Manipulation at the NanoNewton level: Micrograpsing for mechanical characterization of biomaterials

This paper presents the use of a monolithic, force-feedback MEMS (microelectomechanical systems) microgripper for characterizing both elastic and viscoelastic properties of highly deformable hydrogel microcapsules (15-25 mum) at wet state during micromanipulation. The single-chip microgripper integrates an electrothermal microactuator and two capacitive force sensors, one for contact detection (force resolution: 38.5 nN) and the other for gripping force measurements (force resolution: 19.9 nN). Through nanoNewton force measurements, closed-loop force control, and visual tracking, the system quantified Young´s modulus values and viscoelastic parameters of alginate microcapsules, demonstrating an easy-to-operate, accurate compression testing technique for characterizing soft, micrometer-sized biomaterials.