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[IEEE 2018 7th Electronic System-Integration Technology Conference (ESTC) - Dresden, Germany (2018.9.18-2018.9.21)] 2018 7th Electronic System-Integration Technology Conference (ESTC) - Integration with Light
摘要： This paper reports the use of Laser-induced Forward Transfer (LIFT) technology for printing of multilayer flexible circuitries and the fabrication of micro-bumps for flip-chip bonding of packaged LEDs and bare die microcomponents. Bonding of passive and functional surface mount devices (SMD) on low-temperature polyethylene terephthalate (PET) foils have been demonstrated using two selective bonding techniques. Firstly, using a high intensity near-infrared (NIR) lamp, a bare die NFC chip was bonded on micro-bumps formed with LIFT printed isotropic conductive adhesive (ICA) within less than a minute. Secondly, using a high intensity Xenon lamp, passive components and packaged LEDs were bonded within 5 seconds on micro-bumps formed with conventional Sn–Ag–Cu (SAC) lead-free alloys. In the both cases, due to selective light absorption, a limited temperature increase was observed in the PET substrates allowing successful bonding of components onto the delicate polyethylene foil substrates using conventional interconnect materials.
关键词： LIFT,low temperature bonding,NIR curing,conductive adhesive,lead-free SAC solder,photonic soldering,flip-chip bonding,laser printing
更新于2025-09-23 15:23:52
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Determining Line-Crossing Sequences Between Laser Printing and Writing Pen Using Coaxial Light
摘要： Determining the application sequence of hand-written pen ink and printer toner lines has attracted significant interest in questioned document examination. This study uses coaxial light to determine line-crossing sequences, with intersections observed under a VSC600 forensic document workstation and a Leica M205A Stereo-microscope. Results show that reflected light at intersections and color contrast between intersections and nonintersections was observed when a hand-written ink line passes over a toner line, while a toner line passing over a written line appeared dull, with no color contrast. The procedure was tested under a range of conditions, such as types of writing pens and laser printers, the writer, and writing pressure, with the latter playing an important role in the evaluation. To validate the results, a 90% detection rate and 98% accuracy rate were achieved from 50 samples of blind testing, which is more effective than optical microscopy.
关键词： laser printing,coaxial light,reflected light,questioned document examination,writing pen,sequence of intersecting lines
更新于2025-09-23 15:21:01
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Controllable tuning of Fabrya??Perot cavities <i>via</i> laser printing
摘要： The Fabry–Perot (FP) cavity is one of the basic optical components that has been widely applied in interferometry, spectroscopy, lasers and optoelectronic devices. Currently, tailorable FP cavities are highly desirable for fast and in situ modulation, which is crucial for optoelectronic devices and their integration. Here a simple tuning strategy of FP cavity mode is developed based on the plasmon-assisted laser printing technique. The laser irradiation induces photochemical and/or photothermal degradation of the polymer medium in the cavity, which is highly dependent on the film thickness and laser power. Thus, the FP cavity mode can be precisely and continuously tuned with irradiation time, which is then monitored using reflection spectra. Such a laser printing strategy is facile and general, which is capable of generating different structural colours.
关键词： laser printing,structural colours,plasmon-assisted,photochemical degradation,photothermal degradation,Fabry–Perot cavity
更新于2025-09-23 15:21:01
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Lasera??Induced Forward Transfer: A Digital Approach for Printing Devices on Regular Paper
摘要： Inkjet printing (IJP) is the most widespread direct-write technique in paper electronics. However, this technique cannot be used for printing devices on untreated regular paper, since its low-viscosity nanoinks leak through the cellulose fibers. Thus, a planarization coating is frequently used as a barrier, even though this makes substrates more expensive and less eco-friendly. Alternatively, high solid content screen printing (SP) inks could allow printing on regular paper due to their high viscosity and large particle size; however, they cannot be printed through IJP. Another digital technique is then required: laser-induced forward transfer (LIFT). This work aims at proving the feasibility of LIFT for printing devices on regular paper. The main transfer parameters are systematically varied to obtain uniform Ag-SP interconnects, whose performance is improved by a multiple-printing approach. It results in low resistances with much better performance than those typical of IJP. After optimizing the functionality of the printed lines, a proof-of-concept consisting of a radio-frequency inductor is provided. The characterization of the device shows a substantially higher performance than that of the same device printed with IJP ink in similar conditions, which proves the potential of LIFT for digitally fabricating devices on regular paper.
关键词： paper electronics,laser printing,screen printing ink,laser forward transfer,printed electronics
更新于2025-09-23 15:19:57
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Lasera??Printed, Flexible Graphene Pressure Sensors
摘要： While the outstanding properties of graphene have attracted a lot of attention, one of the major bottlenecks of its widespread usage is its availability in large volumes. Laser printing graphene on polyimide films is an efficient single-step fabrication process that can remedy this issue. A laser-printed, flexible pressure sensor is developed utilizing the piezoresistive effect of 3D porous graphene. The pressure sensors performance can be easily adjusted via the geometrical parameters. They have a sensitivity in the range of 1.23 × 10?3 kPa and feature a high resolution with a detection limit of 10 Pa in combination with an extremely wide dynamic range of at least 20 MPa. They also provide excellent long-term stability of at least 15 000 cycles. The biocompatibility of laser-induced graphene is also evaluated by cytotoxicity assays and fluorescent staining, which show an insignificant drop in viability. Polymethyl methacrylate coating is particularly useful for underwater applications, protecting the sensors from biofouling and shunt currents, and enable operation at a depth of 2 km in highly saline Red Sea water. Due to its features, the sensors are a prime choice for multiple healthcare applications; for example, they are used for heart rate monitoring, plantar pressure measurements, and tactile sensing.
关键词： laser printing,graphene,flexible devices,wearables,piezoresistive materials,pressure sensors
更新于2025-09-23 15:19:57
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Fast-response humidity sensor based on laser printing for respiration monitoring
摘要： Respiration monitoring equipment has wide applications in daily health monitoring and modern medical diagnosis. Despite significant progress being made in humidity sensors for respiration monitoring, the fabrication of the humidity sensors with low-cost, simple manufacturing process and easy integration remains a challenge. This work reports a facile and inexpensive laser printing fabrication of PEDOT:PSS micron line as a humidity sensor for respiration monitoring. Laser printing technology can process any material into an arbitrary pattern. The PEDOT:PSS micron line humidity sensor has a fast response–recovery time (0.86 s/0.59 s), demonstrating excellent performance for real-time monitoring of human respiration. Furthermore, the PEDOT:PSS micron line humidity sensor can also monitor the respiration of rats under different physiological conditions along with the drug injection. The PEDOT:PSS micron line humidity sensor features simple manufacturing process with commercial materials, and easy integration with wearable devices. This work paves an important step in real-time monitoring of human health and further physiology and pharmacology study.
关键词： respiration monitoring,laser printing,wearable devices,PEDOT:PSS,humidity sensor
更新于2025-09-23 15:19:57
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Nanogap Plasmonic Structures Fabricated by Switchable Capillarya??Force Driven Selfa??Assembly for Localized Sensing of Anticancer Medicines with Microfluidic SERS
摘要： Nanogap plasmonic structures, which can strongly enhance electromagnetic fields, enable widespread applications in surface-enhanced Raman spectroscopy (SERS) sensing. Although the directed self-assembly strategy has been adopted for the fabrication of micro/nanostructures on open surfaces, fabrication of nanogap plasmonic structures on complex substrates or at designated locations still remains a grand challenge. Here, a switchable self-assembly method is developed to manufacture 3D nanogap plasmonic structures by combining supercritical drying and capillary-force driven self-assembly (CFSA) of micropillars fabricated by laser printing. The polymer pillars can stay upright during solvent development via supercritical drying, and then can form the nanogap after metal coating and subsequent CFSA. Due to the excellent flexibility of this method, diverse patterned plasmonic nanogap structures can be fabricated on planar or nonplanar substrates for SERS. The measured SERS signals of different patterned nanogaps in fluidic environment show a maximum enhancement factor ≈8 × 107. Such nanostructures in microchannels also allow localized sensing for anticancer drugs (doxorubicin). Resulting from the marriage of top-down and self-assembly techniques, this method provides a facile, effective, and controllable approach for creating nanogap enabled SERS devices in fluidic channels, and hence can advance applications in precision medicine.
关键词： anticancer drugs,doxorubicin,nanogap plasmonic structures,capillary-force driven self-assembly,surface-enhanced Raman spectroscopy,SERS,laser printing
更新于2025-09-23 15:19:57
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Assembly of Conductive Polyaniline Microstructures by a Laser-Induced Microbubble
摘要： Micro-patterns of conductive polymers are key for various applications in the fields of flexible electronics and sensing. A bottom-up method that allows high-resolution printing without additives is still lacking. Here, such a method is presented based on micro-printing by the laser-induced microbubble technique (LIMBT). Continuous micro-patterning of polyaniline (PANI) was achieved from a dispersion of the Emeraldine base form of PANI (EB-PANI) in n-methyl-2-pyrrolidone (NMP). A focused laser beam is absorbed by the EB-PANI nanoparticles and leads to formation of a microbubble, followed by convection currents, which rapidly pin EB-PANI nanoparticles to the bubble/substrate interface. Micro-Raman spectra confirmed that the printed patterns preserve the molecular structure of EB-PANI. A simple transformation of the printed lines to the conducting Emeraldine salt form of PANI (ES-PANI) was achieved by doping with various acid solutions. The hypothesized deposition mechanism was verified, and the resulting structures were characterized by microscopic methods. The micro-structures displayed conductivity of 3.8×10-1 S/cm upon HCl doping and 1.5×10-1 S/cm upon H2SO4 doping, on par with state-of-the-art patterning methods. High fidelity control over the width of the printed lines down to ~650 nm was accomplished by varying the laser power and microscope stage velocity. This straightforward bottom-up method using low power lasers offers an alternative to current microfabrication techniques.
关键词： laser printing,nanoparticle assembly,polyaniline,microbubble,directed assembly
更新于2025-09-23 15:19:57
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Ultrafast photo-annealed carbon-coated SiO2 sphere electrodes for NO2 gas sensing
摘要： There is great interest in carbon-based printed electronics as a promising technology to achieve lighter, thinner and ?exible electronic devices at low-costs. Despite the surge of enthusiasm in this area, research advances in printed electronics are not yet able to realize diverse carbon structures yet. This is due to the limitations in conventional solution-based printing methods (e.g., inkjet printing, roll-to-roll, screen printing). Processes such as polymer phase-inversion offer one possibility but a much faster and ef?cient method should be devised for reliable production. Here, we demonstrate laser printing combined with intense pulsed-light (IPL) annealing as a novel and ef?cient technique which can form inter-connected carbon spheres electrode on ?exible polymer substrate. Our observations show that the printed patterns from a laser printer consist of a solid-state polymer matrix with inorganic nanoparticles randomly embedded inside. Through ultrafast (5 ms) IPL treatment, core/shell type nanosphere arrays of carbon-coated SiO2 were successfully fabricated, which could be used as a functional platform for highly selective NO2 gas sensing.
关键词： Laser printing,Gas sensing,Intense pulsed-light,SiO2 spheres,Carbon coating
更新于2025-09-19 17:13:59
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Reversible 3D laser printing of perovskite quantum dots inside a transparent medium
摘要： The three-dimensional (3D) patterning of semiconductors is potentially important for exploring new functionalities and applications in optoelectronics. Here, we show that it is possible to write on demand 3D patterns of perovskite quantum dots (QDs) inside a transparent glass material using a femtosecond laser. By utilizing the inherent ionic nature and low formation energy of perovskite, highly luminescent CsPbBr3 QDs can be reversibly fabricated in situ and decomposed through femtosecond laser irradiation and thermal annealing. This pattern of writing and erasing can be repeated for many cycles, and the luminescent QDs are well protected by the inorganic glass matrix, resulting in stable perovskite QDs with potential applications such as high-capacity optical data storage, information encryption and 3D artwork.
关键词： perovskite quantum dots,optical data storage,femtosecond laser,transparent medium,information encryption,3D laser printing,3D artwork
更新于2025-09-12 10:27:22