The invention is directed to a beard trimmer with an internal vacuum system that collects the hair clippings generated by the trimmer during grooming. A substrate having nanowires attached to a portion of at least one surface is provided. The Mach-Zehnder interferometer and the directional coupler share a common arm. Generally, a sampling of short messages of a plurality of users is obtained. The flow distribution element extends across a direction of exhaust flow through the main body and is mounted at a side of the main body that is opposite the side inlet.