A Real-Time Monitoring System Using a Multimodal Sensor with an Electrical Conductivity Sensor and a Temperature Sensor for Cow Health Control

A multimodal sensor composed of an electrical conductivity (EC) sensor and a temperature sensor on the same Si chip was successfully fabricated using compatible complementary metal oxide semiconductor (CMOS) technology. The EC sensor measured the electrical conductivity between Pt electrodes, and the temperature sensor measured the forward voltage of a p--n junction diode. We confirmed the output signal in a wide dynamic range of ECs. For real-time measurement in the rumen of cows, a wireless system was fabricated. The system included a sensor, a battery, an antenna, an analog signal-processing circuit board, an AC-to-DC converter board, and a receiver--transmitter board. We adjusted the wireless system design with focus on the measurement range to adapt the system to the rumen. Real-time and simultaneous measurements of EC and temperature in the rumen using the multimodal sensor unit were performed. The wireless system successfully received signals continuously, and enabled the measurement of the rumen conditions in real time.