Este trabalho foi apoiado pelo Technologico de Monterrey e pela Universidade da Califórnia em Irvine.

1. Fabricação de estrutura de carbono derivada do cabelo humano 3D NOTA: Use equipamento de proteção pessoal. Siga as instruções do laboratório para usar os instrumentos e trabalhar dentro do laboratório. <ol><li> Prepare o cabelo humano coletado, lavando-o com água DI e secando-o com gás N2. </li><li> Organize os cabelos conforme desejado, como nos fios paralelos, atravesse, com dois cabelos enrolados juntos, etc. </li><li> Anexe os cabelos a um substrato de silício usando SU8 ou mantenha-os diretamente em um barco de cerâmica. </li><li> Coloque o substrato de silício ou o barco em um forno. </li><li> Ligue o forno e abra a válvula de um tanque de gás inerte (N 2 ). NOTA: A taxa de fluxo de gás ideal depende do volume do tubo do forno. Foi aplicado um caudal de 6 L / min para um volume de tubo de 6 L. Para estabelecer um ambiente completamente inerte no tubo do forno, uma taxa de fluxo de gás 1,5 vezes maior do que o gás ótimo fA taxa baixa foi aplicada durante os primeiros 15 min. </li><li> Defina os parâmetros, incluindo temperatura máxima de pirólise, taxa de rampa de temperatura e vazão de gás inerte, e execute o forno. <ol><li> Por exemplo, aumente a temperatura desde a temperatura ambiente até 300 ° C a uma taxa de rampa de 5 ° C / min. Mantenha-o a 300 ° C durante 1 h para estabilização. Aumente ainda mais a temperatura de 900 ° C e mantenha-a durante 1 h mais para carbonização. </li><li> Arrefecer o forno até 300 ° C a uma taxa de 10 ° C / min e desligar o aquecedor do forno, uma vez que o arrefecimento controlado não é necessário após 300 ° C. Deixe as amostras no forno até que a temperatura atinja a temperatura ambiente apenas com fluxo de N 2 . </li></ol></li><li> Desligue o forno e o fluxo de gás após a conclusão do processo de pirólise. </li><li> Retire as amostras do forno. </li></ol> 2. Fabricação de Estrutura de Polímero 3D: Fotolitografia <ol><li> DesIgnore um layout 2D da estrutura de fotorresis 3D desejada usando um pacote de software apropriado e prepare a máscara impressa ( ou seja, uma máscara de filme de polietileno). NOTA: Um serviço comercial foi usado para obter o design impresso. O tamanho da máscara geralmente depende do design. </li><li> Em uma instalação de laboratório limpa, ligue duas placas quentes e ajuste as temperaturas para 65 ° C e 95 ° C, respectivamente. </li><li> Ligue um revestidor de rotação e uma bomba de vácuo. Certifique-se de que a bomba de vácuo esteja conectada através de um tubo à cabeça giratória. </li><li> Defina os parâmetros da rotação em dois passos, como a velocidade de rotação, a rampa e a duração. Para o primeiro passo, ajuste a velocidade de rotação para 500 rpm, a rampa para 100 rpm / s e o tempo de rotação para 10 s para iniciar o ciclo de centrifugação. Para o próximo passo, ajuste a velocidade de centrifugação para 1.000 rpm, a rampa para 100 rpm / s e o tempo de rotação para 30 s para espalhar uniformemente o fotorresistente. </li><li> Coloque um substrato ( isto é, 4 polegadas x 4 polegadas e 5501; m ± 25 μm de espessura de Si com uma camada de SiO 2 de 1 μm de espessura) no centro do suporte. </li><li> Deposite o polímero fotossensível (isto é, o fotossurro SU8) diretamente no centro do substrato. Use o suficiente para cobrir a superfície. </li><li> Pressione o botão &quot;vácuo&quot; para segurar o substrato. </li><li> Pressione o botão &quot;executar&quot; para revestir o substrato com SU8 e atingir uma espessura final de 250 μm. </li><li> Após a conclusão do processo de centrifugação, pressione o botão &quot;vácuo&quot; novamente para liberar o substrato revestido do suporte. </li><li> Segure o substrato revestido com cuidado usando uma pinça para manter a superfície lisa e limpa. Transfira o substrato diretamente na placa quente a uma temperatura de 65 ° C durante 6 min e depois na placa quente a uma temperatura de 95 ° C durante 40 minutos (cozimento suave). NOTA: é necessário um cozimento a 65 ° C para garantir a evaporação lenta do solvente, resultando em melhor revestimento e melhor adesão tO o substrato, enquanto o cozimento a 95 ° C densifica ainda mais o SU8. </li><li> Enquanto isso, pressione o interruptor para ligar o sistema de exposição UV e ajuste o tempo de exposição para &quot;12 s&quot; usando o botão set no sistema. NOTA: Para uma camada SU8 de 250 μm de espessura, a energia de exposição deve ser de 360 ​​mJ / cm 2 . </li><li> Uma vez que o passo de cozedura (etapa 2.10) esteja completo, coloque o substrato no sistema de exposição UV e coloque o lado impresso de uma fotomátema (a partir do passo 2.1) sobre ele. Use toda a área da máscara para cobrir o substrato revestido e pressione suavemente para garantir que não haja espaço entre a máscara e o substrato. </li><li> Exponha o substrato revestido com SU8 para a radiação UV através da fotomask usando configurações UV predefinidas. </li><li> Aqueça o substrato de novo, colocando-o diretamente na placa de aquecimento a 65 ° C durante 5 min e a 95 ° C durante 14 min para uma assadeira pós-exposição (PEB). NOTA: O PEB aumenta o grau de reticulação nas áreas expostas a UV e faz com queRevestimento mais resistente aos solventes no passo de desenvolvimento. </li><li> Remova as regiões fotorresistentes não expostas mergulhando o substrato na solução de revelador dedicada, colocada em um copo, por 20 min. Agite continuamente a solução (cuidadosamente) para garantir a remoção completa das áreas de resistência não expostas. </li><li> Secar as estruturas desenvolvidas segurando o substrato e soprando nitrogênio ou ar comprimido sobre ele. </li><li> Inspecione a bolacha sob um microscópio com ampliação de 50X para comparar os padrões transferidos para a fotorresistência com os padrões desejados. </li></ol> 3. Fabricação de estrutura de carbono 3D: pirólise <ol><li> Coloque as amostras preparadas usando fotolitografia (passos 2.1-2.17) dentro de um forno de tubo pressurizado e aberto. </li><li> Ligue o forno e defina os parâmetros para a pirólise, conforme mencionado acima no passo 1. Repita o processo da etapa 1.6-1.8. </li><li> Manuseie cuidadosamente as amostras usando uma pinça e passe a caracterizarAtion. </li></ol>

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Neste trabalho, foram relatados os métodos para a fabricação de uma variedade de microestruturas de carbono com base na pirólise de materiais precursores naturais ou estruturas de polímero com padrão de foto. Os materiais de carbono resultantes de processos convencionais e não convencionais C-MEMS / C-NEMS são normalmente encontrados como carbonos vítreos. O carbono transparente é um material de eletrodo amplamente utilizado para eletroquímica e também para aplicações de alta temperatura. A microestrutura ...

O carbono tem muitos alotrópios e, dependendo da aplicação específica, pode escolher-se um dos seguintes alotrópicos: nanotubos de carbono (CNTs), grafite, diamante, carbono amorfo, lonsdaleite, buckminsterfullerene (C 60 ), fullerite (C 540 ), fullereno ( C 70 ) e carbono vítreo 1 , 2 , 3 , 4 . O carbono transparente é um dos alototros mais utilizados devido às suas propriedades físicas, incluindo a alta isotropia. Ele também possui as seguintes propriedades: boa condutividade elétrica, baixo coeficiente de expansão térmica e impermeabilidade ao gás. Houve uma busca contínua de materiais precursores ricos em carbono para obter estruturas de carbono. Esses precursores podem ser materiais artificiais ou produtos naturais que estão disponíveis em formas particulares, e até incluem produtos de resíduos. Uma grande variedade de micr<html> O / nanoestruturas são formadas através de processos biológicos ou ambientais na natureza, resultando em características únicas que são extremamente difíceis de criar usando ferramentas de fabricação convencionais. Como o padrão ocorreu naturalmente neste caso, a síntese de nanomateriais que utilizam precursores de hidrocarbonetos naturais e de resíduos pode ser realizada usando um processo simples e de uma só etapa de decomposição térmica em atmosfera inerte ou vácuo, chamada pirólise 5 . O grafeno de alta qualidade, os CNT de parede única, os CNT de paredes múltiplas e os pontos de carbono foram produzidos por decomposição térmica ou a pirólise de precursores e resíduos derivados de plantas, incluindo sementes, fibras e óleos, como óleo de terebintina, óleo de gergelim , Óleo de neem ( Azadirachta indica ), óleo de eucalipto, óleo de palma e óleo de jatropha. Além disso, os produtos de cânfora, extratos de chá-árvore, desperdícios de alimentos, insetos, resíduos agropecuários e produtos alimentares foram utilizados 6 , 7 ,Asset = &quot;xref&quot;&gt; 8 , 9 Recentemente, os pesquisadores já usaram casulos de seda como material precursor para preparar microfibras de carbono porosas 10 . O cabelo humano, geralmente considerado um material de resíduos, foi usado recentemente por essa equipe. É constituído por aproximadamente 91% de polipéptidos, que contêm mais de 50% de carbono; O resto são elementos como oxigênio, hidrogênio, nitrogênio e enxofre 11 . O cabelo também vem com várias propriedades interessantes, como degradação muito lenta, alta resistência à tração, alto isolamento térmico e alta recuperação elástica. Recentemente, utilizou-se para preparar flocos de carbono empregados em supercondensadores 12 e para criar microfibras de carbono oco para detecção eletroquímica 13 . A usinagem de um material de carbono a granel para fabricar estruturas tridimensionais (3D) é uma tarefa difícil, pois o material é muito frágil. O íon focado sejaAm 14 , 15 ou gravura iónica reativa 16 pode ser útil neste contexto, mas eles são processos caros e demorados. A tecnologia do sistema microelectromecânico de carbono (C-MEMS), que se baseia na pirólise de estruturas poliméricas padronizadas, representa uma alternativa versátil. Nas duas últimas décadas, C-MEMS e sistemas nanoelectromecânicos de carbono (C-NEMS) receberam muita atenção devido às etapas de fabricação simples e baratas envolvidas. O processo convencional de fabricação de C-MEMS é realizado em duas etapas: (i) padronização de um precursor de polímero ( por exemplo, um fotorresistente) com fotolitografia e (ii) pirólise das estruturas padronizadas. Os precursores de polímeros duradouros ultravioleta (UV), como os fotoresistos SU8, são freqüentemente usados ​​para modelar estruturas com base na fotolitografia. Em geral, o processo de fotolitografia inclui etapas para revestimento de rotação, cozimento suave, exposição UV, pós cozido e desenvolvimentoLopment. No caso de C-MEMS; silício; Dióxido de silício; Nitreto de silício; quartzo; E, mais recentemente, a safira tem sido usada como substratos. As estruturas de polímero com padrão de foto são carbonizadas a uma temperatura elevada (800-1,100 ° C) em um ambiente livre de oxigênio. Às temperaturas elevadas no vácuo ou atmosfera inerte, todos os elementos não-carbono são removidos, deixando apenas carbono. Esta técnica permite a obtenção de estruturas de carbono vítreo de alta qualidade, que são muito úteis para muitas aplicações, incluindo detecção eletroquímica 17 , armazenamento de energia 18 , nanogeneração triboelétrica 19 e manipulação de partículas eletroquimáticas 20. Além disso, a fabricação de microestruturas 3D com As altas relações de aspecto usando C-MEMS tornaram-se relativamente fáceis e levaram a uma grande variedade de aplicações de eletrodos de carbono 18 , 21 , </sup&gt; 22 , 23 , substituindo frequentemente eletrodos de metal nobre. Neste trabalho, o desenvolvimento recente de uma maneira simples e econômica de fabricar microfibras de carbono oco de cabelos humanos usando a tecnologia C-MEMS não convencional 13 é introduzida. O processo C-MEMS convencional baseado em polímero SU8 também é descrito aqui. Especificamente, o procedimento de fabricação para sólidos de alta relação de aspecto e estruturas SU8 ocas é descrito 24.

<table><tbody><tr><td>SU8-2100</td><td>Microchem</td><td>Product number-Y1110750500L</td><td></td></tr><tr><td>Spinner</td><td>Laurell Technologies Corporation</td><td>Model-WS650HZB-23NPP/UD3</td><td></td></tr><tr><td>Hotplate</td><td>Torrey Pines Scientific</td><td>HS61</td><td></td></tr><tr><td>UV-exposer</td><td>Mercury Lamp, SYLVANIA</td><td>H44GS-100M, P/N-34-0054-01</td><td></td></tr><tr><td>Photomask</td><td>CAD/Art</td><td></td><td>No number</td></tr><tr><td>Developer&amp;nbsp;</td><td>Microchem</td><td>Y020100 4000L&amp;nbsp;</td><td></td></tr><tr><td>DI water system</td><td>Milli Q</td><td>ZOOQOVOTO</td><td></td></tr><tr><td>IPA</td><td>CTR Sientific</td><td>CTR 01244</td><td></td></tr><tr><td>N&lt;sub&gt;2&lt;/sub&gt; gas</td><td>AOC Mexico</td><td></td><td>No number</td></tr><tr><td>Furnace</td><td>PEO 601, ATV Technologie GMBH</td><td>Model-PEO 601, Serial no.-195</td><td></td></tr><tr><td>Si/SiO&lt;sub&gt;2&lt;/sub&gt;</td><td>Noel Technologies</td><td></td><td></td></tr></tbody></table>

fabrication of 3d carbon microelectromechanical systems (c-mems)

Uma ampla gama de fontes de carbono estão disponíveis na natureza, com uma variedade de configurações de micro-nanoestrutura. Aqui, é introduzida uma nova técnica para fabricar microfibras de carbono vítreas longas e vazias derivadas de cabelos humanos. As estruturas de carbono longas e vazias foram feitas por pirólise de cabelo humano a 900 ° C em atmosfera de N2. A morfologia e a composição química dos cabelos humanos naturais e pirolysados ​​foram investigados utilizando microscopia eletrônica de varredura (SEM) e espectroscopia de raios-X elétron-dispersiva (EDX), respectivamente, para estimar as mudanças físicas e químicas devido à pirólise. A espectroscopia Raman foi utilizada para confirmar a natureza vítrea das microestruturas de carbono. O carbono do cabelo Pyrolyzed foi introduzido para modificar eletrodos de carbono impressos por tela; Os eletrodos modificados foram então aplicados ao sensor eletroquímico da dopamina e do ácido ascórbico. O desempenho sensitivo dos sensores modificados foi melhorado em comparação com o não modificadoFied sensores. Para obter o design desejado da estrutura de carbono, desenvolveu-se tecnologia de micro-nanoelectromecânica de carbono (C-MEMS / C-NEMS). O processo de fabricação C-MEMS / C-NEMS mais comum consiste em duas etapas: (i) o padrão de um material base rico em carbono, como um polímero fotossensível, usando fotolitografia; E (ii) carbonização através da pirólise do polímero padronizado em um ambiente livre de oxigênio. O processo C-MEMS / NEMS tem sido amplamente utilizado para desenvolver dispositivos microeletrônicos para várias aplicações, inclusive em micro baterias, supercondensadores, sensores de glicose, sensores de gás, células de combustível e nanogeneradores triboelétricos. Aqui, são discutidos os desenvolvimentos recentes de microestruturas de carbono sólido e oco de alta relação de aspecto com fotorresis SU8. O encolhimento estrutural durante a pirólise foi investigado usando microscopia confocal e SEM. A espectroscopia Raman foi utilizada para confirmar a cristalinidade da estrutura, e a porcentagem atômica dos elementos preseNt no material antes e depois da pirólise foi medida usando EDX.

Um esquema do processo de fabricação de microfibras de carbono vazias derivadas de cabelo humano é mostrado na Figura 1 . O cabelo humano carbonizado foi caracterizado usando SEM para estimar o encolhimento. O diâmetro do cabelo diminuiu de 82,88 ± 0,003 μm para 31,42 ± 0,003 μm devido à pirólise. As imagens microscópicas eletrônicas de varredura (SEM) de vários padrões feitos com microfibras de carbono derivadas de cabelo são mostradas na <st...

Watch this Scientific Journal Video about Fabrication of 3D Carbon Microelectromechanical Systems C-MEMS at JoVE.com

Fabrication of 3D Carbon Microelectromechanical Systems C-MEMS

As microfibras de carbono vítreas longas e vazias foram fabricadas com base na pirólise de um produto natural, cabelo humano. As duas etapas de fabricação de sistemas microelectromecânicos de carbono e nanoelectromecânicos de carbono, ou C-MEMS e C-NEMS, são: (i) fotolitografia de um precursor de polímero rico em carbono e (ii) pirólise do precursor de polímero padronizado.

Fabricação de sistemas 3D Microelectromecânicos de Carbono (C-MEMS)

A wide range of carbon sources are available in nature, with a variety of micro-/nanostructure configurations. Here, a novel technique to fabricate long ...

fabrication-of-3d-carbon-microelectromechanical-systems-c-mems

Research

JoVE Journal

Engineering

Fabrication of 3D Carbon Microelectromechanical Systems (C-MEMS)

12.1K visualizações.  Tecnologico de Monterrey.  As microfibras de carbono vítreas longas e vazias foram fabricadas com base na pirólise de um produto natural, cabelo humano. As duas etapas de fabricação de sistemas microelectromecânicos de carbono e nanoelectromecânicos de carbono, ou C-MEMS e C-NEMS, são: (i) fotolitografia de um precursor de polímero rico em carbono e (ii) pirólise do precursor de polímero padronizado. 

Vídeo: Fabrication of 3D Carbon Microelectromechanical Systems C-MEMS

Fabrication, Densification, and Replica Molding of 3D Carbon Nanotube Microstructures

The introduction of new materials and processes to microfabrication has, in large part, enabled many important advances in microsystems, lab-on-a-chip devices, and their applications. In particular, capabilities for cost-effective fabrication of polymer microstructures were transformed by the advent of soft lithography and other micromolding techniques 1, 2, and this led a revolution in applications of microfabrication to biomedical engineering and biology. Nevertheless, it remains challenging to fabricate microstructures with well-defined nanoscale surface textures, and to fabricate arbitrary 3D shapes at the micro-scale. Robustness of master molds and maintenance of shape integrity is especially important to achieve high fidelity replication of complex structures and preserving their nanoscale surface texture. The combination of hierarchical textures, and heterogeneous shapes, is a profound challenge to existing microfabrication methods that largely rely upon top-down etching using fixed mask templates. On the other hand, the bottom-up synthesis of nanostructures such as nanotubes and nanowires can offer new capabilities to microfabrication, in particular by taking advantage of the collective self-organization of nanostructures, and local control of their growth behavior with respect to microfabricated patterns. 
Our goal is to introduce vertically aligned carbon nanotubes (CNTs), which we refer to as CNT "forests", as a new microfabrication material. We present details of a suite of related methods recently developed by our group: fabrication of CNT forest microstructures by thermal CVD from lithographically patterned catalyst thin films; self-directed elastocapillary densification of CNT microstructures; and replica molding of polymer microstructures using CNT composite master molds. In particular, our work shows that self-directed capillary densification ("capillary forming"), which is performed by condensation of a solvent onto the substrate with CNT microstructures, significantly increases the packing density of CNTs. This process enables directed transformation of vertical CNT microstructures into straight, inclined, and twisted shapes, which have robust mechanical properties exceeding those of typical microfabrication polymers. This in turn enables formation of nanocomposite CNT master molds by capillary-driven infiltration of polymers. The replica structures exhibit the anisotropic nanoscale texture of the aligned CNTs, and can have walls with sub-micron thickness and aspect ratios exceeding 50:1. Integration of CNT microstructures in fabrication offers further opportunity to exploit the electrical and thermal properties of CNTs, and diverse capabilities for chemical and biochemical functionalization 3.

We present methods for fabrication of patterned microstructures of vertically aligned carbon nanotubes (CNTs), and their use as master molds for production of polymer microstructures with organized nanoscale surface texture. The CNT forests are densified by condensation of solvent onto the substrate, which significantly increases their packing density and enables self-directed formation of 3D shapes.

Fabricação, Densificação e Replica Moldagem de Microestruturas de Nanotubos de Carbono 3D

The introduction of new materials and processes to microfabrication has, in large part, enabled many important advances in microsystems, lab-on-a-chip ...

Engenharia

Microfabricated Platforms for Mechanically Dynamic Cell Culture

The ability to systematically probe in vitro cellular response to combinations of mechanobiological stimuli for tissue engineering, drug discovery or fundamental cell biology studies is limited by current bioreactor technologies, which cannot simultaneously apply a variety of mechanical stimuli to cultured cells. In order to address this issue, we have developed a series of microfabricated platforms designed to screen for the effects of mechanical stimuli in a high-throughput format. In this protocol, we demonstrate the fabrication of a microactuator array of vertically displaced posts on which the technology is based, and further demonstrate how this base technology can be modified to conduct high-throughput mechanically dynamic cell culture in both two-dimensional and three-dimensional culture paradigms.

In this protocol, we demonstrate the fabrication of a microactuator array of vertically displaced posts on which the technology is based, and how this base technology can be modified to conduct high-throughput mechanically dynamic cell culture in both two-dimensional and three-dimensional culture paradigms.

Plataformas microfabricated para cultura de células mecanicamente dinâmico

The ability to systematically probe in vitro cellular response to combinations of mechanobiological stimuli for tissue engineering, drug discovery or ...

Bioengenharia

Process of Making Three-dimensional Microstructures using Vaporization of a Sacrificial Component

Vascular structures in natural systems are able to provide high mass transport through high surface areas and optimized structure. Few synthetic material fabrication techniques are able to mimic the complexity of these structures while maintaining scalability. The Vaporization of a Sacrificial Component (VaSC) process is able to do so. This process uses sacrificial fibers as a template to form hollow, cylindrical microchannels embedded within a matrix. Tin (II) oxalate (SnOx) is embedded within poly(lactic) acid (PLA) fibers which facilitates the use of this process. The SnOx catalyzes the depolymerization of the PLA fibers at lower temperatures. The lactic acid monomers are gaseous at these temperatures and can be removed from the embedded matrix at temperatures that do not damage the matrix. Here we show a method for aligning these fibers using micromachined plates and a tensioning device to create complex patterns of three-dimensionally arrayed microchannels. The process allows the exploration of virtually any arrangement of fiber topologies and structures.

The Vaporization of a Sacrificial Component (VaSC) process is used to fabricate microvascular structures. This procedure uses sacrificial poly(lactic) acid fibers to form hollow microchannels with precise 3D geometric positioning provided by laser micromachined guide plates.

Processo de fabricação de microestruturas tridimensionais usando vaporização de um componente sacrificial

Vascular structures in natural systems are able to provide high mass transport through high surface areas and optimized structure. Few synthetic material ...

Manufacturing of Three-dimensionally Microstructured Nanocomposites through Microfluidic Infiltration

Microstructured composite beams reinforced with complex three-dimensionally (3D) patterned nanocomposite microfilaments are fabricated via nanocomposite in&#64257;ltration of 3D interconnected microfluidic networks. The manufacturing of the reinforced beams begins with the fabrication of microfluidic networks, which involves layer-by-layer deposition of fugitive ink filaments using a dispensing robot, filling the empty space between filaments using a low viscosity resin, curing the resin and finally removing the ink.&#160;Self-supported 3D structures with other geometries and many layers (e.g.&#160;a few hundreds layers) could be built using this method. The resulting tubular micro&#64258;uidic networks are then infiltrated with thermosetting nanocomposite suspensions containing nanofillers (e.g.&#160;single-walled carbon nanotubes), and subsequently cured. The infiltration is done by applying a pressure gradient between two ends of the empty network (either by applying a vacuum or vacuum-assisted microinjection). Prior to the infiltration, the nanocomposite suspensions are prepared by dispersing nanofillers into polymer matrices using ultrasonication and three-roll mixing methods. The nanocomposites (i.e.&#160;materials infiltrated) are then solidified under UV exposure/heat cure, resulting in a 3D-reinforced composite structure. The technique presented here enables the design of functional nanocomposite macroscopic products for microengineering applications such as actuators and sensors.

Three-dimensional (3D) microstructured composite beams are fabricated through the directed and localized infiltration of nanocomposites into 3D porous microfluidic networks. The flexibility of this manufacturing method enables the utilization of different thermosetting materials and nanofillers in order to achieve a variety of functional 3D reinforced nanocomposite macroscopic products.

Fabricação de tridimensionalmente microestruturadas nanocompósitos através Microfluidic Infiltração

Microstructured composite beams reinforced with complex three-dimensionally (3D) patterned nanocomposite microfilaments are fabricated via nanocomposite ...

Química

Micro-masonry for 3D Additive Micromanufacturing

Transfer printing is a method to transfer solid micro/nanoscale materials (herein called &#8216;inks&#8217;) from a substrate where they are generated to a different substrate by utilizing elastomeric stamps. Transfer printing enables the integration of heterogeneous materials to fabricate unexampled structures or functional systems that are found in recent advanced devices such as flexible and stretchable solar cells and LED arrays. While transfer printing exhibits unique features in material assembly capability, the use of adhesive layers or the surface modification such as deposition of self-assembled monolayer (SAM) on substrates for enhancing printing processes hinders its wide adaptation in microassembly of microelectromechanical system (MEMS) structures and devices. To overcome this shortcoming, we developed an advanced mode of transfer printing which deterministically assembles individual microscale objects solely through controlling surface contact area without any surface alteration. The absence of an adhesive layer or other modification and the subsequent material bonding processes ensure not only mechanical bonding, but also thermal and electrical connection between assembled materials, which further opens various applications in adaptation in building unusual MEMS devices.

This paper introduces a 3D additive micromanufacturing strategy (termed &#8216;micro-masonry&#8217;) for the flexible fabrication of microelectromechanical system (MEMS) structures and devices. This approach involves transfer printing-based assembly of micro/nanoscale materials in conjunction with rapid thermal annealing-enabled material bonding techniques.

Micro-alvenaria para Aditivo 3D Microfabricação

Transfer printing is a method to transfer solid micro/nanoscale materials (herein called &#8216;inks&#8217;) from a substrate where they are generated to ...

Fabrication of Low Temperature Carbon Nanotube Vertical Interconnects Compatible with Semiconductor Technology

We demonstrate a method for the low temperature growth (350 &#176;C) of vertically-aligned carbon nanotubes (CNT) bundles on electrically conductive thin-films. Due to the low growth temperature, the process allows integration with modern low-&#954; dielectrics and some flexible substrates. The process is compatible with standard semiconductor fabrication, and a method for the fabrication of electrical 4-point probe test structures for vertical interconnect test structures is presented. Using scanning electron microscopy the morphology of the CNT bundles is investigated, which demonstrates vertical alignment of the CNT and can be used to tune the CNT growth time. With Raman spectroscopy the crystallinity of the CNT is investigated. It was found that the CNT have many defects, due to the low growth temperature. The electrical current-voltage measurements of the test vertical interconnects displays a linear response, indicating good ohmic contact was achieved between the CNT bundle and the top and bottom metal electrodes. The obtained resistivities of the CNT bundle are among the average values in the literature, while a record-low CNT growth temperature was used.

A method for the growth of low temperature vertically-aligned carbon nanotubes, and the subsequent fabrication of vertical interconnect electrical test structures using semiconductor fabrication is presented.

Fabricação de Baixa Temperatura de Nanotubos de Carbono Vertical Interconexões Compatível com Semiconductor Tecnologia

We demonstrate a method for the low temperature growth (350 &#176;C) of vertically-aligned carbon nanotubes (CNT) bundles on electrically conductive ...

Microfabrication of Chip-sized Scaffolds for Three-dimensional Cell cultivation

Using microfabrication technologies is a prerequisite to create scaffolds of reproducible geometry and constant quality for three-dimensional cell cultivation. These technologies offer a wide spectrum of advantages not only for manufacturing but also for different applications. The size and shape of formed cell clusters can be influenced by the exact and reproducible architecture of the microfabricated scaffold and, therefore, the diffusion path length of nutrients and gases can be controlled.1 This is unquestionably a useful tool to prevent apoptosis and necrosis of cells due to an insufficient nutrient and gas supply or removal of cellular metabolites.
Our polymer chip, called CellChip, has the outer dimensions of 2 x 2 cm with a central microstructured area. This area is subdivided into an array of up to 1156 microcontainers with a typical dimension of 300 m edge length for the cubic design (cp- or cf-chip) or of 300 m diameter and depth for the round design (r-chip).2
So far, hot embossing or micro injection moulding (in combination with subsequent laborious machining of the parts) was used for the fabrication of the microstructured chips. Basically, micro injection moulding is one of the only polymer based replication techniques that, up to now, is capable for mass production of polymer microstructures.3 However, both techniques have certain unwanted limitations due to the processing of a viscous polymer melt with the generation of very thin walls or integrated through holes. In case of the CellChip, thin bottom layers are necessary to perforate the polymer and provide small pores of defined size to supply cells with culture medium e.g. by microfluidic perfusion of the containers.
In order to overcome these limitations and to reduce the manufacturing costs we have developed a new microtechnical approach on the basis of a down-scaled thermoforming process. For the manufacturing of highly porous and thin walled polymer chips, we use a combination of heavy ion irradiation, microthermoforming and track etching. In this so called "SMART" process (Substrate Modification And Replication by Thermoforming) thin polymer films are irradiated with energetic heavy projectiles of several hundred MeV introducing so-called "latent tracks" Subsequently, the film in a rubber elastic state is formed into three dimensional parts without modifying or annealing the tracks. After the forming process, selective chemical etching finally converts the tracks into cylindrical pores of adjustable diameter.

We present two processes for the microfabrication of porous polymer chips for three-dimensional cell cultivation. The first one is hot embossing combined with a solvent vapour welding process. The second one uses a recently developed microthermoforming process combined with ion track technology leading to a significant simplification of manufacture.

Microfabricação de Chip porte Andaimes para tridimensional de cultivo celular

Using microfabrication technologies is a prerequisite to create scaffolds of reproducible geometry and constant quality for three-dimensional cell ...

Biologia

Free-form Light Actuators &#8212; Fabrication and Control of Actuation in Microscopic Scale

Liquid crystalline elastomers (LCEs) are smart materials capable of reversible shape-change in response to external stimuli, and have attracted researchers&#39; attention in many fields. Most of the studies focused on macroscopic LCE structures (films, fibers) and their miniaturization is still in its infancy. Recently developed lithography techniques, e.g., mask exposure and replica molding, only allow for creating 2D structures on LCE thin films. Direct laser writing (DLW) opens access to truly 3D fabrication in the microscopic scale. However, controlling the actuation topology and dynamics at the same length scale remains a challenge.
In this paper we report on a method to control the liquid crystal (LC) molecular alignment in the LCE microstructures of arbitrary three-dimensional shape. This was made possible by a combination of direct laser writing for both the LCE structures as well as for micrograting patterns inducing local LC alignment. Several types of grating patterns were used to introduce different LC alignments, which can be subsequently patterned into the LCE structures. This protocol allows one to obtain LCE microstructures with engineered alignments able to perform multiple opto-mechanical actuation, thus being capable of multiple functionalities. Applications can be foreseen in the fields of tunable photonics, micro-robotics, lab-on-chip technology and others.

Here, we fabricate 3D polymeric micro/nano structures in which both the shape and the molecular alignment can be engineered with nanometer scale accuracy by the use of direct laser writing. Light induced deformation of several types of liquid crystalline elastomer microstructures can be controlled in the microscopic scale.

Atuadores de luz de forma livre - Fabricação e Controle de atuação em escala microscópica

Liquid crystalline elastomers (LCEs) are smart materials capable of reversible shape-change in response to external stimuli, and have attracted ...

Fabrication of Carbon-Based Ionic Electromechanically Active Soft Actuators

Ionic electromechanically active capacitive laminates are a type of smart material that move in response to electrical stimulation. Due to the soft, compliant and biomimetic nature of this deformation, actuators made of the laminate have received increasing interest in soft robotics and (bio)medical applications. However, methods to easily fabricate the active material in large (even industrial) quantities and with a high batch-to-batch and within-batch repeatability are needed to transfer the knowledge from laboratory to industry. This protocol describes a simple, industrially scalable and reproducible method for the fabrication of ionic carbon-based electromechanically active capacitive laminates and the preparation of actuators made thereof. The inclusion of a passive and chemically inert (insoluble) middle layer (e.g., a textile-reinforced polymer network or microporous Teflon) distinguishes the method from others. The protocol is divided into five steps: membrane preparation, electrode preparation, current collector attachment, cutting and shaping, and actuation. Following the protocol results in an active material that can, for example, compliantly grasp and hold a randomly shaped object as demonstrated in the article.

This article describes a fast and simple manufacturing process of ionic electromechanically active composite materials for actuators in biomedical, biomimetic and soft robotics applications. The key fabrication steps, their importance for the actuators&#39; final properties, and some of the main characterization techniques are described in detail.

Fabricação de atuadores macios eletromecanicamente ativos à base de carbono

Ionic electromechanically active capacitive laminates are a type of smart material that move in response to electrical stimulation. Due to the soft, ...

Melt Electrospinning Writing of Three-dimensional Poly(&#949;-caprolactone) Scaffolds with Controllable Morphologies for Tissue Engineering Applications

This tutorial reflects on the fundamental principles and guidelines for electrospinning writing with polymer melts, an additive manufacturing technology with great potential for biomedical applications. The technique facilitates the direct deposition of biocompatible polymer fibers to fabricate well-ordered scaffolds in the sub-micron to micro scale range. The establishment of a stable, viscoelastic, polymer jet between a spinneret and a collector is achieved using an applied voltage and can be direct-written. A significant benefit of a typical porous scaffold is a high surface-to-volume ratio which provides increased effective adhesion sites for cell attachment and growth. Controlling the printing process by fine-tuning the system parameters enables high reproducibility in the quality of the printed scaffolds. It also provides a flexible manufacturing platform for users to tailor the morphological structures of the scaffolds to their specific requirements. For this purpose, we present a protocol to obtain different fiber diameters using melt electrospinning writing (MEW) with a guided amendment of the parameters, including flow rate, voltage and collection speed. Furthermore, we demonstrate how to optimize the jet, discuss often experienced technical challenges, explain troubleshooting techniques and showcase a wide range of printable scaffold architectures.

This protocol serves as a comprehensive guideline to fabricate scaffolds via electrospinning with polymer melts in a direct writing mode. We systematically outline the process and define the appropriate parameter settings for achieving targeted scaffold architectures.

Derreter a eletrofiação escrita de andaimes Poly(ε-caprolactone) tridimensional com morfologias controláveis para aplicações de engenharia de tecidos

This tutorial reflects on the fundamental principles and guidelines for electrospinning writing with polymer melts, an additive manufacturing technology ...