We all know the fascination with the phenomenon of a sunflower following the Sun. But have you ever wondered how this living species, which lives millions of miles away from the Sun, tracks the sunlight? In fact, the fabulous tracking movement commonly referred to as ‘phototropism’ is not limited to plants but is often observed in the animal kingdom too. The tracking movement can be elucidated by the sperm cell moving towards the egg cell, or the bacteria swimming towards the glucose.
The exact driving force and the mechanistic pathway do not involve detecting the stimuli and response associated with it. In fact, it consists of a series of cascade reactions and pathway which connects the stimulus with its response. Perhaps, that’s why it was so difficult to mimic the system in an artificial route and comprehend the kinetics and the working principle of these fascinating movement traits.
However, with the evolution of science, a group of researchers from the University of California Los Angeles headed by Dr.He has finally fabricated an artificial system reinforced on soft polymers embedded with nanophotoabsorbers, which can respond to light and heat. It is interesting how a non-living material can mimic a living system’s functionalities, thereby highlighting the phrase that ‘Yes, materials can also be smart.’
The system comprised an inner system that possessed a unique material called ‘gold nanoparticles (AuNPs) or reduced graphene oxide’, while the outer segment includes a polymer matrix. Once we shine a light on the material, the inner composition locally heats up can induce a physical movement in the polymer matrix, thereby aiding to respond in the direction of the applied stimulus.
The ‘sunflower-like biomimetic omnidirectional tracker’ named SunBOT is developed in the form of symmetrical pillars that bends with the supplement of local heating once the light is illuminated on the sample, while the portion in the shade reswells. As the process is repeated, the motion of the bending and swelling becomes more prominent, thereby helping the system track sunlight.
The question is, where do we use these smart materials? Well, light tracking could be a revolutionary feature if integrated with the solar panels. The present solar panels are generally stationary, and therefore, they can’t synthesise energy autonomously once the sun shifts. Incorporating a sunlight tracking system helps the solar panels to follow the sunlight’s direction and thus helps the system generate the maximum yield of electricity from the absorbed solar energy. The researchers have demonstrated that the smart materials, if tethered with the current solar panel system could improve annual outputs at the latitude of Los Angeles by 165–200 %.
It’s not only about the panels, but the superior flexibility offered by the SunBOT might be useful in developing new-age smart windows and optical devices for high-end applications (for instance, in spacecraft). Polymers again prove to be a marvel in the materials realm, widening the possibility of developing various tropistic materials by coupling not only light but also various energy sources like infrared, magnetic, acoustic and electromagnetic waves.