Spina Rule in Bubble Mixing: Agilent Technologies, Inc. v. Affymetrix, Inc.

In Agilent Technologies, Inc. v. Affymetrix, Inc. (Fed. Cir., No. 2008-1466, decided June 4, 2009), the Federal Circuit invoked the Spina rule in resolving which specification to consult when construing a claim challenged in an interference. According to the Spina rule, the specification from which the interfering claim was copied is the specification to consult.

Agilent Technologies, Inc. (Agilent) was awarded U.S. Patent No. 6,513,968 (the Schembri patent) on February 4, 2003. The patent had a priority date of August 21, 1998. Affymetrix Inc. (Affymetrix) copied claim 20 of the Schembri patent into its U.S. Patent Application No. 10/619244 (the Besemer application), having a priority date of June 7, 1995, in order to provoke an interference. The Board of Patent Appeals and Interference declared an interference on February 6, 2006. In the interference proceeding, Agilent had the burden of showing entitlement to priority of invention because the Schembri patent had a priority date after the Besemer application.

Agilent charged that the interfering claim was not supported by the Besemer application. The Board found that the interfering claim was supported by the Besemer application and awarded priority to Affymetrix. The Board construed the interfering claim in light of the Besemer application. The district court sustained the Board’s decision. But the Federal Circuit reversed the district court’s decision on the basis that the interfering claim should have been construed in light of the Schembri specification from which the claim was copied instead of the Besemer specification into which the claim was copied.

The technology relates to microfluidics and mixing of fluids for thorough contact with microarray surface. The disputed term in the claim construction was “closed chamber.” Based on the Besemer application, the district court defined “closed chamber” as “an enclosed cavity, or some other enclosure or system of enclosures, which is capable of being sealed or set apart from its surroundings to retain a quantity of fluid.” On the other hand, the interfering claim and the Schembri specification from which it was copied described the closed chamber as being defined between inner surfaces of a first substrate and a second substrate, where at least one of the inner surfaces is functionalized with polynucleotides, polypeptides, or polysaccharides. The Federal Circuit rejected the idea of the closed chamber being some “nebulous space” and instead, guided by the Spina rule, adopted a definition in light of the Schembri specification, i.e., “an enclosed cavity defined by the inner surfaces of the first and second substrates, from which there is no egress of fluid.”

Agilent argued that the Besemer specification did not support a method of mixing with bubbles that takes place in a closed chamber. In the Schembri patent, a bubble is provided in the fluid in the closed chamber and the bubble is moved within the fluid, e.g., in response to heat resistors, to cause mixing. Using the proper construction of the term "closed chamber", the Federal Circuit agreed with Agilent.