Liquid Embolic Agent Penetration Depth Control 2026
Liquid Embolic Agent Penetration Depth Control
Non-adhesive liquid embolic agents (NALEAs) face a central challenge: controlling penetration depth to reach target nidus without over-penetrating into draining veins. This dataset maps patent filings from 1998 to 2026 across material formulations, delivery architectures, and procedural techniques.
Controlling Embolic Penetration Depth: Three Converging Axes
Non-adhesive liquid embolic agents — including Onyx, Squid, and PHIL — represent the current standard of care for endovascular embolization of arteriovenous malformations, fistulas, aneurysms, and hemorrhagic conditions. Their non-adhesive character confers critical advantages over cyanoacrylate glues, including reduced catheter entrapment during deployment.
Penetration depth control is pursued through three converging axes in this dataset: material-level engineering of viscosity, gelation kinetics, and phase-change behavior; delivery system architecture that physically contains or zones the embolic front; and procedural technique innovations that use adjunct devices to modulate local hemodynamics.
The extra-low-viscosity PHIL variant was characterized in a porcine rete mirabile model, showing a directional trend toward higher embolization extent compared to standard formulations. DMSO-based agents (Onyx, Squid) and DMSO-free agents (PHIL) each offer controllable embolization characteristics based on injection rate and viscosity grade selection.
In this dataset, innovation is moderately concentrated: Micro Therapeutics / Covidien LP holds the densest patent family cluster with approximately 10 jurisdictional variants of the catheter co-delivery system, while material science innovation is more distributed across academic and startup assignees including Shinshu University, UC Regents, Vellore Institute of Technology, and 3DT Holdings.
Patent Activity Timeline and Jurisdiction Distribution
Patent filings in this dataset span from 1998 to 2026, with distinct waves of activity corresponding to foundational mechanical systems, commercial EVOH product development, and a current shift toward stimulus-responsive biomaterial architectures.
Patent Filings by Jurisdiction — Retrieved Records (Dataset Snapshot)
United States filings account for the largest share of records in this dataset, followed by WO international filings and EP, reflecting the US-centric assignee base of Micro Therapeutics, Covidien, and MicroVention.
↗ Click bars to exploreFiling Activity by Innovation Stage — Retrieved Records (Dataset Snapshot)
In this dataset, the foundational stage (1998–2005) produced the highest filing density driven by Micro Therapeutics, while the active innovation stage (2019–2026) shows renewed activity from academic and startup assignees in stimulus-responsive materials.
↗ Click bars to exploreKey Clinical Applications of Non-Adhesive Liquid Embolic Agents
Retrieved records span four major clinical application domains where penetration depth control is critical: neurovascular intervention, peripheral vascular embolization, oncological transcatheter arterial embolization, and emerging lymphatic intervention.
Neurovascular AVM and DAVF
The largest application domain in this dataset, NALEAs are the primary agents for cerebral AVM and dural arteriovenous fistula embolization, where depth control determines whether the nidus is obliterated without inappropriately embolizing distal venous drainage. Shinshu University’s active hydrogel composition patents explicitly target cerebrovascular diseases including cerebral aneurysm. MicroVention’s expandable containment device is specifically designed for neurovascular treatment sites.
NeurovascularPeripheral Vascular Embolization
EVOH copolymers were evaluated in 43 patients in one institutional series for type II endoleaks (n=18) and peripheral AVMs (n=14), achieving 100% technical success. PHIL was evaluated in 35 patients for non-neurological embolization including visceral arterial bleeding and splanchnic pseudoaneurysms. Cyanoacrylate-lipiodol mixtures remain in use for peripheral applications where polymerization rate control is available.
Peripheral VascularOncology Transcatheter Arterial Embolization
The NIPAM-co-AA thermosensitive nanogel (2023) targets complete embolization of arterial trunks and peripheral vessels with real-time fluoroscopic imaging capability via co-assembled iohexol. Graphene oxide-enhanced polymer hydrogel (GPH) was evaluated in a rabbit model TAE study (2016). PVA/gelatin/iohexol fiber blocks were developed specifically for liver embolization (2022).
Oncology / TAELymphatic Leakage Occlusion
3DT Holdings LLC filed a US patent in 2022 for a temperature-responsive sealant injectable as a low-viscosity liquid via 3 Fr catheter that undergoes heat-induced solidification to create a form-fitted, non-biodegradable occlusion for lymphatic leakage. This emerging application requires precise depth limitation to the site of leakage and represents the only lymphatic-specific filing in this dataset. The patent is currently listed as inactive.
Lymphatic InterventionKey Patent Assignees in Liquid Embolic Depth Control — Retrieved Records (Dataset Snapshot)
In this dataset, Micro Therapeutics / Covidien LP holds the largest patent family by filing volume with approximately 10 jurisdictional variants of the multi-lumen catheter co-delivery system, while Shinshu University holds the most recently granted active material-level patents in retrieved records.
Top Assignees by Filing Count in Retrieved Records (Dataset Snapshot)
↗ Click bars to exploreMicro Therapeutics / Covidien LP
Micro Therapeutics / Covidien LP holds the largest patent family by filing volume in this dataset, with approximately 10 jurisdictional variants of the multi-lumen catheter co-delivery system spanning filings from 1999 (WO, AU, CA) through 2011 and 2016 (US). The technology covers a catheter system in which liquid embolic and solidification agents are co-delivered through independent lumens, with adjustable lumen outlet positions controlling the spatial location of the solidification front. The majority of these filings are now listed as inactive, suggesting freedom-to-operate for catheter developers building on co-delivery architectures.
United StatesShinshu University
Shinshu University holds three active patents in this dataset — one active US patent (filed 2020, granted 2021) and two active EP patents (filed 2020 and 2022) — on hydrogel-based liquid embolic agent compositions using calcium ion-reactive polysaccharides including alginate, gellan gum, and carrageenan combined with anti-biodegradation polymers. These represent the most recently granted active material-level NALEA patents in retrieved records, explicitly targeting cerebrovascular diseases including cerebral aneurysm. All three filings are currently listed as active.
Japan — JPNext-Generation Approaches to Embolic Depth Control (2021–2026)
The most recent filings and publications (2021–2026) in this dataset signal a shift away from EVOH-DMSO paradigms toward stimulus-responsive, aqueous, and operator-controlled solidification architectures, with DMSO elimination identified as an active whitespace across multiple converging material approaches.
Light-Activated On-Demand Solidification
The Vellore Institute of Technology’s IN patent (filed 2026) describes a shear-thinning hydrogel delivered through a catheter and polymerized using optical energy — enabling operator-triggered solidification at a precise anatomical location. This eliminates reliance on ambient physiological conditions (temperature, ion concentration) for gelation timing and represents the most recent filing by date in this dataset. The approach combines catheter-deliverable low-viscosity injectable behavior with photopolymerization via optical energy.
Blood-Ion-Activated Natural Polymer Gels
The UC Regents gellan gum composition (WO 2021, US pending 2023) advances a single-component, aqueous, non-DMSO embolic activated solely by blood calcium ions. High-concentration gellan gum formulations retain sol state during catheter transit and solidify upon blood contact, eliminating organic solvent toxicity — a known EVOH limitation — while providing depth control through gelation kinetics. Shinshu University’s parallel ion-triggered compositions using alginate, gellan gum, and carrageenan represent a complementary approach with currently active granted patents.
Multi-Lumen Catheter Co-Delivery vs. Stimulus-Responsive Material Architectures
Click any row to explore further.
| Dimension | Multi-Lumen Catheter Co-Delivery (Micro Therapeutics / Covidien) | Stimulus-Responsive Materials (Shinshu Univ. / UC Regents) |
|---|---|---|
| Depth Control Mechanism | Operator adjusts longitudinal position of dual lumen outlets to spatially control solidification front location | Solidification triggered by physiological stimulus (calcium ions, temperature, light) at target anatomy |
| Primary Agent Class | Any liquid embolic (EVOH, copolymer) co-delivered with a separate solidification agent | Hydrogel-forming polysaccharides (alginate, gellan gum, carrageenan) or thermoresponsive copolymers |
| DMSO Requirement | Compatible with DMSO-based agents (Onyx, Squid); DMSO toxicity not addressed by the delivery system | Aqueous or non-DMSO carrier; eliminates organic solvent toxicity as a design objective |
| Patent Status (Dataset) | Predominantly inactive — foundational filings from 1999–2005 are largely lapsed in retrieved records | Active — Shinshu University holds 1 active US and 2 active EP patents; UC Regents has 1 pending US application |
| Filing Date Range | WO 1999, AU 1999, CA 1999, EP 2000, US 2003, 2005, 2011, 2016 | US filed 2020 (granted 2021), EP filed 2020 and 2022 (active), WO 2021, US pending 2023 |
| Freedom to Operate | High — majority of foundational filings are now inactive, suggesting freedom-to-operate for catheter developers | Limited at material level — active Shinshu University patents cover calcium ion-reactive polysaccharide compositions |
| Clinical Validation | Commercially deployed EVOH systems (Onyx, Squid) evaluated in multiple clinical series and comparative reviews | Preclinical stage — porcine and rabbit model evaluations; no large clinical series in retrieved records |
Frequently Asked Questions: Liquid Embolic Agent Penetration Depth Control
The core non-adhesive agents documented across retrieved clinical literature are EVOH-based: Onyx (ethylene vinyl alcohol dissolved in DMSO), Squid (a related EVOH formulation at lower viscosity), and PHIL (precipitating hydrophilic injectable liquid — a non-DMSO, iodine-covalently-bonded copolymer). The extra-low-viscosity PHIL variant was specifically characterized for its penetration profile in the porcine rete mirabile model.
Lower viscosity grades (Squid 12, PHIL 25% low viscosity, PHIL extra-low-viscosity) penetrate more distally, while higher viscosity formulations are used where proximal occlusion is preferred. The 2018 porcine rete mirabile study documented comparable embolization extents across PHIL 25% standard, PHIL 25% low viscosity, and Squid 12, with a directional trend toward deeper penetration with extra-low-viscosity PHIL.
Among material-level NALEA patents in this dataset, only Shinshu University (JP) holds currently active granted patents — one active US patent (filed 2020) and two active EP patents (filed 2020 and 2022) — on hydrogel-based liquid embolic compositions using calcium ion-reactive polysaccharides. The University of California Regents has one pending US application (2023) on a gellan gum-based natural polymer composition.
The foundational Micro Therapeutics / Covidien multi-lumen catheter family, which spans filings from WO/AU/CA 1999 through US 2003, 2005, 2011, and 2016, is now predominantly inactive in retrieved records. This suggests freedom-to-operate for catheter system developers building on co-delivery or multi-lumen architectures.
The most recent filing in this dataset is the Vellore Institute of Technology’s IN patent filed in 2026, which describes a system for light-activated, shear-thinning hydrogel-based vascular embolization. The hydrogel is delivered through a catheter and polymerized using optical energy, enabling operator-triggered solidification at a precise anatomical location without reliance on ambient temperature or ion concentration.
No. Procedural technique innovations including the coil-protected technique, dual-lumen balloon catheter approaches (evaluated in a 2015 swine study), and two-microcatheter techniques for flow modulation (2014 publication) are described in clinical literature within this dataset without associated patent filings. This suggests an opportunity for device-enabled formalization of these techniques into protectable system claims.
Data and insights on this page are based on a limited patent and literature dataset and are for reference only. Figures may not represent the complete technology landscape.