This work was supported by Technologico de Monterrey and the University of California at Irvine.

1. 3D Human Hair-derived Carbon Structure Fabrication
NOTE: Use personal protective equipment. Follow laboratory instructions to use the instruments and to work inside the laboratory.
<ol>
	<li>Prepare collected human hair by washing it with DI water and drying it with N2 gas.</li>
	<li>Arrange the hairs as desired, such as in parallel strands, cross over, with two hairs wound together, etc.</li>
	<li>Attach the hairs to a silicon substrate using SU8 or keep them directly...

<ol>
	<li>Wang, C., Jia, G., Taherabadi, L. H., Madou, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+method+for+the+fabrication+of+high-aspect+ratio+C-MEMS+structures.">A novel method for the fabrication of high-aspect ratio C-MEMS structures.</a> J Microelectromech Syst. 14 (2), 348-358 (2005).</li><li>Jong, K. P. D., Geus, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Carbon+nano&#64257;bers:+catalytic+synthesis+and+applications.">Carbon nano&#64257;bers: catalytic synthesis and applications.</a> Catal Rev Sci Eng. 42, 481-510 (2000).</li><li>Elrouby, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrochemical+applications+of+carbon+nanotube.">Electrochemical applications of carbon nanotube.</a> J Nano Adv Mat. 1 (1), 23-38 (2013).</li><li>Baughman, R. H., Zakhidov, A. A., Heer, W. A. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Carbon+nanotubes-the+route+toward+applications.">Carbon nanotubes-the route toward applications.</a> Science. 297, 787-792 (2002).</li><li>Kumar, R., Singh, R. K., Singh, D. 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(1-3), 184-190 (2006).</li><li>Sharma, S., Kalita, G., Hirano, R., Hayashi, Y., Tanemura, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+gas+composition+on+the+formation+of+graphene+domain+synthesized+from+camphor.">Influence of gas composition on the formation of graphene domain synthesized from camphor.</a> Mater Lett. 93, 258-262 (2013).</li><li>Ghosh, P., Afre, R. A., Soga, T., Jimbo, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple+method+of+producing+single-walled+carbon+nanotubes+from+a+natural+precursor:+eucalyptus+oil.">A simple method of producing single-walled carbon nanotubes from a natural precursor: eucalyptus oil.</a> Mater Lett. 61 (17), 3768-3770 (2007).</li><li>Kumar, R., Tiwari, R., Srivastava, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Scalable+synthesis+of+aligned+carbon+nanotubes+bundles+using+green+natural+precursor:+neem+oil.">Scalable synthesis of aligned carbon nanotubes bundles using green natural precursor: neem oil.</a> Nanoscale Res Lett. 6 (1), 92-97 (2011).</li><li>Liang, Y., Wu, D., Fu, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Carbon+microfibers+with+hierarchical+porous+structure+from+electrospun+fiber-like+natural+biopolymer.">Carbon microfibers with hierarchical porous structure from electrospun fiber-like natural biopolymer.</a> Sci Rep. 3, 1-5 (2013).</li><li>Gupta, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+hair+"waste"+and+its+utilization:+gaps+and+possibilities.">Human hair "waste" and its utilization: gaps and possibilities.</a> J Waste Manag. 2014, 1-17 (2014).</li><li>Qian, W., Sun, F., Xu, Y., Qiu, L., Liu, C., Wang, S., Yan, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+hair-derived+carbon+flakes+for+electrochemical+supercapacitors.">Human hair-derived carbon flakes for electrochemical supercapacitors.</a> Energy Environ Sci. 7, 379-386 (2014).</li><li>Pramanick, B., Cadenas, L. B., Kim, D. M., Lee, W., Shim, Y. B., Martinez-Chapa, S. O., Madou, M. J., Hwang, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+hair-derived+hollow+carbon+microfibers+for+electrochemical+sensing.">Human hair-derived hollow carbon microfibers for electrochemical sensing.</a> Carbon. 107, 872-877 (2016).</li><li>Miura, N., Numaguchi, T., Yamada, A., Konagai, M., Shirakashi, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Room+temperature+operation+of+amorphous+carbon-based+single-electron+transistors+fabricated+by+beam-induced+deposition+techniques.">Room temperature operation of amorphous carbon-based single-electron transistors fabricated by beam-induced deposition techniques.</a> Jpn J Appl Phys. 37 (2), L423-L425 (1998).</li><li>Irie, M., Endo, S., Wang, C. L., Ito, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication+and+properties+of+lateral+p-i-p+structures+using+single+crystalline+CVD+diamond+layers+for+high+electric+&#64257;eld+applications.">Fabrication and properties of lateral p-i-p structures using single crystalline CVD diamond layers for high electric &#64257;eld applications.</a> Diamond Rel Mater. 12, 1563-1568 (2003).</li><li>Tay, B. K., Sheeja, D., Yu, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+stress+reduction+of+tetrahedral+amorphous+carbon+&#64257;lms+for+moving+mechanical+assemblies.">On stress reduction of tetrahedral amorphous carbon &#64257;lms for moving mechanical assemblies.</a> Diamond Rel Mater. 12 (2), 185-194 (2003).</li><li>Kamath, R. R., Madou, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+carbon+interdigitated+electrode+arrays+for+redox-amplification.">Three-dimensional carbon interdigitated electrode arrays for redox-amplification.</a> Anal Chem. 86 (6), 2963-2971 (2014).</li><li>Sharma, S., Khalajhedayati, A., Rupert, T. J., Madou, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=SU8+derived+glassy+carbon+for+lithium+ion+batteries.">SU8 derived glassy carbon for lithium ion batteries.</a> ECS Trans. 61 (7), 75-84 (2014).</li><li>Kim, D., Pramanick, B., Salazar, A., Tcho, I. -. W., Madou, M. J., Jung, E. S., Choi, Y. -. K., Hwang, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=3D+carbon+electrode+based+triboelectric+nanogenerator.">3D carbon electrode based triboelectric nanogenerator.</a> Adv Mater Technol. 1 (8), 1-7 (2016).</li><li>Duarte, R. M., Gorkin, R. A., Samra, K. B., Madou, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+integration+of+3D+carbon-electrode+dielectrophoresis+on+a+CD-like+centrifugal+microfluidic+platform.">The integration of 3D carbon-electrode dielectrophoresis on a CD-like centrifugal microfluidic platform.</a> Lab Chip. 10 (8), 1030-1043 (2010).</li><li>Mund, K., Richter, G., Weidlich, E., Fahlstrom, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrochemical+properties+of+platinum,+glassy+carbon,+and+pyrographite+as+stimulating+electrodes.">Electrochemical properties of platinum, glassy carbon, and pyrographite as stimulating electrodes.</a> Pacing Clin Electrophysiol. 9 (6), 1225-1229 (1986).</li><li>Xua, H., Malladi, K., Wang, C., Kulinsky, L., Song, M., Madou, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Carbon+post-microarrays+for+glucose+sensors.">Carbon post-microarrays for glucose sensors.</a> Biosens Bioelectron. 23 (11), 1637-1644 (2008).</li><li>Sharma, S., Madou, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Micro+and+nano+patterning+of+carbon+electrodes+for+bioMEMS.">Micro and nano patterning of carbon electrodes for bioMEMS.</a> Bioinspir Biomim Nanobiomat. 1, 252-265 (2012).</li><li>Pramanick, B., Martinez-Chapa, S. O., Madou, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication+of+biocompatible+hollow+microneedles+using+the+C-MEMS+process+for+transdermal+drug+delivery.">Fabrication of biocompatible hollow microneedles using the C-MEMS process for transdermal drug delivery.</a> ECS Trans. 72 (1), 45-50 (2016).</li></ol>

The authors have nothing to disclose.

In this paper the methods for manufacturing a variety of carbon microstructures based on the pyrolysis of natural precursor materials or photo-patterned polymer structures were reported. The carbon materials resulting from both the traditional and non-conventional C-MEMS/C-NEMS processes are typically found to be glassy carbons. Glassy carbon is a widely used electrode material for electrochemistry and also for high-temperature applications. The microstructure of glassy carbon is composed of both crystalline and amorphou...

Carbon has many allotropes and, depending on the particular application, one of the following allotropes can be chosen: carbon nanotubes (CNTs), graphite, diamond, amorphous carbon, lonsdaleite, buckminsterfullerene (C60), fullerite (C540), fullerene (C70), and glassy carbon1,2,3,4. Glassy carbon is one of the most widely used allotropes because of its physical properties, including high isotropy. It also has the following properties: good electrical conductivity, low thermal expansion coefficient, and gas impermeability.
There has been a continuous search for carbon-rich precursor materials to obtain carbon structures. These precursors can be manmade materials or natural products that are available in particular shapes, and even include waste products. A wide variety of micro/nanostructures are formed via biological or environmental processes in nature, resulting in unique features that are extremely difficult to create using conventional manufacturing tools. As patterning took place naturally in this case, the synthesis of nanomaterials using natural and waste hydrocarbon precursors could be carried out using an easy, one-step process of thermal decomposition in an inert or vacuum atmosphere, called pyrolysis5. High-quality graphene, single-walled CNTs, multi-walled CNTs, and carbon dots have been produced by thermal decomposition or the pyrolysis of plant-derived precursors and wastes, including seeds, fibers, and oils, such as turpentine oil, sesame oil, neem oil (Azadirachta indica), eucalyptus oil, palm oil, and jatropha oil. Also, camphor products, tea-tree extracts, waste foods, insects, agro wastes, and food products have been utilized6,7,8,9 Recently, researchers have even used silk cocoons as a precursor material to prepare porous carbon microfibers10. Human hair, usually considered a waste material, was recently used by this team. It is made up of approximately 91% polypeptides, which contain more than 50% carbon; the rest are elements such as oxygen, hydrogen, nitrogen, and sulphur11. Hair also comes with several interesting properties, such as very slow degradation, high tensile strength, high thermal insulation, and high elastic recovery. Recently, it has been used to prepare carbon flakes employed in supercapacitors12 and to create hollow carbon microfibers for electrochemical sensing13.
The machining of a bulk carbon material to fabricate three-dimensional (3D) structures is a difficult task, as the material is very brittle. Focused ion beam14,15 or reactive ion etching16 may be useful in this context, but they are expensive and time-consuming processes. Carbon microelectromechanical system (C-MEMS) technology, which is based on the pyrolysis of patterned polymeric structures, represents a versatile alternative. In the past two decades, C-MEMS and carbon nanoelectromechanical systems (C-NEMS) have received much attention because of the simple and inexpensive fabrication steps involved. The conventional C-MEMS fabrication process is carried out in two steps: (i) patterning a polymer precursor (e.g., a photoresist) with photolithography and (ii) pyrolysis of the patterned structures. Ultraviolet (UV)-curable polymer precursors, such as SU8 photoresists, are often used to pattern structures based on photolithography. In general, the photolithography process includes steps for spin coating, soft bake, UV exposure, post bake, and development. In the case of C-MEMS; silicon; silicon dioxide; silicon nitride; quartz; and, more recently, sapphire have been used as substrates. The photo-patterned polymer structures are carbonized at a high temperature (800-1,100 &#176;C) in an oxygen-free environment. At those elevated temperatures in a vacuum or inert atmosphere, all of the non-carbon elements are removed, leaving only carbon. This technique allows for the attainment of high-quality, glassy carbon structures, which are very useful for many applications, including electrochemical sensing17, energy storage18, triboelectric nanogeneration19, and electrokinetic particle manipulation20. Also, the fabrication of 3D microstructures with high aspect ratios using C-MEMS has become relatively easy and has led to a wide variety of carbon electrodes applications18,21,22,23, often replacing noble metal electrodes.
In this work, the recent development of a simple and cost-effective way to fabricate hollow carbon microfibers from human hair using non-conventional C-MEMS technology13 is introduced. The conventional SU8 polymer-based C-MEMS process is also described here. Specifically, the fabrication procedure for high-aspect ratio solids and hollow SU8 structures is described24.

<table border="0" cellpadding="0" cellspacing="0" width="690">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">SU8-2100</td>
			<td style="width:141px;">Microchem</td>
			<td style="width:167px;">Product number-Y1110750500L</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Spinner</td>
			<td style="width:141px;">Laurell Technologies Corporation</td>
			<td style="width:167px;">Model-WS650HZB-23NPP/UD3</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Hotplate</td>
			<td style="width:141px;">Torrey Pines Scientific</td>
			<td style="width:167px;">HS61</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">UV-exposer</td>
			<td style="width:141px;">Mercury Lamp, SYLVANIA</td>
			<td style="width:167px;">H44GS-100M, P/N-34-0054-01</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Photomask</td>
			<td style="width:141px;">CAD/Art</td>
			<td style="width:167px;"></td>
			<td>No number</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Developer&#160;</td>
			<td style="width:141px;">Microchem</td>
			<td style="width:167px;">Y020100 4000L&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">DI water system</td>
			<td style="width:141px;">Milli Q</td>
			<td style="width:167px;">ZOOQOVOTO</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">IPA</td>
			<td style="width:141px;">CTR Sientific</td>
			<td style="width:167px;">CTR 01244</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">N2 gas</td>
			<td style="width:141px;">AOC Mexico</td>
			<td style="width:167px;"></td>
			<td>No number</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Furnace</td>
			<td style="width:141px;">PEO 601, ATV Technologie GMBH</td>
			<td style="width:167px;">Model-PEO 601, Serial no.-195</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Si/SiO2</td>
			<td style="width:141px;">Noel Technologies</td>
			<td style="width:167px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

fabrication of 3d carbon microelectromechanical systems (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 and hollow glassy carbon microfibers derived from human hairs is introduced. The long and hollow carbon structures were made by the pyrolysis of human hair at 900 &#176;C in a N2 atmosphere. The morphology and chemical composition of natural and pyrolyzed human hairs were investigated using scanning electron microscopy (SEM) and electron-dispersive X-ray spectroscopy (EDX), respectively, to estimate the physical and chemical changes due to pyrolysis. Raman spectroscopy was used to confirm the glassy nature of the carbon microstructures. Pyrolyzed hair carbon was introduced to modify screen-printed carbon electrodes ; the modified electrodes were then applied to the electrochemical sensing of dopamine and ascorbic acid. Sensing performance of the modified sensors was improved as compared to the unmodified sensors. To obtain the desired carbon structure design, carbon micro-/nanoelectromechanical system (C-MEMS/C-NEMS) technology was developed. The most common C-MEMS/C-NEMS fabrication process consists of two steps: (i) the patterning of a carbon-rich base material, such as a photosensitive polymer, using photolithography; and (ii) carbonization through the pyrolysis of the patterned polymer in an oxygen-free environment. The C-MEMS/NEMS process has been widely used to develop microelectronic devices for various applications, including in micro-batteries, supercapacitors, glucose sensors, gas sensors, fuel cells, and triboelectric nanogenerators. Here, recent developments of a high-aspect ratio solid and hollow carbon microstructures with SU8 photoresists are discussed. The structural shrinkage during pyrolysis was investigated using confocal microscopy and SEM. Raman spectroscopy was used to confirm the crystallinity of the structure, and the atomic percentage of the elements present in the material before and after pyrolysis was measured using EDX.

A schematic of the fabrication process for human hair-derived hollow carbon microfibers is shown in Figure 1. The carbonized human hair was characterized using SEM to estimate the shrinkage. The hair diameter shrank from 82.88 &#177; 0.003 &#181;m to 31.42 &#177; 0.003 &#181;m due to the pyrolysis. Scanning electron microscopic (SEM) images of various patterns made using hair-derived carbon microfibers are shown in Figure 2. The ...

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

Long and hollow glassy carbon microfibers were fabricated based on the pyrolysis of a natural product, human hair. The two fabrication steps of carbon microelectromechanical and carbon nanoelectromechanical systems, or C-MEMS and C-NEMS, are: (i) photolithography of a carbon-rich polymer precursor and (ii) pyrolysis of the patterned polymer precursor.

Fabrication of 3D Carbon Microelectromechanical Systems (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 ...

The overall goal of this procedure is to fabricate 3D carbon structures using conventional and nonconventional carbon microelectromechanical system processes with carbon sources of SU-8 polymer and human hair, respectively. 20 years ago, we actually started a complete new process where we are replacing silicon as the major material for making MEMS devices, microelectromechanical systems. Our idea is that carbon is a better material than silicon for making these three-dimensional shapes.Specifically, we take a polymer precursor, pattern it, and then convert it to carbon at high temperature, around 900 to 1, 000 degrees C, in an inert atmosphere. What happens in that process is the shape is preserved, but it shrinks. In order words, you have isometric shrinkage, and you end up with any 3D carbon shape you might imagine.That is called carbon MEMS. It is much less expensive because all I do is take a carbon precursor, a polymer, and pattern it in three dimension and then convert it to carbon. Carbon comes in many allotropes, from diamond to graphite to glassy carbon.Depending on how I pretreat the polymer's chains, I can actually end up with a 3D carbon structure that's more graphitic or more diamond-like or glassy carbon-like. Today, the process of carbon MEMS will be demonstrated for you by my graduate student, Esham Shomloo. To begin the polymer structure fabrication procedure, first set a hotplate to 95 degrees Celsius.Turn on a spin coater and the connected vacuum pump. Program a two-step spin coating sequence with a first step of 10 seconds at 500 rpm and a second step of 30 seconds at 1, 000 rpm, both with a ramp rate of 100 rpm per second. Place a silicon wafer or other substrate on the vacuum holder of the spin coater.Start the vacuum to fix the substrate to the holder. Apply sufficient epoxy resin-based negative photoresist to cover the surface of the substrate. Run the two-step spin coating sequence to achieve a final photoresist thickness of one to 250 micron.Release the substrate from the holder. Using tweezers, carefully transfer the substrate to the 95 degrees Celsius hotplate without disturbing the thin film. Bake the substrate at 95 degrees Celsius for one to 40 minutes, depending on the thickness of the photoresist.During the soft bake, turn on the photolithography UV system and set the exposure time to 12 seconds. Once the soft bake has completed, transfer the substrate to the UV system. Clamp the patterned mask with a vacuum mask holder.Place the mask holder with the mask on the UV exposure system. Put the photoresist-coated substrate on the stage of the UV exposure system. Cover the substrate with the patterned mask, and gently press the mask against the substrate.Expose the substrate to UV light for the set duration, and then separate the mask from the substrate, Perform a post-exposure bake at 95 degrees Celsius for one to 15 minutes, depending on the thickness of the photoresist. Immerse the substrate in the appropriate developer solution for one to 20 minutes while gently shaking the container. Dry the patterned wafer under a stream of nitrogen gas or compressed air.Inspect the wafer under a microscope at 50 times magnification to verify that the desired pattern is well shaped. Then, place the patterned wafer in a pressurized, open-ended tube furnace. Set the flow rate for the first 15 minutes of the sequence to 1.5 times the volume of the furnace tube per minute and then to the furnace tube volume per minute for the remainder of the sequence.Set a sequence of ramping to 300 degrees Celsius at five degrees Celsius per minute, holding at 300 degrees Celsius for one hour, ramping to 900 degrees Celsius at the same rate and holding for one hour, and then cooling to 300 degrees Celsius at 10 degrees Celsius per minute. Then, run the heating and cooling sequence. Once the sequence has completed, wait for the pyrolyzed sample to cool to room temperature under a stream of nitrogen gas.Then, turn off the furnace and gas flow. Then, carefully remove the pyrolyzed sample from the furnace and proceed to characterization. To begin fabricating a hair-derived 3D carbon structure, wash a sample of human hair with deionized water.Dry the hair sample under a stream of nitrogen gas. Obtain a silicon wafer or a ceramic boat. Arrange the individual hairs in the desired configuration on the wafer or in the boat.If using a silicon wafer, fix the hairs to the wafer with epoxy-based polymer. Then, place the sample in a pressurized, open-ended tube furnace. Run the pyrolysis sequence to first stabilize and then carbonize the sample.Allow the sample to cool to room temperature under a flow of nitrogen. Then, carefully remove the sample from the furnace, using tweezers when necessary, and proceed to characterization. Hair-derived carbon microfibers were prepared in various patterns, depending on the initial arrangement of the hair sample.Energy-dispersive X-ray spectroscopy and Raman spectroscopy were performed before and after pyrolysis. Only two peaks corresponding to the D and G bands appeared in the Raman spectrum after pyrolysis. The intensity ratio between the peaks indicated that the microstructures were primarily composed of glassy carbon.Electrochemical sensors were fabricated using bare carbon, carbon nanotubes, or the hair-derived carbon fibers. Cyclic voltammetry of dopamine and ascorbic acid solutions showed that the electrode incorporating the hair-derived carbon fibers showed improved performance compared to the bare carbon, though they did not match the performance of carbon nanotubes. I hope that this short video on carbon MEMS inspires many of you to explore the process by yourselves.Indeed, there is many, many more applications that I can see coming out of this simple process. This can range from novel batteries, new fuel cells, new sensors, et cetera. Perhaps, overtaking silicon as the most important MEMS material.

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12.0K visualizações.  Tecnologico de Monterrey. The overall goal of this procedure is to fabricate 3D carbon structures using conventional and nonconventional carbon microelectromechanical system processes with carbon sources of SU-8 polymer and human hair, respectively. 20 years ago, we actually started a complete new process where we are replacing silicon as the major material for making MEMS devices, microelectromechanical systems. Our idea is that carbon is a better material than silicon for making these three-dimensional shapes.