Sensing coverage is an important issue in wireless mobile sensor networks. The strategy of how to deploy sensor nodes in an environment, particularly in an unknown expanse, will affect the utility of the network just like the quality of communication. In this paper, using the concept of molecule spreading from physics, we present an efficient method for sensor deployment, assuming that global information is not available. Our algorithm, i.e., Self-Deployment by Density Control (SDDC), uses density control by each node to concurrently deploy sensor nodes. We make the nodes form clusters to achieve area density balance. The characteristics in SDDC are concurrent multisensor moving, distributed operation, localized calculation, and self-deployment. Simulations show its good performances compared to the incremental self-deployment algorithm.