In the realm of soft matter physics and materials science, the ability to manipulate liquids into dynamically reconfigurable shapes holds immense promise for transformative applications. A recent breakthrough by Roh, Ha, and Abbott unveils a biphasic liquid system capable of reversible, long-lived microdomain transformations driven by electric fields. This discovery transcends prior limitations imposed by the intrinsic physical properties of fluids, opening novel pathways toward tunable optical devices and smart material platforms.
At the heart of this innovation lies a biphasic mixture comprising two immiscible oils: an isotropic oil and a liquid crystalline oil. These two phases naturally separate, creating interfaces that can adopt diverse morphologies from thin wetting films to discrete droplets or threads. Historically, controlling these morphologies with speed and reversibility has proved elusive, largely due to the competing demands of facilitating rapid reshaping while maintaining structural longevity. Low interfacial tension and fluidity expedite transformations but simultaneously accelerate their decay, resulting in fleeting, metastable configurations.
Roh and colleagues have circumvented these perennial challenges by exploiting the interplay between topological defects in the liquid crystalline phase and electric field modulation. The isotropic oil initially wets solid substrates, forming stable, continuous films at the liquid crystal interface. When subjected briefly to a low-frequency alternating electric field (around 10 Hz), these films rupture into spherical microdomains, each stabilized not by surface tension alone but by the intricate defect structures embedded within the surrounding liquid crystal matrix. These shape-shifted spheres represent a metastable—but remarkably persistent—state capable of maintaining form for over 24 hours without further intervention.
Crucially, the transformation is fully reversible. Applying a high-frequency alternating current, on the order of 1 kHz, triggers the formation of solitons—localized, stable wave-like distortions—in the liquid crystal environment. These solitonic structures provide kinetic pathways that rapidly facilitate the coalescence of dispersed spherical domains back into the original wetting film morphology, often within mere seconds. This bistability between distinct liquid configurations provides an unprecedented handle on the long-sought feature of dynamic, reversible shape control in soft matter systems without continuous energy input.
The synergy between biphasic liquid morphology and liquid crystal topological intricacies constitutes a striking advance in the design of responsive materials. Liquid crystals are well known for their sensitivity to electric fields and their diverse defect landscapes, which can be manipulated to encode information geometrically. Here, the novel use of electric-field-triggered defect engineering stabilizes colloidal domains in fluidic matrices, enabling controlled shape transformations with optical implications.
Optically, the two states of the biphasic system possess markedly different scattering and refractive properties, translating to distinct and switchable visual appearances. Importantly, the persistence of each state without ongoing electric field application marks a significant stride toward practical optical technologies. This property addresses a key limitation in prior systems, many of which required constant energy input to maintain altered states, thereby increasing power consumption and complicating device designs.
This research intuitively connects with longstanding interests in bistable liquid crystal devices, flexible optical metamaterials, and dynamic thin-film optics. By combining the self-assembly principles from amphiphilic colloidal science with the tunability of liquid crystals, the authors effectively build a platform that could inform next-generation smart windows, adaptive lenses, and reconfigurable photonic elements. The stability and reversibility of the emulsion states offer pathways to optical elements with dynamically adjustable transmittance, reflectance, and even camouflage capabilities.
One of the most compelling aspects of this work is its kinetic nuance. The rapid cycling between shapes – partitioned by the frequency-dependent electric fields – is reminiscent of toggling between energy minima separated by controlled topological barriers. This interplay of kinetics, topology, and electric control showcases a delicate balance that endows the system with memory-like functions; configurations can be switched ‘on’ or ‘off’ with minimal latency, a vital feature for real-time adaptive materials.
From a chemical perspective, the choice of oils and the liquid crystal phase is meticulously optimized to encourage defect stabilization without compromising fluidity. The liquid crystalline component exhibits ferroelectric or nematic properties conducive to defect formation that engineers a rugged landscape for the isotropic domains. The fact that the isotropic oil forms wetting films initially suggests strong adhesion and favorable interfacial interactions, crucial for maintaining the ‘original’ shape before transformation.
Beyond optics, the implications for microchemical systems and materials synthesis are expansive. Long-lived and switchable emulsions present exciting opportunities as microreactors where localized phase control can direct catalytic activity or selective transport. The reversibility ensures that these microdomains can be dynamically assembled and disassembled, lending programmability to chemical processes at microscopic length scales.
The fundamental insight pertains to the manipulation of topological defect energetics under external stimuli. By temporally tuning electric field parameters, the authors have elucidated mechanisms to navigate the complex energy landscape governing phase coexistence. Such control could extend to other soft matter systems, including polymer blends, biological membranes, and complex fluids, potentially revolutionizing how morphological transitions are employed in applications.
Moreover, the low power and rapid kinetics demonstrated here align well with sustainable material design principles. Devices leveraging such biphasic systems could operate with minimal energy footprints while offering adaptive functionalities crucial for emerging technologies such as low-power displays and adaptive camouflage.
The work by Roh, Ha, and Abbott hence sets a compelling precedent for future investigations into dynamically reconfigurable soft materials. By marrying topological defect engineering with electric field-driven transformations, they have crafted a versatile and robust platform ripe for technological exploitation.
Looking forward, research inspired by these findings may explore scaling effects, incorporation of responsive molecular additives, or interfacing with biological environments. The modularity of the biphasic liquid architecture potentially allows integration into flexible electronics, wearable sensors, or photonic circuitry, all benefiting from the exquisite control over shape and optical states enabled by this approach.
In summary, this discovery represents a paradigm shift in the manipulation of biphasic liquids, rendering them dynamic, bistable, and functionally tunable over meaningful timescales. The ability to produce shape-shifting microdomains stabilized by liquid crystalline defects, switchable via frequency-modulated electric fields, embodies a convergence of fundamental physics with practical material science. As a platform, it promises to energize diverse fields from optics to catalysis, positioning biphasic liquids as a fertile ground for future innovation.
Subject of Research: Shape-shifting and bistable microdomains in biphasic liquid systems driven by interplay between isotropic oils and liquid crystalline oils under electric fields.
Article Title: Biphasic liquids with shape-shifting and bistable microdomains
Article References:
Roh, S., Ha, Y. & Abbott, N.L. Biphasic liquids with shape-shifting and bistable microdomains. Nature (2025). https://doi.org/10.1038/s41586-025-09279-2
Image Credits: AI Generated
