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Journal of Sensors
Volume 2017, Article ID 1857920, 7 pages
https://doi.org/10.1155/2017/1857920
Research Article

The Differential Method for Force Measurement Based on Electrostatic Force

1State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
2National Institute of Metrology, Beijing 100013, China
3Center of MicroNano Manufacturing Technology, Tianjin University, Tianjin 300072, China

Correspondence should be addressed to Le Song; nc.ude.ujt@elgnos

Received 8 December 2016; Revised 20 March 2017; Accepted 27 March 2017; Published 11 May 2017

Academic Editor: Dzung Dao

Copyright © 2017 Peiyuan Sun et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The small force measurement is very important with development of the technology. The electrostatic force is adopted, in which a pair of coaxial cylindrical capacitors generate the electrostatic force when a voltage is applied across the inner and outer electrodes. However, the measured force will be covered by noise (creep, ground vibration, and air flow) and could not be measured accurately. In this paper, we introduce the differential method to reduce the effect of noise. Two identical parallelogram mechanisms (PM) serve as the mechanical spring. One of the PM serves as the reference and another serves as the force sensor. The common signal will be offset, and the difference signal will serve as output. In this way, the effect of the creep will be reduced. The measurement system of the electrostatic force was characterized by applying mechanical forces of known magnitude via loading weights of calibrated masses. The uncertainty from voltage, laser interferometer, and capacitance gradient was estimated. For the measured force, the relative uncertainty is less than 4% .