Reconfigurable multifunctional ferrofluid droplet robots

Abstract

Magnetically actuated miniature soft robots are capable of programmable deformations for multimodal locomotion and manipulation functions, potentially enabling direct access to currently unreachable or difficult-to-access regions inside the human body for minimally invasive medical operations. However, magnetic miniature soft robots are so far mostly based on elastomers, where their limited deformability prevents them from navigating inside clustered and very constrained environments, such as squeezing through narrow crevices much smaller than the robot size. Moreover, their functionalities are currently restricted by their predesigned shapes, which is challenging to be reconfigured in situ in enclosed spaces. Here, we report a method to actuate and control ferrofluid droplets as shape-programmable magnetic miniature soft robots, which can navigate in two dimensions through narrow channels much smaller than their sizes thanks to their liquid properties. By controlling the external magnetic fields spatiotemporally, these droplet robots can also be reconfigured to exhibit multiple functionalities, including on-demand splitting and merging for delivering liquid cargos and morphing into different shapes for efficient and versatile manipulation of delicate objects. In addition, a single-droplet robot can be controlled to split into multiple subdroplets and complete cooperative tasks, such as working as a programmable fluidic-mixing device for addressable and sequential mixing of different liquids. Due to their extreme deformability, in situ reconfigurability and cooperative behavior, the proposed ferrofluid droplet robots could open up a wide range of unprecedented functionalities for lab/organ-on-a-chip, fluidics, bioengineering, and medical device applications.

Multifunctional magnetic soft composites: a review

“…Recent work demonstrates a magnetically responsive composite surface by infiltrating ferrofluid in a porous matrix with microchannels, in which case the magnetic nanoparticles exhibit controllable movement [ 83 ]. Under the applied gradient magnetic field, ferrofluid droplets can dynamically morph into multifunctional shapes and configurations, behaving as liquid robots with both cooperative and independent control [ 84 – 86 ].…”

From shaping to functionalization of micro-droplets and particles

“…8E). 133 ferrouid droplet as a miniature so robot for liquid cargo, channel valves, and so on. In a microuidic system, the ferrouid is used as a dispersed phase to produce droplets whose size or morphology is precisely manipulated.…”

Intelligent Soft Surgical Robots for Next‐Generation Minimally Invasive Surgery

“…Except for the scale issue, next-generation MIS soft devices will also be freer in structure. The soft device can be not only a multicomponent-integrated system, but also a piece of programmed soft material, or even a controlled liquid [428,429] or DNA strand. [430] In addition, the shape of the soft devices can also be diverse, e.g., capsule [431] or sphericity, to achieve better acceptance or accessibility to specific targets.…”