Abstract. Devices like PDAs, mobile phones and Smartcards can communicate with each other and to exchange information and they should be made mutually aware of each other. For privacy reasons, it is essential for the devices to have different levels of awareness and concealment measures so that each device can control how much it wants to be aware of others and how much it wants to be concealed from others. Other works have modelled and implemented awareness among devices, but none, to our knowledge, has provided a formal grounding to their work. We propose a formal model for mutual aware devices, deriving from an existing work on virtual environment called spatial model of interactions. As proof of concept, we also describe two experimental prototypes based on our model.