Progress on a Novel Nanoscale Motor
Researchers at the NSF-funded Nanosystems Engineering Research Center (ERC) for Translational Applications of Nanoscale Multiferroic Systems (TANMS), led by the University of California Los Angeles (UCLA), have developed a new option to control magnetic micro-particles (objects with diameters on the order of 1 micrometer, ~1,000 times smaller than a grain of sand) on micron-length scales without a laser setup or external magnetic fields (see figure). The TANMS team exploits multiferroic materials deposited on special substrate material, and when a voltage (not a current) is applied to the substrate, strain is generated along the surface with efficiencies that approach 60-80%—a revolutionary achievement.
Initially inspired by the vision of creating a micron-scale motor capable of powering a swimming robot that could navigate through the human bloodstream, the researchers have decomposed this motor into two essential elements (controlling magnetism with voltages and moving an external object using this control) and demonstrated both, proving the scientifically important points of motor design. A fully functioning motor remains a future goal, but these intermediate steps provide proof-of-concept demonstrations toward a micron-sized swimming robot as well as toward additional applications requiring micron-scale control (e.g., sorting particles in micro-fluidic devices).
Moving objects from one location to another is commonplace on the macro scale, but as the objects to be moved get smaller, this seemingly simple task becomes increasingly difficult, requiring special tools and in some cases even laser or magnetic-field setups to accomplish. Manipulation of particles much smaller than a grain of sand is very useful in a variety of applications, such as medicine, physics, and biology; however, lasers or magnetic approaches can entail specialized equipment, energy bulk, and high cost (e.g., Watts versus micro-Watts), as well as undesirable heating.
Because the TANMS team has now shown that very tiny particles can be moved without a laser apparatus or an external magnet, this multiferroic control may be suitable for incorporation with next-generation lab-on-a-chip technologies or futuristic applications yet to be envisioned. At its most fundamental level, the particle-trapping capability and subsequent release of such particles represents a new tool useful in many other nanotechnology applications, such as atomic assembly of new materials (e.g., meta-materials).
Accomplishing the goal of manipulating micro-particles required teamwork between many TANMS faculty and students contributing different skills and expertise, including simulation and design of the multiferroic structures and devices, fabrication of the device structures, magnetic imaging, integration of the devices into a fluidic structure, and characterizing the motion of the micro-particles. Pooling these diverse talents was essential to realize both the practical implementation of the proof-of-concept demonstration and creating an extended vision for its impact.