skip to main content

Explore Research Products in the NSF-PAR

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
NSF-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. ; ; ( , 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
  3. ; ; ( , Biomaterials Science)
    null (Ed.)
    The recent advances in bio-integratable electronics are creating new opportunities for investigating and directing biologically significant processes, yet their performance to date is still limited by the inherent physiochemical and signaling mismatches at the heterogeneous interfaces. Hydrogels represent a unique category of materials to bridge the gap between biological and electronic systems because of their structural/functional similarity to biological tissues and design versatility to accommodate cross-system communication. In this review, we discuss the latest progress in the engineering of hydrogel interfaces for bioelectronics development that promotes (1) structural compatibility, where the mechanical and chemical properties of hydrogels can be modulated to achieve coherent, chronically stable biotic-abiotic junctions; and (2) interfacial signal transduction, where the charge and mass transport within the hydrogel mediators can be rationally programmed to condition/amplify the bioderived signals and enhance the electrical/electrochemical coupling. We will further discuss the application of functional hydrogels in complex physiological environments for bioelectronic integration across different scales/biological levels. These ongoing research efforts have the potential to blur the distinction between living systems and artificial electronics, and ultimately decode and regulate biological functioning for both fundamental inquiries and biomedical applications. 
    more » « less
  4. ; ; ; ; ; ( , Advanced Materials)
    Abstract

    For thousands of years, carbon ink has been used as a black color pigment for writing and painting purposes. However, recent discoveries of nanocarbon materials, including fullerenes, carbon nanotubes, graphene, and their various derivative forms, together with the advances in large‐scale synthesis, are enabling a whole new generation of carbon inks that can serve as an intrinsically programmable materials platform for developing advanced functionalities far beyond color. The marriage between these multifunctional nanocarbon inks with modern printing technologies is facilitating and even transforming many applications, including flexible electronics, wearable and implantable sensors, actuators, and autonomous robotics. This review examines recent progress in the reborn field of carbon inks, highlighting their programmability and multifunctionality for applications in flexible electronics and stimuli‐responsive devices. Current challenges and opportunities will also be discussed from a materials science perspective towards the advancement of carbon ink for new applications beyond color.

     
    more » « less
  5. ; ; ; ; ; ; ( , Chemical Society Reviews)
    The piezo-phototronic effect (a coupling effect of piezoelectric, photoexcitation and semiconducting properties, coined in 2010) has been demonstrated to be an ingenious and robust strategy to manipulate optoelectronic processes by tuning the energy band structure and photoinduced carrier behavior. The piezo-phototronic effect exhibits great potential in improving the quantum yield efficiencies of optoelectronic materials and devices and thus could help increase the energy conversion efficiency, thus alleviating the energy shortage crisis. In this review, the fundamental principles and challenges of representative optoelectronic materials and devices are presented, including photocatalysts (converting solar energy into chemical energy), solar cells (generating electricity directly under light illumination), photodetectors (converting light into electrical signals) and light-emitting diodes (LEDs, converting electric current into emitted light signals). Importantly, the mechanisms of how the piezo-phototronic effect controls the optoelectronic processes and the recent progress and applications in the above-mentioned materials and devices are highlighted and summarized. Only photocatalysts, solar cells, photodetectors, and LEDs that display piezo-phototronic behavior are reviewed. Material and structural design, property characterization, theoretical simulation calculations, and mechanism analysis are then examined as strategies to further enhance the quantum yield efficiency of optoelectronic devices via the piezo-phototronic effect. This comprehensive overview will guide future fundamental and applied studies that capitalize on the piezo-phototronic effect for energy conversion and storage. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email