An official website of the United States government
Abstract Gallium‐based liquid metals (LMs) are widely used for stretchable and reconfigurable electronics thanks to their fluidic nature and excellent conductivity. These LMs possess attractive optical properties for photonics applications as well. However, due to the high surface tension of the LMs, it is challenging to form LM nanostructures with arbitrary shapes using conventional nanofabrication techniques. As a result, LM‐based nanophotonics has not been extensively explored. Here, a simple yet effective technique is demonstrated to deterministically fabricate LM nanopatterns with high yield over a large area. This technique demonstrates for the first time the capability to fabricate LM nanophotonic structures of various precisely defined shapes and sizes using two different LMs, that is, liquid gallium and liquid eutectic gallium–indium alloy. High‐density arrays of LM nanopatterns with critical feature sizes down to ≈100 nm and inter‐pattern spacings down to ≈100 nm are achieved, corresponding to the highest resolution of any LM fabrication technique developed to date. Additionally, the LM nanopatterns demonstrate excellent long‐term stability under ambient conditions. This work paves the way toward further development of a wide range of LM nanophotonics technologies and applications.
more »
« less
Shaping Magnetic Liquid Metals Into 3D Leakage‐Free, Shape‐Programmable Structures and Electronics
Abstract Liquid metals (LMs), renowned for their high conductivity and large deformability, find increasing applications including in flexible electronics and soft robotics. One critical process in these applications is the precise patterning of LMs into desired shapes. Yet, existing LM patterning techniques predominantly focus on 2D patterns due to challenges posed by the inherent fluidity and leakage of LMs. Here, we introduce an approach that bypasses these limitations, enabling the creation of complex 3D leakage‐free LM structures. This is achieved through mechanical programming of 2D magnetically immobilized LM paste formed via incorporating magnetic particles into LMs. Such composite effectively resists leakage due to the combined effect of strong magnetic inter‐attraction within the porous magnetic networks and the high surface tension of LMs, while retaining the high conductivity. Diverse freestanding magnetic LM structures, obtained upon LM solidification at ambient temperature, dynamically morph between their 2D and various 3D configurations through multiple cycles of induction heating and magnetic‐assisted reprogramming, featuring large compression resistance and self‐healing capabilities. Potential applications of these leakage‐resistant, shape‐adaptable structures are demonstrated through a helical magnetic LM antenna, which showcases its efficiency in wireless communication and energy harvesting.
more »
« less
- Award ID(s):
- 2236879
- PAR ID:
- 10640133
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Electronic Materials
- Volume:
- 11
- Issue:
- 18
- ISSN:
- 2199-160X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Possessing a unique combination of properties that are traditionally contradictory in other natural or synthetical materials, Ga-based liquid metals (LMs) exhibit low mechanical stiffness and flowability like a liquid, with good electrical and thermal conductivity like metal, as well as good biocompatibility and room-temperature phase transformation. These remarkable properties have paved the way for the development of novel reconfigurable or stretchable electronics and devices. Despite these outstanding properties, the easy oxidation, high surface tension, and low rheological viscosity of LMs have presented formidable challenges in high-resolution patterning. To address this challenge, various surface modifications or additives have been employed to tailor the oxidation state, viscosity, and patterning capability of LMs. One effective approach for LM patterning is breaking down LMs into microparticles known as liquid metal particles (LMPs). This facilitates LM patterning using conventional techniques such as stencil, screening, or inkjet printing. Judiciously formulated photo-curable LMP inks or the introduction of an adhesive seed layer combined with a modified lift-off process further provide the micrometer-level LM patterns. Incorporating porous and adhesive substrates in LM-based electronics allows direct interfacing with the skin for robust and long-term monitoring of physiological signals. Combined with self-healing polymers in the form of substrates or composites, LM-based electronics can provide mechanical-robust devices to heal after damage for working in harsh environments. This review provides the latest advances in LM-based composites, fabrication methods, and their novel and unique applications in stretchable or reconfigurable sensors and resulting integrated systems. It is believed that the advancements in LM-based material preparation and high-resolution techniques have opened up opportunities for customized designs of LM-based stretchable sensors, as well as multifunctional, reconfigurable, highly integrated, and even standalone systems.more » « less
-
Abstract Liquid metals (LMs) have compelling applications in stretchable electronics, wearable devices, and soft robotics ascribing to the unique combination of room temperature fluidity and metallic electrical/thermal conductivity. Adding metallic elements in gallium‐based LMs can produce heterophasic (i.e., solid and liquid) LMs with altered properties including morphology, surface energy, rheology, electrical/thermal conductivity, and chemical reactivity. Importantly, heterophasic LMs can respond to external stimuli such as magnetic fields, temperature, and force. Thus, heterophasic LMs can broaden the potential applications of LMs. This report reviews the recent progress about heterophasic LMs through metallic elements in the periodic table and discusses their functionalities. The heterophasic LMs are systematically organized into four categories based on their features and applications including electrical/thermal conductivity, magnetic property, catalysis/energy management, and biomedical applications. This comprehensive review is aimed to help summarize the field and identify new opportunities for future studies.more » « less
-
Abstract Since the first discovery of graphene, 2D materials are drawing tremendous attention due to their atomic thickness and superior properties. Fabrication of high‐quality micro‐/nanopatterns of 2D materials is essential for their applications in both nanoelectronics and nanophotonics. In this work, an all‐optical lithographic technique, optothermoplasmonic nanolithography (OTNL), is developed to achieve high‐throughput, versatile, and maskless patterning of different atomic layers. Low‐power (≈5 mW µm−2) and high‐resolution patterning of both graphene and MoS2monolayers is demonstrated through exploiting thermal oxidation and sublimation at the highly localized thermoplasmonic hotspots. Density functional theory simulations reveal that Au nanoparticles reduce the formation energy (≈0.6 eV) of C monovacancies through bonding between undercoordinated C and Au, leading to a significant Au‐catalyzed graphene oxidation and a reduction of the required laser operation power. Programmable patterning of 2D materials into complex and large‐scale nanostructures is further demonstrated. With its low‐power, high‐resolution, and versatile patterning capability, OTNL offers the possibility to scale up the fabrication of nanostructured 2D materials for many applications in photonic and electronic devices.more » « less
-
Abstract Biosensors are analytical tools for monitoring various parameters related to living organisms, such as humans and plants. Liquid metals (LMs) have emerged as a promising new material for biosensing applications in recent years. LMs have attractive physical and chemical properties such as deformability, high thermal and electrical conductivity, low volatility, and low viscosity. LM‐based biosensors represent a new strategy in biosensing particularly for wearable and real‐time sensing. While early demonstrations of LM biosensors focus on monitoring physical parameters such as strain, motion, and temperature, recent examples show LM can be an excellent sensing material for biochemical and biomolecular detection as well. In this review, the recent progress of LM‐based biosensors for personalized healthcare and disease monitoring via both physical and biochemical signaling is survey. It is started with a brief introduction of the fundamentals of biosensors and LMs, followed by a discussion of different mechanisms by which LM can transduce biological or physiological signals. Next, it is reviewed example LM‐based biosensors that have been used in real biological systems, ranging from real‐time on‐skin physiological monitoring to target‐specific biochemical detection. Finally, the challenges and future directions of LM‐integrated biosensor platforms is discussed.more » « less
