Hygrophila spinosa T. Anders seeds based biomineral doped cobalt oxide: Synthesis, characterization and its application to humidity sensing

Hygrophila spinosa T. Anders plant seeds (HST) possessing gelling behavior with mineral constituents have been chosen as a dopant in cobalt oxide (Co3O4) to investigate the humidity sensing properties. The study on the structural parameters, functional groups, BET surface area, surface morphology and elemental analysis of the prepared sensor samples was made using XRD, FT-IR, nitrogen adsorption/desorption isotherms at 77 K, SEM and EDX techniques respectively. The humidity sensitivity factor (Sf) of the prepared samples was evaluated by two probe dc-electrical resistance method at different humidity levels. The Sf value determined suggested that the sample with the weight ratio of Co3O4:HST biominerals of 0.25:0.75 respectively was beneficial for increasing the sensitivity factor possessed relatively a higher value, i.e. 4500. Good linearity, reproducibility, stability and fast response time (5.5 ± 0.25 min) and recovery time (2.5 ± 0.08 min) achieved in CH3 sample is indicative to be a good humidity sensor.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A new sensor material based on bioresources was prepared. ► The HST plant contains minerals is a chosen dopant in Co2O3. ► The plants are found in marsh areas and commercially available in many countries. ► CH3 sample (0.25:0.75) predicted to be a good humidity sensing material.