In one embodiment, a method includes applying at least one invisible mark to media, sensing the at least one invisible mark with separate sensors, and determining a speed of the media from signals of the separate sensors. A flowmeter includes a housing, a vortex responsive structure which vibrates in response to vortices produced external to the housing and a sensor which senses vibration of the structure and produces a signal indicative of a flow rate. The second charge injection layer is formed as a mixed layer in which a matrix organic material and a charge injectable metallic material are mixed.