Porous thin-film solar engine developedsuccessfully

On October 25, news came from NankaiUniversity that the team of Professor Zunfeng Liu and Professor Yongsheng Chenfrom the School of Chemistry and Associate Professor Xiang Zhou from the Schoolof Science of China Pharmaceutical University had developed a self-oscillatingartificial muscle actuator based on porous flexible polypropylene/carbon blackfilm, and explored its application as an engine, developing a "solarartificial muscle engine ", which opens up a new path for the efficientuse of solar energy.

According to the report, the research hasachieved for the first time self-oscillating actuation under dispersive lightincluding sunlight, infrared light and simulated sunlight, and alsoself-oscillating motion under different dispersive light irradiation angles.This light-responsive self-oscillating actuator has excellent oscillatory workperformance, outstanding load capacity and high energy conversion efficiency,and maintains continuous oscillatory motion without stopping under constantsolvent supply.

The actuator is a hardware that generatesmechanical deformation in response to external environmental stimuli andconverts various environmental energies such as light, heat and chemical energyinto mechanical energy to generate driving force, and is also an indispensablecore component in application scenarios such as microelectromechanical systemsand light engines. Developing a soft body actuator that spontaneously andcontinuously achieves energy conversion is one of the key difficulties in thisfield.

"Self-oscillation is an importantcharacteristic of biological organisms, such as heartbeat and cell cycle, whichprovides directions for designing soft robots and autonomous intelligentdevices with continuous motion." Zunfeng Liu introduced that a researchteam has successfully constructed a light-responsive self-oscillating actuator,however, the self-oscillating motion that occurs under the stimulation ofscattered light such as sunlight and used for mechanical work has never beenrealized.

The researchers found that the evaporationof solvent in polymer films leads to volume contraction and light irradiationon one side of the film accelerates solvent evaporation inside the film,leading to anisotropic volume contraction, resulting in light bending. "Ithas been experimentally demonstrated that the introduction of porous structuresin thin films can facilitate the mass transfer of solvent molecules, whichleads to faster bending rates and larger bending amplitudes in thin filmmaterials. Therefore, we believe that photo-induced solvent evaporation basedon porous films may be a good candidate for achieving self-oscillationdrive." Zunfeng Liu said.

Based on the above research, the jointresearch team finally designed and developed this sunlight-based self-oscillation-drivenfilm. It achieves oscillation mainly through alternating volume reduction onboth sides of the polypropylene/carbon black polymer film caused byphotothermal-derived solvent evaporation. Anisotropic solvent evaporation andfast gradient diffusion in the polymer film maintain the oscillatory bendingdrive under the irradiation of evanescent light.

"This work provides a new designstrategy for 'solar engines', which will help the development of self-drivendevices and will promote interdisciplinary crossover in other fields andcontribute to the rapid development of smart materials, flexible devices andother smart device fields." Chen Yongsheng introduced.