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 an 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.