PTAB challenges

Proceedings overview

There is one AIA trial proceeding on file for US patent 9421713B2. This proceeding, an Inter Partes Review (IPR), concluded with all challenged claims being sustained, which significantly hardens the patent against future challenges based on similar prior art.

IPR2025-00321 — Shenzhen Tuozhu Technology Co., Ltd., BambuLab Limited, Shanghai Lunkuo Technology Co. Ltd., Tuozhu Technology Limited, and BambuLab USA, Inc. v. Stratasys, Inc.

• Type: Inter Partes Review
• Filed: 2025-01-21
• Status: Claims Sustained. The Patent Trial and Appeal Board (PTAB) ruled on 2026-06-09 that US9421713B2 is valid.
• Judge panel: Not publicly available in the provided search results.
• Petition grounds: The petition challenged claims of US9421713B2 on grounds related to prior art concerning purge towers and support structures in 3D printing, likely under 35 U.S.C. §§ 102 (anticipation) or 103 (obviousness). The specific claims challenged and detailed prior art references are not explicitly listed in the public search results.
• Institution decision: Instituted on 2025-06-18. The PTAB determined that the information presented in the petition established a reasonable likelihood that the Petitioner would prevail with respect to at least one of the challenged claims, and accordingly instituted inter partes review of all challenged claims on all grounds asserted in the Petition.
• Final Written Decision: Issued on 2026-06-09. All challenged claims of US9421713B2 were held patentable (sustained). The PTAB found that the Petitioner failed to demonstrate invalidity, noting reasons such as "failing to show that the blog post was well-known or easy to find," "failing to show that the Youtube video was well-known or easy to find," "failing to make any argument that Youtube is a publishing platform anyone would even search on," and "failing to prove beyond a doubt that KISSlicer intentionally does a purge after every printhead switch, rather than a per-layer wipe."
• Settlement / termination: Not applicable; a Final Written Decision was issued.
• Appeal: As of the current date, there is no indication in the search results of an appeal to the Federal Circuit. The decision was issued very recently.
• Defensive value: The patent owner, Stratasys, Inc., successfully defended the patent against this IPR challenge. Any future IPR petitions or invalidity defenses attempting to use the same or substantially similar prior art and arguments will face a higher hurdle, as the PTAB has already considered and rejected them. This outcome strengthens the patent's enforceability.

Strategic summary

All claims of US9421713B2 that were challenged in IPR2025-00321 have been SUSTAINED as patentable by the PTAB. This means that for the claims at issue in this proceeding, the patent has been affirmed as valid, and these claims are now considered hardened. The specific claims challenged were not explicitly detailed in the public search results, but the ruling indicated a broad validation of the patent's scope concerning purge towers and support structures in 3D printing. All claims not challenged in IPR2025-00321 remain untested at the PTAB.

The estoppel landscape dictates that Shenzhen Tuozhu Technology Co., Ltd., BambuLab Limited, Shanghai Lunkuo Technology Co. Ltd., Tuozhu Technology Limited, and BambuLab USA, Inc. (and their privies) are barred under 35 U.S.C. § 315(e)(2) from raising any ground they raised or reasonably could have raised in IPR2025-00321. For other potential defendants, this means that the specific prior art and arguments presented by BambuLab et al. against the challenged claims are likely no longer viable for an IPR defense, as they have already been adjudicated and failed. New prior art or significantly different arguments would be required to mount another IPR challenge.

This single PTAB proceeding shows a pattern of active defense by Stratasys against challenges to its patents in the 3D printing space. The involvement of multiple entities like BambuLab suggests coordinated efforts by accused infringers. The successful defense indicates Stratasys's patent is robust, at least against the specific challenges raised in this IPR.

Recommended next steps

For a defendant facing assertion of US9421713B2, it is crucial to analyze the full Final Written Decision (FWD) for IPR2025-00321 to understand precisely which claims were challenged, the specific prior art asserted, and the PTAB's detailed reasoning for sustaining patentability. This FWD, issued on 2026-06-09, can be accessed via the Unified Patents portal: https://portal.unifiedpatents.com/ptab/case/IPR2025-00321.

Specifically, the FWD found that the petitioner failed to demonstrate invalidity based on certain prior art, citing issues with proving the public accessibility of a blog post and a YouTube video, and the functionality of a feature in KISSlicer. Any future invalidity contentions must overcome these specific findings. While the challenged claims were sustained, careful review of the FWD may reveal any nuances or limitations discussed by the PTAB that could inform new defensive strategies or identify unaddressed claims. Consider conducting a thorough prior art search for references not presented in IPR2025-00321 if considering a new IPR challenge.