scholarly journals Four-dimensional micro-building blocks

2020 ◽  
Vol 6 (3) ◽  
pp. eaav8219 ◽  
Author(s):  
T.-Y. Huang ◽  
H.-W. Huang ◽  
D. D. Jin ◽  
Q. Y. Chen ◽  
J. Y. Huang ◽  
...  
Keyword(s):  
Design Principle ◽  
Modular Design ◽  
Building Blocks ◽  
Stimuli Responsive ◽  
Race Car ◽  
Two Photon ◽  
Direct Laser ◽  
3D Printed ◽  
Reconfigurable Structures ◽  
Responsive Hydrogels

Four-dimensional (4D) printing relies on multimaterial printing, reinforcement patterns, or micro/nanofibrous additives as programmable tools to achieve desired shape reconfigurations. However, existing programming approaches still follow the so-called origami design principle to generate reconfigurable structures by self-folding stacked 2D materials, particularly at small scales. Here, we propose a programmable modular design that directly constructs 3D reconfigurable microstructures capable of sophisticated 3D-to-3D shape transformations by assembling 4D micro-building blocks. 4D direct laser writing is used to print two-photon polymerizable, stimuli-responsive hydrogels to construct building blocks at micrometer scales. Denavit-Hartenberg (DH) parameters, used to define robotic arm kinematics, are introduced as guidelines for how to assemble the micro-building blocks and plan the 3D motion of assembled chain blocks. Last, a 3D-printed microscaled transformer capable of changing its shape from a race car to a humanoid robot is devised and fabricated using the DH parameters to guide the motion of various assembled compartments.

3D printed self-adhesive PEGDA–PAA hydrogels as modular components for soft actuators and microfluidics

2019 ◽  
Vol 10 (16) ◽  
pp. 2015-2028 ◽  
Author(s):  
Thomas M. Valentin ◽  
Eric M. DuBois ◽  
Catherine E. Machnicki ◽  
Dhananjay Bhaskar ◽  
Francis R. Cui ◽  
...  
Keyword(s):  
Microfluidic Devices ◽  
Building Blocks ◽  
Stimuli Responsive ◽  
3D Printed ◽  
Do It Yourself ◽  
Soft Actuators

Hydrogel building blocks that are stimuli-responsive and self-adhesive could be utilized as a simple “do-it-yourself” construction set for soft machines and microfluidic devices.

scholarly journals Bioinspired high-power-density strong contractile hydrogel by programmable elastic recoil

2020 ◽  
Vol 6 (47) ◽  
pp. eabd2520
Author(s):  
Yanfei Ma ◽  
Mutian Hua ◽  
Shuwang Wu ◽  
Yingjie Du ◽  
Xiaowei Pei ◽  
...  
Keyword(s):  
Power Density ◽  
High Power ◽  
Modular Design ◽  
Polymer Network ◽  
Artificial Muscles ◽  
High Power Density ◽  
Stimuli Responsive ◽  
Elastic Recoil ◽  
Elastic Potential Energy ◽  
Responsive Hydrogels

Stimuli-responsive hydrogels have large deformability but—when applied as actuators, smart switch, and artificial muscles—suffer from low work density due to low deliverable forces (~2 kPa) and speed through the osmotic pressure–driven actuation. Inspired by the energy conversion mechanism of many creatures during jumping, we designed an elastic-driven strong contractile hydrogel through storing and releasing elastic potential energy in polymer network. It can generate high contractile force (40 kPa) rapidly at ultrahigh work density (15.3 kJ/m3), outperforming current hydrogels (~0.01 kJ/m3) and even biological muscles (~8 kJ/m3). This demonstrated elastic energy storing and releasing method endows hydrogels with elasticity-plasticity switchability, multi-stable deformability in fully reversible and programmable manners, and anisotropic or isotropic deformation. With the high power density and programmability via this customizable modular design, these hydrogels demonstrated potential for broad applications in artificial muscles, contractile wound dressing, and high-power actuators.

scholarly journals Assessing the Viscoelasticity of Photopolymer Nanowires Using a Three-Parameter Solid Model for Bending Recovery Motion

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2961
Author(s):  
Jana Kubacková ◽  
Cyril Slabý ◽  
Denis Horvath ◽  
Andrej Hovan ◽  
Gergely T. Iványi ◽  
...  
Keyword(s):  
Glucose Solution ◽  
Bulk Material ◽  
Effective Elastic Modulus ◽  
Building Blocks ◽  
Solid Model ◽  
Two Photon ◽  
Notable Effect ◽  
Direct Laser ◽  
Applied Forces ◽  
Newtonian Liquids

Photopolymer nanowires prepared by two-photon polymerization direct laser writing (TPP-DLW) are the building blocks of many microstructure systems. These nanowires possess viscoelastic characteristics that define their deformations under applied forces when operated in a dynamic regime. A simple mechanical model was previously used to describe the bending recovery motion of deflected nanowire cantilevers in Newtonian liquids. The inverse problem is targeted in this work; the experimental observations are used to determine the nanowire physical characteristics. Most importantly, based on the linear three-parameter solid model, we derive explicit formulas to calculate the viscoelastic material parameters. It is shown that the effective elastic modulus of the studied nanowires is two orders of magnitude lower than measured for the bulk material. Additionally, we report on a notable effect of the surrounding aqueous glucose solution on the elasticity and the intrinsic viscosity of the studied nanowires made of Ormocomp.

scholarly journals Four-Dimensional Stimuli-Responsive Hydrogels Micro-Structured via Femtosecond Laser Additive Manufacturing

Micromachines ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 32
Author(s):  
Yufeng Tao ◽  
Chengchangfeng Lu ◽  
Chunsan Deng ◽  
Jing Long ◽  
Yunpeng Ren ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Femtosecond Laser ◽  
Smart Materials ◽  
High Efficiency ◽  
Stimuli Responsive ◽  
Laser Additive Manufacturing ◽  
Two Photon ◽  
Femtosecond Laser Beam ◽  
Hydrogel Matrix ◽  
Responsive Hydrogels

Rapid fabricating and harnessing stimuli-responsive behaviors of microscale bio-compatible hydrogels are of great interest to the emerging micro-mechanics, drug delivery, artificial scaffolds, nano-robotics, and lab chips. Herein, we demonstrate a novel femtosecond laser additive manufacturing process with smart materials for soft interactive hydrogel micro-machines. Bio-compatible hyaluronic acid methacryloyl was polymerized with hydrophilic diacrylate into an absorbent hydrogel matrix under a tight topological control through a 532 nm green femtosecond laser beam. The proposed hetero-scanning strategy modifies the hierarchical polymeric degrees inside the hydrogel matrix, leading to a controllable surface tension mismatch. Strikingly, these programmable stimuli-responsive matrices mechanized hydrogels into robotic applications at the micro/nanoscale (<300 × 300 × 100 μm3). Reverse high-freedom shape mutations of diversified microstructures were created from simple initial shapes and identified without evident fatigue. We further confirmed the biocompatibility, cell adhesion, and tunable mechanics of the as-prepared hydrogels. Benefiting from the high-efficiency two-photon polymerization (TPP), nanometer feature size (<200 nm), and flexible digitalized modeling technique, many more micro/nanoscale hydrogel robots or machines have become obtainable in respect of future interdisciplinary applications.

scholarly journals 3D Printing Hydrogel-Based Soft and Biohybrid Actuators: A Mini-Review on Fabrication Techniques, Applications, and Challenges

2021 ◽  
Vol 8 ◽  
Author(s):  
Wenhuan Sun ◽  
Saul Schaffer ◽  
Kevin Dai ◽  
Lining Yao ◽  
Adam Feinberg ◽  
...  
Keyword(s):  
3D Printing ◽  
Three Dimensional ◽  
Building Blocks ◽  
Stimuli Responsive ◽  
Future Directions ◽  
The Past ◽  
Naturally Occurring ◽  
Tunable Mechanical Properties ◽  
Responsive Hydrogels ◽  
Robotic Applications

Stimuli-responsive hydrogels are candidate building blocks for soft robotic applications due to many of their unique properties, including tunable mechanical properties and biocompatibility. Over the past decade, there has been significant progress in developing soft and biohybrid actuators using naturally occurring and synthetic hydrogels to address the increasing demands for machines capable of interacting with fragile biological systems. Recent advancements in three-dimensional (3D) printing technology, either as a standalone manufacturing process or integrated with traditional fabrication techniques, have enabled the development of hydrogel-based actuators with on-demand geometry and actuation modalities. This mini-review surveys existing research efforts to inspire the development of novel fabrication techniques using hydrogel building blocks and identify potential future directions. In this article, existing 3D fabrication techniques for hydrogel actuators are first examined. Next, existing actuation mechanisms, including pneumatic, hydraulic, ionic, dehydration-rehydration, and cell-powered actuation, are reviewed with their benefits and limitations discussed. Subsequently, the applications of hydrogel-based actuators, including compliant handling of fragile items, micro-swimmers, wearable devices, and origami structures, are described. Finally, challenges in fabricating functional actuators using existing techniques are discussed.

Advanced Hydrogels Based Drug Delivery Systems for Ophthalmic Delivery

2020 ◽  
Vol 13 (4) ◽  
pp. 291-300 ◽  
Author(s):  
Srividya Gorantla ◽  
Tejashree Waghule ◽  
Vamshi Krishna Rapalli ◽  
Prem Prakash Singh ◽  
Sunil Kumar Dubey ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Drug Delivery Systems ◽  
Delivery Systems ◽  
Age Related Macular Degeneration ◽  
Stimuli Responsive ◽  
Duration Of Action ◽  
Age Related ◽  
Aqueous Gels ◽  
Ophthalmic Delivery ◽  
3D Printed

Hydrogels are aqueous gels composed of cross-linked networks of hydrophilic polymers. Stimuli-responsive based hydrogels have gained focus over the past 20 years for treating ophthalmic diseases. Different stimuli-responsive mechanisms are involved in forming polymer hydrogel networks, including change in temperature, pH, ions, and others including light, thrombin, pressure, antigen, and glucose-responsive. Incorporation of nanocarriers with these smart stimuli-responsive drug delivery systems that can extend the duration of action by increasing ocular bioavailability and reducing the dosing frequency. This review will focus on the hydrogel drug delivery systems highlighting the gelling mechanisms and emerging stimuli-responsive hydrogels from preformed gels, nanogels, and the role of advanced 3D printed hydrogels in vision-threatening diseases like age-related macular degeneration and retinitis pigmentosa. It also provides insight into the limitations of hydrogels along with the safety and biocompatibility of the hydrogel drug delivery systems.

Sticky ends in a self-assembling ABA triblock copolymer: the role of ureas in stimuli-responsive hydrogels

2019 ◽  
Vol 4 (1) ◽  
pp. 91-102 ◽  
Author(s):  
Ryan T. Shafranek ◽  
Joel D. Leger ◽  
Song Zhang ◽  
Munira Khalil ◽  
Xiaodan Gu ◽  
...  
Keyword(s):  
Self Assembly ◽  
Viscoelastic Properties ◽  
Triblock Copolymer ◽  
Thermal Response ◽  
Stimuli Responsive ◽  
Self Assembling ◽  
Polymeric Hydrogels ◽  
Aba Triblock Copolymer ◽  
Responsive Hydrogels

Directed self-assembly in polymeric hydrogels allows tunability of thermal response and viscoelastic properties.

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