US Patent 10275069 Pressure resistant force sensing enclosure

A portable electronic device includes a cover glass, one or more strain gauges operable to indicate force exerted on the cover glass based on deformation of the cover glass, a housing that defines a sway space gap into which the cover glass deforms when the force is exerted on the cover glass, and an incompressible fluid positioned in the sway space gap. The incompressible fluid allows deformation of the cover glass into the sway space gap when the force is exerted on the cover glass and maintains a constant volume under hydrostatic pressure.