Methods and compositions for detecting a targeted analyte, such as volatile organic compound (VOCs), are disclosed. Specifically, a cholesteric liquid crystal composition comprising a nematic liquid crystal and a chiral dopant transitions to a liquid crystal blue phase or undergoes other optical changes when in contact with a sample containing the analyte. The phase transition can be readily detected with the naked eye. The disclosed methods and compositions may be used in, for example, dosimeters for detecting analyte (e.g., VOC) exposure. Methods and compositions for producing arrays of liquid crystal thin films are also disclosed. The surface between the microwells in a microwell array is coated with a liquid-crystal-phobic material, such as a fluorinated polymer or a fluorinated silane, creating isolated microwell domains that are preferentially wetted by liquid crystal. Liquid crystal can be added to the microwell domains by simple techniques such as spin coating.