 작은 기술이 우리의 아기, 우리의onia는 조사하고, 미� meatballs 이킨 In the future, One of the major obstacles to their successful applications is the lack of power sources without relying on human intervention, like wires. We turn to leaving creatures in seeking the solutions as they move harnessing natural energy, 하지만 그 도전을 위해 animals' mobility가 안성적이게 된 것입니다. animals use mussels to generate motions. mussels are very hard to make, and they are consumers, not suppliers of energy. Plants do not have mussels, but still can move. Most botanical movements are based on transport water in and out of plant tissues. The examples include mimosa leaves, mushrooms, Venus light trap, and pine cones. As such, plants propose a new way to power machines, solely through the use of water. In particular, some plant seeds provide a critical clue to reproducing botanical motility. Those seeds with tails are catapulted in the air when their enclosures are cracked open by over drying. The tails acting like a spring, vary the seeds into soil. Humidity variation controls all these processes. The seed tails consist of two layers, one of which responds to humidity while the other not. When wet, the moisture sensitive layer swells by absorbing water molecules, causing the tail to bend toward the inactive layer. The opposite sense of bending occurs when dry. A closer look at the tail reveals that cells in the active part are aligned. This not only helps the tails to move faster, but also makes them helically coil depending on the alignment angles. These seeds suggest that the water-powered machines can move in different ways by slight changes of their inner structure. A key to making an effective seed mimic is to produce and align extremely fine fibers. My lab uses a strong electrical field to pull fibers 1,000 times thinner than human hair out of polymer solutions. Spooling the fibers on the rotating cylinder align them in one direction. An artificial biolayer with aligned fibers bends much more effectively than those without fiber directionality. Tilting the fiber angles causes the actuators to coil and uncoil in response to humidity change. Different fiber arrangements can indeed lead to various global motions of the actuators. Now a question naturally arises of the proper size of those machines. Decal layers take longer to wet, but too thinner machine cannot carry enough load. Mathematical analysis reveals that the size comparable to the seeds or conventional micro-robots is just right for the water-powered machines. Continuous variation of humidity drives the oscillation of the actuators To give them locomotive ability, we can attach legs that slide or stop depending on the posture. A result is an actuation system that moves faster than any other existing soft robots when they were scaled to an equal length. On moist surfaces, the soft robot propellers itself without any human intervention. An anti-biotic coated robot placed on a bacterial cultivating plate 트랩을 spontaneously sterilizing its trail. This hints at enormous biomedical applications of this micro-robot on human skin. We need to address several technological issues to widen their applicability. The forces generated by the water-absorbing materials should be increased for stronger actuation. The durability and scalability are also important. Consulted efforts of mechanical and material science are strongly called for. In summary, we have seen that water can induce mechanical response of soft materials that swell upon wearing. This motion strategy adopted by plants for millions of years is now being exploited to drive various soft machines. Sophisticated deposition of fine fibers sensitive to humidity is a key enabling technology. Diverse motions including bending, twisting and calling are possible by controlling the fiber arrangements. Self-local motion is achieved by adding appendages to break the symmetry of the motions. This nature-inspired energy convergent technology provides an attractive solution to power sources of micro-robots. Two centuries ago, the first industrial revolution was triggered by steam engines whose actual power came from fossil fuel. In the era of the fourth industrial revolution, larval plant mimicking machines are emerging that are literally powered by water. How this environmentally benign technology will prosper depends only on our imagination. Thank you.