A system for measuring gas concentration includes a package having a cavity and a port, a photoacoustic gas sensor device within the package, and a Micro Electro Mechanical System (“MEMS”) valve separate from the photoacoustic gas sensor device placed over the port of the package and to allow ambient gas diffusion into the cavity in a first mode of operation, and to prevent ambient gas diffusion into the cavity and to acoustically isolate the cavity in a second mode of operation.