Sensor Patent Dispute Revived-in-Part Due To Improper Claim Construction

In SSI Technologies, LLC v. Dongguan Zhengyang Electronic Mechanical Ltd., No. 21-2345 (Fed. Cir. Feb. 13, 2023), the Federal Circuit affirmed-in-part, reversed-in-part, vacated-in-part, and remanded a district court decision granting summary judgment of non-infringement and invalidity.

SSI Technologies ("SSI") brought suit against Dongguan Zhengyang Electronic Mechanical ("DZEM") for infringement of two patents directed to sensors for determining the characteristics of fluid in a container. With respect to the first patent, U.S. Patent No. 8,733,153, the dispute focused on the construction of the item (b) in the following Markush group: "a) whether a measured volume is out of range and b) a dilution of the fluid is detected while the measured volume of the fluid decreases." The district court construed item (b) to require the consideration of the measured volume of the fluid. With respect to the second patent, U.S. Patent No. 9,535,038, the district court