Sliding sun shades have long been used to adjust the intensity of sunlight. However, they are all driven by an electromechanical drive. Nature has helped to improve the established habitual scheme - as is often the case recently.
A group of engineers at the Higher Technical School of Zurich, led by Chiara Vailati, decided to use the principle of action of seeds in pine cones for this: in warm, dry weather, the cones open slightly, and in damp and cold weather, on the contrary, they close. As it turned out, the natural mechanism works flawlessly. It is a kind of "balance", consisting of two interconnected fibrous layers, located perpendicular to each other. As soon as the air humidity decreases sharply, compression occurs and the seeds of the cone "bloom" at a certain angle.
The system created by scientists provides maximum shade on a sunny afternoon and turns off at dusk. It consists of two-layer planks - one layer of spruce and the other of beech. The boards are cut and joined in such a way that the layers are perpendicular to each other, simulating the structure of a pine cone that responds to changes in moisture.
To maximize the response rate of the system, the scientists arranged the boards in pairs, with the vertically positioned board resting against the middle of the other. In conditions of high humidity, the boards stand tightly pressed against each other. As it heats up, the configuration of the structure begins to change - the lower bar pushes the upper one out, bringing it to a horizontal position and creating a large shadow.
As conceived by the developers, the system can be used to create sliding roofs and window blinds that automatically respond to changes in temperature and humidity without the participation of electromechanics, which are also made from environmentally friendly materials.