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A tiny smart craft travelling inside the human body will no longer belong to the realm of science fiction thanks to microbot technology, presented in this article. For the past few years, this booming field intends to conquer the world of the infinitely small and to meet the challenges of several civil and military applications. Objectives of this field include miniaturization and structural autonomy. Indeed, microbots will be more effective when equipped with mechanisms free of movement actuators and carrier structures.
A research team from the Kavli Institute, the Atomic and Solid State Physics Laboratory, and New York’s School of Applied and Engineering Physics at Cornell University has created an autonomous exoskeleton that can carry electronic components and increase its performance at the nanometre scale.
Une équipe formée par des chercheurs du Kavli Institute, du Laboratory of Atomic and Solid State Physics et de la School of Applied and Engineering Physics à la Cornell University (New York) a créé un exosquelette autonome qui peut porter et augmenter la performance d’un composant électronique à l’échelle nanométrique.
Microrobotics named Biomorph
This technology is designed with biocompatible materials and is characterized by a folding and biomorphic structure, which can contract and unfold under the influence of external factors. Its material and mechanical properties are paving the way for applications in data capture, energy harvesting and interaction with biological systems at the cellular level. In addition to its flexibility, the exoskeleton is characterized by its sturdiness and electrical conductivity due to the nanometric properties of its panels. It can lift a 500-nanometre thick silicon chip, react to several types of external agents and perform functions at temporal and spatial scales comparable to those of biological microorganisms. Similar exoskeletons have been created before, but this one is made of a semiconductor material that can contribute to the optimization of the capabilities of the electronic components it carries.
Mechanical and Chemical Characteristics, and Manufacturing Process
As this video shows, the structure of the exoskeleton has four triangular units. When folded, they form a pyramid. When unfolded, the exoskeleton is three times larger than a red blood cell and three times smaller than a large neuron. This tetrahedral structure can give shape to other prisms and rhombohedra, making it possible to address the functional constraints of various types of microbots. As an example, researchers have shown that a radio frequency identification chip can be mounted on a cubic exoskeleton panel. An Intel 4004 microprocessor can be housed inside a pyramid structure.
In its study entitled “Graphene-Based Bimorphs for Micron-Sized, Autonomous Origami Machines,” the team presented the exoskeleton’s characteristics and manufacturing process. The article was published in Proceedings of the National Academy of Sciences, PNAS, on November 12, 2017.
The exoskeleton structure is made from ultrathin multilayer membranes. These membranes are two-dimensional materials that react to chemical, thermal and electrical stimuli. They can detect changes in electrolyte content in a time comparable to the reaction time of cardiac muscle cells.
The membranes are made from graphene sheets and nano-glass layers (silicon dioxide) using the chemical vapour deposition method. Contraction or deployment of the exoskeleton occurs in a fraction of a second because the two materials react differently and simultaneously to the changes caused by the stimuli. This type of reaction is only possible at the nanometre scale.
The size and speed of the exoskeleton, combined with the information processing capabilities of nanochips, hold great potential for high-precision measuring and manipulating of matter on a cellular scale.
This study is co-written by lead author Marc Z. Miskin and David Muller, Samuel B. Kyle Dorsey Eckert, Baris Bircan and Yimo Han.