A method of fabricating a nanowire CHEMFET sensor mechanism includes preparing a silicon substrate; depositing a polycrystalline ZnO seed layer on the silicon substrate; patterning and etching the polycrystalline ZnO seed layer; depositing an insulating layer over the polycrystalline ZnO seed layer and the silicon substrate; patterning and etching the insulating layer to form contact holes to a source region and a drain region; metallizing the contact holes to form contacts for the source region and the drain region; depositing a passivation dielectric layer over the insulating layer and the contacts; patterning the passivation layer and etching to expose the polycrystalline ZnO seed layer between the source region and the drain region; and growing ZnO nanostructures on the exposed ZnO seed layer to form a ZnO nanostructure CHEMFET sensor device.