A borehole wall cleaning apparatus and method for obtaining an improved seal between a fluid sampling device and a portion of the borehole wall. The method is based on determining the transformations that occur on a packet and compensating for the transformations. The physical layer receives blocks of data for transport such that the transport blocks includes a MAC header and logical channel data for a selected logical channel associated with a given TrCH. The cone crusher further includes a target means arranged to be detectable by the sensor element, wherein one of the target means and the sensor element are arranged to follow vertical movement of the upper frame member and to move in relation to the other one of the target means and the sensor element. An annealing operation is conducted in an inert atmosphere so that the implanted oxygen ions in the polysilicon gate react with silicon to form a silicon oxide buffer layer. A spring, preferably a gas compression spring, is inserted into each tube so that the lower end of each rod compresses the spring as body weight is put on the subfloor in walking.