3D Multifunctional Composites Based on Large‐Area Stretchable Circuit with Thermoforming Technology

Abstract

decade, substantial efforts were devoted to the research and development of the nextgeneration composites. This new class of materials should not only possess higher strength-to-weight ratio than metals but also tailored with integrated intelligence, which is desirable as infrastructures for next generation of "internet of things." Carbon nanomaterials, such as carbon nanotubes and carbon nanofibers, have received dominant attention for the creation of intelligent composites. [3][4][5][6] They were dispersed in a polymer matrix to form conductive percolating networks as distributed sensors in situ to evaluate the strain, stress, damage, and temperature for self-sensing and on-line structural health monitoring applications. [3][4][5][6] However, these composites are restricted to (piezo) resistive effect based sensing capabilities from the included nanomaterials. Nextgeneration composites, however, should not only encompass sensing capabilities but also be equipped with other functionalities such as lighting, computation, and communication elements, as illustrated in Figure 1. One straightforward solution to achieve this goal is to integrate electronic circuits with off-the-shelf components in the composites. However, these functional composites usually have complex, 3D shapes, but conventional electronic circuits are rigid and planar. The shape mismatch between 3D composites and planar, rigid electronic circuits causes difficulties in integrating electronic circuit-based intelligences.Recent advancement of flexible and stretchable circuits has paved the way for integration of electronics in unusual shapes and forms. Through materials and structure innovation, [7] the circuits become stretchable, deformable, and conformable to curvilinear surfaces, [8][9][10] enabling a spectrum of applications such as stretchable sensors and actuators, [11][12][13][14] transparent conductors, [15,16] lighting, [17][18][19] and energy devices. [20][21][22] Various types of stretchable nanomaterials, such as carbon nanomaterials [23][24][25] and metal nanowires [26][27][28] have been synthesized and integrated to elastomeric polymer matrix for stretchable circuits. Despite their superior mechanical properties and potential to achieve transparent stretchable circuits, so far it has been a struggle to deliver high enough conductivities compared to structure engineered stretchable circuits.Fiber-reinforced polymer composites with integrated intelligence, such as sensors, actuators, and communication capabilities, are desirable as infrastructures for the next generation of "internet of things." However, the shape mismatch between the 3D composites and a planar electronic circuit causes difficulties in integrating electronic circuit-based intelligences. Here, an easily scalable approach, by incorporating a large-area stretchable circuit with thermoforming technology, to fabricate 3D multifunctional composites is reported. The stretchable circuit is first fabricated on a rigid and planar carrier board, then transferred and sandwiched bet...

An Improved Fabrication Technique for the 3-D Frequency Selective Surface based on Water Transfer Printing Technology

“…Thermoforming fabrication technology. Multiple studies have confirmed that thermoforming technology performs well during the fabrication of large-area interconnected circuitry 26 . The thermoforming process develops the 3-D shape of proposed components, using patterns fabricated on a planar substrate.…”

“…Several electronics, such as implantable neuro monitors and stimulators 20 , optoelectronic devices 21 and conformal photovoltaic devices 22 , have been fabricated utilizing these technologies, but the fabrication of large-scale electronic devices, such as FSSs, remains impractical due to the time consuming in the fabrication which also results in high fabrication cost. To address the large-scale manufacturing issue for 3-D devices, alternative solutions, such as aerosol jetting 23 , direct printing 24 and 3-D moulded interconnected devices 25,26 , have been proposed. While these proposals offer solid support for large-scale manufacturing of the metallic and insulator layers of electronic devices 26 , they remain immature and unable to fabricate complex electronics and electronic components that would serve actual industrial applications 26 .…”

“…To address the large-scale manufacturing issue for 3-D devices, alternative solutions, such as aerosol jetting 23 , direct printing 24 and 3-D moulded interconnected devices 25,26 , have been proposed. While these proposals offer solid support for large-scale manufacturing of the metallic and insulator layers of electronic devices 26 , they remain immature and unable to fabricate complex electronics and electronic components that would serve actual industrial applications 26 .…”

Stretchable sensors for environmental monitoring

“…61 Yang et al and Plovie et al documented an easily scalable approach that involves the combined use of the PCB technology inspired stretchable circuit and thermoforming technology for the creation of 3D sensory polymers and composites. 17,[84][85][86] This technology begins with fabricating the circuit on a rigid and planar carrier board, then transferring the circuit, and sandwiching it between thermoplastic polymers or composites using a Applied Physics Reviews REVIEW scitation.org/journal/are lamination process. The final thermoforming step shapes the sandwich structure by heating the encapsulating polymer beyond its glass transition temperature and pushing the polymer layers and the circuit toward the mold.…”

Accelerated Hermeticity Testing of Biocompatible Moisture Barriers Used for the Encapsulation of Implantable Medical Devices

“…To ensure hermeticity, barrier layers have to be selected carefully. Polymers such as polyimide, polydimethylsiloxane (PDMS), and parylene types are well known for their use in the development of flexible or stretchable implantable electronic [8][9][10]. However, these polymers do not meet the stringent barrier requirements (very limited diffusion of water, ions, and molecules) to act as barrier layers for long-term implantation [11][12][13].…”