A PCB-Embedded Pressure Sensor for Wireless Wind Sail Monitoring

A capacitive differential pressure sensor suitable to be implemented in a wireless sensor network has been designed, built, and experimentally tested. The pressure sensing unit is implemented in a printed circuit board (PCB) technology based on a thin 3D triple layers structure composed of: a pre-stressed polymeric diaphragm, woven glass reinforced epoxy resin (FR4) and metal layers. Aim of the developed sensor network is to sense the pressure field acting on the surface of a full battens sail by means of instrumented battens. Inside any instrumented batten an appropriate number of wireless nodes are mounted, the pressure sensing units is integrated in any wireless node, acting as pressure measurement spot. The sensor network is targeted to provide a real time differential pressure map over the sail surface. The pressure sensing unit behavior has been modeled using finite element simulations. By means of a static non-linear coupled mechanical-electrostatic model, has been possible to predict the pressure versus capacitance static characteristic and to tune the geometry of the transducer to reach the required resolution, sensitivity and time response in the appropriate full scale pressure input, ranging from +/- 250 Pascal.