A sensor to aid in diagnosing at least one of infiltration and extravasation in Animalia tissue, the sensor comprising: a housing including a surface configured to confront an epidermis of the Animalia tissue; a first waveguide being configured to transmit a first light signal, the first waveguide having an emitter end face configured to emit the first light signal that enters the Animalia tissue; guiding the first light signal along a first path intersecting the emitter end face at an approximately 90 degree angle; and being partially disposed in the housing; a second waveguide being configured to transmit a second light signal, the second light signal including a portion of the first light signal that is at least one of reflected, scattered and redirected from the Animalia tissue, the second waveguide having a detector end face (!22) configured to collect the second light signal that exits the Animalia tissue; guiding the second light signal along a second path intersecting the detector end face at an approximately 90 degree angle; and being partially disposed in the housing; and a substantially smooth superficies configured to overlie the epidermis, the superficies including the surface, the emitter end face and the detector end face; characterised in that: each individual point of the emitter end face is disposed a minimum distance not less than 3 millimeters from each individual point of the detector end face, and each individual point of the emitter end face is disposed a maximum distance not more than 5 millimeters from each individual point of the detector end face, to readily observe anatomical changes at depths between approximately 2.5 millimeters and approximately 3 millimeters below the stratum corneum for wavelengths between approximately 650 nanometers and approximately 950 nanometers. a housing including a surface configured to confront an epidermis of the Animalia tissue; a first waveguide being configured to transmit a first light signal, the first waveguide having an emitter end face configured to emit the first light signal that enters the Animalia tissue; guiding the first light signal along a first path intersecting the emitter end face at an approximately 90 degree angle; and being partially disposed in the housing; having an emitter end face configured to emit the first light signal that enters the Animalia tissue; guiding the first light signal along a first path intersecting the emitter end face at an approximately 90 degree angle; and being partially disposed in the housing; a second waveguide being configured to transmit a second light signal, the second light signal including a portion of the first light signal that is at least one of reflected, scattered and redirected from the Animalia tissue, the second waveguide having a detector end face (!22) configured to collect the second light signal that exits the Animalia tissue; guiding the second light signal along a second path intersecting the detector end face at an approximately 90 degree angle; and being partially disposed in the housing; and having a detector end face (!22) configured to collect the second light signal that exits the Animalia tissue; guiding the second light signal along a second path intersecting the detector end face at an approximately 90 degree angle; and being partially disposed in the housing; and a substantially smooth superficies configured to overlie the epidermis, the superficies including the surface, the emitter end face and the detector end face; characterised in that: each individual point of the emitter end face is disposed a minimum distance not less than 3 millimeters from each individual point of the detector end face, and each individual point of the emitter end face is disposed a maximum distance not more than 5 millimeters from each individual point of the detector end face, to readily observe anatomical changes at depths between approximately 2.5 millimeters and approximately 3 millimeters below the stratum corneum for wavelengths between approximately 650 nanometers and approximately 950 nanometers.