The assignee ranking behind this search returns 32 companies and institutions, and it is heavily concentrated: the top five combined account for 88.8% of the 241 records in scope, and the top ten reach 93.8%. That means most of the activity sits with a small handful of filers, with the remainder made up of single-filing entrants rather than a broad competitive field. Anyone assessing freedom to operate should focus diligence on that small leading group first, since the long tail contributes comparatively little filing volume.

Filing volume in this exact search peaked in 2021 at 59 records and fell to 4 by 2024, a -93% change over that span, which is the most recent period that can be treated as complete data. Because publication typically lags filing by around 18 months, the years after 2024 are still filling in and should not be read as a genuine slowdown yet. The honest read is that the burst of activity around 2018-2021 has largely run its course on this specific claim combination, and it is too early to say whether a new wave is forming.

A61K, medicinal preparations, appears in 80.5% of the 241 records, and A61P, therapeutic activity of compounds, in 63.9%, meaning most claims are framed around formulation and biological activity rather than pigment or dye chemistry in the classical sense. Microorganism and genetic-engineering classifications (C12N, C12R) also show meaningful presence, at 27.0% and 10.4% respectively. Because a single record can carry several IPC classes, these figures add up to more than 100% and should not be read as mutually exclusive categories.

The thinnest classes in scope are C08L (polymer compositions) at 3.7% of the 241 records and C07K (peptides & proteins) at 5.8%, both well below the dominant A61K and A61P classes. That gap suggests formulation work tying a colorant or active compound to a specific polymer carrier, with a stated additive concentration or purity limitation, is claimed far less densely than the core preparation itself. Co-assignee filing is also thin across the whole dataset at only 9 pairs, so a new filer in these branches is unlikely to be competing against an entrenched joint-filing position.

US20100068740A1, assigned to Trustees of Tufts College and filed 2010-03-18, claims a specific method of building a cylindrical microchannel in a polymer body by casting an uncured polymer matrix, embedding a rod, curing, then extracting the rod, plus a variant adding an optical surface feature. With 115 citations, and its near-identical priority filing WO2008127405A2 at 114, it sits among the most-cited records in this corpus, indicating a large share of later fabrication-method filings build on this exact sequence. Design-arounds generally require a different channel-forming process, such as sacrificial-material dissolution or lithographic patterning, rather than rod embedding and extraction.