Name: fabrication of 3d carbon microelectromechanical systems (c-mems)
Uploaded: 2017-06-17T13:00:00.000+00:00
Duration: 8 min 1 s
Description: Watch this Scientific Journal Video about Fabrication of 3D Carbon Microelectromechanical Systems C-MEMS at JoVE.com

Este trabajo fue apoyado por el Tecnológico de Monterrey y la Universidad de California en Irvine.

1. 3D cabello humano derivado de la estructura de carbono de fabricación NOTA: Use equipo de protección personal. Siga las instrucciones del laboratorio para usar los instrumentos y trabajar dentro del laboratorio. <ol><li> Prepare el pelo humano recogido lavándolo con agua DI y secándolo con gas N2. </li><li> Colocar los pelos como se desee, como en hilos paralelos, cruzar, con dos pelos enrollados juntos, etc. </li><li> Conecte los pelos a un sustrato de silicio utilizando SU8 o guárdelos directamente en un barco de cerámica. </li><li> Coloque el substrato o el barco de silicio unido al cabello en un horno. </li><li> Encienda el horno y abra la válvula de un tanque de gas inerte (N 2 ). NOTA: El caudal de gas óptimo depende del volumen del tubo del horno. Se aplicó un caudal de 6 l / min para un volumen de tubo de 6 L. Para establecer un entorno completamente inerte en el tubo del horno, un caudal de gas 1,5 veces mayor que el gas óptimo fSe aplicó una tasa baja durante los primeros 15 min. </li><li> Ajuste los parámetros, incluyendo la temperatura máxima de pirólisis, la velocidad de rampa de temperatura y el caudal de gas inerte, y ejecute el horno. <ol><li> Por ejemplo, aumente la temperatura desde la temperatura ambiente a 300 ° C a una velocidad de rampa de 5 ° C / min. Manténgalo a 300 ° C durante 1 h para estabilizarlo. Aumentar la temperatura a 900 ° C y mantenerla durante 1 h más para la carbonización. </li><li> Enfriar el horno hasta 300 ° C a una velocidad de 10 ° C / min y apagar el calentador del horno, ya que después de 300 ° C no es necesario el enfriamiento controlado. Dejar las muestras en el horno hasta que la temperatura alcance la temperatura ambiente por flujo de N2 solamente. </li></ol></li><li> Apague el horno y el flujo de gas al finalizar el proceso de pirólisis. </li><li> Saque las muestras del horno. </li></ol> 2. Fabricación de la estructura del polímero 3D: Fotolitografía <ol><li> DesUn diseño 2D de la estructura fotorresistente 3D deseada utilizando un paquete de software apropiado y preparar la máscara impresa ( es decir, una máscara de fotofilme de polietileno). NOTA: Se utilizó un servicio comercial para obtener el diseño impreso. El tamaño de la máscara generalmente depende del diseño. </li><li> En un laboratorio limpio, encienda dos placas calientes y establezca las temperaturas a 65 ° C y 95 ° C, respectivamente. </li><li> Encienda una máquina de rotación y una bomba de vacío. Asegúrese de que la bomba de vacío esté conectada a través de un tubo a la cabeza giratoria. </li><li> Ajuste los parámetros del giro de dos pasos, como la velocidad de giro, la rampa y la duración. Para el primer paso, ajuste la velocidad de giro a 500 rpm, la rampa a 100 rpm / sy el tiempo de giro a 10 s para comenzar el ciclo de centrifugado. Para el siguiente paso, ajuste la velocidad de giro a 1.000 rpm, la rampa a 100 rpm / sy el tiempo de giro a 30 s para extender uniformemente el fotorresistente. </li><li> Coloque un sustrato ( es decir, un 4 pulgadas x 4 pulgadas y 5501; m 2,25 μm de espesor de la oblea de Si con una capa de SiO2 de 1 μm de espesor) en el centro del soporte. </li><li> Depósito de polímero fotosensible (es decir, fotorresistencia SU8) directamente sobre el centro del sustrato. Use lo suficiente para cubrir la superficie. </li><li> Presione el botón de &quot;vacío&quot; para sostener el sustrato. </li><li> Presione el botón &quot;run&quot; para cubrir el sustrato con SU8 y lograr un espesor final de 250 μm. </li><li> Después de completar el proceso de hilatura, presione el botón &quot;vacío&quot; de nuevo para liberar el sustrato recubierto del soporte. </li><li> Sostenga cuidadosamente el sustrato revestido con una pinza para mantener la superficie lisa y limpia. Transferir el sustrato directamente sobre la placa caliente a 65 ° C durante 6 minutos y luego sobre la placa caliente a 95 ° C durante 40 minutos (horneado suave). NOTA: Se requiere hornear a 65 ° C para asegurar la evaporación lenta del disolvente, resultando en un mejor recubrimiento y mejor adherencia.O el sustrato, mientras que la cocción a 95 ° C densifica aún más el SU8. </li><li> Mientras tanto, presione el interruptor para encender el sistema de exposición a los rayos UV y ajuste el tiempo de exposición a &quot;12 s&quot; utilizando el botón de ajuste del sistema. NOTA: Para una capa SU8 de 250 μm de espesor, la energía de exposición debe ser de 360 ​​mJ / cm 2 . </li><li> Una vez completada la etapa de cocción (paso 2.10), coloque el sustrato en el sistema de exposición a los rayos UV y coloque el lado impreso de una fotomáscara (del paso 2.1) sobre el mismo. Utilice todo el área de la máscara para cubrir el sustrato recubierto y presione suavemente para asegurar que no haya espacio entre la máscara y el sustrato. </li><li> Exponer el sustrato recubierto de SU8 a la radiación UV a través de la fotomáscara utilizando configuraciones UV predefinidas. </li><li> Calentar nuevamente el sustrato colocándolo directamente sobre la placa de cocción a 65 ° C durante 5 min ya 95 ° C durante 14 min para una cocción post-exposición (PEB). NOTA: El PEB aumenta el grado de reticulación en las áreas expuestas a los rayos UV yRevestimiento más resistente a los disolventes en la etapa de desarrollo. </li><li> Eliminar las regiones fotorresistentes no expuestas sumergiendo el sustrato en la solución reveladora dedicada, colocada en un vaso de precipitados, durante 20 min. Agite continuamente la solución (con cuidado) para asegurar la eliminación completa de las áreas de resistencia no expuestas. </li><li> Seque las estructuras desarrolladas sujetando el sustrato y soplando nitrógeno o aire comprimido sobre él. </li><li> Inspeccione la oblea bajo un microscopio con una ampliación de 50X para comparar los patrones transferidos a la fotorresistencia con los patrones deseados. </li></ol> 3. Fabricación de la estructura del carbón 3D: Pirólisis <ol><li> Colocar las muestras preparadas usando fotolitografía (pasos 2.1-2.17) dentro de un horno a presión de tubo abierto. </li><li> Encienda el horno y establezca los parámetros para la pirólisis, como se mencionó anteriormente en el paso 1. Repita el proceso desde el paso 1.6-1.8. </li><li> Manejar las muestras con cuidado usando pinzas y proceda a caracterizarCión. </li></ol>

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En este trabajo se informaron los métodos para fabricar una variedad de microestructuras de carbono basadas en la pirólisis de materiales precursores naturales o estructuras poliméricas con motivos fotográficos. Los materiales de carbono resultantes de los procesos C-MEMS / C-NEMS tradicionales y no convencionales se encuentran típicamente que son carbones vítreos. El carbono vítreo es un material de electrodo ampliamente utilizado para la electroquímica y también para aplicaciones de alta temperatura. La micro...

El carbón tiene muchos alótropos y, dependiendo de la aplicación particular, se puede elegir uno de los siguientes alótropos: nanotubos de carbono (CNTs), grafito, diamante, carbono amorfo, lonsdaleita, buckminsterfullereno (C 60 ), fullerita (C 540 ), fullereno C $ _ $ ), y carbono vítreo 1 , 2 , 3 , 4 . El carbono vítreo es uno de los alótropos más utilizados debido a sus propiedades físicas, incluyendo alta isotropía. También tiene las siguientes propiedades: buena conductividad eléctrica, bajo coeficiente de dilatación térmica e impermeabilidad al gas. Ha habido una búsqueda continua de materiales precursores ricos en carbono para obtener estructuras de carbono. Estos precursores pueden ser materiales artificiales o productos naturales que están disponibles en formas particulares, e incluso incluyen productos de desecho. Una amplia variedad de micr<html> Las nanoestructuras se forman a través de procesos biológicos o ambientales en la naturaleza, dando como resultado características únicas que son extremadamente difíciles de crear usando herramientas de fabricación convencionales. Como el patrón se llevó a cabo naturalmente en este caso, la síntesis de nanomateriales utilizando precursores de hidrocarburos naturales y residuos podría llevarse a cabo utilizando un fácil, un paso de proceso de descomposición térmica en una atmósfera inerte o vacío, llamada pirólisis [ 5] . Se han producido grafeno de alta calidad, CNT de una pared, CNTs de paredes múltiples y puntos de carbono por descomposición térmica o pirólisis de precursores y desechos derivados de plantas, incluyendo semillas, fibras y aceites, tales como aceite de trementina, aceite de sésamo , Aceite de neem ( Azadirachta indica ), aceite de eucalipto, aceite de palma y aceite de jatrofa. También se han utilizado productos de alcanfor, extractos de árboles de té, alimentos de desecho, insectos, desechos agrícolas y productos alimenticios 6 , 7 ,8 , 9 Recientemente, los investigadores han utilizado incluso los capullos de seda como material precursor para preparar microfibras porosas de carbono [ 10] . El cabello humano, generalmente considerado como un material de desecho, fue utilizado recientemente por este equipo. Está constituido por aproximadamente 91% de polipéptidos, que contienen más de 50% de carbono; El resto son elementos como oxígeno, hidrógeno, nitrógeno y azufre 11 . El cabello también viene con varias propiedades interesantes, como degradación muy lenta, alta resistencia a la tracción, alto aislamiento térmico y alta recuperación elástica. Recientemente, se ha utilizado para preparar copos de carbono empleados en supercondensadores 12 y para crear microfibras huecas de carbono para detección electroquímica 13 . El mecanizado de un material de carbono a granel para fabricar estructuras tridimensionales (3D) es una tarea difícil, ya que el material es muy quebradizo. Ión enfocadoAm 14 , 15 o grabado con iones reactivos 16 pueden ser útiles en este contexto, pero son procesos costosos y que consumen tiempo. La tecnología del sistema microelectromecánico de carbono (C-MEMS), que se basa en la pirólisis de estructuras poliméricas modeladas, representa una alternativa versátil. En las últimas dos décadas, C-MEMS y sistemas nanoelectromecánicos de carbono (C-NEMS) han recibido mucha atención debido a los sencillos y económicos pasos de fabricación involucrados. El proceso de fabricación de C-MEMS convencional se lleva a cabo en dos etapas: (i) modelar un precursor de polímero ( por ejemplo, un fotorresistente) con fotolitografía y (ii) pirólisis de las estructuras modeladas. Los precursores del polímero ultravioleta (UV) -curables, tales como fotorresistencias SU8, se usan a menudo para modelar estructuras basadas en fotolitografía. En general, el proceso de fotolitografía incluye etapas para el recubrimiento por centrifugado, cocción suave, exposición a UV, post horneado y desarrollo.Desarrollo. En el caso de C-MEMS; silicio; dióxido de silicio; Nitrido de silicona; cuarzo; Y, más recientemente, el zafiro se han utilizado como sustratos. Las estructuras de polímero con motivos fotográficos se carbonizan a una temperatura elevada (800-1100 ° C) en un entorno libre de oxígeno. A esas elevadas temperaturas en vacío o atmósfera inerte, se eliminan todos los elementos que no son de carbono, dejando sólo carbono. Esta técnica permite la obtención de estructuras de carbono vítreo de alta calidad, que son muy útiles para muchas aplicaciones, incluyendo la detección electroquímica 17 , el almacenamiento de energía 18 , la nanogeneración triboeléctrica 19 y la manipulación de partículas electroquinéticas 20. También, la fabricación de microestructuras 3D con Las proporciones de aspecto altas usando C-MEMS se han vuelto relativamente fáciles y han conducido a una amplia variedad de aplicaciones de electrodos de carbono 18 , 21 , </sup&gt; 22 , 23 , reemplazando a menudo los electrodos de metal noble. En este trabajo se introduce el desarrollo reciente de una manera sencilla y rentable de fabricar microfibras huecas de carbono a partir del cabello humano usando tecnología C-MEMS no convencional 13 . El proceso C-MEMS convencional basado en polímero SU8 también se describe aquí. Específicamente, se describe el procedimiento de fabricación para sólidos de relación de aspecto alto y estructuras SU8 huecas 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)

Una gran variedad de fuentes de carbono están disponibles en la naturaleza, con una variedad de configuraciones de micro / nanoestructura. Aquí, se introduce una nueva técnica para fabricar microfibras de carbono vítreo largas y huecas derivadas de pelos humanos. Las estructuras de carbono largas y huecas se hicieron mediante la pirólisis del cabello humano a 900 ° C en una atmósfera de N2. La morfología y composición química de cabellos humanos naturales y pirolizados fueron investigadas mediante microscopía electrónica de barrido (SEM) y espectroscopia de rayos X de dispersión de electrones (EDX), respectivamente, para estimar los cambios físicos y químicos debidos a la pirólisis. La espectroscopia Raman se utilizó para confirmar la naturaleza vítrea de las microestructuras de carbono. Se introdujo carbón de cabello pirolizado para modificar electrodos de carbón de pantalla impresa; Los electrodos modificados se aplicaron luego a la detección electroquímica de dopamina y ácido ascórbico. El rendimiento de detección de los sensores modificados se mejoró en comparación con el método unmodiSensores. Para obtener el diseño de la estructura de carbono deseada, se desarrolló la tecnología del sistema micro-nanoelectromecánico de carbono (C-MEMS / C-NEMS). El proceso más común de fabricación de C-MEMS / C-NEMS consiste en dos etapas: (i) el modelado de un material base rico en carbono, tal como un polímero fotosensible, usando fotolitografía; Y (ii) carbonización a través de la pirólisis del polímero modelado en un entorno libre de oxígeno. El proceso de C-MEMS / NEMS ha sido ampliamente utilizado para desarrollar dispositivos microelectrónicos para diversas aplicaciones, incluyendo micro-baterías, supercapacitores, sensores de glucosa, sensores de gas, pilas de combustible y nanogeneradores triboeléctricos. Aquí, se discuten desarrollos recientes de microestructuras sólidas y huecas de carbono de alto aspecto con fotorresistencias SU8. La contracción estructural durante la pirólisis se investigó utilizando microscopía confocal y SEM. La espectroscopia Raman se utilizó para confirmar la cristalinidad de la estructura, y el porcentaje atómico de los elementos preseNt en el material antes y después de la pirólisis se midió usando EDX.

En la figura 1 se muestra un esquema del proceso de fabricación de microfibras huecas de carbono derivadas del cabello humano. El cabello humano carbonizado se caracterizó utilizando SEM para estimar la contracción. El diámetro del cabello disminuyó de 82,88 ± 0,003 μm a 31,42 ± 0,003 μm debido a la pirólisis. En la Figura 2 se muestran imágenes microscópicas electrónicas de barrido (SEM) de diversos patrones realiz...

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

Se fabricaron microfibras de carbono vítreo largas y huecas basadas en la pirólisis de un producto natural, cabello humano. Las dos etapas de fabricación de los sistemas microelectromecánicos de carbono y nanoelectromecánicos de carbono, o C-MEMS y C-NEMS, son: (i) fotolitografía de un precursor de polímero rico en carbono y (ii) pirólisis del precursor de polímero modelado.

Fabricación de sistemas microelectromecánicos de carbono 3D (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

Universidad San Sebastian

Research

JoVE Journal

Engineering

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

12.0K vistas.  Tecnologico de Monterrey.  Se fabricaron microfibras de carbono vítreo largas y huecas basadas en la pirólisis de un producto natural, cabello humano. Las dos etapas de fabricación de los sistemas microelectromecánicos de carbono y nanoelectromecánicos de carbono, o C-MEMS y C-NEMS, son: (i) fotolitografía de un precursor de polímero rico en carbono y (ii) pirólisis del precursor de polímero modelado. 

Video: 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.

Fabricación, densificación, y la réplica de Moldeo por inyección de microestructuras 3D nanotubos de carbono

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

Investigación

Ingeniería

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 el cultivo celular mecánico dinámico

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

Bioingeniería

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-mampostería para 3D Aditivo Microfabricación

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

Using Micro-Electro-Mechanical Systems (MEMS) to Develop Diagnostic Tools

Using Micro-Electro-Mechanical Systems MEMS to Develop Diagnostic Tools

I'm U De Mercy, I'm the principal investigator of Bio Stick MAMs in Medicine Labs. I did my PhD at Stanford University in electrical engineering. I did a postdoc at Harvard Medical School at MGH working on bio acoustic MAMs or mostly bio MAs.And now I'm continuing as a faculty at Harvard Medical School at Harvard MIT Health Sciences and Technology. And continuing with my research that I enjoy very much. The work that I did during my PhD was very much related to droplets and using acoustics to generate precise size droplets and control their location and position to deposit very sensitive polymers.Now we apply similar technologies to encapsulate cells in droplets and then position them on the surfaces for various applications in tissue engineering to print cells on the surfaces to pattern cells. Also, there are applications where you want to see that you can encapsulate few cells or a single cell or from the same population and to see the differences between the same population from one cell to another there being able to encapsulate cells in droplets at high throughput rates like 10, 000 cells per second kind of rates becomes very important and very useful to understand biological problems. So my research currently has two legs, I would say.One is this cell encapsulation work that I just talked about. How do we pack a cell in a droplet that's, and how can we do this repeatedly and reliably and without harming the cells? So after the cell is ejected or encapsulated in the droplet, we should be able to precisely located on a surface the cell should be functional and alive and viable.It shouldn't be harmed by the effects of ejection and so forth. So currently we have a system where we use acoustic drop focused waves to generate these droplets from open pools where we can encapsulate down to single cells in these really small droplets that are comparable to the cell size. That's very exciting in terms of applying this to cell printing and tissue engineering.The other side of my research is again using these MAMs micro electromechanical system technologies to develop low cost diagnostic tools. Mostly this research uses microfluidic approaches where we can introduce whole blood, very small volumes such as blood from a prick finger prick, less than 10 microliters that you can introduce to a chip. And from that blood we can encapsulate or you can capture certain sub-cellular populations from whole blood.Why is this important? Why should this be cheap for global health applications On top of the mountain in Africa, you want to be able to tell for a HIV patient, for instance, how many CD four T lymphocytes this patient has. Because World Health Organization says that below 200 CD four cells per microliter, you have to start treating the patients In the developed world, you use hundreds of thousands dollars of vert flow cytometers to be able to get this data.And it takes of course time to use and skill of course to be able to use these like huge table size machines. Our small chip can be introduced this small finger brick 10 microliters of whole blood and it'll capture the CD four cells using the surface protein affinities. And then you can rapidly count these cells that are captured because you know that there are CD four cells which are attached to CD four proteins antibodies on the surface of the chip.By controlling the flow rates and shear, you can make sure that the specificity and efficiency for these cell types are optimized. And there's of course always non specific binding, but by our sheer approaches we minimize these effects and make sure that between plus minus 10%errors, which is sufficient to make a diagnostic or prognostic decision on top mountain in Africa. So this has interesting applications for global health as well as these low cost techniques that are disposable can impact the developed world because now these fast blood tests which are really low cost can impact the tests that we use in the developed world.If they're optimized to higher levels of efficiency and specificity, which our initial data shows that they can be, then it'll definitely impact our lives. When I first finished my PhD, I knew more about microfluidics and that in MAMs more than anything else I could see, especially with the droplet application, I could see that if I could print cells and encapsulate cells or manipulate the few cells, single cells, that it'll have great applications in biotechnology area. And I was very interested in working on things that will actually impact people's lives.I used to apply these technologies to semiconductor industry, but then I wanted to to be useful directly to people. So I, that's what directed me towards problems in healthcare. And then that's why I made a big shift and came to a hospital, mass general hospital to the postdoc.And there, you know, I got exposed more and more to problems and it seems, and it's all clear that one of the biggest problems of the world today is global health and there comes illnesses like tuberculosis, HIV that kills thousands of people per day. And these people die not because the drugs are not there, but because there aren't enough diagnostic tools which is much more expensive than the existing drugs. So I know the technology side of the things very well.I get, I got exposed to the biological problems and the more I learned about them, the more I could see that I could make an impact. And that's how it all grew from there. And it's still continuing now.Like I seen biotechnology and in medicine there are like so many problems that actually directly cause our result into loss of people's lives and the technologies, the technology aspect of it and being able to apply it to real world medical problems is a great, I think path to follow. This is like how this whole biotechnology area I think is kind of growing and it's becoming very impactful. If you think about it, HIV cancer, those are big killers in the world.And current micro technologies, current approaches could maybe benefit from early detection of cancer by capturing these cells from blood or making it really cheap, which will make it available to masses. So all these things coming together, I think this whole microtechnology applications in healthcare in medicine could impact the future of human beings. So that's how all these things kind of come together I guess.And being in the Harvard MIT health sciences and technology where on one end you have the technology and on the other end you direct aspect, direct access to patients, direct access to doctors in Brigham and Women's Hospital where I work is a great environment. cause every person that you talk to have their problems and you could maybe it's coming from a different background, provide interesting solutions to those existing real world problems. So this is, I think how I see the whole perspective of how these medical problems meet the technology side.And we try to impact people's lives in a positive way. In single cell cap encapsulation or in cell encapsulation, the major challenge is to be able to encapsulate reliably and repeatably single cells. So you're ejecting 10, 000 hundred thousand cells per second.And how do you make sure that each droplet that you eject has a single cell? This statistics where you are changing the droplet size and minimizing the, optimizing the cell size over the droplet size, which goes into the old problem of packing spheres in a volume and what is the most efficient way to do it. So that's the biggest challenge in the cell printing area for from the technological side.The other aspect of it is now you can say print and precisely locate these cells. How can you generate these three dimensional tissues and how can you keep them alive and how can you transplant them? There comes in the biological end of the problems where you want to now exactly mimic the tissue.We have current approaches to be able to print an eyelet, a pancreas eyelet, and to be able to print using smooth muscle cells, a bladder tissue, directly mimicking what is in human or red bladder so that then we can make this tissue and test how well it performs compared to the real world existing native tissues. So that's the major challenge I guess by taking these novel technologies, how can you make this the ideal tissue that can be replaced, that can be transplanted, that's the, you know, biggest problem from the beginning because the control on single cell gives you the capability to precisely locate them. And then how do you kind of grow it from there?So it's something transplantable there where the impact of human life comes. So that's on that end, what the challenges are in the tissue engineering side of the things in southern encapsulation and in diagnostics using microfluidics, the challenge is to be able to capture a cell out of billions of cells. It's like you have a sugar particle in a salt can and you're trying to pull out that sugar particle and that's like one in a billion.So you, you're processing microliters to milliliters of whole blood and you want to be able to specifically and efficiently without any technological problems like clogging or any biological problems like non-specific binding, you want to be able to isolate at one cell out of billion cells in one microliter of whole blood, you have a few millions of cells. And for the CD four T lymphocyte case in that one microliter, we are after about thousand cells per microliter. So it's like one cell in a thousand kind of a problem where we have shown that it's doable.But when you want to go after circulating tumor cells for cancer, then the challenge becomes one in a billion. So to some summarize it, the challenge is how do we capture this one cell out of billions of other cells around it? And what is the technological aspects?What are the flow rates? What is the device design? What, what are the flow rates?What, what are the volumes of blood that has to be processed and how do you make sure that the cells you capture are the ones that you actually wanted to capture? All these aspects kind formed the whole challenge that can be summarized in one sentence, which is how do you capture this one rare cell out of billion others? So it's really a needle in a haystack kind of problem, which is exciting.And I think this is moving the technologies forward to address these problems is the current technological challenge. Being able to bring them to a level where they do the job that they're supposed to do is one thing. And then taking it to the clinic and making it a product has all different expertise such as being able to start a company, being able to patent these things and all those other aspects come into the picture.And I think we as scientists primarily don't have all of those skills that takes the products from desktop to products. So there comes in again, the importance of collaborations with people who have different backgrounds. And there are many technologies out there that I think could be very impactful and useful.They sometimes don't make it to the clinic or to the use of humankind either because it just didn't happen, wasn't the right time or other effects came into the picture that I just talked about. Or sometimes there isn't a direct link that you couldn't see that the technology could actually solve that problem. And the person who deals with the problem, or let's say the biologists or people in medicine are used to doing it one way for many years.And the people on the technology side mostly if you're not having a biotechnology focus, are not aware of the problems in medicine. So bringing these two sides together is a serious interdisciplinary research. And I think in the past years, the whole emphasis both at NIH level and that we see in research labs and universities is to generate interdisciplinary research.So people end up getting PhDs where they have to know multiple fields. For instance, for my PhD, I had to know acoustics, I had to know mems, I had to know microfluidics and I had to apply this for polymers. So now you see kinda very depth of knowledge in one field where you had to know actually three other fields quite well to be able to solve that problem.So I think the answer is in interdisciplinary research combined with people with business skills to make it available to use of the people, it's a whole big process and some inefficiencies that come in at certain locations. Cause that low percent of tech transfer.

Utilizando Micro-Electro-Mechanical Systems (MEMS) para desarrollar herramientas de diagnóstico

Biología

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.

Microfabricación de chip del tamaño de andamios para el cultivo de células en tres dimensiones

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

Compact Lens-less Digital Holographic Microscope for MEMS Inspection and Characterization

A micro-electro-mechanical-system (MEMS) is a widely used component in many industries, including energy, biotechnology, medical, communications, and automotive. However, effective inspection and characterization metrology systems are needed to ensure the functional reliability of MEMS. This study presents a system based on digital holography as a tool for MEMS metrology. Digital holography has gained increasing attention in the past 20 years. With the fast development and decreasing cost of sensor arrays, resolution of such systems has increased broadening potential applications. Thus, it has attracted attention from both research and industry sides as a potential reliable tool for industrial metrology. Indeed, by recording the interference pattern between an object beam (which contains sample height information) and a reference beam on a CCD camera, one can retrieve the quantitative phase information of an object. However, most of digital holographic systems are bulky and thus not easy to implement on industry production lines. The novelty of the system presented is that it is lens-less and thus very compact. In this study, it is shown that the Compact Digital Holographic Microscope (CDHM) can be used to evaluate several characteristics typically consider as criteria in MEMS inspections. The surface profiles of MEMS in both static and dynamic conditions are presented. Comparison with AFM is investigated to validate the accuracy of the CDHM.

We present a compact reflection digital holographic system (CDHM) for inspection and characterization of MEMS devices. A lens-less design using a diverging input wave providing natural geometrical magnification is demonstrated. Both static and dynamic studies are presented.

Compacto holográfica microscopio digital Lente menos por MEMS Inspección y Caracterización

A micro-electro-mechanical-system (MEMS) is a widely used component in many industries, including energy, biotechnology, medical, communications, and ...

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.

Fabricación de actuadores electromecánicos electromecánicos activos basados en carbono

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

Fabrication of Micro-Patterned Chip with Controlled Thickness for High-Throughput Cryogenic Electron Microscopy

A major limitation for the efficient and high-throughput structure analysis of biomolecules using cryogenic electron microscopy (cryo-EM) is the difficulty of preparing cryo-EM samples with controlled ice thickness at the nanoscale. The silicon (Si)-based chip, which has a regular array of micro-holes with graphene oxide (GO) window patterned on a thickness-controlled silicon nitride (SixNy) film, has been developed by applying microelectromechanical system (MEMS) techniques. UV photolithography, chemical vapor deposition, wet and dry etching of the thin film, and drop-casting of 2D nanosheet materials were used for mass-production of the micro-patterned chips with GO windows. The depth of the micro-holes is regulated to control the ice thickness on-demand, depending on the size of the specimen for cryo-EM analysis. The favorable affinity of GO toward biomolecules concentrates the biomolecules of interest within the micro-hole during cryo-EM sample preparation. The micro-patterned chip with GO windows enables high-throughput cryo-EM imaging of various biological molecules, as well as inorganic nanomaterials.

A newly developed micro-patterned chip with graphene oxide windows is fabricated by applying microelectromechanical system techniques, enabling efficient and high-throughput cryogenic electron microscopy imaging of various biomolecules and nanomaterials.

Fabricación de chip micropatrón con espesor controlado para microscopía electrónica criogénica de alto rendimiento

A major limitation for the efficient and high-throughput structure analysis of biomolecules using cryogenic electron microscopy (cryo-EM) is the ...

An Additive Manufacturing Technique for the Facile and Rapid Fabrication of Hydrogel-based Micromachines with Magnetically Responsive Components

Polyethylene glycol (PEG)-based hydrogels are biocompatible hydrogels that have been approved for use in humans by the FDA. Typical PEG-based hydrogels have simple monolithic architectures and often function as scaffolding materials for tissue engineering applications. More sophisticated structures typically take a long time to fabricate and do not contain moving components. This protocol describes a photolithography method that allows for facile and rapid microfabrication of PEG structures and devices. This strategy involves an in-house developed fabrication stage that allows for the rapid fabrication of 3D structures by building upwards in a layer-by-layer fashion. Independent moving components can also be aligned and assembled onto support structures to form integrated devices. These independent components are doped with superparamagnetic iron oxide nanoparticles that are sensitive to magnetic actuation. In this manner, the fabricated devices can be actuated using external magnets to yield movement of the components within. Hence, this technique allows for the fabrication of sophisticated MEMS-like devices (micromachines) that are composed entirely out of a biocompatible hydrogel, able to function without an onboard power source, and respond to a contact-less method of actuation. This manuscript describes the fabrication of both the fabrication set-up as well as the step-by-step method for the microfabrication of these hydrogels-based MEMS-like devices.

An additive manufacturing strategy for processing UV-crosslinkable hydrogels has been developed. This strategy allows for the layer-by-layer assembly of microfabricated hydrogel structures as well as the assembly of independent components, yielding integrated devices containing moving components that are responsive to magnetic actuation.

Un aditivo fabricación técnica para la fabricación fácil y rápida de Micromachines base de hidrogel con componentes magnéticamente sensibles

Polyethylene glycol (PEG)-based hydrogels are biocompatible hydrogels that have been approved for use in humans by the FDA. Typical PEG-based hydrogels ...

Fabrication of a Multiplexed Artificial Cellular MicroEnvironment Array

Cellular microenvironments consist of a variety of cues, such as growth factors, extracellular matrices, and intercellular interactions. These cues are well orchestrated and are crucial in regulating cell functions in a living system. Although a number of researchers have attempted to investigate the correlation between environmental factors and desired cellular functions, much remains unknown. This is largely due to the lack of a proper methodology to mimic such environmental cues in vitro, and simultaneously test different environmental cues on cells. Here, we report an integrated platform of microfluidic channels and a nanofiber array, followed by high-content single-cell analysis, to examine stem cell phenotypes altered by distinct environmental factors. To demonstrate the application of this platform, this study focuses on the phenotypes of self-renewing human pluripotent stem cells (hPSCs). Here, we present the preparation procedures for a nanofiber array and the microfluidic structure in the fabrication of a Multiplexed Artificial Cellular MicroEnvironment (MACME) array. Moreover, overall steps of the single-cell profiling, cell staining with multiple fluorescent markers, multiple fluorescence imaging, and statistical analyses, are described.

This article describes the detailed methodology to prepare a Multiplexed Artificial Cellular MicroEnvironment (MACME) array for high-throughput manipulation of physical and chemical cues mimicking in vivo cellular microenvironments and to identify the optimal cellular environment for human pluripotent stem cells (hPSCs) with single-cell profiling.

Fabricación de una Matriz microambiente celular Artificial multiplexados

Cellular microenvironments consist of a variety of cues, such as growth factors, extracellular matrices, and intercellular interactions. These cues are ...