Figure 6.

Effects of tip radius. (a) Experiment results of varying tip radii on the unnormalized BMS. The results show that as the probe dulls the unnormalized BMS increases significantly from the ideal value measured with a sharp tip. Much of this problem is, however, currently solved by always normalizing by the actual measured value of the indentation distance increase from the impact on a calibration phantom with the same tip. We anticipate that probes will be mass produced, sharp, and only used once per patient so that the need for this normalization we have been using during the development stage may vanish. Thus, in (b) the radius of the probe tip does not affect BMS values on the materials tested and we would hope that this is also true for measurements on patients, who typically fall in this same range of values. This will, however, have to be confirmed with actual measurements on patients to be sure. (c) Images taken under an optical microscope showing the extreme probe radii.