Tag Archives: Xinglong Gong

Transforming natural leather and graphene into electronic skin

I have two stories about electronic skin (e-skin or artificial skin), each featuring a very different approach to developing the technology.

Leather for electronic skin

Michael Berger’s May 28, 2025 Nanowerk Spotlight article provides context for the research into producing artificial (electronic) skin using leather as the base,

Flexible electronics are reshaping how humans interact with machines, creating new possibilities for systems that conform to the body and respond intelligently to physical stimuli. Among the most ambitious goals in this field is the development of electronic skin—e-skin—that replicates the sensory and protective functions of biological tissue.

Real skin does more than just sense touch; it buffers mechanical impacts, regulates temperature, and shields the body from harmful radiation. Replicating all these functions in a single synthetic material has proven technically complex. Most artificial skins focus narrowly on pressure sensing or surface temperature monitoring, often falling short when required to provide mechanical robustness or electromagnetic shielding.

A variety of material systems have been explored in pursuit of a true e-skin, including hydrogels, silicone elastomers, carbon nanotube composites, and layered polymer matrices. While many of these have achieved impressive sensitivity to pressure or temperature, their mechanical fragility, structural instability, or limited responsiveness under stress have restricted their practical use. Some efforts have turned to bio-derived substrates like cellulose or silk. Although lightweight and flexible, these materials are often fragile and lack the structural hierarchy needed for reliable multifunctionality.

Leather—processed animal skin—presents an intriguing alternative. It possesses intrinsic toughness, flexibility, and a multilayered collagen fiber structure that resembles the dermal framework of natural skin. Its use in clothing and protective gear underscores its reliability.

However, until now, efforts to adapt leather for flexible electronics have been hampered by poor structural integration, limited sensitivity under dynamic conditions, and weak electromagnetic shielding. These limitations have prevented leather from advancing beyond a passive substrate into a truly intelligent material capable of emulating skin’s full range of functions.

Berger’s May 28, 2025 article goes on to describe a new approach to transforming leather into e-skin,

In a study published in Advanced Functional Materials (“Exceed the Traditional Dead Leather to Intelligent E‐Skin”), researchers from the University of Science and Technology of China and Hong Kong Baptist University present a leather-based composite that addresses these limitations. By integrating silver nanostructures and a viscoelastic polymer into natural leather, the team developed a multifunctional e-skin that unites pressure sensing, thermal control, impact protection, and electromagnetic shielding in a single material platform.

This composite, referred to as LAP (Leather/Ag/Polyborosiloxane Elastomer), mirrors the layered anatomy of human skin. The leather forms the outer protective surface, analogous to the epidermis. Embedded within this layer is a hybrid network of silver nanowires and silver flakes. These fill the gaps between collagen fibers, creating a dense, conductive network that functions like the skin’s dermis. The inner layer comprises a polyborosiloxane elastomer—a viscoelastic material that stiffens upon impact, much like the hypodermis’ role in absorbing mechanical shocks.

The conductive layer benefits from the combination of one-dimensional nanowires and two-dimensional flakes. The flakes act as broad conductive platforms while the nanowires link them, forming a three-dimensional network. This arrangement significantly enhances conductivity and mechanical cohesion. The optimal ratio of silver nanowires to flakes—determined to be 1:2—yielded both low resistance and high tensile strength. The material reached a tensile strength of 9.28 MPa at a silver content of 5.0 mg/cm², nearly doubling the strength of the underlying leather-polymer base. Fracture strains of up to 70.8% demonstrate the composite’s flexibility and capacity for wearable use.

One of the most distinctive capabilities of the LAP e-skin is its dual-mode sensing response. Under slow compression, the conductive network densifies, reducing resistance and enabling precise piezoresistive sensing. The sensor detected strains as low as 2% with consistent signal output over 500 cycles. Under high-speed impact, however, the network momentarily fractures, increasing resistance instead. This difference allows the material to distinguish between light contact and sudden impacts, a feature that mimics how real skin perceives touch versus pain.

This study illustrates how biologically inspired materials can be reengineered to achieve functional integration across sensing, protection, and regulation domains. The choice to reconfigure leather—already optimized by evolution for wearability and toughness—provides a structurally rich and mechanically resilient platform. By layering conductive and responsive components onto this substrate, the researchers have constructed a versatile material that pushes the capabilities of e-skin systems toward those of natural tissue.

If you have time, do read Berger’s May 28, 2025 article in its entirety.

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

Exceed the Traditional Dead Leather to Intelligent E-Skin by Yue Yao, Ziyang Fan, Xinglong Gong, Danyi Li, Wei Yang, Ken Cham-Fai Leung, Xinyi Wang, Shuai Liu, Junjie Yang, Shouhu Xuan. Advanced Functional Materials DOI: https://doi.org/10.1002/adfm.202500572 First published online: 24 May 2025

This paper is behind a paywall.

Graphene-based electronic skin

A June 24, 2025 Technical University of Denmark(DTU) press release (also on EurekAlert) announces a ‘graphene forward’ approach, Note: A link has been removed,

Researchers at DTU have made a significant achievement by developing a new kind of electronic material that behaves almost exactly like human skin. That kind of substance could be useful in soft robotics, medicine, and healthcare.

Picture electronic devices that heal the way our skin repairs itself. Researchers at DTU have developed a new material that makes it possible—a flexible, tough and self-healing material that may in future come into use in the healthcare sector, in robotics and much more. This new material overcomes the weaknesses of the rigid, brittle electronic materials currently used, which can’t repair themselves.

By dint of an innovative approach, the scientists at DTU have combined the exceptional properties of graphene, a two-dimensional carbon form that is extremely strong, and has great electrical conductivity, with the see-through polymer PEDOT: PSS, that is also electrically conductive and is, for example, used in flexible electronics and sometimes as transparent electrodes in solar cells. When these two parts are mixed, they turn what’s usually a weak, jellylike material into a solid, flexible, self-healing electronic material.

“The devices that exist today and have self-healing, soft, and responsive properties often fail to seamlessly integrate all these attributes into a single, scalable, and cohesive platform. And that is what I believe we have accomplished,” says Alireza Dolatshahi-Pirouz, Associate Professor at DTU Health Tech and lead author of a recent paper in Advanced Science, detailing their accomplishment: Self‐Maintainable Electronic Materials with Skin‐Like Characteristics Enabled by Graphene‐PEDOT:PSS Fillers.

“Our skin-inspired material is multifunctional, endowed with the desired tactile properties, specifically designed for the usage of electronic devices. This may open the doors to the more advanced and versatile technologies that could more closely mingle with the human body and the surroundings.”

Flexible and self-repairing

Among the most promising attributes of the new material is its ability to self-heal. If it is damaged, it can heal in a matter of seconds, the way the human skin heals after, say, a cut. On top of that, the material is extremely malleable and can be stretched up to six times beyond its original length and still bounce back. This makes it well suited for integration within wearable and soft robotic devices, which require that materials can be moved and bent without diminishing their performance.

It can also control heat and detect a range of environmental factors, such as pressure, temperature and pH levels, which could make it beneficial for health monitoring systems that must keep track of vital signs and adjust to body changes.

Electronics built from this material could therefore be amorphous and shape-changing, capable of adapting to their environment, the researchers say, and able to recover from damage the way biological systems do.

“The fact that the material can self-heal, regulate heat, and monitor vital signs makes it suitable to be used in a large range of equipments, says Alireza Dolatshahi-Pirouz:

“Space suits spring to mind, but I believe that we will find the most relevant uses for the individual citizen within healthcare. We could, for instance, incorporate it in bandages that would monitor how a wound is healing, or in devices that continuously track heart rate and temperature. The stretchable nature of the material makes it ideal for minimally invasive surgery or implantable applications. And we could easily imagine prosthetics that are more comfortable to wear and have better performance.”

At present, the researchers are continuing their work and investigating methods to make it on a larger scale, aimed at setting the stage for real-life applications.

By combining graphene and a polymer blend, DTU researchers have developed a self-healing electronic material that mimics the properties of skin. Illustration: Daniel Müller.

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

Self-Maintainable Electronic Materials with Skin-Like Characteristics Enabled by Graphene-PEDOT:PSS Fillers by Morteza Alehosseini, Firoz Babu Kadumudi, Sinziana Revesz, Parham Karimi Reikandeh, Jonas Rosager Henriksen, Tiberiu-Gabriel Zsurzsan, Jon Spangenberg, Alireza Dolatshahi-Pirouz. Advanced Science DOI: https://doi.org/10.1002/advs.202410539 First published online: 25 April 2025

This paper is open access.

What is that old saying, “there’s more than one way to … .”

Nanotechnology-enabled contact lenses that give infrared vision to humans

A May 22, 2025 news item on Nanowerk announced a nanotechnology-enabled contact lens that made international news, Note: A link has been removed,

Neuroscientists and materials scientists have created contact lenses that enable infrared vision in both humans and mice by converting infrared light into visible light. Unlike infrared night vision goggles, the contact lenses, described in the Cell Press journal Cell (“Near-infrared spatiotemporal color vision in humans enabled by upconversion contact lenses”), do not require a power source—and they enable the wearer to perceive multiple infrared wavelengths. Because they’re transparent, users can see both infrared and visible light simultaneously, though infrared vision was enhanced when participants had their eyes closed.

“Our research opens up the potential for non-invasive wearable devices to give people super-vision,” says senior author Tian Xue, a neuroscientist at the University of Science and Technology of China. “There are many potential applications right away for this material. For example, flickering infrared light could be used to transmit information in security, rescue, encryption or anti-counterfeiting settings.”

A May 22, 2025 Cell Press news release on EurekAlert, which originated the news item, goes on to describe how researchers were able to introduce new capabilities for contact lenses,

The contact lens technology uses nanoparticles that absorb infrared light and convert it into wavelengths that are visible to mammalian eyes (e.g., electromagnetic radiation in the 400-700 nm range). The nanoparticles specifically enable detection of “near-infrared light,” which is infrared light in the 800-1600 nm range, just beyond what humans can already see. The team previously showed that these nanoparticles enable infrared vision in mice when injected into the retina, but they wanted to design a less invasive option.  

To create the contact lenses, the team combined the nanoparticles with flexible, non-toxic polymers that are used in standard soft contact lenses. After showing that the contact lenses were non-toxic, they tested their function in both humans and mice. 

They found that contact lens-wearing mice displayed behaviors suggesting that they could see infrared wavelengths. For example, when the mice were given the choice of a dark box and an infrared-illuminated box, contact-wearing mice chose the dark box whereas contact-less mice showed no preference. The mice also showed physiological signals of infrared vision: the pupils of contact-wearing mice constricted in the presence of infrared light, and brain imaging revealed that infrared light caused their visual processing centers to light up.  

In humans, the infrared contact lenses enabled participants to accurately detect flashing morse code-like signals and to perceive the direction of incoming infrared light. “It’s totally clear cut: without the contact lenses, the subject cannot see anything, but when they put them on, they can clearly see the flickering of the infrared light,” said Xue. “We also found that when the subject closes their eyes, they’re even better able to receive this flickering information, because near-infrared light penetrates the eyelid more effectively than visible light, so there is less interference from visible light.”  

An additional tweak to the contact lenses allows users to differentiate between different spectra of infrared light by engineering the nanoparticles to color-code different infrared wavelengths. For example, infrared wavelengths of 980 nm were converted to blue light, wavelengths of 808 nm were converted to green light, and wavelengths of 1,532 nm were converted to red light. In addition to enabling wearers to perceive more detail within the infrared spectrum, these color-coding nanoparticles could be modified to help color blind people see wavelengths that they would otherwise be unable to detect. 

“By converting red visible light into something like green visible light, this technology could make the invisible visible for color blind people,” says Xue. 

Because the contact lenses have limited ability to capture fine details (due to their close proximity to the retina, which causes the converted light particles to scatter), the team also developed a wearable glass system using the same nanoparticle technology, which enabled participants to perceive higher-resolution infrared information.   

Currently, the contact lenses are only able to detect infrared radiation projected from an LED light source, but the researchers are working to increase the nanoparticles’ sensitivity so that they can detect lower levels of infrared light.  

“In the future, by working together with materials scientists and optical experts, we hope to make a contact lens with more precise spatial resolution and higher sensitivity,” says Xue.  

Jennifer Ouellette’s May 22, 2025 article for Ars Technica emphasizes the military aspect of this work,

Tired of using bulky night vision goggles for your clandestine nocturnal activities? An interdisciplinary team of Chinese neuroscientists and materials scientists has developed near-infrared contact lenses that enabled both mice and humans to see in the dark, even with their eyes closed, according to a new paper published in the journal Cell.

Humans and other mammals can only perceive a limited range of the electromagnetic spectrum (light), usually in the 400–700 nm range. There are creatures that can see in infrared (snakes, mosquitoes, bullfrogs) or ultraviolet (bees, birds), and goldfish can perceive both. But humans must augment themselves with technology in order to expand our range of vision.

Night vision goggles and similar devices have been around since the 1930s, including infrared-visible converters, but these require external energy sources, and the converters have a multilayer structure that makes them opaque and hence challenging to integrate with a human eye. The authors previously were able to confer near-infrared vision to mice by injecting nanoparticles that bind to photoreceptors into their eyes—basically creating a near-infrared nanoantenna—but realized that most people would be averse to the prospect of sticking needles in their eyes. So they looked for a better alternative. Contact lenses seemed the obvious choice.

Ouellette’s May 22, 2025 article is a good read.

Caption: Study participant putting contacts in Credit: Yuqian Ma, Yunuo Chen, Hang Zhao

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

Near-infrared spatiotemporal color vision in humans enabled by upconversion contact lenses by Yuqian Ma (马玉乾), Yunuo Chen (陈雨诺), Sheng Wang, Zi-Han Chen, Yuanwei Zhang, Ling Huang, Xinxin Zhang, Fei Yin, Yunxuan Wang, Mingzhu Yang, Zhanjun Li, Kai Huang, Xin Fang, Zishuo Li, Minghong Wang, Wenhui Liu, Jia-Nan Li, Longfei Li, Hang Zhao, Min Wei, Yiming Shi, Rong Liu, Mei Zhang, Jutao Chen, Jiawei Shen, Jianjun Meng, Yupeng Yang, Fan Zhang, Xinglong Gong, Gang Han, Tian Xue (薛天). Cell Volume 188, Issue 13, 26 June 2025, Pages 3375-3388.e18 DOI: https://doi.org/10.1016/j.cell.2025.04.019 Available online 22 May 2025, Version of Record 26 June 2025

This paper is behind a paywall.