The present invention relates to an apparatus for diagnosis or treatment of a vessel or organ, comprising : a deformable body (1) defining a longitudinal axis and having a distal extremity including a tissue ablation end effector (33) having irrigation ports (34)； at least one irrigation channel disposed within said deformable body, said at least one irrigation channel being in fluid communication with said irrigation ports； at least two sensors disposed within said distal extremity to detect deformations imposed on said deformable body resulting from a contact force applied to said distal extremity. Said sensors are responsive to a wave in a specified range of frequency to detect said deformation and being substantially immune to electromagnetic interference. A microprocessor is operatively coupled with sensors and adapted to receive outputs therefrom, said microprocessor being configured to resolve a multi-dimensional force vector from said outputs, said multi-dimensional force vector corresponding to said contact force applied to said distal extremity.
