Three-dimensional electronics (3D electronics) is a cutting-edge form of electronic devices, which has attracted much attention because of its wide application in biomedicine, energy storage, optics, and sensor fields. In many application scenarios, electronic devices often cannot be refactored to change their functionality. In some special occasions, such as space or the seabed, electronic devices need to use limited space to perform different functions in different three-dimensional configurations. In recent years, three-dimensional self-assembly, 3D printing technology, and intelligent conductive materials have provided new ideas for the reconfigurability of three-dimensional electrons. However, in the case of existing reconfigurable 3D electronics, the main research goal is to simplify complex drive mechanisms and reduce the demanding requirements for conductive materials.
Figure 1. Schematic of the preparation of a bistable driver and a reconfigurable 3D electronic device.
Zhou Chen, postdoctoral fellow at the National Engineering Research Centre for Precious Metals, City University of Hong Kong, and Kong Shangcheng, phD student at the State Key Laboratory of Terahertz and Millimeter Wave, used flexible bistable structures to achieve structural reconstruction and functional expansion of 3D electronic devices. The bistable structure has special mechanical behavior and has been widely used as a soft actuator, energy absorption device, smart switch, microlens surface, etc. In this work, one side of the arched bistable soft structure is treated with ultraviolet/ozone (UVO) treatment to become an intelligent bistable driver. Since the UFO treated and untreated layers have swelling reactions to solvents with different properties, the actuator is able to exhibit snap-through and snap-back behavior under solvent action. The flexible bistable structure can drive the flexible circuit board bonded to it to switch repeatedly between the original curved configuration and the three-dimensional buckling configuration, enriching the three-dimensional configuration of the electronic device and expanding the functions of the electronic device, as shown in Figure 1. This idea not only provides a way to reconstruct three-dimensional electronic devices, but also enriches the functional design ideas of three-dimensional electronic devices.
Figure 2. Example of a reconfigurable 3D structure based on a bistable driver.
Following the above research ideas, various flexible devices can change the three-dimensional configuration of the bistable actuator and thus change the function of the device through the jump behavior of the bistable actuator. We use finite element modeling and experimental verification to demonstrate the rich configuration of reconfigurable 3D electronic devices: different bonding methods derive different 3D configurations (Fig. 2b-d), and different superposition methods transform complex 3D structures (Fig. 2e-h). The diversity of 3D reconfigurable structures provides a large number of design ideas for the functional expansion of 3D electronic devices.
Figure 3:A frequency-reconfigurable unipolar antenna (ESMA) driven by a bistable structure.
Figure 3 shows a frequency-reconfigurable unipolar antenna (ESMA), opening up new avenues for fabrication strategies for reconfigurable RF electronics. The reconfigurable antenna can be reversibly folded from operating mode I to operating mode II, as shown in Figure 3b. It is well known that the operating frequency of a dipole or unipolar antenna is inversely proportional to its length. Three-dimensional antennas operate as quarter-wave unipolar antennas, which means that the effective length of the antenna is a quarter of the wavelength of free space. When the antenna switches to mode II, the antenna length of the presented configuration is halved, doubling the operating frequency of the antenna.
This work reports on a strategy for building 3D reconfigurable electronics from bistable smart drivers. The flexible electronic device is introduced into the bistable intelligent driver, and the flexible electronic device is reconstructed by using the jump behavior of the flexible intelligent driver on different solvents. The bistable behavior of the actuator and the three-dimensional configuration of the flexible electronic substrate were systematically studied through numerical values and experiments. Taking the frequency reconfigurable antenna as an example, the application of this method in the field of RF electronics is demonstrated, and it provides a useful reference for its expansion to other application fields.
The main author of the paper is: Professor Lü Jian's research group postdoctoral Chen Zhou, the main research direction is flexible driver, 3D printing; Professor Chen Zhihao's research group doctoral student Kong Shangcheng, the main research direction is millimeter wave and terahertz on-chip antenna. The research was funded by the Department of Science and Technology of Guangdong Province and the Innovation and Technology Commission of Hong Kong.
Introduction of Academician Lü Jian
Jian Lu is a fellow of the National Academy of Technology (NATF), a member of the Hong Kong Academy of Engineering Sciences, a chair professor of the Department of Mechanical Engineering at the City University of Hong Kong, a director of the Hong Kong Branch of the National Engineering Research Center for Precious Metal Materials, and the director of the Center for Advanced Structural Materials. His research interests include the preparation and mechanical properties of advanced structural and functional nanomaterials, and the simulation and design of mechanical systems. He has served as a Senior Research Engineer and Laboratory Leader at CETIM, Head of the Department of Mechanical Systems Engineering at the Technical University of Troyes, France, Director of the Laboratory of Mechanical Systems and Parallel Engineering at the French Ministry of Education and the French National Science Centre (CNRS), Chair Professor of the Department of Mechanical Engineering at the Hong Kong Polytechnic University, Deputy Dean of the School of Engineering of the Hong Kong Polytechnic University, and Vice-President of the City University of Hong Kong. He has been the head of several research projects in France, the European Union and China, and has cooperative research relationships or scientific consulting work with Fortune 500 companies such as Airbus, EADS, Baosteel, ArcelorMittal, AREVA, ALSTOM, EDF, ABB, Renault, Peugeot and other Fortune 500 companies. He once served as a review expert of the Fifth Framework Of the European Union, a consulting expert of the Sixth Framework of the European Union, an overseas review expert of the National Natural Science Foundation of China, the first batch of overseas review experts of the Chinese Academy of Sciences, a visiting chief researcher of the Shenyang Institute of Metal Research of the Chinese Academy of Sciences, an honorary professor of Northeastern University, University of Science and Technology Beijing, Nanchang University, a consultant professor of Xi'an Jiaotong University and Northwestern Polytechnical University, a visiting professor of Shanghai University, Sun Yat-sen University, Central South University and other universities, and a member of the team of well-known scholars of the Chinese Academy of Sciences. In 2011, he was elected as an academician by the French National Academy of Technology (NATF), the first Chinese academician among the nearly 300 academicians of the academy. In 2006 and 2017, he was appointed by the President of France to be a Chevalier de l'Ordre national de laureate and a chevalier of the French National Legion of Honor, and in 2018, he was awarded the Guanghua Engineering Science and Technology Award of the Chinese Academy of Engineering. Has obtained 34 European, American and Chinese patents, and has obtained 34 european, American and Chinese patents, and the top magazines in the field, Nature(Cover Article), Science, Nature Materials, Materials Today, Advanced Materials, Advanced FunctionalMaterials, Nature Communications, Science Advances, Advanced Science、PRL、Angew. Chem. He has published more than 400 papers in professional journals and cited more than 28,000 times (Google Scholar).
Original link:
Chen Z., Kong S., He Y., Yi S., Liu G., MaoZ., Huo M., Chan C.H., Lu J., Soft, bistable actuators for reconfigurable 3Delectronics, ACS Appl. Mater. Inter.https://doi.org/10.1021/acsami.1c08722.
*Thanks to the team of dissertation authors for their great support for this article.
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