極小四足歩行ロボットを大量作製　皮下注射で体内に注入可能　米研究

【ロンドンＡＦＰ＝時事】米国の研究者らが、皮下注射で体内に注入でき、レーザー光の刺激で動く、肉眼では見えないほど小型の四足歩行ロボットを大量に作製した。特に医療分野でさまざまな用途に利用できる可能性があるという。研究結果は26日、英科学誌ネイチャーに掲載された。（写真は極小の四足歩行ロボットの3D画像。コーネル大学／クリストフ・ホフマン氏提供）
　論文によると、極小ロボットの幅は人間の毛髪とほぼ同じ０．１ミリ以下、搭載された太陽光電池で４本足を動かす仕組み。ナノメートルサイズのプラチナ製の足は、レーザー光の刺激によって屈曲し、歩行動作を行う。
　１分間で平均、極小ロボット１体分の距離を移動できる。これは微生物の移動速度に等しいという。また、極小ロボットは強酸性や２００ケルビン（零下７３度）を超える温度の変化に耐性がある。
　論文の共著者で、ペンシルベニア大学のマーク・ミスキン氏はＡＦＰに対し、シリコンエレクトロニクスを使ってアクチュエータである足を制御できることが、今回の研究の革新的な点だと述べた。
　同氏は「高機能な回路を作ることが次の段階だ。周囲の環境を感知し、反応するロボットは作れるだろうか。プログラム可能な極小機器はどうだろうか。人間の介入なしで動かせるだろうか」と語った。
　研究者らは同時に、４インチ（約１０センチ）のシリコンウエハーの表面上に１００万個以上の歩行ロボットも作製した。
　マサチューセッツ工科大学（ＭＩＴ）のアラン・ブルックス氏とマイケル・ストラーノ氏は、ネイチャー誌の論評で、「著者らのロボットは、現在の形状では自立していないが、『脳』とバッテリーを装着できるプラットフォームとみることができる」と述べている。【翻訳編集ＡＦＰＢＢＮｅｗｓ】
〔ＡＦＰ＝時事〕（2020/08/28-13:56）

Scientists have created an army of microscopic four-legged robots too small to see with the naked eye that walk when stimulated by a laser and could be injected into the body through hypodermic needles, a study said Wednesday.
Microscopic robotics are seen as having an array of potential uses, particularly in medicine, and US researchers said the new robots offer the potential to explore biological environments.
One of the main challenges in the development of these cell-sized robots has been combining control circuitry and moving parts in such a small structure.
The robots described in the journal Nature are less than 0.1 millimetre wide -- around the width of a human hair -- and have four legs that are powered by on-board solar cells.
By shooting laser light into these solar cells, researchers were able to trigger the legs to move, causing the robot to walk around.
The study's co-author Marc Miskin, of the University of Pennsylvania, told AFP that a key innovation of the research was that the legs -- its actuators -- could be controlled using silicon electronics.
Fifty years of shrinking down electronics has led to some remarkably tiny technologies: you can build sensors, computers, memory, all in very small spaces, he said. But, if you want a robot, you need actuators, parts that move.
- 'Figuring out what's possible' -
The researchers acknowledged that their creations are currently slower than other microbots that swim, less easy to control than those guided by magnets, and do not sense their environment.
The robots are prototypes that demonstrate the possibility of integrating electronics with the parts that help the device move around, Miskin said, adding they expect the technology to develop quickly.
The next step is to build sophisticated circuitry: can we build robots that sense their environment and respond? How about tiny programmable machines? Can we make them able to run without human intervention?
Miskin said he envisions biomedical uses for the robots, or applications in materials science, such as repairing materials at the microscale.
But this is a very new idea and we're still trying to figure out what's possible, he added.
- 'Swallow the surgeon' -
Researchers said that they were able to produce the components for the robots in parallel, meaning they could make more than one million of them in each four-inch wafer of silicon.
The legs were made from nanometre-thick platinum that bends when stimulated by laser light, creating the walking motion.
Their average speed was about one body length per minute, the study said, adding this was comparable to crawling biological microorganisms.
The robots can survive highly acidic environments and temperature variations of more than 200 degrees Kelvin (-73 degrees Celsius), the study said.
In a commentary also published in Nature, Allan Brooks and Michael Strano of the Massachusetts Institute of Technology said the concept of robots small enough to travel through blood vessels had been around since Nobel laureate Richard Feynman talked about the potential to swallow the surgeon in 1959.
They said the new study provides a clear vision for solving the challenge of creating a tiny robot that can both convert energy into motion and is able to be programmable.
The authors' robots, although not autonomous in their current form, can be seen as a platform to which 'brains' and a battery can be attached, they said, predicting the hurdle of developing autonomous programmability for microrobots will soon be overcome.