Development of a Microforce Sensor Based on a Fiber Bragg Grating Used for Micro/Nano Manipulation

In the micro/nano manipulation process, the detection of micro-forces is essential not only for sample protection but also for mechanical property tests. In general, optical fiber sensors have excellent sensitivities so they can be used as a kind of new sensing element for microforce sensor design. This paper proposes a cantilever-type fiber Bragg grating (FBG)-based microforce sensor with micro-Newton resolution. A complete theoretical model is proposed to establish the mapping between the optical wavelength and the external force, and simulations are also carried out. A series of experiments are performed to evaluate the sensor, which agrees well with the calculation results, showing the sensor has the resolution of 7 μN force in the range of 10 mN. Finally, the calibrated sensor is applied in a micro/nano manipulation system to achieve the mechanical property test of the zebrafish embryo. The result fits well with the reference results, proving the microforce sensor has the capability of measuring the mechanical property of the biological sample.