SCIENCE CHINA Materials, Volume 61, Issue 10: 1291-1296(2018) https://doi.org/10.1007/s40843-018-9249-y

Moisture-triggered actuator and detector with high-performance: interface engineering of graphene oxide/ethyl cellulose

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  • ReceivedJan 22, 2018
  • AcceptedMar 13, 2018
  • PublishedApr 16, 2018


Actuators that can directly convert other forms of environmental energy into mechanical work offer great application prospects in intriguing energy applications and smart devices. But to-date, low cohesion strength of the interface and humidity responsive actuators primarily limit their applications. Herein, by experimentally optimizing interface of bimorph structure, we build graphene oxide/ethyl cellulose bidirectional bending actuators --- a case of bimorphs with fast and reversible shape changes in response to environmental humidity gradients. Meanwhile, we employ the actuator as the engine to drive piezoelectric detector. In this case, graphene oxide and ethyl cellulose are combined with chemical bonds, successfully building a bimorph with binary synergy strengthening and toughening. The excellent hygroscopicity of graphene oxide accompanied with huge volume expansion triggers giant moisture responsiveness greater than 90 degrees. Moreover, the open circuit voltage of piezoelectric detector holds a peak value around 0.1 V and exhibits excellent reversibility. We anticipate that humidity-responsive actuator and detector hold promise for the application and expansion of smart devices in varieties of multifunctional nanosystems.

Funded by

This work was financially supported by the National Basic Research Program of China(2015CB932302)

National Natural Science Foundation of China(U1432133,11621063,21701164)

National Program for Support of Top-notch Young Professionals and the Fundamental Research Funds for the Central Universities(WK2060190084,WK2060190058)


This work was financially supported by the National Basic Research Program of China (2015CB932302), National Natural Science Foundation of China (U1432133, 11621063, 21701164), National Program for Support of Top-notch Young Professionals and the Fundamental Research Funds for the Central Universities (WK2060190084, WK2060190058). We would like to thank the Catalysis and Surface Science Endstation (National Synchrotron Radiation Laboratory) for providing the beam time. This work was also supported from the Major/Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology.

Interest statement

The authors declare that they have no conflict of interest.

Contributions statement

Wu C conceived the idea, co-wrote the paper, supervised the entire project and is responsible for the infrastructure and project direction. Yang B experimentally realized the study, analyzed the data and co-wrote the paper. Bi W, Zhong C and Huang M experimentally realized the study, Ni Y and He L supervised the whole experimental procedure and co-wrote the paper. All authors discussed the results and commented on and revised the manuscript.

Author information

Bo Yang received his BSc (2013) and MEng (2016) degrees from School of Physics and Materials Science, Anhui University. He is currently pursuing his PhD under the supervision of Prof. Changzheng Wu and Prof. Linghui He at University of Science and Technology of China (USTC). His research focuses on the design and exploration of smart materials.

Changzheng Wu obtained his BSc (2002) and PhD (2007) degrees from the Department of Chemistry, USTC. Thereafter, he has been working as a postdoctoral fellow in the Hefei National Laboratory for Physical Sciences at Microscale. He is now a full professor of Department of Chemistry, USTC. His current research focuses on the synthesis and characterization of inorganic two-dimensional nanomaterials and regulation of their intrinsic physical properties for a wide range of applications in energy storage or energy conversion.


Supplementary information

Supporting data are available in the online version of the paper.


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  • Figure 1

    Preparation processes and characterizations of GO/EC actuator. (a) Bimorph structure of GO/EC. (b) Schematic illustration of the fabrication process of GO/EC actuator. (c) Cross-sectional SEM image of the GO/EC bimorph. (d) FT-IR spectra of GO, EC and GO-EC. (e) detail in FT-IR spectra of GO, EC and GO-EC.

  • Figure 2

    Demonstration and evaluation of the bimorph as a practical humidity actuator. (a) The mechanism of humidity-responsive actuator. (b) A home-made setup to measure the bending angle of the humidity actuator. (c) Bending angle and humidity as a function of the distance between the water and actuator. (d) Bending angle as a function of humidity. (e) Relative humidity and weight change versus time of GO. (f) Dynamic water vapor sorption isotherm analysis for GO.

  • Figure 3

    Demonstration of the humidity-responsive actuator as a practical piezoelectric detector. (a) Schematic demonstration of the structure for the detector. (b) Photograph of the detector. (c) A moisture-triggered detector. (d, e) Transient responses of the detector driven by moisture.

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