Pramanick Bidhan, Martinez-Chapa Sergio O, Madou Marc, Hwang Hyundoo
School of Engineering and Sciences, Tecnologico de Monterrey.
School of Engineering and Sciences, Tecnologico de Monterrey; Department of Mechanical and Aerospace Engineering, University of California.
J Vis Exp. 2017 Jun 17(124):55649. doi: 10.3791/55649.
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 °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.
自然界中有各种各样的碳源，具有多种微观/纳米结构构型。在此，介绍一种从人发制备长而中空的玻璃态碳微纤维的新技术。长而中空的碳结构是通过在900℃的氮气气氛中对人发进行热解而制成的。分别使用扫描电子显微镜（SEM）和能量色散X射线光谱（EDX）研究天然和热解人发的形态和化学成分，以评估热解引起的物理和化学变化。拉曼光谱用于确认碳微结构的玻璃态性质。将热解后的毛发碳引入以修饰丝网印刷碳电极；然后将修饰后的电极应用于多巴胺和抗坏血酸的电化学传感。与未修饰的传感器相比，修饰后传感器的传感性能得到了改善。为了获得所需的碳结构设计，开发了碳微/纳机电系统（C-MEMS/C-NEMS）技术。最常见的C-MEMS/C-NEMS制造工艺包括两个步骤：（i）使用光刻技术对富含碳的基材（如光敏聚合物）进行图案化；（ii）在无氧环境中通过对图案化聚合物进行热解来碳化。C-MEMS/NEMS工艺已被广泛用于开发用于各种应用的微电子器件，包括微型电池、超级电容器、葡萄糖传感器、气体传感器、燃料电池和摩擦纳米发电机。在此，讨论了使用SU8光刻胶制备的高纵横比实心和中空碳微结构的最新进展。使用共聚焦显微镜和SEM研究热解过程中的结构收缩。拉曼光谱用于确认结构的结晶度，并使用EDX测量热解前后材料中存在的元素的原子百分比。
