Graphene in Artificial Muscles

Xuanhe Zhao, Assistant Professor at Duke University, talks to AZoNano about the Application of Graphene in Artificial Muscles.

Can you briefly outline your latest research on the application of graphene to form artificial muscles?

The artificial muscle is based on a dielectric elastomer sandwiched between two compliant electrodes. As an electric voltage is applied between the compliant electrodes, the dielectric elastomer is deformed to give an actuation strain over 100%, mimicking the deformation of muscles. In our current work, we use large-area crumpled graphene as novel electrodes for the artificial muscles.

What is the advantage of using graphene for artificial muscles?

There are a number of advantages of the crumpled graphene electrodes, such as lightweight, high transparency, and superhydrophobicity. In addition, the transparency and wettability of the crumpled graphene is tunable by deforming the elastomer.

When considering the movement of artificial muscles, how will the degree of crumpling affect graphene’s properties and performance?

The crumpled graphene will be unfolded as the artificial muscle is actuated. The unfolding of crumpled graphene enables it to accommodate the large deformation of the artificial muscle.

How do you plan on reversibly controlling the crumpling and unfolding of large sheets of graphene for the purpose of forming artificial muscles?

We are working on graphene with larger areas and higher qualities to form better electrodes for the artificial muscles. We are also improving the energy density of the dielectric elastomers for better performance as artificial muscles.

How does this research face the challenge of developing more realistic acting robots?

The light weight and high energy efficiency of the artificial muscles make them ideal candidates for actuators used in micro-scale robots.

What are the challenges ahead for this research?

The challenges are two folds. Firstly, we need to achieve a systematic understanding of the crumpling and unfolding of graphene on various polymers with different mechanical properties such as modulus and adhesion strength to graphene.

Secondly, we need to develop a fabrication technique to manufacture large-scale crumpled graphene for practical applications and commercialization.

What types of tasks are likely to be tested with the use of graphene to form artificial muscles?

For example, test the new artificial muscle as actuators in micro-robots or soft robots.

How do you see this research developing over the next decade?

The artificial muscle is just one application of the crumpled graphene. A number of future research directions become possible, such as systematic and quantitative investigations of the effects of crumpling on graphene's electrical and electrochemical properties.

A number of future research directions become possible, such as systematic and quantitative investigations of the effects of crumpling on graphene's electrical and electrochemical properties.

Also, the ridges and vertices in the crumpled graphene can potentially lead to other new properties and functions, such as patterned chemical reactions or to applications in biomedical devices. Furthermore, by controlling the microscopic patterns of graphene with a simple macroscopic tool, one can develop new graphene-based systems with novel tunability and flexibility to make nanoscale mechanisms visible at the macroscale.

Where can we find further information on your research?

Readers can find further information on my research by visiting my group website.

About Xuanhe Zhao

Xuanhe Zhao received his PhD in Mechanical Engineering from Harvard University in 2009, MS in Materials Engineering from University of British Columbia in 2006, and BE in Electrical Engineering from Tianjin University in 2003.

Upon finishing his postdoctoral training in Biomedical Engineering at Harvard in 2010, Zhao joined the faculty of Duke University and founded the Soft Active Materials Laboratory.

Dr Zhao's research is to understand the fundamental mechanics and physics of materials and phenomena emerging on the interface between engineering and biological systems and to design new materials and structures capable of extraordinary functions.

He is currently particularly interested in soft materials which are easily deformed by multiple thermodynamic forces such as mechanical stress, electric field, magnetic field, and chemical potential and their applications in various technologies such as energy storage, energy harvesting, biofouling, drug delivery, tissue engineering, robotics, microfluidics, and water treatment.