Abstract: An optrode for insertion into a blood vessel can include at least one fiber optic, a sheath enclosing at least part of the fiber optic and sensor material in optical communication with one end of the fiber optic. The sensor material is operative for diffracting electromagnetic waves received from the fiber optic and is responsive to changes in an amount of glucose in contact therewith for changing a diffraction of the electromagnetic waves as a function thereof. A membrane covering a distal end of the sheath passes to the sensor material glucose from blood in contact with the side of the membrane opposite the sensor material. Electromagnetic waves input into the fiber optic cable are diffracted by the sensor material. A concentration of glucose in the blood can be estimated from the amount of diffraction of the electromagnetic waves. A signal can be output related to the estimated glucose concentration.

Abstract: The present invention is a colored contact lens whose color is produced by Bragg diffraction. The contact lens includes a hydrogel comprised of either dimethyl acrylamide, HEMA (hydroxylethyl methacrylate) or 3-(trimethoxysilyl)propyl methacrylate and a light diffracting crystalline colloidal ordered array of particles polymerized in the hydrogel. The crystalline colloidal ordered array has a fixed lattice spacing.