NANOWIRE BASED HYDROGEN SENSORS

DETAILED ACTION Notice of Pre-AIA or AIA Status 1. 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 § 103 2. 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. The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows: 1. Determining the scope and contents of the prior art. 2. Ascertaining the differences between the prior art and the claims at issue. 3. Resolving the level of ordinary skill in the pertinent art. 4. Considering objective evidence present in the application indicating obviousness or nonobviousness. 4. Claims 1, 2, 3, 4, 6, 7, and 8 are rejected under 35 U.S.C. 103 as being unpatentable over Yang et al. and Lu et al. Yang et al. (US Pub. No. 2010/0269569 A1) is directed toward the detection of hydrogen gas using single palladium nanowires (title). Lu et al. (“Engineering ZIF-8 Thin Films for Hybrid MOF-Based Devices,” Adv. Mater. 2012, 24, 3970-3974 and electronic supporting information) is directed toward a MOF-based device (pg. 3970: title and abstract). Regarding Claim 1, Yang et al. discloses a method for patterning a plurality of palladium nanowires onto a glass substrate as depicted in FIG. 1a which is useful for the detection of hydrogen gas (i.e.: a hydrogen sensor). The palladium nanowires are prepared using lithographically patterned nanowire electrodeposition (LPNE) according ¶24 and ¶25. However, Yang et al. does not disclose the use of ZIF-8 deposited onto the palladium nanowires (as a bi-layer nanowire sensor as per Claim 1). Lu et al. is directed toward the deposition of ZIF-8 on various substrates including Si/SiO2 or palladium resulting in low roughness films (pg. 3971). As a test case, Lu et al. devised a system comprised of a Pd layer with ZIF-8 deposited on top, which showed activity toward H2 (i.e.: binding) based on optical transmission measurements (pg. 3972 and FIG. 3). The use of ZIF-8 is expected to act as a (moderate) chemical filter as the material’s pore size will control the size of gas molecules (e.g.: hydrogen gas) that can pass through it reaching the underlying palladium layer (to reversibly form palladium hydrides) according to pg. 3972-3973. The method of forming the ZIF-8 layer on a palladium layer is described in the ESI on pg. 2 in the section entitled “Typical process for preparation of ZIF-8 thin films.” The process follows: preparation of methanolic stock solutions of Zn(NO3)2·6H2O (25 mM) and of 2-methylimidazole (50 mM). ZIF-8 thin films were obtained by immersing the treated platforms (i.e.: Pd on the substrate) in a fresh mixture of 10 ml Zn(NO3)2 stock solution and 10 ml 2-methyl-imidazole stock solution for 30 minutes at room temperature, then washed with methanol, and dried under nitrogen flow. Thicker films can be obtained by simply repeating the process with freshly mixed solutions. The previous description matches the process required by Claim 1. It would be obvious to one of ordinary skill in the art prior to the effective filing date of the claimed invention to modify the Pd-nanowire senor of Yang et al. by depositing the ZIF-8 layer on top of the plurality of wires. One of ordinary skill would be motivated to combine the two teachings since the presence of the ZIF-8 would improve the selectivity for hydrogen due to the pore size of ZIF-8 and the use of a plurality of Pd nanowires instead of a flat Pd layer because the nanowires have a higher surface area enhancing the sensitivity for hydrogen detection. The deposition process would initially deposit onto the Pd-nanowires and then continue to grow as deposition continues to cover the substrate areas not comprising a palladium surface (i.e.: SiO2 or glass). The heterogenous deposition is supported by the deposition on both the Pd surface and the SiO2 surface (i.e.: glass substrate) in Lu et al. (pg. 3971: FIG. 1). Thus, a bi-layer structure is formed as required by Claim 1. Regarding Claims 2, 3, 4, Yang et al. and Lu et al. disclose the method of Claim 1 indicating that the deposition time for forming the ZIF-8 layer is 30 minutes. However, Lu et al. indicates that the thickness of the film can be controlled by increasing the deposition cycles or increasing the deposition time. Lu et al. indicates that 100 nm of ZIF-8 is deposited with each new deposition cycle. Therefore, the deposition time is a result-effective variable, i.e., a variable which achieves a recognized result, and the determination of the optimum or workable ranges of said variable might be characterized as routine experimentation (See MPEP 2144.0.II.B.). Accordingly, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to have discovered the optimum or workable ranges of the deposition time, including values within the claimed range, through routine experimentation. One would have been motivated to do so in order to form a defect-free ZIF-8 film with the appropriate thickness to ensure good selectivity of H2 to control the rate of the gas reaching the Pd nanowire to enable good performance for the bi-layer sensor. Regarding Claim 6, Yang et al. in view of Lu et al. discloses the method of Claim 1 wherein the substrate is glass as supported by FIG. 1b in Yang et al. which shows the Pd nanowires and the glass substrate. Regarding Claim 7, Yang et al. in view of Lu et al. discloses the method of Claim 1 resulting in the Pd nanowire/ZIF-8 bilayer sensor described in Claim 1. Yang et al. in view of Lu et al. is silent on the response time in a range of the sensor formed by the method of Claim 1 to 1% H2. In ¶114 and ¶121 of the present application (referenced as US Pub. No. 2024/0310344 A1), an embodiment of the sensor is described as having a response time in a range of 7 seconds to 13 seconds to 1% of H2. Therefore, the bi-layer sensor made by the method of Claim 1 disclosed by Yang et al. and Lu et al. would inherently a response time in a range of 7 seconds to 13 seconds to 1% of H, as evidenced by, at least, the Applicant’s own disclosure (¶114 and 121). See MPEP 2112-III. Regarding Claim 8, Yang et al. in view of Lu et al. discloses the method of Claim 1 resulting in the Pd nanowire/ZIF-8 bilayer sensor described in Claim 1. Yang et al. in view of Lu et al. is silent on the response time range of the sensor formed by the method of Claim 1 to 1% H2. In ¶114 and ¶121 of the present application (referenced as US Pub. No. 2024/0310344 A1), an embodiment of the sensor is described as having a response time in a range of 8 seconds to 15 seconds to 1% of H2. Therefore, the bi-layer sensor made by the method of Claim 1 disclosed by Yang et al. and Lu et al. would inherently a response time in a range of 8 seconds to 15 seconds to 1% of H, as evidenced by, at least, the Applicant’s own disclosure (¶114 and 121). See MPEP 2112-III. 5. Claim 5 is rejected under 35 U.S.C. 103 as being unpatentable over Yang et al. and Lu et al. as applied to Claim 1 above with evidentiary support from Xiang et al. Yang et al. (US Pub. No. 2010/0269569 A1) is directed toward the detection of hydrogen gas using single palladium nanowires (title). Lu et al. (“Engineering ZIF-8 Thin Films for Hybrid MOF-Based Devices,” Adv. Mater. 2012, 24, 3970-3974 and electronic supporting information) is directed toward a MOF-based device (pg. 3970: title and abstract). Xiang et al. (“Lithographically Patterned Nanowire Electrodeposition: A Method for Patterning Electrically Continuous Metal Nanowires on Dielectrics,” ACS Nano 2008, 2(9), 1939-1949) is directed toward the deposition of nanowires (pg. 1939: title). Regarding Claim 5, Yang et al. in view of Lu et al. discloses the method of Claim 1, but does not describe all of the steps for the LPNE process of forming the patterned Pd-nanowires in Yang et al. According to ¶24 of Yang et al., Xiang et al. is incorporated by reference and said reference describes the LPNE process used to form the Pd nanowires in Yang et al. Xiang et al. is an academic paper directed to lithographically patterned nanowire electrodeposition (“LPNE”) as per the title. Xiang describes the LPNE procedure on pg. 1940-1942 in the “metal nanowire fabrication using LPNE section” and depicts the process in FIG. 1 which is reproduced below. [AltContent: textbox ([img-media_image1.png] From Xiang et al. on pg. 1940)] Therefore, Yang et al. and Lu et al. with evidentiary support from Xiang et al. teaches that the patterning of the plurality of palladium nanowires onto the substrate occurs by depositing a thin layer of nickel (Ni) on the substrate using a metal evaporator (Step 1 in Figure 1 above); spin-coating a photo-resist layer (PR) onto the thin layer of nickel (Ni) (Step 2 in Figure 1 above); fabricating a horizontal trench by etching exposed Ni in a nitric acid (Step 4 in Figure 1 above); electro-depositing the plurality of palladium nanowires into the trench (Step 5 in Figure 1 above shows Au, but Xiang et al. also described Pd); and removing residual photo-resist (PR) and nickel (Ni) using acetone and nitric acid (Steps 6 and 7 in Figure 1 above). Allowable Subject Matter 6. Claims 9, 10, and 11 are objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims. 7. The combination of Yang et al. and Lu et al. indicate that increasing deposition time or increasing the number of deposition cycles increases the thickness of the deposited ZIF-8 film. In fact, each subsequent 30-minute immersion cycle yields an increase of approximately 100 nm to the ZIF-8 film. On the other hand, the instant application and Claims 9, 10, and 11 teach that increasing the deposition or reaction time result in a decrease in the film thickness (i.e.: 2 hours results in 160-nm thick ZIF-8 film, 4 hours results in a 130-nm thick ZIF film, and 8 hours results in a 35-nm thick ZIF-8 film). Therefore, the combination of Yang et al. and Lu et al. is a teaching away from the crux of Claims 9, 10, and 11. The applicant must keep the increasing reaction time and the decreasing ZIF-8 thickness limitations together in order to prevent an obviousness rejection based on routine optimization or routine experimentation. Conclusion 8. The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. Xiao (US Pub. No. 2012/0085145 A1) is directed toward sensors and devices containing ultra-small nanowire arrays (title). 9. Any inquiry concerning this communication or earlier communications from the examiner should be directed to KEVIN SYLVESTER whose telephone number is (703)756-5536. The examiner can normally be reached Mon - Fri 8:15 AM to 4:30 PM EST. 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. 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If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /KEVIN SYLVESTER/Examiner, Art Unit 1794 /CIEL P CONTRERAS/Primary Examiner, Art Unit 1794