A walking machine driven by a light beam

摘要

Optically driven small machines have such features as easily miniaturized in fabrication and as controlled by optical energy supplied in wireless. We report an optically controlled machine which moves like a caterpillar on the basis of photo-thermal effect. This miniaturized machine fundamentally consists of two parts: a body made of shape memory alloys and springs and feet made of magnets and temperature-sensitive ferrites. The feet can stick to the carbon steel floor due to magnetic force balance caused by projected beam, and the body repeats stretching and shrinking using deformation of shape memory alloys caused by switching on and off of projected beam. A prototype is fabricated in trial with a size of 35 mm x 12 mm. As an experimental result, it proved that they could move at the speed of 8.7 mm per cycle on a ceiling as well as on a horizontal floor and it could climb a slope as steep as 50 degree. To improve the ability of this prototype, we newly developed a smaller machine with the total length of 20 mm x 15 mm and the weight of 1.1 g. Because of lighter weight of this machine, it could climb any slope including a vertical wall.