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Home > Nanotechnology Columns > Magda Carvalho PhD, JD > In Ex Parte Vyas et al: A Coating thickness measured in nanometers will not necessarily contain nanopores.

Magda Carvalho
Patent Attorney
Patent Law at M. Carvalho

The technology of fuel cell only requires hydrogen and oxygen gas or air fuel to generate electric power. This case before the BPAI involved bipolar plates for a fuel cell hydrophilic that contain nanopores. The BPAI concluded that a reference disclosing a coating layer with nanosized thickness does not necessarily imply that it contain nanopores.

June 11th, 2011

In Ex Parte Vyas et al: A Coating thickness measured in nanometers will not necessarily contain nanopores.

A basic hydrogen fuel cell includes an anode and a cathode separated by a membrane (electrolyte). The anode receives hydrogen gas and the cathode receives oxygen or air. The hydrogen reacts to a catalyst on the electrode anode that converts the hydrogen gas into negatively charged electrons (e-) and positively charged ions (H+). The protons pass through the electrolyte to the cathode. The protons combine with the oxygen and the electrons in the cathode to produce water. The electrons from the anode cannot pass through the electrolyte, and thus are directed through a load to perform work before being sent to the cathode.

The fuel cell stack includes a series of separator plates or bipolar plates positioned between the several membrane electrode assembly (MEA) in the stack. One of the roles of the bipolar plates is to establish uniform distribution of reactants across the fuel cell. Another role is to remove the product water or gas. The surfaces of a separator plate/bipolar plate contain a flow field for flow of reactants and provide electrical contact.

The membranes within a fuel cell need to have a certain relative humidity so that the ionic resistance across the membrane is low enough to effectively conduct protons. During operation of the fuel cell, moisture from the MEAs and external humidification may enter the anode and cathode flow channels. If water accumulates within the flow channels it may block the flow channel and halt production of electricity.

However, for long-term durability the fuel cells must remain hydrated.

Ex parte Vyas et. al., Appeal No. 2010-004061 (BPAI 05/09/2011).

Non-obviousness requirement is codified in 35 U.S.C. 103. The critical inquiry is whether there is something in the prior art to suggest the desirability of combining previously known elements. In this case, the inventor overcame a rejection by the Examiner under an obviousness analysis because the Examiner failed to provide factual evidence supporting the rejection.

The invention relates to flow field plates or bipolar plates for fuel cells that improve channel water transport by means of a hydrophobic or hydrophilic coating deposited on a roughened surface of the plate. The coating is made of a metal that is conductive and that includes nanopores.

Representative claim 1 reads as follows: A fuel cell comprising a flow field plate being made of a plate material, said flow field plate including a plurality of flow channels responsive to a reactant gas, said flow field plate further including at least one coating that makes the flow field plate both hydrophilic and conductive, said coating being a metal that is conductive and that includes nanopores formed as a result of a material being removed from the coating to make the coating hydrophilic.

The Examiner made a determination that the claims were obvious in view of two references. The Yasuo reference involves a porous metal coating on a flow field plate but it fails to disclose the "nanopores" limitation of claim 1. Another reference, Vyas, also did not disclose "nanopores" but taught a flow field plate that has a metal coating with a thickness in the range of nanosize (10-20 nm). As such, the Examiner concluded that it would have been obvious for one with ordinary skill in the art to provide the nanosized thickness metal coating of Yasuo in view of Vyas. The Examiner believed this provision would satisfy the nanopores limitation of claim 1 because, "by having the conductive coating layer of 10-20 nm, the pores will be nano sized pores." According to the Examiner, "it is not unreasonable to conclude, for one of ordinary skill to infer[,] that since the coating is nanosized it will contain nanosized pores." The Board disagreed.

Instead, the Board found the inventors' argument persuasive. Inventors argued that neither Yasuo nor Vyas contains any teaching or suggestion of providing their respective coatings with nanopores. Besides, the Examiner has provided no support for assertion that a coating thickness measured in nanometers would contain nano-sized pores. The Board found that the Examiner has provided no evidence or technical rationale for the proposition that coating thicknesses in the nanosize range will necessarily and inherently contain pores in the nanosize range.

In summary, although it seems that KSR has made it easier for an Examiner to make a rejection under section 103, the Examiner must establish "an apparent reason to combine known elements." Here, the inventors focused on the fact that the Examiner failed to provide a sufficient rationale for the asserted combination.

KSR International Co. v.Teleflex Inc., 550 U.S. 398, 82 U.S.P.Q.2d 1385 (2007).

Please send your comments to Magda Carvalho at

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