Session: 04-07: Novel Actuators

Paper Number: 111166

111166 - An Innovative Multi-Layer System for Thermally Activated Switching Actions 

Smart and shape-changing materials are entering a wide range of disciplines including the autonomous activation of devices. Here, a novel thermally driven multifunctional material that works as switch that independently reconfigures itself to trigger an electrical circuit, is presented.

The material consists of multiple polymeric layers that are capable to spontaneously adapt their shape, as a system, when exposed to specific thermal gradients. The multi-layer system hosts in itself an electrically conductive layer. In particular, the film is flat at low temperature and is curved at higher temperature. In this case study the flat configuration corresponds to the closed circuit (current flow) while the bent configuration corresponds to the opened circuit. The shape changing capability of the film is given by its unique structure which comprises multiple layers (PE and PET) characterized by specific and indeed opposite glass transition temperatures.  The beauty of this design is that the material can be “educated” to reach both the desire shape and the desired degree of shape change. Moreover, and most importantly, such morphing actions are cyclic without the need of re-educating the material. The study highlights the possibility to fine-tune with great repeatability and precision, the shape of the film as a function of temperature. The transition from a shape to the other, occurs smoothly and gradually within a temperature range between 0°C (closed circuit) and 20 °C (open circuit). Such target temperatures are selected strategically, to demonstrate the strength of the proposed design in working in an uncommon and relatively small temperature range. The capability of the system to work in such narrow range in fact can hardly be reached with standard approaches, including shape memory polymers or multi-layers. Multi-layers in fact typically exploit internal stresses induced by the coupling of materials with different coefficient of thermal expansion. Such internal stresses require relatively large temperature gradients to augment the degree of morphing amplitude. Moreover, multi-layers are limited in the achievable shapes and can typically only move from a flat to a bent configuration.

Presenting Author: Ginevra Hausherr University of Rome, RomaTre

Presenting Author Biography: Ginevra Hausherr is a student at the University of Rome. She is working on the design of innovative morphing materials.