Penetration-force estimation approach for a flexure-jointed micro-injection mechanism with Lorentz force actuation

Abstract

This paper presents a novel linear-motion compliant mechanism with Lorentz force actuation and integrated force-sensing capability for automated cell micro-injection. A model-based force estimation approach is introduced such that no force sensor is required. Model identification is undertaken by applying a sinusoidal actuation signal while the mechanism contacts with objects of known stiffness. Displacement data is then used to calculate model coefficients via a least-squares optimization. By using an observer-based state estimation scheme with actuation and displacement signals as inputs, force sensing accuracy within 70 μN RMS error could be achieved within a sensing range of 0 - 5 mN. This sensing capability confirms the suitability of the system for penetration force measurement in certain cases of cell micro-injection.