Fiber-Tip Magnetically Driven Microgripper for Micromanipulation

This paper presents a fiber-tip magnetically driven microgripper integrated with a size sensor that measures the size of micro-objects during gripping. It has fixed and driving claws fabricated on an optical fiber's end face via two-photon polymerization. The magnetic drive component includes a rectangular groove and a magnetically responsive iron ball. The groove's bottom plane and the fiber end face form a Fabry–Perot interferometer (FPI), which functions as the size sensor. Driven by magnetic field, the driving claw moves toward the fixed claw to grip the micro-object. This tilts the groove's bottom plane, thus shifting the FPI interference spectrum. The object size is measured by demodulating the spectral data during gripping. Experiments demonstrate the microgripper's opening and closing, driven by a magnetic field, as well as its ability to grip five sizes of silica microspheres with diameters ranging from 4.12 to 14.85 μm. With the help of the size sensor, the microgripper successfully measured the size of the microspheres with a maximum error of 0.22 μm. This integrated actuation–sensing design is a novel solution for micron-scale micromanipulation.