Tag Archives: Jonathan Rossiter

Paracrystalline carbon nanoparticles and morphing soft robots

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Michael Berger’s June 19, 2025 Nanowerk spotlight article focuses on a new development where soft robots are concerned, Note: A link has been removed,

The flexibility of living tissue inspires efforts to build robots that are soft, adaptive, and capable of complex movements. Creating such machines is technically demanding, especially when they must operate without physical tethers. Soft robots need materials that deform easily, actuators that respond quickly, and control methods that are both precise and lightweight. Most existing approaches fail to deliver on all three. Magnetic systems require bulky hardware. Light and heat actuation offer wireless control, but struggle with speed and complexity. Electric fields offer a promising alternative—but only if the materials can translate field stimuli into fast, large-scale movement without relying on wires or embedded circuitry.

Traditional electrically responsive gels deform slowly, limited by the movement of ions. Other systems, such as dielectric elastomer actuators, produce stronger and faster responses but rely on internal electrodes or onboard electronics that compromise their softness and range of motion. To make electric-field actuation practical for untethered soft robots, materials must respond quickly, deform extensively, and be controlled entirely from the outside. Advances in soft polymers and conductive nanomaterials have opened the door to this possibility.

A study published in Advanced Materials (“Electric Field Driven Soft Morphing Matter”) reports a material system that meets these criteria. Developed by researchers at the University of Bristol and Imperial College London, the material—called electro-morphing gel, or e-MG—combines a soft elastomer, a dielectric liquid, and paracrystalline carbon nanoparticles. When exposed to externally applied electric fields, e-MG exhibits fast, large, and reversible shape changes. These include stretching, twisting, bending, and locomotion. All movements are controlled wirelessly through low-cost external electrodes.

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Demonstration of the deformability of e-MG robots. a) Illustration of the e-MG material structure and its principle of actuation under an electric field. b) Conceptual diagram showcasing the potential of e-MG robots in space applications. c) An e-MG gymnast swinging along a ceiling. d) An e-MG snail jumping over a gap. e) An e-MG robot delivering cargo through a channel. Demonstrations in (c–e) were performed in a dielectric liquid environment. Scale bars are 5 mm. Courtesy: Authors and Advanced Materials [downloaded from https://advanced.onlinelibrary.wiley.com/doi/10.1002/adma.202419077]

Berger describes the new material, electro-morphing gel (e-MG), in more detail,

At the heart of e-MG’s performance is its material composition. The elastomer provides structural flexibility, while the dielectric liquid softens the matrix and adjusts its electrical properties. The carbon particles, just tens of nanometers wide, introduce mobile charges. When the concentration of carbon exceeds a critical level—between 0.1 and 0.5 percent by weight—these particles form continuous paths for charge transport. The result is a percolated, electrically responsive gel that deforms rapidly in response to non-uniform electric fields.

The material responds to two physical mechanisms: electrostatic and dielectrophoretic forces. Electrostatic force acts on charges within the gel, pushing it in the direction of the field. Dielectrophoretic force acts on polarized material in a gradient field, pulling it toward stronger regions. When both forces align, the effect is amplified. By varying the carbon content, the researchers could tune which mechanism dominated. Low-carbon samples relied mainly on dielectrophoresis and showed slower actuation. Higher-carbon samples displayed rapid deformation driven by both forces. A carbon loading of 0.5 percent offered the best balance of speed, strength, and fabrication reliability.

The researchers demonstrated a range of complex behaviors enabled by this material. Robots built from e-MG could stretch by nearly three times their length, rotate in place, bend around corners, and spread out across surfaces. In one test, a snail-like robot jumped over a gap using a rapid sequence of stretch and release. In another, a humanoid-shaped robot swung along a ceiling by gripping and releasing electrodes. Because e-MG is soft, the robots can deform to anchor themselves against walls or climb vertical surfaces using only field stimuli.

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To ensure practical utility, the researchers tested the material’s durability and environmental stability. After 10,000 actuation cycles, e-MG continued to perform reliably. Tests in both air and dielectric liquid confirmed consistent behavior across media. The system also remained functional in low-pressure environments designed to mimic space conditions. The use of mineral oil in some tests mimicked reduced gravity and surface friction, showing potential for extraterrestrial applications. The individual components of the material—silicone elastomer, silicone oil, and carbon nanoparticles—are all compatible with known aerospace standards.

The researchers also explored scalability. Miniature versions of the robot, over 4,000 times smaller in volume than their largest counterparts, still displayed the same range of actuation behaviors. This suggests that the material and actuation principles can be applied across different size scales. Potential uses could include navigating narrow spaces, manipulating fragile components, or performing soft contact tasks in confined environments.

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By combining a soft, responsive material with remote electrical control, the e-MG system overcomes key limitations of previous wireless soft robotics. It removes the need for internal circuitry, expands the range of deformation patterns, and enables precise actuation using lightweight external components. Its demonstrated ability to morph, grip, and move through contactless stimulation provides a flexible foundation for new robotic platforms. These could be used in biomedical procedures, industrial inspection, or space exploration—where low weight, high adaptability, and remote control are essential.

Berger’s June 19, 2025 Nanowerk spotlight article has more detail and an embedded video of the soft morphing robots, “This video showcases the versatility of electro-morphing gel (e-MG) robots without internal wiring and controlled by external electric fields. A jelly-like humanoid swings across a ceiling using agile limb movements. A snail-inspired robot jumps across a gap by stretching and contracting its soft body. Another robot navigates a narrow channel, anchoring itself to walls to push a cargo ball forward. These demonstrations highlight the adaptability and wireless control of e-MG systems in diverse tasks.“

Here’s a link to and a citation for the paper,

Electric Field Driven Soft Morphing Matter by Ciqun Xu, Charl F. J. Faul, Majid Taghavi, Jonathan Rossiter. Advanced Materials DOI: https://doi.org/10.1002/adma.202419077 First published: 12 June 2025

This paper is open access.

Camouflage for everyone

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The Institute of Physics (IOP) journal, Bioinspiration and BIomimetics, has published an open access article on camouflage inspired by zebrafish and squid. From the IOP’s May 2, 2012 news release

Researchers from the University of Bristol have created artificial muscles that can be transformed at the flick of a switch to mimic the remarkable camouflaging abilities of organisms such as squid and zebrafish.

They demonstrate two individual transforming mechanisms that they believe could be used in ‘smart clothing’ to trigger camouflaging tricks similar to those seen in nature.

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The soft, stretchy, artificial muscles are based on specialist cells called chromatophores that are found in amphibians, fish, reptiles and cephalopods, and contain pigments of colours that are responsible for the animals’ remarkable colour-changing effects.

Here’s the video mentioned in the IOP’s May 2, 2012 news release,

The lead author Jonathan Rossiter provides a description of the work (which may help you better understand what you’re seeing on the video), from the May 2, 2012 news item,

Two types of artificial chromatophores were created in the study: the first based on a mechanism adopted by a squid and the second based on a rather different mechanism adopted by zebrafish.

A typical colour-changing cell in a squid has a central sac containing granules of pigment. The sac is surrounded by a series of muscles and when the cell is ready to change colour, the brain sends a signal to the muscles and they contract. The contracting muscles make the central sacs expand, generating the optical effect which makes the squid look like it is changing colour.

The fast expansion of these muscles was mimicked using dielectric elastomers (DEs) – smart materials, usually made of a polymer, which are connected to an electric circuit and expand when a voltage is applied. They return to their original shape when they are short circuited.

In contrast, the cells in the zebrafish contain a small reservoir of black pigmented fluid that, when activated, travels to the skin surface and spreads out, much like the spilling of black ink. The natural dark spots on the surface of the zebrafish therefore appear to get bigger and the desired optical effect is achieved. The changes are usually driven by hormones.

The zebrafish cells were mimicked using two glass microscope slides sandwiching a silicone layer. Two pumps, made from flexible DEs, were positioned on both sides of the slide and were connected to the central system with silicone tubes; one pumping opaque white spirit, the other a mixture of black ink and water.

“Our artificial chromatophores are both scalable and adaptable and can be made into an artificial compliant skin which can stretch and deform, yet still operate effectively. This means they can be used in many environments where conventional ‘hard’ technologies would be dangerous, for example at the physical interface with humans, such as smart clothing,” continued Rossiter.

I wonder what these smart clothes/smart skin would feel like against your personal skin given that we are talking about ‘artificial muscles’. For example, how much movement would your clothing/smart skin have independent of you?

By independent, I mean that everything occurs externally. While we’re not ordinarily conscious of all our physical responses they are stimulated internally and part of a whole body response (even though we may notice only localized responses, e.g., a rash). In the research, there’s an external stimulus and an external response via smart clothes/smart skin.

This is just speculation as I imagine we’re several years away from any field testing of these smart clothes/smart skin, assuming that scientists are able to address all the technical hurdles between a laboratory breakthrough and developing applications.

Thanks to Nanowerk where I first came across this information (May 2, 2012 news item).