A Phase I SBIR is proposed for the development of a wearable sensor to protect law enforcement and first responders from inadvertent exposure to potentially toxic levels of fentanyl and/or fentanyl analogs. The Phase I project will demonstrate the ability of the new sensor to selectively detect the presence of fentanyl analog vapors from solid samples or air-borne particulates in concentrations below ECt50 levels. The work will focus on the development of a new selective fentanyl-binding polymer integrated into a chemical sensing antenna structure and the development of a preliminary design of a low-cost, low-power set of read electronics to use with the sensing antenna. Response data from tests of the sensing antenna against non-hazardous fentanyl analogs and common clutter agents including heroin and heroin cutting compounds will be used to show the feasibility of the new sensor. The new fentanyl analog sensor will have commercial application, not only in individual personnel safety, but also in facilities or event protection where aerosolized fentanyl and fentanyl analogs could be deployed as weapons. Further, modification of the fentanyl-binding polymer layer to enable selective binding of toxic industrial chemicals or volatile organic compounds could expand the commercial potential of the sensor to fire and mine safety, as well as hazmat applications.