Summary: Using a system dubbed μRobotex system, researchers have created a microhouse so small a mite can not fit through the front door. Researchers say the creation pushes forward the frontiers of optical nanotechnologies.
Source: American Institute of Physics.
A French nanorobotics team from the Femto-ST Institute in Besançon, France, assembled a new microrobotics system that pushes forward the frontiers of optical nanotechnologies. Combining several existing technologies, the μRobotex nanofactory builds microstructures in a large vacuum chamber and fixes components onto optical fiber tips with nanometer accuracy. The microhouse construction, reported in the Journal of Vacuum Science and Technology A, from AIP Publishing, demonstrates how researchers can advance optical sensing technologies when they manipulate ion guns, electron beams and finely controlled robotic piloting.
Until now, lab-on-fiber technologies had no robotic actuators for nanoassembly, so working at this scale inhibited engineers from building microstructures. This innovation allows miniaturized sensing elements to be installed on fiber tips so engineers can see and manipulate different components. With this advancement, optical fibers as thin as human hair can be inserted into inaccessible locations like jet engines and blood vessels to detect radiation levels or viral molecules.
“For the first time we were able to realize patterning and assembly with less than 2 nanometers of accuracy, which is a very important result for the robotics and optical community,” said Jean-Yves Rauch, an author on the paper.
The French engineers combined all the technological components for nanoassembly — a focused ion beam, a gas injection system and a tiny maneuverable robot — in a vacuum chamber, and installed a microscope to view the assembly process. “We decided to build the microhouse on the fiber to show that we are able to realize these microsystem assemblies on top of an optical fiber with high accuracy,” Rauch said.
Building a microhouse is like making a giant dice from a piece of paper, but nanoassembly requires more sophisticated tools. The focused ion beam is used like scissors to cut or score the silica membrane “paper” of the house. Once the walls fold into position, a lower power setting is selected on the ion gun, and the gas injection system sticks the edges of the structure into place. The low-power ion beam and gas injection then gently sputters a tiled pattern on the roof, a detail that emphasizes the accuracy and flexibility of the system.
In this process, the ion gun had to focus on an area only 300 micrometers by 300 micrometers to fire ions onto the fiber tip and silica membrane. “It’s very challenging to pilot the robot with high accuracy at this cross point between the two beams,” Rauch said. He explained that two engineers worked at multiple computers to control the process. Many steps are already automated, but in the future the team hopes to automate all the robotic stages of assembly.
Now, using the μRobotex system, these engineers are constructing functionalized microstructures to detect specific molecules by attaching their microstructures onto optical fibers. The nanorobotics team is hoping to push the limits of the technology further still, by constructing smaller structures and fixing these onto carbon nanotubes, only 20 nanometers to 100 nanometers in diameter.
Funding: National Institutes of Health, National Science Foundation, American Heart Association funded this study.
Source: American Institute of Physics
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Image Source: NeuroscienceNews.com image is credited to FEMTO-ST Institute.
Original Research: Open access research for “Smallest microhouse in the world, assembled on the facet of an optical fiber by origami and welded in the μRobotex nanofactory” by Jean-Yves Rauch, Olivier Lehmann, Patrick Rougeot, Joel Abadie, and Joel Agnus in Journal of Vacuum Science & Technology A. Published May 2018.
Smallest microhouse in the world, assembled on the facet of an optical fiber by origami and welded in the μRobotex nanofactory
In this study, the authors have demonstrated that it is possible to realize several three-dimensional (3D) micro- and nanostructures, by the fabrication of the smallest microhouse using a dual beam scanning electron microscope (SEM)/focused ion beam (FIB) Auriga 60 from Zeiss together with a six degree of freedom robot built with SmarAct components. In this new type of nanolab, cutting, etching, folding, assembling, and then welding thin membranes of silica on top of a cleaved optical fiber SMF28, or production of micro- and nanostructures, like the microhouse, are possible. The authors have experimentally shown that FIB can be used, in this new generation of micro/nanofactory, in combination with SEM, and gas injection system, in order to fabricate three-dimensional microstructures: a microhouse in this study, with ultrahigh accuracy assembly down to 10 nm. By using the theory of sputtering, the authors are able to propose a model of folding thin membranes of numerous materials such as metals, polymers, or crystals, i.e., silica, silicon, potassium tantalite, or lithium niobate. This method is usually described as origami in the literature [W. J. Aroa, H. I. Smith, and G. Barbastathis, Microelectron. Eng. 84, 1454 (2007); W. J. Aroa et al., J. Vac. Sci. Technol., B 25, 2184 (2007); and K. Chalapat et al., Adv. Mater. 25, 91 (2013)]. The experimental results indicate that the introduction of a microrobot inside the SEM vacuum chamber will provide the means to enlarge the scope of clean room facilities to build complex and smart 3D microsystems with heterogeneous materials, especially on the facet of an optical fiber in the lab on fiber new field. The authors propose a new way to easily manufacture many kinds of optical functions for light trapping based on nanoantennas, nanophotonic crystal, axicon or lattice, 3D biosensor with origami, and nanopatterning surfaces or carbon nanotubes, etc.