| 21. |
- Kaindl, Reinhard, et al.
(författare)
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Aerosol Jet Printing of Graphene and Carbon Nanotube Patterns on Realistically Rugged Substrates
- 2021
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 6:50, s. 34301-34313
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Tidskriftsartikel (refereegranskat)abstract
- Direct-write additive manufacturing of graphene and carbon nanotube (CNT) patterns by aerosol jet printing (AJP) is promising for the creation of thermal and electrical interconnects in (opto)electronics. In realistic application scenarios, this however often requires deposition of graphene and CNT patterns on rugged substrates such as, for example, roughly machined and surface oxidized metal block heat sinks. Most AJP of graphene/CNT patterns has thus far however concentrated on flat wafer-or foil type substrates. Here, we demonstrate AJP of graphene and single walled CNT (SWCNT) patterns on realistically rugged plasma electrolytic-oxidized (PEO) Al blocks, which are promising heat sink materials. We show that AJP on the rugged substrates offers line resolution of down to similar to 40 mu m width for single AJP passes, however, at the cost of noncomplete substrate coverage including noncovered mu m-sized pores in the PEO Al blocks. With multiple AJP passes, full coverage including coverage of the pores is, however, readily achieved. Comparing archetypical aqueous and organic graphene and SWCNT inks, we show that the choice of the ink system drastically influences the nanocarbon AJP parameter window, deposit microstructure including crystalline quality, compactness of deposit, and inter/intrapass layer adhesion for multiple passes. Simple electrical characterization indicates aqueous graphene inks as the most promising choice for AJP-deposited electrical interconnect applications. Our parameter space screening thereby forms a framework for rational process development for graphene and SWCNT AJP on application-relevant, rugged substrates.
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| 22. |
- Lai, Huaxiang, et al.
(författare)
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Effects of BN and SiC nanoparticles on properties of conductive adhesive
- 2010
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Ingår i: Proceedings - 2010 11th International Conference on Electronic Packaging Technology and High Density Packaging, ICEPT-HDP 2010; Xi'an; 16 August 2010 through 19 August 2010. - 9781424481422 ; :Article number 5582434, s. 235-239
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Konferensbidrag (refereegranskat)abstract
- Isotropic conductive adhesives (ICAs) are a type of interconnect material used more and more widely in computer, robot, mobile phone, LED and so on. Compared with traditional solders, isotropic conductive adhesives have better working plasticity, creep resistance and heat resistance. In particular, isotropic conductive adhesives are more responsive in high density packaging than solder, which determines the dominance of ICAs in high density packaging in the future. In order to improve the thermal conductivity of ICA with acceptable electrical conductivity, Ag flakers, BN and SiC nanoparticles were added into the matrix. The content of silver flakes was 75wt%, and the content of nanoparticles (BN or SiC) in the isotropic conductive adhesives were 0wt%, 0.5wt%, 1.5wt%, 2.5wt%, 3wt%, 5wt% in weight. The conductive adhesives were coated on the PCBs with stencil printing and fifty SR1206 chip components were mounted on a PCB using conductive adhesive. All samples were cured at 150°for 1h. Further research into the reliability of the above isotropic conductive adhesives after temperature & humidity and thermal-cycling was carried out to analyze the effects of BN and SiC nanoparticals on the properties of ICA. The condition of the temperature & humidity test was 85 ° /85%RH, 500h. The thermal-cycling test was -40 °∼125°, 500 cycles and the soaking time and ramping rate were 19min and ±15°/min. Changes to electrical resistance were used to estimate the reliability of the isotropic conductive adhesives in this study. The microstructure of the failure samples was observed using a Scanning Electron Microscope (SEM). The water absorption of all ICAs is the same after 94h temperature and humidity aging and the rate of water absorption is also the same during the aging. The ICA with 3% boron nitride nanoparticles and 75% micron silver flakes shows the best temperature and humidity reliability, with the fewest cracks on the interface between ICA and component. After 500h thermal cycling aging, the resistance reduces in the first 100h and maintains in a certain value after 332h cycled thermal. The samples have no wide cracks but a few small ones on the interface. © 2010 IEEE.
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| 23. |
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| 24. |
- Liu, Hao, et al.
(författare)
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Graphene oxide for nonvolatile memory application by using electrophoretic technique
- 2020
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Ingår i: Materials Today Communications. - : Elsevier BV. - 2352-4928. ; 25
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Tidskriftsartikel (refereegranskat)abstract
- The experimental work presented here, for the first time using electrophoretic technique to fabricate graphene oxide (GO)-based resistive random access memory (RRAM). By using electrophoretic technique, nonvolatile RRAM devices with Aluminum (Al)/GO/Indium tin oxide (ITO) cross-bar sandwich-like structure were fabricated. The fabricated devices show typical bipolar resistant switching behavior with ON/OFF ratio more than 10, retention time more than 102 s, and transition voltage less than 1.7 V. The switching mechanism for the devices is ascribed to the formation and rupture of the conducting filament induced by the diffusion of oxygen ions. The results show that the electrophoretic technique holds great potential for film manufacturing for RRAM.
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| 25. |
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| 26. |
- Liu, Hao, et al.
(författare)
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Thermally Conductive Graphene Film/Indium/Aluminum Laminated Composite by Vacuum Assisted Hot-pressing
- 2020
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Ingår i: 2020 21ST INTERNATIONAL CONFERENCE ON ELECTRONIC PACKAGING TECHNOLOGY (ICEPT). - 9781728168265
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Konferensbidrag (refereegranskat)abstract
- In order to meet the ever more demanding requirements of modern thermal management with the increasing high power density, an easy-fabricated laminated graphene film/indium/aluminum (GF/In/Al) composite was developed. The GF was fabricated through assemble graphene oxide (GO) sheets in a layer-by-layer structure and then subjected to graphitization process at high temperature as well as press forming process. The fabricated GF exhibits ultrahigh in-plane thermal conductivity together with good tensile strength. The GF/In/Al laminated composite was fabricated by hot-pressing indium coated GF and Al layers in vacuum environment. The indium layer was easily coated onto the GF due to its low melting point along with good flowing property. The thermal resistance measurements show that the indium bonding possess greater preponderance of reducing contact resistance than without bonding material and thermal conductive adhesive (TCA) bonding, because indium layer could fill the gap between GF and Al layers, and provide more stable connection. The results show that the obtained laminated composite could be potentially used in the thermal management of high power systems.
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| 27. |
- Liu, Johan, 1960, et al.
(författare)
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Stem Cell Growth and Migration on Nanofibrous Polymer Scaffolds and Micro-Fluidic Channels on Silicon-Chip
- 2009
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Ingår i: Proceedings of the 2009 Electronic Components and Technology Conference. - 0569-5503. - 9781424444762 ; , s. 1080-1085
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Konferensbidrag (refereegranskat)abstract
- Stem cell growth and migration on nanofibrous scaffolds and micro-fluidic channels on Silicon-Chip were studied by using neural stem cells isolated from adult rats' brain. Electrospinning and lithographic technique were used for developing nanofibrous-polylactic acid (PLA) and polyurethane (PU) based-scaffolds and micro-fluidic channels on Si-Chips respectively. Immunocytochemical and morphological analysis showed better cell-matrix interaction with profound adhesion, proliferation and migration on the developed scaffolds. Cell culture assay with microfluidic channel revealed the ability of developed channel system in guiding neuronal stem cell growth towards specified directions. These studies extend the possibility of using developed nanofibrous scaffolds and micro-fluidic channel system for future electrical signal transmission based on living neural stem cells.
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| 28. |
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| 29. |
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| 30. |
- Liu, Ya, 1991, et al.
(författare)
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A Novel Graphene Quantum Dot-Based mRNA Delivery Platform
- 2021
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Ingår i: ChemistryOpen. - : Wiley. - 2191-1363. ; 10:7, s. 666-671
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Tidskriftsartikel (refereegranskat)abstract
- During the last decades, there has been growing interest in using therapeutic messager RNA (mRNA) together with drug delivery systems. Naked, unformulated mRNA is, however, unable to cross the cell membrane and is susceptible to degradation. Here we use graphene quantum dots (GQDs) functionalized with polyethyleneimine (PEI) as a novel mRNA delivery system. Our results show that these modified GQDs can be used to deliver intact and functional mRNA to Huh-7 hepatocarcinoma cells at low doses and, that the GQDs are not toxic, although cellular toxicity is a problem for these first-generation modified particles. Functionalized GQDs represent a potentially interesting delivery system that is easy to manufacture, stable and effective.
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