Demand articulation plays a central role in innovation processes as it reduces uncertainties for innovating firms and offers guidance in innovation processes. Studies into demand articulation processes have mostly focused on users and user-producer interactions and paid less attention to the role of the broader environment in which users and producers are embedded. We conduct an exploratory case study into demand articulation regarding emerging micro & nanotechnology-based sensor technologies for drinking water applications. We trace the occurrence and dynamics of demand articulation processes at a sectoral level. We show that demand articulation processes at the level of a sector fulfill an important function in guiding demand articulation processes of individual and organizational actors. We develop a process model of sectoral demand articulation and discuss the relevance of sectoral contexts in explaining the direction of demand articulation processes.