Design and characterization of polymeric pressure sensors for wireless wind sail monitoring

This paper presents the design, fabrication and experimental characterization of a capacitive differential pressure transducer, suitable to be implemented in a wireless sensor network for wind sail monitoring. The network is aimed at sensing the pressure field acting on the surface of a sail by means of instrumented battens, providing the real-time differential pressure map over the sail surface. Each batten was constructed to house a number of wireless nodes within which a pressure sensing unit was integrated, providing independent pressure measurements. The pressure sensor was fabricated using printed circuit board technology, resulting in a thin, triple-layered structure which comprised a pre-stressed polymeric diaphragm, woven glass reinforced epoxy resin layers and metal layers. During the design phase, numerical simulations were used to estimate the pressure–capacitance static characteristic of the sensor by means of a non-linear, coupled mechanical-electrostatic numerical model. In this paper, we show both numerically and experimentally that inducing a pre-stress in the sensor diaphragm reduced undesired effects due to viscoelasticity, resulting in improved output accuracy. The sensors were experimentally characterized in a pressure range of ±250 Pa and the results were compared with numerical simulations.