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Article

Valve-Actuator-Integrated Reference Electrode for an Ultra-Long-Life Rumen pH Sensor

1
Department of Human and Engineered Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8563, Japan
2
Sensing System Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8564, Japan
*
Author to whom correspondence should be addressed.
Sensors 2020, 20(5), 1249; https://doi.org/10.3390/s20051249
Received: 29 January 2020 / Revised: 17 February 2020 / Accepted: 20 February 2020 / Published: 25 February 2020
(This article belongs to the Special Issue Water and Health pH Sensors)
We demonstrated a newly developed Ag/AgCl reference electrode- with a valve-actuator for two years or longer rumen pH monitoring. Previous studies on pH sensors reported that the short lifetime of Ag/AgCl reference electrodes is caused by an outflow of internal electrolyte. We introduced a valve-actuator into a liquid junction to reduce the outflow by intermittent measurement. The results indicated that the potential change when switching the liquid junction was less than 0.5 mV and its response time was less than 0.083 s. In the 24-h potential measurement with the valve-actuator-integrated reference electrode (VAIRE), the valve was actuated once every hour, and the standard deviation of the potential was 0.29 mV. The lifetime of the VAIRE was estimated at 2.0 years calculating from an electrolyte outflow, which is significantly longer than that of conventional reference electrodes. A pH sensor using the VAIRE was estimated to operate for 2.0 years with the pH error ≤0.1, which meets the requirement of cows’ rumen pH monitoring. View Full-Text
Keywords: pH sensor; reference electrode; liquid junction; shape memory alloy actuator pH sensor; reference electrode; liquid junction; shape memory alloy actuator
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MDPI and ACS Style

Higuchi, S.; Okada, H.; Takamatsu, S.; Itoh, T. Valve-Actuator-Integrated Reference Electrode for an Ultra-Long-Life Rumen pH Sensor. Sensors 2020, 20, 1249. https://doi.org/10.3390/s20051249

AMA Style

Higuchi S, Okada H, Takamatsu S, Itoh T. Valve-Actuator-Integrated Reference Electrode for an Ultra-Long-Life Rumen pH Sensor. Sensors. 2020; 20(5):1249. https://doi.org/10.3390/s20051249

Chicago/Turabian Style

Higuchi, Shogo, Hironao Okada, Seiichi Takamatsu, and Toshihiro Itoh. 2020. "Valve-Actuator-Integrated Reference Electrode for an Ultra-Long-Life Rumen pH Sensor" Sensors 20, no. 5: 1249. https://doi.org/10.3390/s20051249

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