Fig. 1. Set-up of miniature force gauge (A) and force calibration curve (B). Force was measured by the deflection of the stainless steel arm. The worm tube on a coverslip was secured to the spring arm by being sandwiched between a pair of magnets, as shown in the close-up picture of the deflection measurement set-up (C). Pull-out tests were viewed at a magnification of 40 using a binocular light microscope.