Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 Jul 24;14(15):2997.
doi: 10.3390/polym14152997.

Photothermal Thin Films with Highly Efficient NIR Conversion for Miniaturized Liquid-Crystal Elastomer Actuators

Wei-Yi Wang  1 , Bo-You Lin  1 , Yen-Peng Liao  1 , Yao-Joe Yang  1
Affiliations

Photothermal Thin Films with Highly Efficient NIR Conversion for Miniaturized Liquid-Crystal Elastomer Actuators

Wei-Yi Wang et al. Polymers (Basel). .

Abstract

This work presents the development of highly efficient photothermal thin films (PTFs) and the demonstration of their application on miniaturized polymer-based soft actuators. The proposed PTF, which comprises acrylic-based black paint and EGaIn liquid metal (LM) microdroplets, serves as an excellent absorber for efficiently converting near-infrared (NIR) irradiation into heat for actuating liquid-crystal elastomer (LCE) actuators. The introduction of LM microdroplets into the PTFs effectively increases the overall thermal efficiency of PTFs. Miniaturized soft crawlers monolithically integrated with the NIR-driven LCE actuators are also implemented for demonstrating the application of the proposed PTF. The crawler's locomotion, which is inspired by the rectilinear movement of snakes, is generated with the proposed PTF for inducing the LC-to-isotropic phase transition of the LCEs. The experimental results show that introducing LM microdroplets into the PTF can effectively reduce the thermal time constants of LCE actuators by 70%. Under periodic on/off NIR illumination cycles, the locomotion of crawlers with different dimensions is also demonstrated. The measurement results indicate that the proposed PTF is not only essential for enabling photothermal LCE actuation but also quite efficient and durable for repeated operation.

Keywords: NIR-driven actuator; liquid metal; liquid-crystal elastomer; photothermal film; rectilinear locomotion; shape-memory polymer.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Schematic of a light-driven LCE device with PTF.
Figure 2
Figure 2
The fabrication process of forming the structure of the light-driven LCE device.
Figure 3
Figure 3
The shape programming process for realizing the arched actuator with PTF.
Figure 4
Figure 4
Fabrication results: (a) picture of the fabricated LCE device; (b) SEM image of the top surface of the LCE device deposited with PTF.
Figure 5
Figure 5
(a-i) Transient temperature responses of different types of LCEs heated by NIR light (808 nm, 2.4 W/cm2): (a-ii) The close-up figure of (a-i); (b-i) the close-up of (a-i); (b-ii) The close-up of (b-i).
Figure 6
Figure 6
Fabricated LCE devices of different sizes: (a) side view of the devices with a scale bar. (b) side view of devices at standing position ready for locomotion.
Figure 7
Figure 7
(a) Transient temperature responses of Device-A, Device-B, and Device-C under NIR light illumination (808 nm; 2.4 W/cm2); (b) the close-up of Figure 7a.
Figure 8
Figure 8
The transient temperature responses of (a) Device-A, (b) Device-B, and (c) Device-C as a function of time with the NIR light illumination (808 nm, 2.4 W/cm2).
Figure 9
Figure 9
The experimental setup for measuring the crawling locomotion of devices.
Figure 10
Figure 10
The snapshot images of an LCE crawler (Device-B) for one actuation cycle.
Figure 11
Figure 11
Measured transient displacement and the measured actuators curvature change in (a) Device-A, (b) Device-B, and (c) Device-C for 10 actuation cycles. The NIR light intensity is 2.4 W/cm2.
See this image and copyright information in PMC

References

    1. Dong L., Tong X., Zhang H., Chen M., Zhao Y. Near-infrared light-driven locomotion of a liquid crystal polymer trilayer actuator. Mater. Chem. Front. 2018;2:1383–1388. doi: 10.1039/C8QM00190A. - DOI
    1. Sun D., Zhang J., Li H., Shi Z., Meng Q., Liu S., Chen J., Liu X. Toward Application of Liquid Crystalline Elastomer for Smart Robotics: State of the Art and Challenges. [(accessed on 25 September 2021)];Polymers. 2021 13:1889. doi: 10.3390/polym13111889. Available online: https://www.mdpi.com/2073-4360/13/11/1889. - DOI - PMC - PubMed
    1. Ikeda T., Mamiya J.-I., Yu Y. Photomechanics of Liquid-Crystalline Elastomers and Other Polymers. Angew. Chem. Int. Ed. 2007;46:506–528. doi: 10.1002/anie.200602372. - DOI - PubMed
    1. Du C., Cheng Q., Li K., Yu Y. A Light-Powered Liquid Crystal Elastomer Spring Oscillator with Self-Shading Coatings. [(accessed on 12 May 2022)];Polymers. 2022 14:1525. doi: 10.3390/polym14081525. Available online: https://www.mdpi.com/2073-4360/14/8/1525. - DOI - PMC - PubMed
    1. Hwang I., Mun S., Shin H., Yun S. A NIR-Light-Driven Twisted and Coiled Polymer Actuator with a PEDOT-Tos/Nylon-6 Composite for Durable and Remotely Controllable Artificial Muscle. [(accessed on 2 March 2022)];Polymers. 2022 14:432. doi: 10.3390/polym14030432. Available online: https://www.mdpi.com/2073-4360/14/3/432. - DOI - PMC - PubMed

LinkOut - more resources