a sensor guided needle to be used for the delivery of medication or placement of indwelling catheters , angiocatheters , spinal or epidural catheters , central lines , arterial lines , intraneoplastic , pediatric lines . the needle is comprised of an outer metal sheath with a biocompatible inner core containing sensor or signal elements . the measurements collected by the sensors are analyzed by a control unit to determine tissue type and possibly tissue state . this information can be utilized to track the progress of the needle and determine safe placement in the patient