The skin preparation device and sensor of the present invention include an array of rigid tines. The tines serve to “self-prepare” the skin at each electrode site. These tines, when pressed against the skin, penetrate the stratum corneum, thereby reducing skin impedance and improving signal quality. A self-prepping device of the present invention is an optimized array of short non-conductive rigid tines in which the individual tines are created in a geometry that allows for a sharp point at the tip when molding, machining or etching is used as a method of fabrication.