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A Flexure Balance With Adjustable Restoring Torque for Nanonewton Force Measurement



Jon R. Pratt, David B. Newell, John A. Kramar


The NIST electrostatic force balance compares mechanical probe forces to an SI realization of force derived from measurements of the capacitance gradient and voltage in an electronic null balance. As we approach the nanonewton regime, the finite stiffness of the guiding flexure in the balance becomes a limiting factor. Here, we consider an equal arm balance mechanism constructed using flexure pivots as an alternative to the compound rectilinear spring of the present design. We review how the sensitivity of such mechanisms can be adjusted either by manipulating the center of gravity, or by applying a negative restoring torque using a spring. We examine tradeoffs associated with tuning the stiffness of these mechanisms with regards to tilt sensitivity and various nonideal flexure behaviors. Results obtained with a prototype mechanism are presented.
Conference Dates
September 24-26, 2002
Conference Location
Celle, GE
Conference Title
International Measurement Confederation. IMEKO Congress


flexure balance, nanoforce


Pratt, J. , Newell, D. and Kramar, J. (2002), A Flexure Balance With Adjustable Restoring Torque for Nanonewton Force Measurement, International Measurement Confederation. IMEKO Congress, Celle, GE (Accessed April 21, 2024)
Created January 1, 2002, Updated February 19, 2017