| Nov 18, 2024 |
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(Nanowerk Spotlight) High-performance engineering thermoplastics are widely applied in aerospace, automotive, biomedical, and electronics fields. To enhance the safety and extend the service life of these materials, it is crucial to integrate them with sensors for structural health monitoring and environmental information tracking. Copper is often used in such systems due to its high conductivity and cost-effectiveness.
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However, copper tends to oxidize easily during and after processing, which poses challenges for long-term sensor functionality, especially at high temperatures. Therefore, developing a method to integrate copper-based sensor systems with improved oxidation resistance is essential for applications in advanced equipment.
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In a recent study published in (“An in-situ hybrid laser-induced integrated sensor system with antioxidative copper”), researchers from Zhejiang University report an in-situ integrated sensor system on engineering thermoplastics via hybrid laser direct writing, which primarily consists of laser-passivated functional Cu interconnects and laser-induced carbon-based sensors (Figure 1).
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| Figure : Schematic of an in-situ hybrid laser-induced integrated sensor system (LISS) for conformal electronics. (Image: Reprinted from DOI:10.1088/2631-7990/ad6aae, CC BY 4.0)
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Through a one-step photothermal treatment, the resulting functional Cu interconnects after reductive sintering and passivation are capable of resisting long-term oxidation failure at high temperatures (up to 170 ◦C) without additional encapsulations (Figure 2).
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This Cu interconnects were interfaced with signal processing units, and they function as an all-in-one system for long-term and real-time temperature monitoring. This strategy featured with facile laser manufacturing holds potentials for health monitoring and fault diagnosis of advanced equipment such as aircrafts, automobiles, high-speed trains, and medical devices.
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| Figure 2: Schematic of the functional CuO ink on a substrate fabricated by a CW laser including the process of (i) laser reductive sintering and (ii) laser-induced passivation. (Image: Reprinted from DOI:10.1088/2631-7990/ad6aae, CC BY 4.0)
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The XU research group at ZJU is a highly interdisciplinary research group dedicated to the advanced manufacturing of flexible and conformal electronics for wearable/implantable monitoring at regular or extreme environment.
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“Our research mainly includes the development of innovative fabrication techniques, multifunctional devices, as well as system level applications. Based on the principle of laser and matter interactions, we focus on manufacturing of versatile devices mainly using hybrid (ultrafast) laser processing platforms, which are endowed with multitasking features,” said Kaichen Xu, corresponding author of this paper.
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The research employed a hybrid laser direct writing technique to fabricate an in-situ integrated sensor system on engineering thermoplastics. The method involved two key steps: the creation of functional copper (Cu) interconnects through photothermal reduction and passivation of CuO using a continuous wave (CW) laser, and the formation of laser-induced carbon (LIC) sensors from the thermoplastic substrate using an infrared (IR) laser.
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The process allowed for the simultaneous reduction, sintering, and passivation of Cu to enhance its oxidation resistance at high temperatures. The integrated sensor system was then tested for its durability and performance in real-time temperature monitoring under various environmental conditions.
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Future research directions include expanding the capabilities of the system to incorporate additional sensing units for parameters like pressure, strain, and humidity. Moreover, there is a need to develop advanced manufacturing techniques to enable high-quality conformal electronics on curved surfaces, moving beyond the current limitations of planar surfaces.
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Provided by Zhejiang University as a Nanowerk exclusive
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