Prosecution Insights
Last updated: April 19, 2026
Application No. 18/289,373

HOLLOW-FIBRE MEMBRANE FILTER HAVING IMPROVED SEPARATION PROPERTIES

Non-Final OA §103§112
Filed
Nov 03, 2023
Examiner
KEYWORTH, PETER
Art Unit
1777
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Fresenius Medical Care
OA Round
1 (Non-Final)
58%
Grant Probability
Moderate
1-2
OA Rounds
3y 5m
To Grant
82%
With Interview

Examiner Intelligence

Grants 58% of resolved cases
58%
Career Allow Rate
447 granted / 775 resolved
-7.3% vs TC avg
Strong +24% interview lift
Without
With
+23.9%
Interview Lift
resolved cases with interview
Typical timeline
3y 5m
Avg Prosecution
47 currently pending
Career history
822
Total Applications
across all art units

Statute-Specific Performance

§101
0.9%
-39.1% vs TC avg
§103
50.9%
+10.9% vs TC avg
§102
14.9%
-25.1% vs TC avg
§112
28.5%
-11.5% vs TC avg
Black line = Tech Center average estimate • Based on career data from 775 resolved cases

Office Action

§103 §112
Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Claim Rejections - 35 USC § 112 The following is a quotation of 35 U.S.C. 112(b): (b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention. The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph: The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention. Claim 11 recites the limitation "the first and second end cap." There is insufficient antecedent basis for this limitation in the claim. Claim 12 recites the limitation "the first and second end cap." There is insufficient antecedent basis for this limitation in the claim. Claim Rejections - 35 USC § 103 The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. Claim(s) 1-12 and 15-20 is/are rejected under 35 U.S.C. 103 as being unpatentable over Baurmeister et al. (US 4,724,900 in IDS). Regarding claim 1, Baurmeister teaches a hollow fiber membrane comprising a cylindrical housing (2) having a first and second end region, a plurality of hollow fiber membranes (4) arranged in the housing embedded in a sealing compound/potting compound as claimed, first inflow/outflow spaces (13), second inflow/outflow spaces (7), seals (8 9 11), and passage openings (10) as claimed (Figs. 1-5 and C4/L4-C5/L21). It is noted that Baurmeister would inherently have a ratio of the sum of the flow cross sections as defined by Applicant’s specification [0018] (sum of the surface areas of all individual passage openings) to the flow cross section of the second inflow/outflow spaces as defined in Applicant’s specification [0019] and parallel lines in Fig. 1b. However, Baurmeister does not teach the size and amount of passage openings or the size of the second inflow/outflow spaces and thus the ratio as defined above cannot be calculated. It is Examiner’s position that given the close structural design between Baurmeister and the present invention as well as the broad teachings of Baurmeister (at least one port 10), one skilled in the art would arrive at the claimed ratios merely by increasing or decreasing the amount/size of passage openings consistent with the teachings of Baurmeister as it is merely an obvious matter of duplicating the passage openings and/or changing the size proportion of the Baurmeister membrane that would perform the same function as in both Baurmeister and the present invention (In re Rose, 220 F.2d 459, 105 USPQ 237 (CCPA 1955) (Claims directed to a lumber package "of appreciable size and weight requiring handling by a lift truck" were held unpatentable over prior art lumber packages which could be lifted by hand because limitations relating to the size of the package were not sufficient to patentably distinguish over the prior art.); In re Rinehart, 531 F.2d 1048, 189 USPQ 143 (CCPA 1976) ("mere scaling up of a prior art process capable of being scaled up, if such were the case, would not establish patentability in a claim to an old process so scaled." 531 F.2d at 1053, 189 USPQ at 148.). In Gardner v. TEC Syst., Inc., 725 F.2d 1338, 220 USPQ 777 (Fed. Cir. 1984), cert. denied, 469 U.S. 830, 225 USPQ 232 (1984), the Federal Circuit held that, where the only difference between the prior art and the claims was a recitation of relative dimensions of the claimed device and a device having the claimed relative dimensions would not perform differently than the prior art device, the claimed device was not patentably distinct from the prior art device). Regarding claims 2-3 and 17, Baurmeister teaches that the second inflow/outflow spaces form an annular ring as claimed. Regarding claim 4, as can be seen in Fig. 4, at least one end region is formed from a distal end region, a transition region, and a proximal end region as claimed with the distal end region having a diameter slightly larger than the proximal end region. It is noted that Baurmeister does not teach it is at least 2% larger but as discussed above, slight modifications to the relative size/dimensions/proportion consistent with Baurmeister would have been obvious when the slight changes would not amount to a change in function. Regarding claim 5, Baurmeister teaches that the passage openings are formed in the distal end region (Fig. 5). Regarding claim 6, Baurmeister teaches that the passage openings would be substantially circular (Fig. 5). Regarding claim 7, Baurmeister teaches that the passage openings are formed in a section of an end region (Fig. 5). Regarding claims 8 and 18-20, as discussed in claim 1 above, Baurmeister does not specifically teach the size and amount of passage openings but broadly teaches more than one can be provided. As such, one skilled in the art would have found it obvious to provide as many passage openings as needed, which would provide a basis for reading on the claimed sum of flow cross section areas as claimed based on duplication of parts or obvious modifications to size/proportion. Regarding claim 9, see claims 1 and 8 above for modification of the size/proportion of the flow cross section of the second inflow/outflow spaces. Regarding claim 10, Baurmeister teaches that two end caps are provided as claimed (abstract). Regarding claim 11, Baurmeister teaches an annular outer circumferential projection (9) as claimed. Regarding claim 12, Baurmeister teaches the end caps on the ends of the housing as claimed (abstract). Regarding claims 15-16, see claim 1 above for analysis on why changing the ratio would have been an obvious matter. Claim(s) 13-14 is/are rejected under 35 U.S.C. 103 as being unpatentable over Baurmeister et al. (US 4,724,900 in IDS) as applied to claim 1 above, and further in view of Donato et al. (US 2020/0147287 in IDS). Regarding claims 13-14, Baurmeister fails to teach the specific sizing, diameter, and lengths of the filter and therefore fails to teach the inner diameter of 20-45 mm or an aspect ratio as claimed. Donato teaches that for hollow fiber membrane filter used for the same/similar purpose, known sizing for the inner diameter would be 31-35 mm ([0015]), which is inside the inner diameter range claimed, and a length of 207-287 mm ([0012]), which equates to an aspect ratio of 5.91-9.25, which overlaps the aspect ratio claimed. As such, one skilled in the art would have found it obvious to use known hollow fiber membrane sizes with a reasonable expectation of success as such sizes are already known and use din the art at the time of invention. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to PETER KEYWORTH whose telephone number is (571)270-3479. The examiner can normally be reached 9-5 MT (11-7 ET). Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Jennifer Dieterle can be reached at (571) 270-7872. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /PETER KEYWORTH/Primary Examiner, Art Unit 1777
Read full office action

Prosecution Timeline

Nov 03, 2023
Application Filed
Jan 28, 2026
Non-Final Rejection — §103, §112 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

1-2
Expected OA Rounds
58%
Grant Probability
82%
With Interview (+23.9%)
3y 5m
Median Time to Grant
Low
PTA Risk
Based on 775 resolved cases by this examiner. Grant probability derived from career allow rate.

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