Abstract: A method for verifying the identity of a person comprises providing a plurality of pressure transducers and deriving a key from pressures measured by the pressure transducers when a person presses a hand (or other body part) against the pressure transducers. The key can be compared to a previously stored reference key. Apparatus for verifying the identity of a person may have an array of pressure transducers coupled to a controller. The controller produces the key and compares it to a reference key.

Abstract: A sensor for detecting changes in a variety of conditions is provided, including temperature, chemical conditions including pH and ion levels, biological antigens, radiation levels, electrical field and pressure applied to the sensor. The sensor body is formed from a material which incorporates an evenly dispersed matrix of light-scattering elements. A light source emits light into the body to form an effective optical cavity in which the light is scattered by the matrix. One or more receivers detects the intensity of scattered or integrated light inside and/or outside of the optical cavity. The matrix and/or the sensor body are composed of materials which reduce or increase the density of light-scattering elements, depending on the conditions applied to the matrix. An increase in the density of the light-scattering elements results in a corresponding increase in the integrated intensity of light received by the receiver, when the receiver is positioned within the optical cavity.