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The team had a paper published in the journal Nature in April 2014, showing impressive advances in the construction of nano motors.

Assistant Professor Donglei Fan's Ph.D. students in the Department of Mechanical Engineering at The University of Texas at Austin, Kwanoh Kim, Jianhe Guo and Xiaobin Xu, have recently been honored for their outstanding, groundbreaking work in Nano-Electrical Mechanical Systems (NEMS).

Smaller, Faster, More Durable Nanomotors

The team has designed nanomotors that have all dimensions below 1 um, work signficantly longer, rotate at variable speeds to at least 18,000 rpm, and can change direction —all significant improvements over existing nanomotors. The technology may someday be used in medicine at the cellular level for drug delivery and powering nanorobots.

Paper published in Nature Communications

The team had a paper published in the journal Nature in April 2014, showing impressive advances in the construction of nano motors.

In the paper entitled "Ultrahigh-speed rotating nanoelectromechanical system devices assembled from nanoscale building blocks," Ph.D. student Knanoh Kim and researchers Xiaobin Xu, Jianhe Guo (also Ph.D. students) and Donglei Fan have make great strides into the complex world of nanoscale motors, known as NEMS (nanoelectromechanical system) devices. These tiny motors will likely open doors into other nanotechnologies, such as macro/nanofluidics and lab-on-a-chip, as well as enable many medical research advances in disease diagnosis, DNA amplification, and drug discovery.

This video produced by the Cockrell School of Engineering explains how these nanomotors work and future uses.

diagram of nanowire

Figure C. Overlapped images of an Au/Ni/Au (gold/nickel/gold) nanowire transported and assembled on a nanobearing by the electric tweezers. Scale bar, 10 μm. Scanning electron microscope image of an assembled nanomotor (scale bar, 5 μm) and a schematic diagram of electric tweezers manipulating a nanowire.

In this paper, they use a powerful and non-destructive technique invented by Dr. Fan, known as "electric tweezers" to build nanoscale motors which, in testing, ran continuously for up to 15 hours, were able to rotate at variable speeds upward to 18,000 RPMs (the same as a jet engine), and complete over 240,000 rotations before stopping due to the wear and tear on the gold end tips. Currently, no one has been able to build a nano motor capable of variable speeds, and most can only run for a few seconds or minutes. In addition, the electric tweezers method dramatically improved the speed of assembling the motors, taking assembly time down to less than 10 seconds per motor by an unskilled worker.

diagrams of a nanowire rotating on a nanobearing

Figure D. Snapshots of a nanowire rotating on a nanobearing clockwise and counterclockwise every 71 ms. Scale bar, 10 μm.

The tiny motors consist of nanowire rotators comprised of nickel centers and gold end wires over magnetic bearings. By using the electric tweezers, the team is able to quickly put the rotators in place on top of a magnetic nanobearing made of gold, nickel and chromium. Once the rotator rods are moved into place by the combined AC and DC electric field, the nickel center is held securely in place atop the nanobearing's magnetic base during its rotation. The tiny motors are used in an array formation to increase energy output and can stop, start and reverse direction simultaneously by controlling the voltages and phase shifts of the AC electric fields. To their best knowledge, the nanomotors are the smallest (with all dimensions less than 1 um), fastest (to at least 18000 rpm), and most durable (15 hours continueous rotation) inorganic nanomotors. They also applied the nanomotors for tunable biochemical release, where the higher the rotation speed, the higher the molecule release rate. The devices and the molecule release principle are the first of its kind.

The team continues work on other aspects of the research. One direction is to test the motors for studying cell-cell communications relevant to understanding disease formation mechanisms.

Xiaobin Xu Receives Awards from Chinese Government and the Materials Research Society (MRS)

Xiaobin Xu received the prestigious 2014 Chinese Government Award for Self-Financed Students Abroad from the China Scholarship Council. This award was founded by the Chinese government in 2003 with the purpose of rewarding the academic excellence of self-financed Chinese students studying overseas. Students displaying outstanding performance in their Ph.D. studies are considered by the award selection panel, and no more than 500 young talents worldwide are granted the award each year. Xu received a $6,000 scholarship.

In addition, Xiaobin Xu received the Materials Research Society (MRS) Graduate Student Award in 2014, one of the highest honors for students in materials science, according to Dr. Fan. Xu attended the presentation competition held in San Francisco and received a Silver Award. The student awards were presenting during the week of the MRS meeting and announced in the MRS Bulletin. Xu received $200 remuneration and an honorary certificate.

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