Patent ID: 7318358

Claim:
A strain sensor for measuring strain in a contact surface, comprising: a sensor body extending substantially in a plane, the sensor body being substantially symmetric in the plane about a first axis and a second axis that is perpendicular to the first axis, the sensor body comprising a plurality of sensor body portions symmetrically spaced apart about the first axis, and the second axis, the plurality of sensor body portions being disposed around an inner perimeter and extending outwardly to an outer perimeter circumscribing the plurality of sensor body portions, each of the plurality of sensor body portions being flexibly secured to the contact surface proximate the outer perimeter and being free to move relative to the contact surface proximate the inner perimeter, the plurality of sensor body portions interconnected by respective beams, each beam extending between two adjacent sensor body portions of the plurality of sensor body portions and extending substantially perpendicularly across one of the first and second axes, the beams and plurality of sensor body portions defining a centrally located hole extending completely through the sensor body; and a first strain sensing element mounted on one of the respective beams.