Fabrication of a low leakage current type impedance sensor with shielding structures to detect a low water content of soil for slope failure prognostics

Abstract A low-leakage-current-type impedance sensor chip with shield structures has been fabricated. The low limit detection of soil-water-content measurement was improved compared with that of the other semiconductor-type sensors. The shield structures were fabricated under the impedance sensor areas. To measure the weak signal current eliminated by the leakage current, we proposed a new operation circuit to separate the leakage current. Our sensor was able to measure low water content of 10% or less. The sensor could detect the change of water content in the slope of mountain when it rained.