skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Thermo-responsive and shape-adaptive hydrogel actuators from fundamentals to applications
Shape adaptable hydrogel actuators, capable for changing their shapes in response to single or multiple thermo/other external stimulus, are considered as new emerging smart materials for a broad range of fundamental/industrial research and applications. This review mainly focuses on the recent progress (particularly over the past 5 years) on such thermo-responsive hydrogel actuators. Recent fundamental advances and engineering applications in materials design/synthesis/characterization, distinct actuation mechanisms, and intriguing examples of these hydrogel actuators of single or dual stimuli are selectively presented. Specific or general design principles for thermo-induced hydrogel actuators are also provided to better illustrate the structure-property relationship. In the end, we offer some personal perspectives on current major challenges and future research directions in this promising field. Overall, this review discusses current status, progress, and challenges of hydrogel actuators, and hopefully will motivate researchers from different fields to explore all the potentials of hydrogel actuators.  more » « less
Award ID(s):
1825122
PAR ID:
10096190
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ;
Date Published:
Journal Name:
Engineered science
Volume:
6
ISSN:
2576-988X
Page Range / eLocation ID:
1-11
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; (, Frontiers in Robotics and AI)
    null (Ed.)
    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. 
    more » « less
  2. ; ; ; ; ; (, Molecules)
    Hydrogels made from proteins are attractive materials for diverse medical applications, as they are biocompatible, biodegradable, and amenable to chemical and biological modifications. Recent advances in protein engineering, synthetic biology, and material science have enabled the fine-tuning of protein sequences, hydrogel structures, and hydrogel mechanical properties, allowing for a broad range of biomedical applications using protein hydrogels. This article reviews recent progresses on protein hydrogels with special focus on those made of microbially produced proteins. We discuss different hydrogel formation strategies and their associated hydrogel properties. We also review various biomedical applications, categorized by the origin of protein sequences. Lastly, current challenges and future opportunities in engineering protein-based hydrogels are discussed. We hope this review will inspire new ideas in material innovation, leading to advanced protein hydrogels with desirable properties for a wide range of biomedical applications. 
    more » « less
  3. ; ; (, Emergent Materials)
    null (Ed.)
    Recently, the developments of two-dimensional (2D) ferroelectrics and multiferroics have attracted much more attention among researchers. These materials are useful for high-density devices for multifunctional applications such as sensors, transducers, actuators, non-volatile memories, photovoltaic, and FETs. Although several theoretical works have been reported on layered ferroelectrics, experimental work is still lacking in single to few-atomic layers of 2D ferroelectric materials. In this review, we have discussed the recent theoretical as well as experimental progress of 2D ferroelectric and multiferroic materials. The emphasis is given to the development of single to few-atomic layers of 2D ferroelectric materials. In this regard, the recent developments of 2D ferroelectric polarization on vanadium oxyhalides VOX2 (X=I, Br, Cl, and F), distorted phase d1-MoTe2, In2Se3, and SnSe are discussed. d1-MoTe2 shows Curie temperature (TC) above room temperature, while few-layered In2Se3 shows in-plane ferroelectricity and interesting domain wall dynamics in a single atomic layer of SnSe. This follows the discussion of multiferroic materials based on transition metal oxyiodide MOI2 (M=Ti, V, and Cr), double perovskite bilayer, and iron-doped In2Se3. While pristine In2Se3 shows ferroelectric properties, iron-doped In2Se3 shows multiferroicity. Finally, the potential applications of 2D ferroelectrics and multiferroics have been discussed that follow the challenges and opportunities in this field, which can guide the research community to develop next-generation 2D ferroelectric and multiferroic materials with interesting properties. 
    more » « less
  4. ; ; ; ; ; ; ; ; ; ; et al (, Journal of Materials Chemistry B)
    null (Ed.)
    Stimuli-responsive hydrogel strain sensors that synergize the advantages of both soft-wet hydrogels and smart functional materials have attracted rapidly increasing interest for exploring the opportunities from material design principles to emerging applications in electronic skins, health monitors, and human–machine interfaces. Stimuli-responsive hydrogel strain sensors possess smart and on-demand ability to specifically recognize various external stimuli and convert them into strain-induced mechanical, thermal, optical, and electrical signals. This review presents an up-to-date summary over the past five years on hydrogel strain sensors from different aspects, including material designs, gelation/fabrication methods, stimuli-responsive principles, and sensing performance. Hydrogel strain sensors are classified into five major categories based on the nature of the stimuli, and representative examples from each category are carefully selected and discussed in terms of structures, response mechanisms, and potential medical applications. Finally, current challenges and future perspectives of hydrogel strain sensors are tentatively proposed to stimulate more and better research in this emerging field. 
    more » « less
  5. ; (, Journal of Polymer Science)
    Abstract Thermo‐responsive polymers have been widely explored because of their diverse structures and functions in response to temperature stimuli. Great attention has been attracted to exploring and designing such polymers composites, which offer tremendous opportunities to build up a systematic understanding of their structure–function relationships and pave the ways for their extensive applications in electronics, soft robotics, and electrochemical energy storage devices. Here, we review the most recent research of thermal regulation in electrochemical energy storage devices (e.g., batteries, supercapacitors) via thermo‐responsive polymers. We summarize how battery components (i.e., electrolytes, separators, electrodes, or current collectors) can be coupled with thermo‐responsive polymers based on different operation mechanisms, such as volume expansion, polymerization, phase reversion, and de‐doping effects, to effectively prevent catastrophic thermal runaway. Different types of thermo‐responsive polymers are evaluated to compare their key features and/or limitations. This review is concluded with perspectives of future design strategies towards more effective thermo‐responsive polymers for battery thermal regulation. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email