Abstract: A diaphragm-actuated pressure differential switch assembly includes a blade spring for switching an electrical circuit. The blade spring comprises a proximal end portion configured for electrically conductive attachment to an electrical terminal, a plurality of flexible tension arms extending from the proximal end portion, a pressure contact region configured to accept transmission of a physical force to bend at least one of the plurality of flexible tension arms, a distal end portion integral with the flexible tension arms, the distal end portion including an electrical contact, and a compression spring integral with the distal end portion extending generally proximally from the distal end portion, the compression spring including a first leg and a second leg. Methods of constructing and using the diaphragm-actuated pressure differential switch assembly and the blade spring are also disclosed.