prior art actually sits.
Because a single record often carries several IPC classes, the composition figures below add up to more than the record total — a pressure-decay leak test claim, for instance, can sit in both G01M and F17C at once. Treat the ranking and trend as directional signals for where to search and where filing has slowed, not as a finished map of every company working the problem.
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Filing trend and technology composition
Two views of the same 1,600 records: how filing volume has moved year over year, and how those records split across the IPC subclasses that define the field's technical center of gravity.
Filing rose to a 2023 peak, then held roughly steady
Annual filings climbed from 34 in 2017 to a peak of 129 in 2023. The 2021-to-2024 comparison (109 to 103, a 6% decline) is the fairer read on recent direction, since 2025 and 2026 are still filling in under the usual publication lag — the apparent drop in the newest years is an artifact of timing, not a real retreat.
Testing and analysis classes outweigh fuel-cell hardware
G01M (testing machines and structure balance) leads at 24.9% of the 1,600 records, followed closely by H01M (batteries, cells and fuel cells) at 19.9% and G01N (material analysis and testing) at 19.6%. F17C (pressure vessels and gas storage) trails at 11.2%, with B60L, C25B, C02F and A61L each under 6% — evidence that most claim activity is going into how a leak is verified and measured, not into the storage or propulsion hardware around it.
Shares are the percentage of the 1,600 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
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Try EurekaThe most-cited prior art and a representative recent filing
Fuel cell system and hydrogen leak decision method in fuel cell system
A fuel cell system that shuts a valve on the hydrogen supply flow path during a power-generation halt, then reduces internal pressure to a first value with a pressure reducer while a controller reads a pressure sensor to decide whether a leak is present. The method turns a routine shutdown event into a built-in leak check rather than requiring a dedicated standalone sensor cycle.Filed by Toyota, published 2018-08-16 as US20180233755A1.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US3969077A | Alkali metal leak detection method and apparatus | 201 |
| 2 | US20070274858A1 | Method and system for conducting vapor phase decontamination of sealable entities and their contents | 116 |
| 3 | US20050008908A1 | Portable fuel cartridge for fuel cells | 107 |
| 4 | US6471136B1 | Biosensors for monitoring air conditioning and refrigeration processes | 107 |
| 5 | US20060144700A1 | Apparatus and process for mediated electrochemical oxidation of materials | 104 |
| 6 | US20100193045A1 | Low consumption and intelligent safe gas-supply system for gas tanks | 101 |
| 7 | US20050262943A1 | Apparatus, methods, and systems to detect an analyte based on changes in a resonant frequency of a spring ele… | 95 |
| 8 | US20040256247A1 | Mediated electrochemical oxidation of organic waste materials | 95 |
| 9 | WO2000003426A1 | Methods and apparatus for electropolishing metal interconnections on semiconductor devices | 88 |
| 10 | US20040232007A1 | Mediated electrochemical oxidation of food waste materials | 84 |
Citation counts reward older filings that have had more years to accumulate references — read this table as a map of influential prior art, not a ranking of current technical importance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Browse MCP servers →What the concentration and composition figures mean for filing strategy
The ranking, the trend and the IPC split each point to a different practical decision — who to watch, when to file, and which claim territory is already occupied.
Leadership is real but the field is not locked up
The leading assignee holds 51 records and the fifth-place company holds 22, yet the top five together account for only 11.6% of the 1,600 records in scope. That leaves the large majority of filings spread across a long tail of automakers, gas-handling firms and single-patent entrants — a structure where a well-drafted claim still has room to stand out rather than compete directly against an entrenched leader.
Detection method claims outweigh hardware claims
G01M, H01M and G01N together cover the bulk of filing activity, all clustered around how a leak is measured, tested or chemically verified rather than around the sensor or storage hardware itself. A team filing on a genuinely new transducer or material may find less direct prior art than a team filing on a new test protocol or decision algorithm.
Activity has plateaued near its 2023 peak, not declined
Filings rose steadily to 129 in 2023 before settling to 103 in 2024, a modest 6% pull-back rather than a downturn. Because publication lags filing by roughly 18 months, the lower counts showing for 2025 and 2026 are expected and should not be read as the field cooling.
The US, Europe and PCT routes carry the most filings
The United States leads receiving offices with 397 records, ahead of the EPO at 200 and WIPO/PCT at 159; China, South Korea and India each sit in the 106–133 range. That spread suggests hydrogen leak detection is being protected across multiple major markets in parallel rather than filed primarily for one jurisdiction.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to hydrogen safety & detection: hydrogen leak sensor patent landscape, with the prior art for and against each one.
Where to take this analysis next
The dataset points to specific follow-up questions rather than a single conclusion — use these to decide where a closer read or a freedom-to-operate check is worth the time.
Check the white space in under-claimed branches
C25B, C02F and A61L each sit under 6% of records despite touching plausible hydrogen safety applications — electrolytic production monitoring, water treatment integration and disinfection contexts. A targeted search of these branches against your own claim draft can surface whether the gap is real or simply unindexed.
Explore white space in EurekaWatch the co-filing clusters for signs of joint development
The strongest co-assignee pairing in this dataset appears at a materially higher count than the others, which typically signals a sustained internal R&D partnership rather than a one-off joint filing. Tracking how that pairing's claims evolve year over year can flag where a competitor's next filing is likely to land.
Trace assignee relationships in EurekaRe-run the citation table against your own claim set
The most-cited records in this dataset are older, general-purpose leak and decontamination methods rather than hydrogen-specific sensor art — a reminder that citation volume favours age, not relevance. Running a fresh novelty search against a live claim draft will surface the newer, less-cited filings that actually compete with it.
Run a novelty search in EurekaCommon questions about hydrogen leak sensor patents
The dataset's ranked list of 100 assignees shows a clear leader with 51 records, well ahead of the fifth-placed company at 22 and the tenth at 18. Even so, the top five combined account for only 11.6% of all 1,600 records in scope, so no single company controls the field outright. The remainder of the ranking is a long tail of automakers, gas and industrial-equipment firms, and smaller entrants with just a handful of filings each, which means competitive monitoring needs to look well past the top names to be reliable.
Filings rose from 34 in 2017 to a peak of 129 in 2023, and the fairest recent comparison — 109 filings in 2021 against 103 in 2024 — shows only a 6% pull-back, essentially a plateau rather than a decline. Counts for 2025 and 2026 look lower still, but that reflects the roughly 18-month lag between filing and publication, not reduced activity. Anyone tracking this space should expect the most recent one to two years of published data to fill in upward over time.
Testing and measurement methods dominate: G01M (testing machines and structure balance) covers 24.9% of the 1,600 records, H01M (batteries, cells and fuel cells) covers 19.9%, and G01N (material analysis and testing) covers 19.6%. Pressure vessel and gas storage claims under F17C sit further back at 11.2%, and vehicle propulsion, electrolytic production, water treatment and sterilising applications each account for under 6%. Because records can carry multiple IPC classes, these figures overlap rather than sum to 100%, and they indicate that detection and verification methods are the busiest claim territory, not the storage or fuel cell hardware itself.
This Toyota filing, published 2018-08-16, describes a fuel cell system that uses a valve, a pressure reducer and a pressure sensor to detect a hydrogen leak specifically during a power-generation halt, turning a routine shutdown into a built-in diagnostic check. It matters because it ties leak detection to a specific system state and hardware sequence rather than to a standalone sensor, which narrows what it actually blocks. A team building leak detection that operates during active power generation, or that uses a different sensing modality such as electrochemical or optical detection, is working outside this particular claim scope.
The IPC composition shows C25B (electrolytic production), C02F (water and wastewater treatment) and A61L (sterilising and disinfecting) each sitting at 3.4-3.7% of the 1,600 records, well below the testing and fuel cell classes that dominate filing. These branches touch plausible hydrogen safety use cases — monitoring leaks during electrolytic hydrogen production, or in water-treatment and disinfection settings where hydrogen byproducts occur — but carry comparatively little claim density so far. That gap is worth a closer look before assuming it is crowded, since low filing counts in an adjacent, technically relevant branch often mean the claim space is genuinely open rather than simply unimportant.
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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.