Femto-Newton force sensitivity quartz tuning fork sensor

We describe a quartz tuning fork resonator that is smaller in size than previously reported sensors of the same shape. Smaller dimensions result in the reduced spring constant of the tuning fork resonator with important potential performance improvements in scanning probe microscopes and force sensing instruments. The spring constant of 480 N/m and mechanical quality factor Q of 27,500 are nearly optimal values needed for frequency modulated atomic force microscopy. The tuning fork resonator force noise floor of 6.5 fN/root Hz provides better force sensitivity than previously reported larger size quartz tuning forks. (C) 2007 Published by Elsevier B.V.