An intracorporeal substance measuring assembly to be provided in an embedded-type substance sensor for detecting and measuring an intercorporeal analyte includes: a detection layer containing at least one fluorescent indicator for generating fluorescence according to the concentration of the analyte; and an optical separation layer which is provided on the detection layer, is optically opaque, permits the analyte to penetrate therethrough, and prevents the penetration therethrough of at least one of living body substances possibly deteriorating the detection layer and/or obstructing the fluorescence.
A fluorescent monomer compound represented by the following formula (1) is provided: ##STR00001## wherein Q, Q' and D.sup.3 may be the same or different, may be combined together into a fused ring, and are each a substituent selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, and substituted or unsubstituted alkyl, acyl, oxyalkyl, carboxyl, carboxylate ester, carboxamido, cyano, nitro, amino and aminoalkyl groups; and D.sup.1, D.sup.2 and D.sup.4 each represent a substituent, wherein at least one of D.sup.1, D.sup.2 and D.sup.4 is a substituent group comprising a vinyl group at an end thereof, and wherein the substituent group comprising a vinyl group at an end thereof enables the fluorescent monomer compound to be soluble in water.
