A method of making a low dimensional material chemical vapor sensor comprising providing a monolayer of a transition metal dichalcogenide, applying the monolayer to a substrate, applying a PMMA film, defining trenches, and placing the device in a n-butyl lithium (nbl) bath. A low dimensional material chemical vapor sensor comprising a monolayer of a transition metal dichalcogenide, the monolayer applied to a substrate, a region or regions of the transition metal dichalcogenide that have been treated with n-butyl lithium, the region or regions of the transition metal dichalcogenide that have been treated with n-butyl lithium have transitioned from a semiconducting to metallic phase, metal contacts on the region or regions of the transition metal dichalcogenide that have been treated with the n-butyl lithium.