Methods and apparatuses are provided that greatly expand the utility of conventional hollow waveguide-based sensors via either straight, substrate-integrated channels or via meandering (e.g., circuitous, curved or folded optical paths) waveguide sensor designs. Full- or hybrid-integration of the meandering hollow waveguide with light source, detector, and light-guiding optics facilitates compact yet high-performance gas/vapor and/or liquid sensors of the substrate-integrated hollow waveguide sensor.