Concentrating devices, systems, and methods include those for separating fluids to be sensed (e.g., analytes, such as volatile organic compounds (VOCs) and / or other chemical substances) from other fluid (e.g., a carrier gas, air, etc.) of a fluid mixture received from a target area of a subject's
anatomy (e.g., a subject's
skin, a wound on a subject, etc.). In some cases, the concentration
system may include a housing and a rotor positioned in a compartment of the housing. The housing may receive a fluid mixture in the compartment and rotation of the rotor relative to the housing may separate fluid to be sensed in the fluid mixture from other fluid of the fluid mixture.