During the growth of Japanese cows, the ruminal pH value is an important physiological parameter, which remarkably affects their nutritional status. To monitor the health condition of the cows and help farmers efficiently manage their livestock, a clear need exists to develop a novel method to efficiently sense the daily range of the rumen pH. Thus, we developed a solid-state pH sensor for real-time monitoring of the rumen pH value of Japanese cows. The indium tin oxide and field-effect transistor-based pH sensor was fabricated and well packaged, and its performance was comprehensively evaluated. The isolation resistance and waterproofing of the packaged sensor were measured, and the functional features fully satisfied the specific requirements. The power consumption of the developed sensor was measured and calculated. The compact pH sensor only incurred a power consumption of 8.2 × 10−4 mA h, which is a low value for a cell battery-powered system. Stability test of the packaged pH sensor was performed, and the developed sensor could well measure an acid solution with a stable output for a relatively long time. The output characteristic of the pH sensor and its field measurement were also presented in this paper.
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