Opto-Thermocapillary Nanomotors on Solid Substrates

Abstract

Motors that can convert different forms of energy into mechanical work are of profound importance to the development of human societies. The evolution of micromotors has stimulated many advances in drug delivery and microrobotics for futuristic applications in biomedical engineering and nanotechnology. However, further miniaturization of motors toward the nanoscale is still challenging because of the strong Brownian motion of nanomotors in liquid environments. Here, we develop light-driven optothermocapillary nanomotors (OTNM) operated on solid substrates where the interference of Brownian motion is effectively suppressed. Specifically, by optically controlling particle−substrate interactions and thermocapillary actuation, we demonstrate the robust orbital rotation of 80 nm gold nanoparticles around a laser beam on a solid substrate. With on-chip operation capability in an ambient environment, our OTNM can serve as light-driven engines to power functional devices at the nanoscale.

Recent Progress on Optical Micro/Nanomanipulations: Structured Forces, Structured Particles, and Synergetic Applications

“…With nonspherical particles, this setup can also function as nanomotors. 68 There are other auxiliary forces that can facilitate the optical manipulations with tunability include the acoustic force, 121 biological binding force 95,101,122 and so forth. By combining into auxiliary forces, the optical manipulation techniques are continuously growing.…”

“…In eq , η, v , and a are the viscosity of the environment, the relative velocity, and the size of the particle. ,,, Other forces to manipulate particles also include the thermal-electrical force, , capillary forces and thermophoretic forces. , Through introduction of these multiphysical fields, the forces can be engineered to improve the manipulation ability and meet requirement such as high efficiency and large throughput, as will be discussed in detail later. Typical paradigms to utilize these force fields are shown in Figure h, including the liquid environment and heating components such as metal substrate or particles .…”

“…After turning off the laser, the particles are immobilized by the vdW force, which promise techniques such as nanofabrication of functional surfaces. With nonspherical particles, this setup can also function as nanomotors . There are other auxiliary forces that can facilitate the optical manipulations with tunability include the acoustic force, biological binding force ,, and so forth.…”

From Marble Games to Colloidal Nanomotors: The Journey of a First-Generation Student

“…This technique is promising for the nanofabrication of reconfigurable on-chip photonic devices, such as tunable chiral nanostructures . Recently, I also developed a new type of optical nanomotor that can operate on solid substrates to perform work and potentially serve as a nanoscale power source . Moreover, I have been exposed to many other intriguing topics in nanophotonics, including light–matter interactions at the nanoscale, optical nanolithography, and optical refrigeration …”

“…6 Recently, I also developed a new type of optical nanomotor that can operate on solid substrates to perform work and potentially serve as a nanoscale power source. 7 Moreover, I have been exposed to many other intriguing topics in nanophotonics, including light−matter interactions at the nanoscale, 8 optical nanolithography, 9 and optical refrigeration. 10 Throughout my path, I realized that, besides economic and social barriers, first-generation students usually lack the courage and confidence to explore new opportunities.…”