Zinc oxide is a preferred choice for several optoelectronic applications owing to their unique properties, such as wider band gaps combined with high exciton binding energies. A zinc oxide thin film was grown on glass substrates through sol-gel depositing method followed by heat treatments. We prepared the zinc oxide thin films using zinc acetate dihydrate, 2-methoxy ethanol and diethanolamine as zinc alkoxide precursor, solvent and sol stabilizer respectively. Structural and optical characterizations were carried out that included X-ray diffraction, Atomic force microscopy, Profilometry and UV-Visible spectrophotometry. A coplanar configuration of device has been chosen where the structure has Zinc oxide thin film on which metal contacts of 100 nm thickness were deposited onto the films via thermal evaporation. A two probe source meter was used for I-V measurements in dark environment. I-V measurements have been done for various concentrations of biomolecules (Vitamin B6). It is found that there are variations in current for increasing concentrations.