Figure 2

Automatic skull surface profiling: (a) We engineered a low-force contact sensor for profiling the surface of the skull. Incorporating a custom spring (Supplementary Note 2) enabled the contact sensor to accurately detect the skull surface without causing any visible deflection when observed through a stereomicroscope at 60X. Scale bar, 10 mm. (b) The relationship between the probe actuation force required to detect contact with the skull and the nominal turns of the adjustment screws. The actuation force ranged from 49 to 98 mN in all experiments. The average actuation force from 20 measurements is shown for each quarter turn of the adjustment screws as a filled circle and the individual measurements are shown as hollow circles. (c) The average point-cloud generated by surface profiling the dorsal skull of an 8-week old male C57BL/6J mouse with a needle tip stylus at 192 points overlaid on the micro-CT scan of the same skull (i) top view, (ii) side view from the left, (iii) side view from the right, and (iv) isometric view. Scale bar, 1 mm. (d) Distribution of the measurement error as a function of the distance from bregma. (e) The cumulative histogram of the measurement errors for n = 6 mice (n = 3 males and n = 3 females).