US Patent 9693890 Variable stiffness flexure

An intrauterine device includes a central support member, first and second internal flexures and first and second external flexures. The first and second internal flexures each include a first section having a first stiffness, a second section having a second stiffness, and third section having a third stiffness, wherein the second stiffness is more flexible than the first and third stiffness and wherein the first section of each internal flexure is coupled to the central support member. The first and second external flexures are coupled to the central support member and coupled to the third sections of the first and second internal flexures, the first and second external flexures in combination with the first and second internal flexures being configured to extend from a collapsed position parallel to the central support member to a deployed position flexing away from the central support member.