Development of Highly Sensitive Force Sensor with Accurate Gap Control Using Double-Ended Tuning Fork

Abstract

A novel force sensor that can provide high sensitivity with accurate gap control has been presented. It combines a double-ended tuning fork (DETF) resonator with a rigid beam. When the force to be measured is applied to the rigid beam, the resonant frequency of the tuning fork changes due to the change of the tension. The DETF-based sensor can detect the force as the amplitude change corresponding to the resonant frequency change. The performance of the sensor was theoretically and experimentally investigated. The sensor can measure the force under the condition that the change of the probe-sample gap is less than 1 nm. The experimentally attained minimum detection limit of the force was 19.6 μ N and this can be improved by two orders of magnitude according to theoretical estimation. The DETF-based force sensor can be useful tool for various field such as development of micro/nano-machine, micro/nano-tribology, probe microscopy.