The assignee ranking covers 100 companies drawn from the 1,032 records in scope, and filings are concentrated at the top: the five leading assignees together hold 315 records, or 30.5% of the total, and the ten leading assignees hold 440 records, or 42.6%. The single leader alone accounts for 109 records. Beyond the leaders there is a long tail of single- and few-filing entrants, so a freedom-to-operate search should weight the leading portfolios heavily but not ignore the tail entirely.

US11278827B2, assigned to EMD Millipore Corporation and granted in 2022, covers single-pass tangential flow filtration with optional partial recirculation of retentate through the same system. It does not claim tangential flow filtration in general — a conventional multi-pass batch process or a single-pass system with zero recirculation falls outside its literal claim language. Anyone evaluating exposure should check specifically whether their process recirculates any fraction of retentate back through the same membrane pass, since that is the operative fact pattern in the claims.

Wastewater and water-treatment applications of crossflow filtration (C02F, 6.5% of the 1,032 records) and body-fluid device applications (A61M, 6.1%) both appear in the corpus but at far lower density than the pharmaceutical-manufacturing core built on B01D and C12N classes. That gap does not mean the technology is unproven — it means fewer claims have been staked there, which is where a narrowly scoped first claim is more likely to clear prior art than in the crowded retentate-recirculation space.