Sensors and sensing technologies have made a tremendous impact on modern society over the past 20 years, and this will continue into the future, as performance characteristics and capabilities evolve to new levels. Sensors are the basis for the emerging smart world, embedding 'intelligence' into previously dumb devices, objects and equipment, and are the foundation of the huge growth in services that track and control an increasing range of parameters. In its initial phase, the internet connected people, and facilitated exchange of documents, images, conversations and messages. This has expanded to encompass objects that have a sensing capability primarily based on very reliable physical transducers that enable important parameters like temperature, movement, light intensity, pressure, and location to be tracked remotely - the foundation of the 'Internet of Things'. Sensors are revolutionising services as diverse as personal health diagnostics, tracking food freshness, monitoring water and air quality, and optimising industry processes. Sensor research has a corresponding broad span, encompassing topics as diverse as the fundamental science of molecular recognition and transduction, design and validation of novel sensing devices, and new services based on machine learning of big data from scaled-up sensor networks. Frontiers in Sensors welcomes submissions from across this diverse research activity.