A The semiconductor device has a heavily doped substrate and an upper layer with doped silicon of a first conductivity type disposed on the substrate, the upper layer having an upper surface and including an active region that comprises a well region of a second, opposite conductivity type. The invention also relates to a method for purifying certain antimicrobial proteins, as well as to a use of said antimicrobial proteins for antibiotic therapy or to a use of cells which were transfected with a DNA which codes for the proteins provided for in the invention. A user interface is provided which is based on a familiar paper-based method already in common use, thus reducing the training required to effectively use the system.