A bio control surface (100) comprising a substrate (5) and a first plurality of discrete, spaced-apart particles (1) disposed on the substrate (5) and a second plurality of discrete, spaced-apart particles (6) disposed on the substrate (5), wherein the first (1) and second (6) pluralities of discrete, spaced-apart particles are formed from species having different chemical and/or electrical properties. An intermediate layer (4) may be interposed between the particles (1, 6) and the substrate (5). The bio control surface (100) can be activated by exposure to particular conditions, which cause the first (1) and second (6) pluralities of particles to adopt different potentials (+, −), such that flow of charge, heat, ions etc. can be used to neutralise or kill bacteria or microorganisms resident on the surface (100).
