A device for monitoring a test subject includes a light source and at least one optical waveguide configured for at least one of directing light from the light source onto a biological substrate and receiving the light directed onto the biological substrate. The device also includes a sensor operable to detect the light received, a logic component operable to analyze the light detected by the sensor, an output component operable to convey information from the logic component to a user of the device, and a housing containing the light source, the sensor, the logic component, and the output component, where the at least one optical waveguide forms at least one bristle extending outside of the housing.