Abstract: A sensor device is provided for attachment to a surface of a fluid fitting, including a sensor portion comprising a sensor configured for detecting a physical parameter, a flexible circuit portion comprising a flexible circuit board and one or more circuit components supported by the flexible circuit board, and a rigid circuit portion comprising a rigid circuit board and one or more other circuit components by the circuit board. The sensor portion, flexible circuit portion, and rigid circuit portion are operatively coupled together and adapted to be affixed to said surface of said fluid fitting. In one example, a strain sensor is used. In another example, the fluid fitting comprises a coupling body defining a bore for receiving said fluid element therein. A ring is configured to fit over at least one end of the coupling body for mechanically attaching the coupling body to said fluid element.