Methods and sensors for detection

A chromogenic sensor, comprising:

• a tunable shape memory polymer membrane,
• wherein the tunable shape memory polymer membrane is an optically transparent glassy polymer having a glass transition temperature higher than room temperature,
• wherein the glassy polymer is selected from poly(urethane), polyethylene terephthalate (PET), polyethyleneoxide (PEO), epoxy, polyarylates, block copolymers containing polystyrene and poly(1,4-butadiene), poly(2-methyl-2-oxazoline), and polytetrahydrofuran, and polynorbornene,
• wherein the tunable shape memory polymer membrane is a macroporous photonic crystal membrane having a three-dimensional polymer framework separating macropores;
• and
• wherein when an area of the tunable shape memory polymer membrane is exposed to a liquid mixture containing a first liquid, the area changes color if the liquid mixture includes the first liquid;
• wherein the color change is correlated to a concentration of the first liquid in the liquid mixture or is correlated to a pressure of vapor of the first liquid in the liquid mixture;
• wherein the area changes color depending upon the concentration of the first liquid in the liquid mixture,
• wherein the color changes from a greenish color to a bluish color in response to a first concentration, yellowish color in response to a second concentration, and orange color in response to a third concentration, and
• wherein the first concentration, the second concentration, and the third concentration are different from one another.