The invention provides various signal processing devices for integrating two or more biological signals (e.g., the presence, absence or concentration of specific ligands, etc.) to generate a status output, or a response that modulates one or more biological activities based on the status of the biological signals. The various described signal processing/integration mechanisms may be combined with one another to provide the device with more flexibility in integrating high-order cellular information. The signal processing devices of the invention have many uses in various biological systems, including gene expression control or ligand-concentration sensing.
