Prosecution Insights
Last updated: April 19, 2026
Application No. 17/759,758

PISTON STOP FOR A MEDICAL SYRINGE AND MEDICAL SYRINGE WITH A PISTON STOP

Non-Final OA §103
Filed
Jul 29, 2022
Examiner
FARRAR, LAUREN PENG
Art Unit
3783
Tech Center
3700 — Mechanical Engineering & Manufacturing
Assignee
Fresenius Kabi Deutschland GmbH
OA Round
3 (Non-Final)
79%
Grant Probability
Favorable
3-4
OA Rounds
3y 8m
To Grant
94%
With Interview

Examiner Intelligence

Grants 79% — above average
79%
Career Allow Rate
593 granted / 753 resolved
+8.8% vs TC avg
Strong +15% interview lift
Without
With
+15.1%
Interview Lift
resolved cases with interview
Typical timeline
3y 8m
Avg Prosecution
60 currently pending
Career history
813
Total Applications
across all art units

Statute-Specific Performance

§101
0.5%
-39.5% vs TC avg
§103
51.9%
+11.9% vs TC avg
§102
25.4%
-14.6% vs TC avg
§112
13.7%
-26.3% vs TC avg
Black line = Tech Center average estimate • Based on career data from 753 resolved cases

Office Action

§103
DETAILED ACTION 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 . Continued Examination Under 37 CFR 1.114 A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 12/8/25 has been entered. 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, 3, 6-12, 14, 16-20, 22 is/are rejected under 35 U.S.C. 103 as being unpatentable over Swal et al. (US 2017/0021108 A1) in view of Drake et al. (US 2021/0121635 A1) and in further view of Laubach et al. (US 2016/0082193 A1) and in further view of Hetting (US 2021/0046248 A1). With regard to claim 1, Swal discloses A plunger stopper (Fig. 3b) for a medical syringe (Fig. 1, the syringe is not positively claimed and therefore is not required to be taught by the art, however citations will be made when able), wherein the plunger stopper comprising: an end wall (24), a side wall (where 20 is pointing in Fig. 3b), and an internal thread (27) for securing a plunger rod (30), wherein the end wall (24) is conical in the distal direction both on the outside and on the inside (see Fig. 3b), wherein the end wall merges towards the side wall into a first sealing ring (see annotated drawing below), which extends around the circumference of the side wall, and wherein the side wall has a second sealing ring (where 20 is pointing in Fig. 3b) having a circular segment-shaped cross-section and a fourth sealing ring (see annotated drawing below) having a proximal flank (see drawing below) that is flattened relative to a distal flank (see drawing below). PNG media_image1.png 294 396 media_image1.png Greyscale However, Swal does not disclose the piston is made of butyl rubber. Drake teaches a piston that is made of butyl rubber ([0052]). Therefore, it would be prima facie obvious for one of ordinary skill in the art before the effective filing date of the claimed invention to modify the material of Swal with a butyl rubber because the substitution one well-known material for another is well-known in the art and does not alter the overall function of the device. However, Swal/Drake do not explicitly disclose a third sealing ring. Laubach teaches a stopper (Fig. 2, having a first distalmost sealing ring (26), a second sealing ring (32), a third sealing ring (other of 32), and a fourth sealing ring (36) having a flattened proximal flank. Therefore, it would be prima facie obvious for one of ordinary skill in the art before the effective filing date of the claimed invention to modify the material of Swal/Drake with the third sealing ring as taught by Laubach for the purpose of providing stabilization and sealing ([0020]). Further, it would be prima facie obvious to include a third sealing ring as a mere duplication of parts as the claims have not provided a significant reason for including a third sealing ring. However, Swal/Drake/Laubach do not teach the exact shape of the fourth sealing ring. Hetting teaches a plunger stopper (Fig. 1) having a proximal most sealing ring (1005at the end 1003) which is considered equivalent to the fourth sealing ring. Hetting teach the sealing ring having a proximal flank that is flattened (see annotated Fig. below) relative to a distal flank (see Fig. below), the distal flank having a circular segment-shaped cross-section (see the circled portion in Fige below that is more rounded in comparison to the flattened proximal flank) and merging into a tangent of the circular segment-shaped cross-section on the proximal flank, and the tangent forming an acute angle towards the side wall (see annotated drawing below showing the acute angle. Without any recite significance to this specific shape, the shape of the fourth sealing ring may be the one taught by Hetting as it performs the same function as the Swal/Drake/Laubach for sealing the stopper within a barrel ([0114]). PNG media_image2.png 358 438 media_image2.png Greyscale Therefore, it would be prima facie obvious for one of ordinary skill in the art before the effective filing date of the claimed invention to modify the stopper of Swal/Drake/Laubach with the specifically shaped fourth sealing ring as taught by Hetting because the change in shape is within the skill of one of ordinary skill in the art and does not alter the overall function of the stopper which is to seal the stopper in the syringe barrel ([0114]). With regard to claim 3, Swal discloses the claimed invention except for the material. Drake teaches the butyl rubber is a halogenated butyl rubber comprising bromobutyl ([0052]). Therefore, it would be prima facie obvious for one of ordinary skill in the art before the effective filing date of the claimed invention to modify the material of Swal with a butyl rubber because the substitution one well-known material for another is well-known in the art and does not alter the overall function of the device. With regard to claim 6, 16 and 17, Swal/Drake teach the claimed invention except for the specific ratio of wall thickness versus the diameter of the plunger stopper. However, without reciting specific criticality to the specific ratio, it would be prima facie obvious to optimize the ratio between the wall thickness and the diameter of the plunger stopper to be more than 0.5 and/or 2.0 as doing so would not alter the overall function of the device. With regard to claim 7, Swal discloses wherein a proximal tip angle of the end of the end wall (see Fig. 5, angle alpha) corresponds substantially to a distal tip angle of the end wall (see Fig. 5 and 6). With regard to claim 8 and 18, Swal/Drake teach the claimed invention except for the specific tooth height. However, without reciting specific criticality to the specific ratio, it would be prima facie obvious to optimize the ratio between the tooth height and the diameter of the plunger stopper to be more than 0.04 and/or under 0.15 as doing so would not alter the overall function of the device. With regard to claim 9, Swal discloses the wall thickness of the end wall (24) that is 1 times the wall thickness of the side wall (as shown in Fig. 3b, the wall thickness of the end wall and side wall is the same). With regard to claim 10 and 20, Swal/Drake teach the claimed invention except for the pitch of the threads. However, without reciting specific criticality to the specific pitch, it would be prima facie obvious to optimize the pitch of the internal thread to be between 0.4 and 0.8mm as doing so would not alter the overall function of the device. With regard to claim 12, Swal/Drake teach a syringe (Fig. 1) and the plunger stopper according to claim 1 (see rejection of claim 1). With regard to claim 14, Swal discloses wherein the syringe is filled with a medical fluid ([0028]) and sealed with a stopper (Fig. 1). With regard to claim 19, Swal/Drake teach the claimed invention except for the ratio between the thickness of the end wall and the thickness of the side wall. However, without reciting specific criticality to the specific ratio, it would be prima facie obvious to optimize the ratio between the wall thickness of the end wall and the thickness of the side wall to be 1.2 to 1.6 times as doing so would not alter the overall function of the device. With regard to claim 22, Swal discloses the claimed invention including an acute angle. While Swal does not explicitly disclose the acute angle being 60 degrees to 80 degrees towards the side wall, it would be prima facie obvious to optimize the acute angle as doing so would not alter the overall function of the device and the claims do not provide a significance to having the specific angle of 60 to 80 degrees. Claim(s) 4 is/are rejected under 35 U.S.C. 103 as being unpatentable over Swal et al. (US 2017/0021108 A1) in view of Drake et al. (US 2021/0121635 A1) an in further view of Laubach et al. (US 2016/0082193 A1) and Hetting (US 2021/0046248 A1) and Sudo (US 2013/0030382 A1). With regard to claim 4, Swal/Drake/Laubach/Hetting do not teach the threads being double trapezoidal. Sudo teaches a stopper having double trapezoidal thread ([0045]). Therefore, it would be prima facie obvious for one of ordinary skill in the art before the effective filing date of the claimed invention to modify the device of Swal/Drake/Laubach/Hetting with the trapezoidal threads of Sudo because the substation of one shaped thread for another is well-known in the art and does not alter the overall function of the device ([0045]). Claim(s) 5 and 13 is/are rejected under 35 U.S.C. 103 as being unpatentable over Swal et al. (US 2017/0021108 A1) in view of Drake et al. (US 2021/0121635 A1) an in further view of Laubach et al. (US 2016/0082193 A1) and Hetting (US 2021/0046248 A1) and LaRose (US 2017/0203046 A1). With regard to claim 5, Swal/Drake/Laubach/Hetting teaches the claimed invention except for a coating. LaRose teaches a stopper having a coating at least on the sidewall and/or the end wall comprising a PTFE ([0057). Therefore, it would be prima facie obvious for one of ordinary skill in the art before the effective filing date of the claimed invention to modify the device of Swal/Drake/Laubach/Hetting with the coating as taught by LaRose for the purpose of reducing friction as the stopper slides within the syringe barrel ([0057]). With regard to claim 13, Swal/Drake/Laubach/Hetting teach the claimed invention except for the conical plunger rod. LaRose teaches further comprising a plunger rod (Fig. 2b) wit ha distal conical end (at 210) that rests on the conical inside of the end wall (at 310). Therefore, it would be prima facie obvious for one of ordinary skill in the art before the effective filing date of the claimed invention to modify the device of Swal/Drake/Laubach/Hetting with the conical plunger rod end as taught by LaRose for the purpose of retaining the plunger rod within the stopper with sufficient force ([0053]). Claim(s) 15 is/are rejected under 35 U.S.C. 103 as being unpatentable over Swal et al. (US 2017/0021108 A1) in view of Drake et al. (US 2021/0121635 A1) an in further view of Laubach et al. (US 2016/0082193 A1) and Hetting (US 2021/0046248 A1) and Beedon et al. (US 2005/0010175 A1). With regard to claim 15, Swal/Drake/Laubach/Hetting teach the syringe is autoclaved (this is considered a product by process claim, therefore only the structure of the syringe needs to be taught by the prior art). However, Swal/Drake/Laubach/Hetting does not teach an outer package. Beedon teaches a syringe that is placed in an outer package ([0077]). Therefore, it would be prima facie obvious for one of ordinary skill in the art before the effective filing date of the claimed invention to modify the device of Swal/Drake/Laubach/Hetting with the packaging as taught by Beedon for the purpose of preparing the syringes for shipment and preventing contamination ([0077]). Response to Arguments Applicant’s arguments with respect to claim(s) 1, 3-10, 12-20, 22 have been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to LAUREN P FARRAR whose telephone number is (571)270-1496. The examiner can normally be reached Monday - Friday 9am - 5pm. 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, Kevin Sirmons can be reached at 571-272-4965. 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. /Lauren P Farrar/Primary Examiner, Art Unit 3783
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Prosecution Timeline

Jul 29, 2022
Application Filed
Jun 04, 2025
Non-Final Rejection — §103
Sep 08, 2025
Response Filed
Oct 28, 2025
Final Rejection — §103
Dec 03, 2025
Examiner Interview Summary
Dec 03, 2025
Applicant Interview (Telephonic)
Dec 08, 2025
Request for Continued Examination
Dec 21, 2025
Response after Non-Final Action
Dec 22, 2025
Non-Final Rejection — §103 (current)

Precedent Cases

Applications granted by this same examiner with similar technology

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PEN-LIKE SYRINGE SYSTEM
2y 5m to grant Granted Mar 03, 2026
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2y 5m to grant Granted Feb 24, 2026
Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

3-4
Expected OA Rounds
79%
Grant Probability
94%
With Interview (+15.1%)
3y 8m
Median Time to Grant
High
PTA Risk
Based on 753 resolved cases by this examiner. Grant probability derived from career allow rate.

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