One assignee holds 118 of the 288 records in this dataset, far ahead of the fifth-ranked filer at 10 records. The top five assignees combined account for 73.3% of all 288 records in scope, and the top ten hold 86.1%. This level of concentration means most foundational filter validation and membrane integrity claims are already staked by a small number of long-established filers.

No — filings peaked in 2017 at 35 and have fallen since, with the last complete comparison showing a drop from 23 filings in 2021 to 6 in 2024, a 74% decline. Several of the largest historical filers show zero filings in the most recent tracked year. Figures for 2025 and 2026 are still incomplete because publication typically lags filing by about 18 months, so a full rebound cannot be ruled out, but the multi-year trend through 2024 is clearly downward.

Separation processes under IPC class B01D appear in 52.8% of the 288 records, making membrane and filter housing design the dominant technical theme. But medicinal preparation claims (A61K, 26.7%) and sterilising method claims (A61L, 17.4%) are also common, showing that many patents combine a filtration element with a drug formulation or a sterilizing process rather than claiming filter hardware alone. Material testing methods (G01N, 14.2%) reflect the significant share of the field devoted to validation methodology.

The thinnest coverage relative to the field's core sits in water and wastewater treatment applications (C02F, 5.2% of records) and containers for medicine (A61J, 4.5%), compared with the 52.8% carrying core B01D separation claims. Extractable/leachable profiling and redundant filtration train design also appear comparatively under-claimed given how often they are referenced in validation practice. A first claim in these areas would need to clearly differentiate from the dense B01D and A61L prior art rather than restate it in a new application context.

With 73.3% of 288 records held by five assignees and 86.1% held by ten, this field shows a steep concentration curve: one dominant filer, a handful of mid-sized portfolios, and a long tail of much smaller filers below tenth place. This pattern is typical of a mature, compliance-driven technology area where core validation and integrity-test methods were established early and later filers largely add incremental process or formulation claims around that core.