Envisioning a new generation of sensor network applications in healthcare and workplace safety, we seek mechanisms that provide timely and reliable transmissions of mission-critical data. Inspired by the physics in magnetism, we propose a simple diffusion-based data dissemination mechanism, referred to as the magnetic diffusion (MD). In that, the data sink, functioning like the magnet, propagates the magnetic charge to set up the magnetic field. Under the influence of the magnetic field, the sensor data, functioning like the metallic nails, are attracted towards the sink. We compare MD to the state-of-the-art mechanisms and find that MD 1) performs the best in timely delivery of data, 2) achieves high data reliability in the presence of network dynamics, and yet 3) works as energy efficiently as the state of the art. These suggest that MD is an effective data dissemination solution to the mission-critical applications. Categories and Subject Descriptors: C.3: Special-purpose an...