Abstract: A needle (1) and needle probe are provided. The needle (1) has a conducting inner core (12) separated for a conducting outer cannula (14) by an insulating element (16). A first end of the needle is for insertion into a patient, whereas the second end (6) is adapted for electrical connection to the remainder of the instrument. The second end (6) is formed in a substantially conical or substantially pyramidal shape. The inner core (12) at the second end contacts a contact plate (45) of a spring contact probe (22) to provide one electrical contact. To provide the other electrical contact, the outer cannula (16) at the second end is connected to an inner wall (18) which contacts spring fingers (51) mounted around the spring contact probe (22).