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 .
Claim Rejections - 35 USC § 103
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claims 1-8 and 10-16 rejected under 35 U.S.C. 103 as being unpatentable over
Gutierrez (“Multiplexing of electrospray sources for space propulsion and physical sputtering” 2015) in view of Jung-Kubiak et al (US 10,384,810 B2) and Perna (US 2023/0112566 A1).
Gutierrez discloses a fabrication method for an emitter electrode of an electrospray thruster (page 24, Fig. 10) configured to provide electrostatic acceleration of charged droplets and ions produced by electrospraying a liquid propellant (page 29, Fig. 15, “integrated electrospray head”), the method comprising:
etching at least one microfluidic channel on a backside of a wafer (Fig. 10, step (3)), wherein the at least one microfluidic channel provides hydraulic impedance to the flow of the liquid propellant (page 23, last paragraph “channels responsible for the hydraulic impedance”; the same structure is constructed as in the instant invention, and therefore the same results are expected, inherently);
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Gutierrez, Fig. 10
etching an emitter array on a front side of the wafer (see page 23, section titled “Emitter array fabrication” and Fig. 10, step (6)), wherein the emitter array comprises at least one emitter:
wherein the liquid propellant reaches a tip of the at least one emitter through an inner channel etched through the at least one emitter (“central hole is pre-etched” and “then carved for 300 μm” Fig. 10, step 10); and
wherein each channel of the at least one microfluidic channel feeds liquid propellant to the at least one emitter of the emitter array via a hole communicating the at least one microfluidic channel with the inner channel of the at least one emitter (as depicted and described in Fig. 15, page 29, in the integrated electrospray source head, a capillary is for feeding the liquid propellant).
As to amended claim 1, Gutierrez fails to disclose coating with a noble metal. Jung-Kubiak teaches that it is useful to coat electrospray emitter tips with gold, which is a noble metal, to encourage the flow of propellant along the emitters during operation (col.10, lines 24-27). Encouraging flow encompasses eliminating clogging because the same material is formed as in the instant invention, therefore the same results are expected. Perna ’566 also teaches that it is useful to coat electrospray emission tips with noble metals such as platinum or gold [0046]. Perna ’566 teaches that the coating is useful to control the surface energy of interior surfaces or exterior surfaces [0046]. The surface energy modifies the wetting behavior and working material interfacial interactions [0046]. Material interactions as contemplated by Perna ’566 includes byproducts resulting from electrospraying the liquid propellant because the same material is formed as in the instant invention, therefore the same results are expected. The teaching of Perna ’566 also encompasses eliminating clogging because if a material interaction does not promote flow, then material clogs.
It would have been obvious to one with ordinary skill in the art before the effective filing date of the claimed invention to provide a noble metal such as gold or platinum as cited in the modified method of Gutierrez because Jung-Kubiak and Perna ’566 teach that to do so is useful for encouraging flow of propellant along the emitters during operation and to promote material interactions for optimized emitter use.
As to claim 2, Gutierrez discloses that the wafer is a double-polished silicon wafer (page 23, last paragraph).
As to claim 3, Gutierrez discloses patterning on the backside using photoresist as cited (page 23, “Shipley 1827 photoresist” step (2)).
As to claim 4, Gutierrez discloses etching with DRIE for 20 μm and stripping the photoresist (page 23, description of step (3)). Gutierrez fails to explicitly disclose that the “20 μm” DRIE is a “timed DRIE” as cited in claim 4. However, one with ordinary skill in the art would immediately envisage that a timed etch is meant by the description of 20 μm etch, and thus this description anticipates the claimed invention.
As to claims 5 and 7, Gutierrez discloses providing SiO2 by PECVD on the backside of the wafer (Fig. 10, step (5) with the wafer flipped; page 24, line 1; the wafer is “flipped” and the new topside is the original backside).
As to claim 6, Gutierrez discloses “steamed oxidized at 1100 °C for 2 hours growing a layer of 1 μm Silicon Dioxide” at step 4 (page 23, last two lines). This would inherently also grow SiO2 by thermal oxidation as cited because an extra masking is not provided to protect the backside from thermal oxidation.
As to claim 8, the thermal oxidation as described with respect to claim 6 also inherently provides thermal oxide on the front side of the wafer as cited because an extra masking is not provided to protect the front side from thermal oxidation.
As to claim 10, Gutierrez discloses an “AZ4620 layer” which is a lithography mask that is used to etch the SiO2 on the front side of the wafer (page 24, step (6)). As depicted in Fig. 10, step (9), the SiO2 mask is for pattering the well and emitter geometry on the front side of the wafer.
As to claim 11, as depicted in Fig. 10, steps (10) and (11), the well and emitter geometry on the front side and microfluidic channel on the back side are aligned.
As to claim 12, Gutierrez discloses DRIE as cited (page 24, Fig. 10, step (10)).
As to claim 13, Gutierrez discloses partially etching as cited (Fig. 10, step (9)).
As to claim 14, Gutierrez discloses that the well and inner channels are etched as cited (Fig. 10, step (9)).
As to claim 15, Gutierrez discloses connecting by DRIE as cited (“last DRIE etch” page 24, step (10)).
As to claim 16, as broadly interpreted, the DRIE also shapes the emitter tip.
Claim 9 is rejected under 35 U.S.C. 103 as being unpatentable over Gutierrez (“Multiplexing of electrospray sources for space propulsion and physical sputtering” 2015) in view of Jung-Kubiak et al (US 10,384,810 B2) and Perna (US 2023/0112566 A1), as applied to claim 8, and further in view of Sarrut et al (US 2010/0018864 A1).
As to claim 9, Gutierrez discloses to form SiO2 on the front side by thermal oxidation. Gutierrez fails to disclose depositing SiO2 by PECVD. Sarrut teaches that in methods of etching to form microstructures in silicon substrates, similar to Gutierrez, that a silicon plate 41 is coated with PECVD oxide to form an etch mask [0076]. It would have been obvious to one with ordinary skill in the art before the effective filing date of the claimed invention to form the silicon dioxide in the method of Gutierrez by PECVD because Sarrut teaches that it is a known and useful technique for forming silicon oxide layers, and such is expected to give the predictable result of a mask layer useful for further etching of the silicon substrate.
Claims 17-18 are rejected under 35 U.S.C. 103 as being unpatentable over
Gutierrez (“Multiplexing of electrospray sources for space propulsion and physical sputtering” 2015) in view of Jung-Kubiak et al (US 10,384,810 B2) and Perna (US 2023/0112566 A1), as applied to claim 16, and further in view of Espinosa et al (US 2007/0151989 A1).
As to claim 17, Gutierrez fails to disclose xenon difluoride etching. Perna ’566 teaches that in forming electrospray emitter tips (see abstract), that the edge of the shape can usefully be linear, curved, or of other shapes [0042]. However, Perna ’566 fails to disclose how form the different shapes.
Espinosa teaches that tips can be shaped by various etching techniques such as xenon difluoride etching [0042].
It would have been obvious to one with ordinary skill in the art before the effective filing date of the claimed invention to form a shaped tip in the method of Gutierrez because Perna ’566 teaches that various tip geometries are useful for electrospray emitter tips and such are expected to give the predictable results of an electrospray emitter for the tip formed in the method of Gutierrez.
It would have been further obvious to one with ordinary skill in the art before the effective filing date of the claimed invention to shape the tip by xenon difluoride etching in the modified method of Gutierrez because Espinosa teaches that it is a useful etchant for forming the tip shapes taught by Gutierrez as modified by Perna ’566 to be useful for electrospray emitter tips.
As to claim 18, Espinosa teaches that tips can be shaped by various etching techniques such as HNA etching (hydrofluoric acid, nitric acid, and acetic acid) [0042]. It would have been obvious to one with ordinary skill in the art before the effective filing date of the claimed invention to shape the tip by wet etching with hydrofluoric acid, nitric acid, and acetic acid in the modified method of Gutierrez because Espinosa teaches that it is a useful etchant for forming the tip shapes taught by Gutierrez as modified by Perna ’566 to be useful for electrospray emitter tips.
Claim 20 is rejected under 35 U.S.C. 103 as being unpatentable over Gutierrez (“Multiplexing of electrospray sources for space propulsion and physical sputtering” 2015) in view of Jung-Kubiak et al (US 10,384,810 B2) and Perna (US 2023/0112566 A1), as applied to claim 1, and further in view of Smith et al (US 2022/0068623 A1).
As to claim 20, Gutierrez discloses to remove the silicon oxide with hydrofluoric acid (page 24, step (11)), but fails to explicitly disclose a buffered oxide etch (BOE). Smith teaches that a BOE is useful for removing silicon oxide [0062]. It would have been obvious to one with ordinary skill in the art before the effective filing date of the claimed invention to remove with BOE in the method of Gutierrez because Smith teaches that it is a useful technique for removing silicon oxide layer and such is expected to give the predictable result of a removed layer.
Response to Amendment
The objection to claim 17 is withdrawn because claim 17 has been amended to include the correct chemical symbol for xenon.
The claims remain rejected over Gutierrez. Perna (US 2023/0112566 A1) is additionally relied upon to teach the newly amended claim 1 limitation of noble metal coating. Smith was mistakenly not relied upon for claim 20 and is included now for completeness.
Claims 1-8 and 10-16 rejected under 35 U.S.C. 103 as being unpatentable over
Gutierrez (“Multiplexing of electrospray sources for space propulsion and physical sputtering” 2015) in view of Jung-Kubiak et al (US 10,384,810 B2) and Perna (US 2023/0112566 A1).
Claim 9 is rejected under 35 U.S.C. 103 as being unpatentable over Gutierrez (“Multiplexing of electrospray sources for space propulsion and physical sputtering” 2015) in view of Jung-Kubiak et al (US 10,384,810 B2) and Perna (US 2023/0112566 A1), as applied to claim 8, and further in view of Sarrut et al (US 2010/0018864 A1).
Claims 17-18 are rejected under 35 U.S.C. 103 as being unpatentable over
Gutierrez (“Multiplexing of electrospray sources for space propulsion and physical sputtering” 2015) in view of Jung-Kubiak et al (US 10,384,810 B2) and Perna (US 2023/0112566 A1), as applied to claim 16, and further in view of Espinosa et al (US 2007/0151989 A1).
Claim 20 is rejected under 35 U.S.C. 103 as being unpatentable over Gutierrez (“Multiplexing of electrospray sources for space propulsion and physical sputtering” 2015) in view of Jung-Kubiak et al (US 10,384,810 B2) and Perna (US 2023/0112566 A1), as applied to claim 1, and further in view of Smith et al (US 2022/0068623 A1).
Response to Arguments
Applicant's arguments filed July 13, 2026, have been fully considered but they are not persuasive, to the extent they still apply.
Applicant argues that wetting to encourage flow as taught by Jung-Kubiak is not equivalent to coating “to eliminate clogging … by byproducts resulting from electrospraying of the liquid propellant” as in amended claim 1. Instead, applicant argues that applicant uses a noble metal to solve a different problem, electrochemical byproduct formation and clogging at the active emission site. Applicant reasons that because the emitter is etched on a front side of the wafer, the noble metal coating of amended claim 1 does not materially change the flow-restrictive microfluidic channels that feed the emitters and thus protects the active emitter surface and “eliminate[s] clogging of the at least one emitter by byproducts resulting from electrospraying of the liquid propellant.”
As an initial matter, because the claimed invention are process claims, the coating should be recited as a positive step.
Further, it is not persuasive that clogging at the tip is simply a function of the external surface energies. Clogging at the tip is expected to also be present at the internal surfaces at the tip. Therefore, coating at the tip, including internal surfaces, is expected to relieve clogging by the noble metals as provided by Jung-Kubiak or Perna ’566. Moreover, Perna ’566 teaches that surface energies of both the internal surface and the exterior surface may be modified by coating [0046]. Thus, it is obvious to coat exterior surfaces, although this is not yet claimed.
The prior art may coat for a different reason and still read on the claimed invention (MPEP 2112, section I: the claiming of a new use, new function or unknown property which is inherently present in the prior art does not necessarily make the claim patentable. In re Best, 562 F.2d 1252, 1254, 195 USPQ 430, 433 (CCPA 1977).). Here, applicant may coat for a different reason, although this is not admitted, however Jung-Kubiak and Perna coat a noble metal, and the same materials and method steps are conducted as claimed, therefore the same results are expected.
Thus, the claimed invention is obvious over Gutierrez in view of Jung-Kubiak and Perna ’566.
As to claim 16, applicant argues that Gutierrez does not teach or suggest shaping at least one emitter tip. Applicant reasons that the claimed shaping is a “further” process step distinct from DRIE to shape the emitter tip. In response, the claims have open “comprising” language and are interpreted broadly. Accordingly, etching to form an emitter encompasses shaping to form an emitter. Examiner suggests that applicant provide more particularity to the shaping step in order to distinguish the process from Gutierrez.
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 ANITA K ALANKO whose telephone number is (571)270-0297. The examiner can normally be reached Monday-Friday, 9 am-5pm.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Joshua Allen can be reached at 571-270-3176. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/ANITA K ALANKO/Primary Examiner, Art Unit 1713
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