In a groundbreaking study, researchers from the University of Connecticut, alongside collaborators from the University of Edinburgh and Syracuse University, have developed a novel method to control liquids using magnetically reconfigurable, multistable ribbons. These ribbons can alter their shape on command and maintain that shape without the need for continuous power. The research, led by Professor Xueju “Sophie” Wang, is detailed in the journal Device.
The innovative approach employs thin ribbons made from magnetic polydimethylsiloxane (PDMS), a soft silicone embedded with magnetic particles. These ribbons can be shaped into three distinct, stable forms through compressive buckling. With brief magnetic actuation, each ribbon can transition among these states and retain its configuration, offering a form of “mechanical memory” in soft materials.
Revolutionizing Microfluidic Systems
The research team, including first author and Ph.D. student Zizheng Wang, demonstrated the application of these ribbons in a switchable fluid junction within a two-dimensional microfluidic channel. By toggling the ribbon’s state, the device can redirect liquid to different outlet paths on demand, functioning like a reconfigurable and energy-efficient valve. This capability is particularly advantageous for portable or battery-powered systems, as the structure remains in its chosen shape after the magnetic field is removed, ensuring persistent flow configuration without ongoing input.
Building on this concept, the team designed dynamic surface textures by arranging ribbons into addressable arrays. Adjusting the state of individual ribbons altered the surface’s critical angles, which are the threshold conditions that determine whether a droplet is pinned in place or released. In a 2×3 ribbon array testbed, the researchers demonstrated complex droplet manipulations, such as holding, releasing, and routing droplets along programmed paths. This level of control suggests potential for “pixel-level” liquid handling in future lab-on-a-chip platforms.
Theoretical Insights and Design Implications
To support their experiments, the researchers conducted meso-scale simulations using coupled electrocapillary models. These simulations provided a theoretical framework to guide the design of more sophisticated device layouts and operating modes. The models help map how surface topology and interfacial forces interact, which is crucial for designing larger arrays and predicting droplet behavior under different configurations.
According to Gabriel Alkuino, a Ph.D. student in Teng Zhang’s group at Syracuse, and Samuel J. Avis, a former Ph.D. student in Halim Kusumaatmaja’s group at Edinburgh, the theoretical and numerical analyses conducted were instrumental in providing rational guidelines for experimental designs.
“Soft, reconfigurable elements that store their state without power could simplify the control architecture of microfluidic systems,” said Professor Wang. “Instead of relying on complex networks of pumps, valves, and continuous fields, arrays of multistable ribbons can encode routing instructions directly in their shapes.”
Implications for Future Technologies
The development of these magnetically reconfigurable ribbons represents a significant advancement in the field of materials science and engineering. By offering a simple yet powerful method to control liquids, this technology could pave the way for more efficient and versatile microfluidic systems. The ability to manipulate liquids precisely and without continuous energy input is a game-changer for applications ranging from medical diagnostics to chemical processing.
As the research progresses, the team anticipates further exploration into scaling the technology for larger systems and integrating it with existing microfluidic platforms. The potential for these ribbons to revolutionize liquid handling in various industries is immense, offering a glimpse into a future where complex fluidic operations are conducted with ease and minimal energy consumption.
Moving forward, the researchers aim to refine their designs and explore new applications for their technology. The collaboration between international institutions highlights the global effort to push the boundaries of what is possible in liquid manipulation and control.
