The invention provides coated sensors for detecting the presence of analytes. The sensor comprises one or more fluorescent sources, such as one or more quantum dots or one or more fluorescent dyes, a polymeric matrix, a surface coating, and one or more analyte sensing components. The surface coating may be a conformal polymeric film, permeable to the analyte, which may be deposited via a solventless process such as initiated chemical vapor deposition or photoinitiated chemical vapor deposition. The surface coating may increase the biocompatibility of the sensor, reduce nonspecific protein adsorption, and/or sequester functional sensor components within the sensor. The invention also provides methods for detecting the presence of an analyte with coated sensors of the invention.