title: Low-Cost Soil Moisture Profile Probe Using Thin-Film Capacitors and a Capacitive Touch Sensor.
abstract: Soil moisture is an important property for agriculture, but currently commercialized soil moisture sensors are too expensive for many farmers. The objective of this study is to develop a low-cost soil moisture sensor using capacitors on a film substrate and a capacitive touch integrated circuit. The performance of the sensor was evaluated in two field experiments: a grape field and a mizuna greenhouse field. The developed sensor captured dynamic changes in soil moisture at 10, 20, and 30 cm depth, with a period of 10-14 days required after sensor installation for the contact between capacitors and soil to settle down. The measured soil moisture showed the influence of individual sensor differences, and the influence masked minor differences of less than 0.05 m³·m(-3) in the soil moisture at different locations. However, the developed sensor could detect large differences of more than 0.05 m³·m(-3), as well as the different magnitude of changes, in soil moisture. The price of the developed sensor was reduced to 300 U.S. dollars and can be reduced even more by further improvements suggested in this study and by mass production. Therefore, the developed sensor will be made more affordable to farmers as it requires low financial investment, and it can be utilized for decision-making in irrigation.
authors.affiliation: Faculty of Engineering, Gifu University, Gifu 501-1193, Japan. kojima@gifu-u.ac.jp.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kojima
authors.affiliation: Graduate School of Information Science and Technology, The University of Tokyo, Tokyo 113-8656, Japan. shigeta@akg.t.u-tokyo.ac.jp.
authors.forename: Ryo
authors.initials: R
authors.lastname: Shigeta
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan. miyamoto@isas.a.u-tokyo.ac.jp.
authors.forename: Naoya
authors.initials: N
authors.lastname: Miyamoto
authors.affiliation: Graduate School of Information Science and Technology, The University of Tokyo, Tokyo 113-8656, Japan. shirahama@akg.t.u-tokyo.ac.jp.
authors.forename: Yasutomo
authors.initials: Y
authors.lastname: Shirahama
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan. nishioka@isas.a.u-tokyo.ac.jp.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Nishioka
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan. amizo@mail.ecc.u-tokyo.ac.jp.
authors.forename: Masaru
authors.initials: M
authors.lastname: Mizoguchi
authors.affiliation: Graduate School of Information Science and Technology, The University of Tokyo, Tokyo 113-8656, Japan. kawahara@akg.t.u-tokyo.ac.jp.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kawahara
keywords: capacitive touch sensor; printing circuit; soil moisture; soil moisture profile probe