Vertical Controllable Motion Of The Smart Device And Its Energy Conversion

From nearly half a century, self-propelled mini-motor has been developed for various potential applications in many fields, such as dynamic self-assembly, bio-mimetic, oil-water separation and so on. It can be propelled by electric field, magnetic field, bubbles, the Marangoni effect and some properties of materials. However, most of the self-propelled systems have slight control over the initial motion of mini-motor. Therefore, we propose the concept of "functionally cooperating smart system" by introducing two or more stimuli-responsive smart surface and using their synergy to accomplish complex functions. Owing to the conversion property from superhydrophobicity to superhydrophilicity, the pH-responsive smart surface could be a switch to initiate the motion.In the classic bubble-propelled system "platinum catalyzes the decomposition of hydrogen peroxide solution",the device's lifetime would become shorter due to the damage of wetting property of smart surface, which was caused by the active molecular generated during the reaction. To avoid such issues we developed several methods for persistent motion. Furthermore,we achieved a diving-surfacing cycled motion by optimizing the wetting property of smart surface. To develop a new application of controllable motion,our group worked on cycled motion of smart device and classic Faraday's law of electromagnetic induction to generate electricity stably and persistently by cutting the magnetic induced flux during the vertical motion. The present thesis focuses on the works given below:1. We have fabricated the functionally cooperating smart system by combining a pH-responsive smart surface and acid-responsive magnesium.Based on the transformation from superhydrophobicity to superhydrophilicity, the pH-responsive smart surface could be a switch to initiate the motion; and the reaction between magnesium and hydrochloric acid generate bubbles which help in diving-surfacing motion in vertical direction. In this way, we have enhanced the device's lifetime by replacing the oxygen bubble with reductive hydrogen bubble. Utilizing the above-mentioned controllable motion in vertical direction to cut the magnetic induced line, we realized the energy conversion from the chemical energy to electricity. Concerning on the re-diving problem caused by hardly releasing of bubbles, we optimized the wetting property of the smart surface to let bubbles out quickly in the water-air interface. As a result, the pH-hydrophobic smart device could finish the diving-surfacing cycled motion and generate electricity stably and enduringly.2. We have designed and fabricated a pressure-responsive smart device by biomimicking the swim bladder. Introducing a superhydrophobic smart surface to hold quantitative bubble, then adjusting the density of the smart device higher or lower than that of water by applying or releasing the pressure, we completed the diving-surfacing motion in vertical motion.This method effectively avoided refuelling to continue the cycled motion.Furthermore, combining the diving-surfacing motion of pressure-responsive smart device and classic Faraday's law of electromagnetic induction, we have realized a stable electricity output. By measuring the relationship between different frequency and induced current, we found the smart device could move regularly in a relatively long range.3. Based on the principle of light-heat conversion, we introduced the near infrared light to adjust the volume of bubble on the superhydrophobic surface, and then changed the density of smart device higher or lower than the density of water solution to finish diving-surfacing motion in vertical direction. Furthermore, we developed a sun light-driven controllable diving-surfacing motion in vertical direction.