DETAILED ACTION
Notice to Applicant
In the amendment dated 2026-07-23, the following has occurred: Claims 1 and 7 have been amended; Claims 2-3 and 5-6 have been canceled; Claims 8-17 have been added.
Claims 1, 4, and 7-17 are pending and are examined herein. This is a Final Rejection.
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claim Rejections - 35 USC § 112
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
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.
Claims 1, 4, and 7-17 are rejected under 35 U.S.C. 112(a) as failing to comply with the written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor the time the application was filed, had possession of the claimed invention.
Claims 1 and 7 require “wherein the low-frequency side is a frequency band lower than a frequency band used to determine the membrane resistance.” Neither this phrase, nor any other sentence appears to indicate that the “low frequency side” is explicitly a “band lower than a frequency band used to determine the membrane resistance.”1 The dependent claims are rejected for depending on claims 1 and 7.
Claims 12 and 17 require a processor configured to “divide the low-frequency side into a first frequency range and a second frequency range, the first frequency range having a higher density of measurement points than the second frequency range; and calculate the degree of variations by using a greater number of measurement points from the first frequency range than from the second frequency range.” This language does not appear in the specification.
Claims 12 and 17 are rejected under 35 U.S.C. 112(b) as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor regards as the invention.
Claims 12 and 17 require a processor configured to “divide the low-frequency side into a first frequency range and a second frequency range, the first frequency range having a higher density of measurement points than the second frequency range; and calculate the degree of variations by using a greater number of measurement points from the first frequency range than from the second frequency range.” This language does not appear in the specification. It is unclear how or why the dividing into ranges is done, what the ranges encompass with respect to the greater “low-frequency side,” and/or whether the division is an active process or is just a result of the already performed measurements. So, the claim requires a “higher density of measurement points” in one subdivision, but it is unclear whether this is a function of the division or a function of the measurement technique. It is unclear whether the “calculation […] using a greater number of measurement points” from one range rather than another is a result of arbitrary selectin by the calculation algorithm or is just a consequence of fewer measurement points in the ranges. The claims have been interpreted broadly as describing the conventional log-scale frequency axis used in measurements of similar kind.
Claim Rejections - 35 USC § 103
Claims 1, 4, and 7-17 are rejected under 35 U.S.C. 103 as being unpatentable over Won (US Patent 10,964,962 to Won et al.) in view of Xu (Xu et al. “A Closed-Loop Water Management Methodology for PEM Fuel Cell System Based on Impedance Information Feedback.” Energies 2022, 15, 7561), Zheng (Zheng et al. “A double-fuzzy diagnostic methodology dedicated to online fault diagnosis of proton exchange membrane fuel cell stacks.” Journal of Power Sources 271 (2014) 570-581), and Lochner (Lochner, Tim. “Impedance Analysis and Monitoring of Automotive Fuel Cells.” Technical University of Munich, PhD thesis, 2021) with reference to Le Canut (Le Canut et al. “Detection of Membrane Drying, Fuel Cell Flooding, and Anode Catalyst Poisoning on PEMFC Stacks by Electrochemical Impedance Spectroscopy.” J. Electrochem. Soc. 153 A857) for ordinary skill in the art.
Regarding Claim 1, Won teaches:
a device comprising a control unit, having a processor and memory to run its control program, configured to determined a water content state of a fuel cell stack with one or more cells based on impedance measurement obtained by applying a load waveform (abstract, column 2)
the control unit configured to determine whether one or more cells are in a dry state according to a value of a membrane resistance of the cell(s) based on the impedance measurement exceeding a first threshold (Fig. 7—S21 and S23, column 12 lines 13-20)
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the control unit configured to determine a flooded state when the value of the membrane resistance is smaller than the first threshold (Fig. 7—S21 to S25), and when a second frequency, lower than the first frequency (column 11 lines 16-30), yields an impedance value ‘LFR’, that when summed with the ‘HFR’ yields a variation in the LFR and HFR greater than a reference value “RT”, which is different from “HFR1” (column 11 lines 54-65)
Won teaches a two-step protocol, wherein when the membrane resistance is lower than a first threshold, a second measure is taken, wherein a second threshold limit determines whether the membrane is flooded or not. Won does not explicitly teach:
a degree of variations calculated from a roughness measure of a phase difference plotted on an XY coordinate plane with frequency, the roughness measure being a total area of polygons formed by linking three consecutive measurement points adjacent to each other along the frequency X-axis
determining flooding when the degree of variations calculated from the total area of the polygons exceeds a given threshold
Xu, from the same field of invention, regarding water-monitoring and control of a fuel cell, teaches plotting the change in phase angle with respect to frequency, including low frequencies, and finds that the hydration state of the membrane corresponds to the feature of the resulting curve (Fig. 3), including that a “flooding state” can be distinguished from other states at low frequencies by the shape and amplitude of the plotted curve. While Xu’s method for determining flooding concentrates on a particular frequency (45 Hz), it is cited here for evidence that the flooding, normal, and dry curves are distinguishable when plotting phase difference vs frequency even at “low” frequencies.
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Zheng, meanwhile, from the same field of invention, teaches selecting features of EIS measurements using a combination of fuzzy logic and fuzzy clustering to diagnose the hydration state of a membrane (abstract), notes the uncertainty in diagnosing these states, and teaches selecting features with high interpretability as a way of reducing uncertainty (p. 571). It was well-known in the art that flooding conditions were associated with oscillations and variability in low frequency portions of phase angle-frequency EIS plots. Lochner, for example teaches that flooding is associated with total harmonic distortions at 15 Hz (pp. 108-110). Le Canut, from 2006, also shows that flooding conditions are associated with oscillations and measurement point scattering at low frequencies (Fig. 6), and compare the oscillation and variability shown at low frequencies for flooding conditions in Xu.
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It would have been obvious to select this low frequency oscillation, jaggedness, or variability as a flooding condition flag in the control system of Won, since it was known in the art that this was a feature of flooding conditions. It further would have been obvious to use multiple features of the EIS measurements to diagnose the hydration state of the membrane, as taught in Xu, and it would have been obvious to use any of a variety of well-known roughness measures for quantifying the oscillation and variability, such as roughness measures constructed from polygon areas of sequential parts measuring variation along a curve, as a standard analytical technique. Use of a known technique to improve similar devices, methods, or products in the same way, and applying a known technique to a known device, method, or product ready for improvement to yield predictable results has been found to be obvious. See KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007).
Regarding Claim 4, Won teaches:
a fuel cell vehicle comprising the device of claim 1 (column 19 line 26)
Regarding Claim 7, Won teaches:
a device comprising circuitry configured to determine a water content state of a fuel cell stack with one or more cells based on impedance measurement obtained by applying a load waveform (abstract, column 2)
the control unit configured to determine whether one or more cells are in a dry state according to a value of a membrane resistance of the cell(s) based on the impedance measurement exceeding a first threshold (Fig. 7—S21 and S23, column 12 lines 13-20)
the control unit configured to determine a flooded state when the value of the membrane resistance is smaller than the first threshold (Fig. 7—S21 to S25), and when a second frequency, lower than the first frequency (column 11 lines 16-30), yields an impedance value ‘LFR’, that when summed with the ‘HFR’ yields a variation in the LFR and HFR greater than a reference value “RT”, which is different from “HFR1” (column 11 lines 54-65)
Won teaches a two-step protocol, wherein when the membrane resistance is lower than a first threshold, a second measure is taken, wherein a second threshold limit determines whether the membrane is flooded or not. Won does not explicitly teach:
a degree of variations calculated from a roughness measure of a phase difference plotted on an XY coordinate plane with frequency, the roughness measure being a total area of polygons formed by linking three consecutive measurement points adjacent to each other along the frequency X-axis
determining flooding when the degree of variations calculated from the total area of the polygons exceeds a given threshold
Xu, from the same field of invention, regarding water-monitoring and control of a fuel cell, teaches plotting the change in phase angle with respect to frequency, including low frequencies, and finds that the hydration state of the membrane corresponds to the feature of the resulting curve (Fig. 3), including that a “flooding state” can be distinguished from other states at low frequencies by the shape and amplitude of the plotted curve. While Xu’s method for determining flooding concentrates on a particular frequency (45 Hz), it is cited here for evidence that the flooding, normal, and dry curves are distinguishable when plotting phase difference vs frequency even at “low” frequencies.
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Zheng, meanwhile, from the same field of invention, teaches selecting features of EIS measurements using a combination of fuzzy logic and fuzzy clustering to diagnose the hydration state of a membrane (abstract), notes the uncertainty in diagnosing these states, and teaches selecting features with high interpretability as a way of reducing uncertainty (p. 571). It was well-known in the art that flooding conditions were associated with oscillations and variability in low frequency portions of phase angle-frequency EIS plots. Le Canut, from 2006, shows that flooding conditions are associated with oscillations and measurement point scattering at low frequencies (Fig. 6), and compare the oscillation and variability shown at low frequencies for flooding conditions in Xu.
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It would have been obvious to select this low frequency oscillation, jaggedness, or variability as a flooding condition flag in the control system of Won, since it was known in the art that this was a feature of flooding conditions. It further would have been obvious to use multiple features of the EIS measurements to diagnose the hydration state of the membrane, as taught in Xu, and it would have been obvious to use any of a variety of well-known roughness measures for quantifying the oscillation and variability, such as roughness measures constructed from polygon areas of sequential parts measuring variation along a curve, as a standard analytical technique. Use of a known technique to improve similar devices, methods, or products in the same way, and applying a known technique to a known device, method, or product ready for improvement to yield predictable results has been found to be obvious. See KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007).
Regarding Claims 8-9 and 13-14, Xu and Le Canut teach:
frequencies in the claimed ranges (see Figs. cited above)
Regarding Claims 10 and 15, Won teaches:
determination of normal state when the second threshold is not met (see flow chart)
Xu and Zheng recognize that membrane resistance might be lower than a first threshold without necessarily being flooded. Dry and normal states were known to have distinct profiles. It would have been obvious to determine the membrane was not flooded when the second threshold was not met, since the second threshold is a sine qua non for determining flooding in each of the prior art documents.
Regarding Claims 11 and 16, Won teaches:
that the values are determined empirically
Every prior art document understands that the threshold is set empirically, not a priori. It would have been obvious to determine the thresholds for wetness and dryness empirically, which necessarily requires “preliminary experiment” within the broadest reasonable interpretation of that phrase.
Regarding Claim 12 and 17, Xu teaches:
log-scale frequency axis
Log-scale was common in the art and prompts higher density of measurement at lower values in order to yield workable curves.
Response to Arguments
The Remarks filed 2026-07-23 have been considered but do not place the application in condition for allowance. Among other things, Applicant makes two arguments, against Zheng and Le Canut that are not persuasive. Applicant argues that Zheng teaches that low frequencies cannot be diagnostic, where “low frequencies” as <1 Hz (p. 9). This is irrelevant. The instant claims have a broad range for “low frequency” and the prior art as a whole teaches that frequencies between 1-100 Hz can contain diagnostic signal. Applicant argues against Le Canut that never suggests using the low frequency scatter as an affirmative flooding indicator. Le Canut, however, clearly indicates that the impedance magnitudes associated with flooding were large, and deviated significantly from normal operation. Indicating that it is “difficult to detect a clear trend” is not the same thing as saying that there is no signal, particularly when it is the roughness itself that is the signal. Lochner teaches low frequency harmonic distortions in the impedance measurements reflects water droplet formation, unpredictably impacting the measurement (pp. 109-114). It was therefore known that plots of phase difference vs frequency for flooded membranes showed distortions and unpredictable movement at low frequencies with amplitudes different from normal functioning. It would have been obvious to select roughness as a way of measuring distortion in that low frequency band as a diagnostic cycle, and polygonal-area measures were one of the most basic roughness measurement methods known in the art, taught in undergraduate curricula.
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 Michael Dignan, whose telephone number is (571) 272-6425. The examiner can normally be reached from Monday to Friday between 10 AM and 6:30 PM. If any attempt to reach the examiner by telephone is unsuccessful, the examiner’s supervisor, Tiffany Legette, can be reached at (571)270-7078. Another resource that is available to applicants is the Patent Application Information Retrieval (PAIR). Information regarding the status of an application can be obtained from the (PAIR) system. Status information for published applications may be obtained from either Private PAIR or Public PAX. Status information for unpublished applications is available through Private PAIR only. For more information about the PAIR system, see http://pair-direct.uspto.gov. Should you have questions on access to the Private PAIR system, please feel free to contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). Applicants are invited to contact the Office to schedule an in-person interview to discuss and resolve the issues set forth in this Office Action. Although an interview is not required, the Office believes that an interview can be of use to resolve any issues related to a patent application in an efficient and prompt manner.
/MICHAEL L DIGNAN/Examiner, Art Unit 1723
1 The Remarks filed 2026-07-23 point to instant paragraphs 0049-0050, 0064, 0066-0068, and 0074. None of these appear to provide support for this limitation.
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