Prosecution Insights
Last updated: April 19, 2026
Application No. 15/558,238

MULTI-LAYERED MICROFIBERS AND USE THEREOF

Final Rejection §103
Filed
Sep 14, 2017
Examiner
CHAU, LINDA N
Art Unit
1785
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Nanospun Technologies Ltd.
OA Round
10 (Final)
43%
Grant Probability
Moderate
11-12
OA Rounds
4y 0m
To Grant
60%
With Interview

Examiner Intelligence

Grants 43% of resolved cases
43%
Career Allow Rate
241 granted / 558 resolved
-21.8% vs TC avg
Strong +16% interview lift
Without
With
+16.4%
Interview Lift
resolved cases with interview
Typical timeline
4y 0m
Avg Prosecution
54 currently pending
Career history
612
Total Applications
across all art units

Statute-Specific Performance

§101
0.2%
-39.8% vs TC avg
§103
53.4%
+13.4% vs TC avg
§102
20.0%
-20.0% vs TC avg
§112
18.6%
-21.4% vs TC avg
Black line = Tech Center average estimate • Based on career data from 558 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 . Examiner’s Comments The examiner has cited particular columns and line numbers, paragraphs, or figures in the references as applied to the claims for the convenience of the applicant. Although the specified citations are representative of the teachings in the art and are applied to the specific limitations within the individual claim, other passages and figures may apply as well. It is respectfully requested from the applicant, in preparing the responses, to fully consider the references in entirety as potentially teaching all or part of the claimed invention, as well as the context of the passage as taught by the prior art or disclosed by the examiner. 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. Claims 1-5, 7-9, 14-15, and 20-21 are rejected under 35 U.S.C. 103 as being unpatentable over Ben Dror et al. (WO 2014/006621). The Examiner notes that US 2015/0183661 is the English language equivalent of WO 2014/006621 and all citations will refer to US 2015/0183661. Regarding claims 1, 9, and 21, Ben Dror discloses a microfiber comprising immobilized cells encapsulated within a concentric layered microfiber [0155], wherein the immobilized cells are viable cells capable of proliferations [0162] and are located in an internal lumen of the microfiber [0165], the concentric layered microfiber consists of a PVDF-HFP exterior polymeric layer and a PVD [0018] intermediate polymeric layer and/or other materials as claimed [0089, 0104]. Although Ben Dror discloses hollow fibers during the production of electrospun microtube, Ben Dror explicitly disclose that the immobilized cells are encapsulated and attached or in contact by the intermediate polymeric layer [0155-0157]. Because of the encapsulation and attachment of the immobilized cells, the microfiber is considered to be a non-hollow fiber. Ben Dror fails to explicitly disclose that the exterior polymeric layer and the intermediate polymeric layer each has a thickness of about 5 nm to 10 µm as presently claimed. However, Ben Dror discloses that the thickness of inner diameter is 50 nm to about 50 µm and an outer diameter is 0.5-100 µm and the thickness of the microfiber is 100 nm – 20 µm [0072-0075], and that all values within the range appears to be functionally equivalent. It would have been obvious to choose any thickness from that ranged based on the desired properties and that choosing thickness values would have rendered the claimed relationship between layer thicknesses obvious in the absence of showing criticality. Additionally, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have selected the overlapping portion of the ranges disclosed by the reference because overlapping ranges have been held to be a prima facie case of obviousness, In re Malagari, 182 USPQ 549. Or the alternative, Ben Dror discloses that the mechanical strength dependent on the thickness layers [0083] as well as flow rates [0159]. Thus, the thickness is a result effective variable. A person having ordinary skill in the art before the effective filling date of the invention would have arrived at the claimed invention by general experimentation alone, without exercising any general experimentation. Additionally, a person having ordinary skill in the art has good reason to pursue known option within his or her technical grasp. It would have been obvious to one or ordinary skill in the art at the time of the invention was made to optimize the thickness of each polymeric layers since it has been held that, where the general conditions of a claim are disclosed in the prior art, it is not invention to discover optimum or workable ranges by routine experimentation. In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955). The burden is upon the Applicant to demonstrate that the claimed amount is critical and has unexpected results. In the present invention, one would have been motivate to optimize the thickness of the polymeric layers dependent on what the end use fiber was used for. Regarding the limitation “electrospun”, even though product-by-process claims are limited by and defined by the process, determination of patentability is based on the product itself. The patentability of a product does not depend on its method of production. If the product in the product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process.”, (In re Thorpe, 227 USPQ 964,966). Once the Examiner provides a rationale tending to show that the claimed product appears to be the same or similar to that of the prior art, although produced by a different process, the burden shifts to applicant to come forward with evidence establishing an unobvious different between the claimed product and the prior art product (In re Marosi, 710 F.2d 798, 802, 218 USPQ 289, 292 (Fed. Cir. 1983), MPEP 2113). Nevertheless, Ben Dror discloses electrospun fibers. Regarding claims 2 and 14-15, the claim narrows the definition of a water-soluble material, but do not remove from the water-soluble material being not present. Regarding claim 3, Ben Dror discloses that the microfiber being a triple-layer microfiber, However, the rate of the solidifying of the polymeric solution is a product by process limitation (please see withdrawn claim 26). Even though product-by-process claims are limited by and defined by the process, determination of patentability is based on the product itself. The patentability of a product does not depend on its method of production. If the product in the product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process.”, (In re Thorpe, 227 USPQ 964,966). Once the Examiner provides a rationale tending to show that the claimed product appears to be the same or similar to that of the prior art, although produced by a different process, the burden shifts to applicant to come forward with evidence establishing an unobvious different between the claimed product and the prior art product (In re Marosi, 710 F.2d 798, 802, 218 USPQ 289, 292 (Fed. Cir. 1983), MPEP 2113). Nevertheless, Ben Dror discloses a relationship such that the polymeric solution solidifies faster from the exterior of the fiber to the interior of the fiber [0029]. Regarding claim 4, Ben Dror discloses that organic-soluble polymer and also discloses a water-soluble polymer in an amount as claimed (Table 2). Regarding claim 5, Ben Dror discloses that the layer is substantially porous layers [0120]. Regarding claim 6, please see [0063], [0096]. Regarding claims 7-9, Ben Dror discloses that the materials of the polymers as claimed [0087-0099]. Regarding claim 20, Ben Dror discloses the molecules of interest as claimed ([0063, 0096]). Claims 1-5, 7-8, 14-15, and 20 are rejected under 35 U.S.C. 103 as being unpatentable over Kuhn et al. (US 2011/0039296). Regarding claim 1, Kuhn discloses the microfiber as claimed (Please see the annotated figure 3A-3B below). PNG media_image1.png 540 990 media_image1.png Greyscale Annotated Figs. 3A-3B Kuhn discloses the material of the exterior polymeric layer as claimed [0079-0090], the material of the intermediate polymeric layer as claimed [0091], and the material of the internal lumen as claimed ([0065], [0184]). Furthermore, because Kuhn discloses the encapsulation and attachment of the immobilized cells, the microfiber is considered to be a non-hollow fiber. Kuhn fails to explicitly disclose that the exterior polymeric layer and the intermediate polymeric layer each has a thickness of about 5 nm to 10 µm as presently claimed. However, Kuhn discloses that the thickness of inner diameter is 50 nm to about 50 µm and an outer diameter is 0.5-100 µm and the thickness of the microfiber is 100 nm – 20 µm [0051-0053], and that all values within the range appears to be functionally equivalent. It would have been obvious to choose any thickness from that ranged based on the desired properties and that choosing thickness values would have rendered the claimed relationship between layer thicknesses obvious in the absence of showing criticality. Additionally, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have selected the overlapping portion of the ranges disclosed by the reference because overlapping ranges have been held to be a prima facie case of obviousness, In re Malagari, 182 USPQ 549. Or the alternative, Kuhn discloses that the mechanical strength dependent on the thickness layers [0074] as well as flow rates [0077]. Thus, the thickness is a result effective variable. A person having ordinary skill in the art before the effective filling date of the invention would have arrived at the claimed invention by general experimentation alone, without exercising any general experimentation. Additionally, a person having ordinary skill in the art has good reason to pursue known option within his or her technical grasp. It would have been obvious to one or ordinary skill in the art at the time of the invention was made to optimize the thickness of each polymeric layers since it has been held that, where the general conditions of a claim are disclosed in the prior art, it is not invention to discover optimum or workable ranges by routine experimentation. In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955). The burden is upon the Applicant to demonstrate that the claimed amount is critical and has unexpected results. In the present invention, one would have been motivate to optimize the thickness of the polymeric layers dependent on what the end use fiber was used for. Regarding the limitation “electrospun”, even though product-by-process claims are limited by and defined by the process, determination of patentability is based on the product itself. The patentability of a product does not depend on its method of production. If the product in the product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process.”, (In re Thorpe, 227 USPQ 964,966). Once the Examiner provides a rationale tending to show that the claimed product appears to be the same or similar to that of the prior art, although produced by a different process, the burden shifts to applicant to come forward with evidence establishing an unobvious different between the claimed product and the prior art product (In re Marosi, 710 F.2d 798, 802, 218 USPQ 289, 292 (Fed. Cir. 1983), MPEP 2113). Nevertheless, Kuhn discloses electrospun fibers. Regarding claims 2 and 14-15, please see [0080-0081], [0091]. Regarding claim 3, Kuhn discloses that the microfiber being a triple-layer microfiber, However, the rate of the solidifying of the polymeric solution is a product by process limitation (please see withdrawn claim 26). Even though product-by-process claims are limited by and defined by the process, determination of patentability is based on the product itself. The patentability of a product does not depend on its method of production. If the product in the product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process.”, (In re Thorpe, 227 USPQ 964,966). Once the Examiner provides a rationale tending to show that the claimed product appears to be the same or similar to that of the prior art, although produced by a different process, the burden shifts to applicant to come forward with evidence establishing an unobvious different between the claimed product and the prior art product (In re Marosi, 710 F.2d 798, 802, 218 USPQ 289, 292 (Fed. Cir. 1983), MPEP 2113). Nevertheless, Kuhn discloses a relationship such that the polymeric solution solidifies faster from the exterior of the fiber to the interior of the fiber (Abstract, [0073]). Regarding claim 4, please see Table 2. Regarding claim 5, please see [0032]. Regarding claims 7-8, please see [0078-0083]. Regarding claim 20, please see [0060]. Regarding claims 9 and 21, Kuhn et al. (US 2011/0039296) in view of Ben Dror et al. (WO 2014/006621). The Examiner notes that US 2015/0183661 is the English language equivalent of WO 2014/006621 and all citations will refer to US 2015/0183661. Regarding claim 21, Kuhn discloses the microfiber as claimed (Please see the annotated figure 3A-3B below). PNG media_image1.png 540 990 media_image1.png Greyscale Annotated Figs. 3A-3B Kuhn discloses that the material of the exterior polymeric layer is organic soluble polymer [0079-0090], the material of the intermediate polymeric layer as claimed [0091], and the material of the internal lumen as claimed ([0065], [0184]). Furthermore, because Kuhn discloses the encapsulation and attachment of the immobilized cells, the microfiber is considered to be a non-hollow fiber. Kuhn fails to explicitly disclose that the exterior polymeric layer and the intermediate polymeric layer each has a thickness of about 5 nm to 10 µm as presently claimed. However, Kuhn discloses that the thickness of inner diameter is 50 nm to about 50 µm and an outer diameter is 0.5-100 µm and the thickness of the microfiber is 100 nm – 20 µm [0051-0053], and that all values within the range appears to be functionally equivalent. It would have been obvious to choose any thickness from that ranged based on the desired properties and that choosing thickness values would have rendered the claimed relationship between layer thicknesses obvious in the absence of showing criticality. Additionally, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have selected the overlapping portion of the ranges disclosed by the reference because overlapping ranges have been held to be a prima facie case of obviousness, In re Malagari, 182 USPQ 549. Or the alternative, Kuhn discloses that the mechanical strength dependent on the thickness layers [0074] as well as flow rates [0077]. Thus, the thickness is a result effective variable. A person having ordinary skill in the art before the effective filling date of the invention would have arrived at the claimed invention by general experimentation alone, without exercising any general experimentation. Additionally, a person having ordinary skill in the art has good reason to pursue known option within his or her technical grasp. It would have been obvious to one or ordinary skill in the art at the time of the invention was made to optimize the thickness of each polymeric layers since it has been held that, where the general conditions of a claim are disclosed in the prior art, it is not invention to discover optimum or workable ranges by routine experimentation. In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955). The burden is upon the Applicant to demonstrate that the claimed amount is critical and has unexpected results. In the present invention, one would have been motivate to optimize the thickness of the polymeric layers dependent on what the end use fiber was used for. Regarding the limitation “electrospun”, even though product-by-process claims are limited by and defined by the process, determination of patentability is based on the product itself. The patentability of a product does not depend on its method of production. If the product in the product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process.”, (In re Thorpe, 227 USPQ 964,966). Once the Examiner provides a rationale tending to show that the claimed product appears to be the same or similar to that of the prior art, although produced by a different process, the burden shifts to applicant to come forward with evidence establishing an unobvious different between the claimed product and the prior art product (In re Marosi, 710 F.2d 798, 802, 218 USPQ 289, 292 (Fed. Cir. 1983), MPEP 2113). Nevertheless, Kuhn discloses electrospun fibers. Although Kuhn discloses an organic soluble polymer to be of a copolymer, Kuhn fails to explicitly disclose that it is of PVDF-HFP as presently claimed. Ben Dror discloses a microfiber comprising immobilized cells encapsulated within a concentric layered microfiber [0155], wherein the immobilized cells are viable cells capable of proliferations [0162] and are located in an internal lumen of the microfiber [0165], the concentric layered microfiber consists of a PVDF-HFP exterior polymeric layer and a PVD [0018] intermediate polymeric layer and/or other materials as claimed [0089, 0104]. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Kuhn’s organic soluble polymer to be of PVDF-HFP, since Ben Dror discloses that this is a suitable polymeric material as an exterior of the microfiber. Alternatively, Kuhn discloses a microfiber comprising an exterior layer as set forth above, however, fails to explicitly disclose that it comprises of PVDF-HFP. Kuhn discloses the claimed invention except it uses PCL, as one of the examples, instead of PVDF-HFP. Ben Dror shows that PVDF-HFP is an equivalent structure known in the art ([0110], [0095]). Therefore, because these two materials were art-recognized equivalents before the effective filing date of the claimed invention, one of ordinary skill in the art would have found it obvious to substitute PCL for PVDF-HFP in the invention of Kuhn. Substitution of equivalents requires no express motivation as long as the prior art recognizes the equivalency. In re Fount 213 USPQ 532 (CCPA 1982); In re Siebentritt 152 USPQ 618 (CCPA 1967); Grover Tank & Mfg. Co. Inc V. Linde Air Products Co. 85 USPQ 328 (USSC 1950). Response to Arguments Applicant’s arguments with respect to claims 1 and 21 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 Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a). A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action. Any inquiry concerning this communication or earlier communications from the examiner should be directed to LINDA N CHAU whose telephone number is (571)270-5835. The examiner can normally be reached 9AM-5PM EST M-F. 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, Mark Ruthkosky can be reached at (571)272-1291. 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. Linda Chau /L.N.C/Examiner, Art Unit 1785 /Holly Rickman/Primary Examiner, Art Unit 1785
Read full office action

Prosecution Timeline

Sep 14, 2017
Application Filed
Dec 12, 2019
Non-Final Rejection — §103
Jun 18, 2020
Response Filed
Sep 11, 2020
Final Rejection — §103
Mar 15, 2021
Response after Non-Final Action
Mar 22, 2021
Request for Continued Examination
Mar 25, 2021
Response after Non-Final Action
Jun 14, 2021
Non-Final Rejection — §103
Dec 15, 2021
Response Filed
Mar 01, 2022
Final Rejection — §103
Sep 05, 2022
Request for Continued Examination
Sep 06, 2022
Response after Non-Final Action
Sep 21, 2022
Non-Final Rejection — §103
Mar 27, 2023
Response Filed
Jun 20, 2023
Final Rejection — §103
Dec 27, 2023
Request for Continued Examination
Dec 31, 2023
Response after Non-Final Action
Feb 27, 2024
Non-Final Rejection — §103
Aug 26, 2024
Response Filed
Oct 28, 2024
Final Rejection — §103
Apr 29, 2025
Request for Continued Examination
Apr 30, 2025
Response after Non-Final Action
May 01, 2025
Non-Final Rejection — §103
Nov 05, 2025
Response Filed
Nov 18, 2025
Final Rejection — §103 (current)

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Prosecution Projections

11-12
Expected OA Rounds
43%
Grant Probability
60%
With Interview (+16.4%)
4y 0m
Median Time to Grant
High
PTA Risk
Based on 558 resolved cases by this examiner. Grant probability derived from career allow rate.

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