The present invention provides a device and method for measuring tissue deformation during an invasive medical procedure. A device is provided comprising a flexible fiber having a proximal end and a distal end； at least one sensor embedded in the flexible fiber； a rigid mount having a transverse opening for the flexible fiber； a mechanism for inserting the flexible fiber into a tissue； a detector for receiving information from the sensor； and a tracking system for receiving information from the detector to calculate the sensor location.
