Force transducer (10) include two structural members (11, 12) spaced apart to define a gap (101) and being linked to each other. Optical fibres (13) are to the members and are freely suspended in the gap. The optical fibres are configured to provide a change in a detectable optical property responsive to a change in relative position between the two members in one or more predetermined degrees of freedom. Each of the optical fibres (13) is fixed to both structural members and continuous between the members to link the two structural members to each other. The optical fibres are substantially the only structure forming a link between the two structural members (11, 12), such that the arrangement of the optical fibres defines substantially the stiffness of the link between the two structural members in the one or more predetermined degrees of freedom, which stiffness is mainly, such as for at least 95%, determined by the optical fibres.
