Actuation of Three‐Dimensional‐Printed Nanocolloidal Hydrogel with Structural Anisotropy

Abstract

Polymer hydrogels exhibit actuation properties that result in reversible shape transformations and have promising applications in soft robotics, drug delivery systems, sensors, and microfluidic devices. Actuation occurs due to differential hydrogel swelling and is generally achieved by modulating hydrogel composition. Here a different approach to hydrogel actuation that originates solely from its structural anisotropy is reported. For 3D-printed single-layer hydrogels formed by cellulose nanocrystals (CNCs) and gelatin methacryloyl it is shown that shear-induced orientation of CNCs results in anisotropic mechanical and swelling properties of the hydrogel. Upon swelling in water, planar hydrogels acquire multiple complex 3D shapes that are achieved by i) varying CNC orientation with respect to the shape on the hydrogel sheet and ii) patterning the hydrogel with the regions of shearmediated and random CNC orientation. This study shows the capability to generate multiple shapes from the same hydrogel actuator based on the degree of its structural anisotropy. In addition, it introduces a biocompatible nanocolloidal ink with shear-thinning and self-healing properties for additive manufacturing of hydrogel actuators.

Computational Modelling and Big Data Analysis of Flow and Drug Transport in Microfluidic Systems: A Spheroid-on-a-Chip Study

“…Over the past few decades, microfluidics (MFs) has emerged as a powerful platform for fundamental and applied research in cell biology, soft robotics, medicine, drug screening, materials science, and analytical chemistry ( Whitesides, 2006 ; Tian and Finehout, 2009 ; Young et al, 2012 ; Pak et al, 2015 ; Rajendra et al, 2015 ; Moore et al, 2017 ; Humayun et al, 2018 ; Khuu et al, 2019 ; Gevorkian et al, 2021 ). For all applications, the design of an MF device with optimized geometry is a vital first step of the engineering process, but the optimization process is usually conducted in a trial-and-error manner and is, therefore, time- and labour-intensive ( Chakraborty, 2010 ; Huang, 2013 ).…”

An Experimental and Theoretical Determination of Oscillatory Shear-Induced Crystallization Processes in Viscoelastic Photonic Crystal Media

“…Recent studies have described the effects of oscillatory shear under a range of conditions in such systems [36][37][38][39][40][41][42], where continuous shear can crystalize colloidal monodisperse particles when there is a suitable fluid medium present. A notable variant of these methods is shear alignment in anisotropic ensembles [43,44]. As a fundamental distinction, POs do not contain a discrete fluid phase, and therefore cannot be directly compared to these systems of colloidal suspensions.…”

Cellulose‐Based Soft Actuators

“…It is known that many plants including pinecones exhibit actuating performance based on different local swelling behavior produced by the directional orientation of cellulose fibrils. [75,79] For instance, Gevorkian and coauthors showed a novel method to fabricate planar single-layer hydrogels with anisotropic structures. [75] The orientation of cellulose nanocrystals (CNCs) was achieved by lowering the temperature and subsequent photo-crosslinking with gelatin methacryloyl.…”