A diaphragm-based pressure sensor packaged using liquid crystal polymer and silicone oil for underwater applications

Reliable hermetic packaging of microelectromechanical system (MEMS) pressure sensor arrays for underwater applications always presents a formidable challenge, which is further compounded by the unforgiving harsh sea environments, during the design, fabrication and characterization stages of the sensor arrays. As such, a flexible underwater diaphragm-based pressure sensor array packaging scheme is proposed that is based on the liquid crystal polymer (LCP) material and silicone oil. In this packaging scheme, the LCP material is used as an external sensing diaphragm to detect the fluid pressure variations and a packaging structure to enclose the silicone oil, which serves as a medium for energy transmission, within the cavity of the sensor structure. The material properties and processing capabilities of the LCP material are briefly described and where applicable, processing data and experimental results are provided. The fabrication sequence of the packaged sensor is also briefly detailed.