A molecular sensing apparatus comprises a first electrode (10), a second electrode (12), a first molecule (20), a second molecule (22), and a third molecule (34). The first molecule (20) has a first chain of nucleic bases (30) and a first group (24). The first group (24) is bound to the first electrode (10). The second molecule (22) has a second chain of nucleic bases (32) and a second group (26). The second group (26) is bound to the second electrode (12). The third molecule (34) is bound to the first molecule (20) and the second molecule (22). A method which uses the molecular sensing apparatus is disclosed.