Liquid metals are attractive for flexible electronics because they conduct electricity while remaining deformable. Yet when liquid-metal particles are incorporated into polymer networks, their surfaces can be unstable. Droplets may collide and coalesce, producing irregular conductive pathways and compromising the material’s mechanical and electrical performance. The Fuzhou University team, led by Yan Yu and Sheng-Hong Zhong, tackled this problem with gelatin, a natural biomolecule widely used in food, medicine and biomaterials. Instead of relying on conventional synthetic stabilizers, the researchers used gelatin to form a protective molecular layer around liquid-metal particles before embedding them in a hydrogel.

The stabilization mechanism is based on coordination bonding at the metal-particle surface. Liquid-metal droplets naturally develop a thin oxide layer when exposed to air. Functional groups in gelatin, particularly amino and carboxyl groups, interact strongly with this oxide coating. The resulting molecular associations create a gelatin-rich shell that helps keep individual liquid-metal particles separated and uniformly distributed. This arrangement prevents uncontrolled coalescence while preserving contact between neighboring particles, allowing the droplets to form a continuous and deformable conductive network throughout the hydrogel.

The gelatin performs another important chemical function during fabrication. According to the researchers, it helps initiate the polymerization of acrylic acid without the traditional chemical initiators normally required to start the reaction. In this process, acrylic acid molecules link together to form the polymer framework, while gelatin-coated liquid-metal particles become integrated into the developing network. Eliminating harsh initiators simplifies preparation and may improve the material’s environmental and biological compatibility. The researchers describe the method as rapid, scalable and more sustainable than approaches that require multiple synthetic additives or complicated processing steps.

The resulting material, known as a Gelatin-Mediated Hydrogel, or GMH, combines the water-rich softness of a hydrogel with the conductivity and deformability of liquid metal. It can be stretched beyond 700 percent of its original length and recover its shape without a major loss of function. Such resilience is essential for electronic skin, where a sensor must follow bending joints, moving muscles and repeatedly flexing fingers. Because the liquid-metal particles remain distributed throughout the polymer matrix, mechanical deformation changes the conductive pathways in a measurable way. This produces electrical signals that can be correlated with strain, pressure and motion.

In one demonstration, the researchers attached the hydrogel to a finger and used it to record electrical changes produced while writing the 26 letters of the English alphabet. Each movement generated a distinctive signal pattern as the hydrogel stretched and relaxed. The data were then analyzed using a convolutional neural network, a type of deep-learning model commonly used for image and pattern recognition. The system identified handwritten letters in real time with an accuracy of 93.3 percent. The result turns a soft sensor into more than a passive detector: it becomes an interface capable of converting body movement into machine-readable information.

This combination of flexible sensing and artificial intelligence could have wide implications for wearable technology. Conventional keyboards and touchscreens require rigid surfaces or deliberate finger contact, while a hydrogel sensor can gather information directly from natural movement. Similar systems could support gesture recognition, rehabilitation monitoring, sign-language interfaces or controls for wearable and robotic devices. The researchers’ demonstration remains a laboratory proof of concept, but its use of a simple biomolecule and a deformable conductive network highlights how materials science and machine learning can be integrated into lightweight human-machine interfaces.

The GMH also demonstrated a method for converting solar or near-infrared light into electricity. Liquid metal acts as an efficient photothermal component: it absorbs incoming light and rapidly converts part of that energy into heat. When the hydrogel was exposed to near-infrared illumination, its temperature increased. Coupling the material to a thermoelectric module allowed the temperature difference to be converted into an electrical voltage of approximately 16 millivolts. That output is modest, but the principle could support low-power sensors or help extend the operating time of wearable systems by reducing dependence on conventional batteries.

The researchers say the work establishes a versatile platform for multifunctional hydrogel electronics, but practical deployment will require further development. Future studies will need to examine long-term stability, performance under repeated environmental exposure, large-scale manufacturing and integration with complete power-management circuits. Even so, the material offers an unusually broad combination of properties: liquid-metal conductivity, hydrogel softness, gelatin-mediated stabilization, AI-compatible sensing and photothermal energy conversion. By using a common natural biomolecule to control an otherwise difficult-to-handle electronic material, the Fuzhou University team has brought flexible “electronic skin” a step closer to becoming adaptive, intelligent and partially self-powered.

Subject of Research: Gelatin-stabilized liquid-metal conductive hydrogels for flexible sensing, AI-assisted handwriting recognition and photothermal energy harvesting.

Article Title: Gelatin-Stabilized Liquid Metal for Conductive Hydrogels with Multifunctional Sensing Applications and Energy Harvesting

News Publication Date: 23-Jun-2026

Web References: https://doi.org/10.26599/NR.2026.94908692; Nano Research

References: Nano Research, DOI: 10.26599/NR.2026.94908692

Image Credits: Nano Research, Tsinghua University Press

Keywords

Liquid metal; gelatin; conductive hydrogel; electronic skin; wearable sensors; artificial intelligence; handwriting recognition; photothermal conversion; thermoelectric energy harvesting; flexible electronics

The essence of this approach lies in combining the electrical conductivity of PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)) with the biocompatibility and mechanical compliance of gelatin, a natural polymer derived from collagen. This hybrid material embodies an ideal physiological milieu, offering softness and stretchability compatible with living tissues while sustaining the electron transport integral to bioelectronic functionality. Yet, achieving detailed spatial control over the microstructure of such composite hydrogels has posed a significant challenge—until now.

Two-photon lithography, a high-resolution 3D printing technique that leverages nonlinear absorption of femtosecond laser pulses, enables the direct writing of micro- and nanoscale features inside photosensitive materials with unprecedented precision. This team adeptly harnessed the power of two-photon lithography to induce localized cross-linking of the gelatin matrix in the presence of PEDOT:PSS, thereby creating conductive pathways embedded within a hydrated, gel-like environment. The resulting constructs possess tailored geometries at sub-micrometer resolution, a scale critical for interfacing with cellular components and neuronal networks.

The meticulous orchestration of photopolymerization parameters allowed the researchers to finely tune the electrical properties and mechanical stiffness of the hydrogels. By adjusting laser exposure and material formulations, they achieved a delicate balance—maximizing conductivity while maintaining tissue-like softness and ensuring aqueous stability. Such control amplifies the potential application scope, from soft sensors conforming to organ surfaces to implantable devices that facilitate seamless electrophysiological monitoring.

Beyond material composition and fabrication, the study provides extensive characterization of the hydrogels’ biocompatibility and functionality. In vitro assays demonstrated that cultured cells exhibit superior adhesion and viability on these microstructured hydrogels compared to traditional rigid electrodes. This biocompatibility is pivotal for chronic implantation, where minimizing inflammatory responses and promoting cellular integration are paramount for device longevity and performance.

The team further showcased the potential of their conductive hydrogels in soft bioelectronic circuits by integrating microelectrode arrays capable of detecting electrical signals with high sensitivity and spatial resolution. Such devices could revolutionize biomedical diagnostics and therapeutics by enabling real-time, minimally invasive monitoring of neural activity, cardiac rhythms, or muscle contractions. The flexible nature of the hydrogels facilitates intimate contact with soft tissues, mitigating mechanical mismatch that commonly impairs electrode-tissue interfaces.

An especially compelling aspect of this research is its modularity. The two-photon lithography technique permits the fabrication of complex three-dimensional architectures, including multilayered and branched structures, that mimic the intricate extracellular matrix found in vivo. This biomimetic capability opens avenues for the creation of advanced neural interfaces, biosensors, and tissue engineering scaffolds that actively interact with biological systems rather than merely recording from them.

This combination of electrical conductivity and biofunctionality within a 3D microfabrication paradigm holds promise for advancing precision medicine. For instance, soft neural probes constructed from these hydrogels could be customized to individual patient anatomy and disease states, enabling tailored interventions with enhanced efficacy and reduced side effects. Furthermore, incorporation of functional biomolecules or drug reservoirs within the hydrogel matrix could transform these platforms into multifunctional therapeutic devices.

In addition to health care, the implications extend to wearable electronics and soft robotics, where flexible, stretchable sensors capable of detecting electrophysiological signals or mechanical forces in real-time are in high demand. The scalable production of such conductive hydrogels may pave the way for consumer devices embedded into fabrics or skin-mounted patches that are comfortable, biocompatible, and mechanically resilient.

The study addresses long-standing challenges in soft bioelectronics by overcoming the limitations posed by traditional electrode materials such as metals and silicon, which are often rigid and prone to degradation in physiological environments. Moreover, the utilization of gelatin, an abundant and biodegradable biopolymer, aligns with growing sustainability trends in material science, offering eco-friendly alternatives to synthetic polymers.

Detailed electrical testing revealed that the fabricated hydrogels sustain stable conductivity under cyclic mechanical strain, an essential characteristic for devices implanted in dynamic biological environments where deformation is frequent. Such robustness in performance underscores the material’s suitability for real-world medical applications requiring durability and reliability over extended periods.

Furthermore, the ability to pattern conductive elements in three dimensions enables the integration of multiple sensing modalities within compact volumes, enhancing the functional density of bioelectronic implants without increasing their physical footprint. This feature is critical for enabling high-resolution mapping of biological signals, facilitating new insights into complex physiological processes at cellular and tissue levels.

The underlying chemical interactions governing the cross-linking process and conductivity retention were elucidated using spectroscopic and microscopic analysis. These insights provide a foundation for future refinement of the hydrogel composition and fabrication parameters, potentially leading to even higher conductivities, enhanced mechanical properties, or new functionalities such as responsiveness to environmental stimuli.

Looking ahead, this innovative 3D micropatterning strategy sets the stage for interdisciplinary collaborations spanning materials science, neurobiology, biomedical engineering, and clinical medicine. Its translation from lab-scale demonstrations to practical medical devices could revolutionize how clinicians diagnose, monitor, and treat diseases, particularly those related to neural and cardiac dysfunction.

The convergence of soft hydrogel materials with precise laser-based micropatterning technologies heralds a new era in bioelectronics where devices are not just tools but integrated partners in the biological ecosystem. Through this synergy, the boundary between living tissue and electronic circuitry begins to blur, opening transformative possibilities in health care, human-machine interfaces, and beyond.

As this research continues to evolve, the scientific community eagerly anticipates the forthcoming clinical validations and commercial adaptations that will bring these conductive hydrogels from experimental innovation to everyday medical reality. The study by Buzio and colleagues, published in npj Flexible Electronics, stands as a landmark contribution illuminating the path toward truly seamless bioelectronic integration.

Subject of Research: 3D micropatterning of PEDOT:PSS/Gelatin conductive hydrogels for applications in soft bioelectronics.

Article Title: 3D micropatterning of PEDOT:PSS/Gelatin conductive hydrogels via two-photon lithography for soft bioelectronics.

Article References:
Buzio, M., Gini, M., Schneider, T.C. et al. 3D micropatterning of PEDOT:PSS/Gelatin conductive hydrogels via two-photon lithography for soft bioelectronics. npj Flex Electron (2026). https://doi.org/10.1038/s41528-026-00529-5

Image Credits: AI Generated