Abstract: A semiconductor device that detects deterioration of a secondary battery is provided. The semiconductor device includes a power gauge, an anomalous current detection circuit, and a control circuit. The power gauge includes a current divider circuit and an integrator circuit. The anomalous current detection circuit includes a first memory, a second memory, and a first comparator. The integrator circuit can convert a detection current detected at the current divider circuit into a detection voltage by integrating the detection current. The anomalous current detection circuit is supplied with the detection voltage, a first signal at a first time, and a second signal at a second time. The first signal can make the detection voltage at the first time be stored in the first memory and the second signal can make the detection voltage at the second time be stored in the second memory.

Abstract: An enzyme electrode includes an electrode, and a detection layer that is in contact with the electrode and includes an oxidoreductase, a water-soluble conductive polymer, and conductive particles, electrons being transferred between the enzyme and the electrode by direct electron transfer in the detection layer.