Lifescan Scotland, Ltd. v. Shasta Tech., LLC, No. 13-1271 (Fed. Cir. 2013)Annotate this Case
The patent concerns blood glucose monitoring systems, used by individuals with diabetes. Such systems typically consist of an electrochemical meter and disposable test strips onto which the user places a drop of blood. The strip contains “working electrodes” or “reference electrodes,” that connect to the meter during operation. Each working electrode is coated with an enzyme and a mediator. The enzyme reacts with glucose in the blood sample, releasing electrons. The mediator then transfers those electrons to the working electrode, which is connected to the meter, which measures the resulting electric current to determine blood glucose level. Meters and test strips of this general design became available in the 1980s. LifeScan’s patent claims to improve earlier systems with a method of comparing measurements from separate working electrodes. Significant differences in the readings of the working electrodes indicate problems such as inadequate sample volume or manufacturing defects, and the readings are to be discarded. A reference electrode on the strip serves as a common reference for both working electrodes. LifeScan manufactures such a system, the “OneTouch Ultra” and claimed infringement by defendant. The district court found likely infringement and entered an injunction. The Federal Circuit reversed, finding that defendant established a patent exhaustion defense.