According to foreign media reports, retractable awning has long been used to adjust the amount of daylight during daylight, but usually they are motor driven.
But just recently, engineers from the ETH Zurich have developed a sunshade system that can be opened and closed automatically--without the need for electricity, after being inspired by the pine cones. In order to release seeds at the most appropriate time, the pine cones open scales in warm, dry weather and remain closed in cold, humid weather.
The natural mechanism behind this can be said to be very intelligent-the scales consist of two interconnected layers of fibres that shrink in the drying of the surrounding space and form a conical shape. This mechanism has inspired some scientists in the past. A team of researchers developed a garment with open and closed pores that reacts to temperature to give the wearer a comfortable temperature.
Other researchers have also used this mechanism to develop memory materials that can bend or curl with changes in humidity. Now, the EHT Zurich team, led by Chiara Vailati, builds on this concept a shading system prototype that provides maximum shading at noon and is closed in the early morning without shading. It is reported that the system consists of two different layers of wood, namely spruce and beech. Among them, the spruce grain is unidirectional and the beech's grain is perpendicular.
The system mimics the structure of the pineal gland, allowing it to adjust to changes in humidity. To maximize the reaction speed, the researchers lined up the boards in pairs, one in a basic vertical state, and the other suspended in midair.
When the weather becomes damp, such as at night or in the morning, the board will be relatively upright, and when the air is dry, such as at noon, the board will be bent, the lower piece of the plank will push the top of the board outward, thus forming a shadow below. The research team said the system could be used to create a roof or curtain that could be opened or closed by itself.
