Koninklijke Philips Electronics of Eindhoven, The Netherlands, has received US Patent No. 7,048,890, "Sensor and method for measuring the areal density of magnetic nanoparticles on a microarray." The patent claims a method and device for the magnetic detection of binding of biological molecules on a biochip. The patent describes a magneto-resistant device that measures an areal density of magnetic nanoparticles on a microarray that are directly or indirectly coupled to a target sample.