Rüggeberg Markus, Burgert Ingo
Institute for Building Materials, Swiss Federal Institute of Technology Zürich (ETH Zürich), Zürich, Switzerland; Applied Wood Materials, Swiss Federal Laoratories of Materials Science and Technology (EMPA), Dübendorf, Switzerland.
PLoS One. 2015 Apr 2;10(3):e0120718. doi: 10.1371/journal.pone.0120718. eCollection 2015.
Implementing programmable actuation into materials and structures is a major topic in the field of smart materials. In particular the bilayer principle has been employed to develop actuators that respond to various kinds of stimuli. A multitude of small scale applications down to micrometer size have been developed, but up-scaling remains challenging due to either limitations in mechanical stiffness of the material or in the manufacturing processes. Here, we demonstrate the actuation of wooden bilayers in response to changes in relative humidity, making use of the high material stiffness and a good machinability to reach large scale actuation and application. Amplitude and response time of the actuation were measured and can be predicted and controlled by adapting the geometry and the constitution of the bilayers. Field tests in full weathering conditions revealed long-term stability of the actuation. The potential of the concept is shown by a first demonstrator. With the sensor and actuator intrinsically incorporated in the wooden bilayers, the daily change in relative humidity is exploited for an autonomous and solar powered movement of a tracker for solar modules.
在材料和结构中实现可编程驱动是智能材料领域的一个主要课题。特别是，双层原理已被用于开发对各种刺激做出响应的驱动器。已经开发了许多小至微米尺寸的小规模应用，但由于材料机械刚度或制造工艺的限制，扩大规模仍然具有挑战性。在这里，我们展示了木质双层对相对湿度变化的驱动，利用其高材料刚度和良好的可加工性来实现大规模驱动和应用。测量了驱动的振幅和响应时间，并且可以通过调整双层的几何形状和组成来预测和控制。全风化条件下的现场测试揭示了驱动的长期稳定性。第一个演示器展示了该概念的潜力。由于传感器和驱动器本质上集成在木质双层中，因此利用相对湿度的每日变化实现太阳能模块跟踪器的自主和太阳能驱动运动。
