Study on the novel capacitive moisture sensing behaviour of nickel chromite nanoparticle based thick film

Abstract

Abstract In this work, the novel and appreciable humidity sensing properties of microporous, spinel nickel chromite thick films are reported for the first time. NiCr2O4 microporous, thick film prepared by tape casting of sol-gel derived nanopowder followed by sintering was sandwiched between two parallel silver electrodes to develop capacitive humidity sensor. Condensation in the surface pores and physisorption on the sensor surface are found to be responsible for the humidity sensing properties. The sensor shows excellent humidity sensing properties in the range of 5 to 95% RH (relative humidity) with a resolution of ∼3 pF/%RH in the lower humidity range (5% - 30% RH) at 1kHz external electric field. The sensor also exhibited excellent repeatability (at least 50 cycles of 5%-95%RH), good stability of at least 6 months, and low hysteresis loss. The thick film sensors were characterized by XRD, FT-IR, FESEM, TEM, EDX, and contact angle measurement.