Presentation Information
[7p-N305-2]Fabrication of CMOS ion sensors for measuring nitrogen and phosphorus in smart agriculture
〇Rintaro Okamoto1, Yusuke Matsushita1, Ik-Hyun Kwon1, Hideo Doi1, Kotaro Takayama1, Kazuaki Sawada1, Kazuhiro Takahashi1, Yong-Joon Choi1, Toshihiko Noda1 (1.Toyohashi Univ.)
Keywords:
Agricultural Sensors,Semiconductor Image Sensors,Ionophore
This study presents CMOS ion sensors for measuring ammonium (NH4+) and phosphate (HPO4^2-) ions to support smart agriculture. Building on previous work with in vivo pH and potassium (K+) sensing in plants, we fabricated sensors using a 256x256 pixel CMOS potentiometric array with 30 µm pixel pitch. Ion-sensitive membranes were prepared by dissolving PVC, plasticizer, and ionophore in an organic solvent and coating the sensor surface. The NH4+ sensor showed a sensitivity of 48.9 mV/decade with high linearity over a range relevant to plant physiology. The HPO4^2- sensor exhibited a sensitivity of -17.5 mV/decade with a similarly suitable response range. Noise during plant insertion was 9 mVp-p, confirming a sufficient signal-to-noise ratio. These results indicate that all three major plant nutrients (NH4+, HPO4^2-, and K+) can be measured using a single CMOS imaging sensor. This technology has strong potential for real-time, multi-nutrient monitoring in smart agriculture.