Stimulus-responsive gel with optical chracteristic molecule introduced therein, external stimulus measuring apparastus making use of the same, and method of measuring external stimulus

A sensor element for converting into optical data a volume change in a stimulus-responsive gel, which changes its volume in response to an external stimulus, the volume change being caused in response to the external stimulus, comprising:

• an optical characteristic molecule-introduced stimulus-responsive gel, in which an optical characteristic molecule is introduced,
• wherein:
• the optical characteristic molecule is a molecule having a fluorescence chromophore, or a molecule capable of absorbing visible light or ultraviolet light;
• the molecule having the fluorescence chromophore, or the molecule capable of absorbing visible light or ultraviolet light is contained in the optical characteristic molecule-introduced stimulus-responsive gel in such a quantitative range that density of the molecule having the fluorescence chromophore, or of the molecule capable of absorbing visible light or ultraviolet light is substantially proportional to fluorescence intensity or absorbance of the visible light or ultraviolet light in the optical characteristic molecule-introduced stimulus-responsive gel;
• logarithms of the volume change in the optical characteristic molecule-introduced stimulus-responsive gel and logarithms of the fluorescence intensity or absorbance of the visible light or ultraviolet light have a linear relationship;
• and
• the sensor element is capable of measuring the external stimulus by using, as a quantitative indicator of the volume change, results of the measurement of the fluorescence intensity or absorbance of the visible light or ultraviolet light of the optical characteristic molecule-introduced stimulus-responsive gel.