Abdulhameed Abdullah, Halin Izhal Abdul, Mohtar Mohd Nazim, Hamidon Mohd Nizar
Department of Electronic Engineering, Faculty of Engineering, Hadhramout University, Mukalla 50511, Yemen.
Department of Electrical and Electronic Engineering, Faculty of Engineering, Universiti Putra Malaysia, Serdang 43400, Malaysia.
ACS Omega. 2022 Jan 18;7(4):3680-3688. doi: 10.1021/acsomega.1c06323. eCollection 2022 Feb 1.
Surfactants such as sodium dodecyl sulfate (SDS) are used to improve the dispersity of carbon nanotubes (CNTs) in aqueous solutions. The surfactant concentration in CNT solutions is a critical factor in the dielectrophoretic (DEP) manipulation of CNTs. A high surfactant concentration causes a rapid increase in the solution conductivity, while a low concentration results in undesirably large CNT bundles within the solution. The increase in the solution conductivity causes drag velocity that obstructs the CNT manipulation process due to the electrothermal forces induced by the electric field. The presence of large CNT bundles is undesirable since they degrade the device performance. In this work, mathematical modeling and experimental work were used to optimize the concentration of the SDS surfactant in multiwalled carbon nanotube (MWCNT) solutions. The solutions were characterized using dynamic light scattering (DLS) and ultraviolet-visible spectroscopy (UV-Vis) analysis. We found that the optimum SDS concentration in MWCNT solutions for the successful DEP manipulation of MWCNTs was between 0.1 and 0.01 wt %. A novel DEP configuration was then used to assemble MWCNTs across transparent electrodes. The configuration was based on ceiling deposition, where the electrodes were on top of a droplet. The newly proposed configuration reduced the drag velocity and prevented the assembly of large MWCNT bundles. MWCNTs were successfully assembled and aligned across interdigitated electrodes (IDEs). The assembly of MWCNTs from aqueous solutions across transparent electrodes has potential use in future transparent electronics and sensor devices.
诸如十二烷基硫酸钠（SDS）之类的表面活性剂被用于提高碳纳米管（CNT）在水溶液中的分散性。CNT溶液中的表面活性剂浓度是对CNT进行介电泳（DEP）操控的关键因素。高表面活性剂浓度会导致溶液电导率迅速增加，而低浓度则会使溶液中出现不合要求的大尺寸CNT束。溶液电导率的增加会产生拖曳速度，由于电场感应产生的电热力，这种拖曳速度会阻碍CNT的操控过程。大尺寸CNT束的存在是不可取的，因为它们会降低器件性能。在这项工作中，采用数学建模和实验方法来优化多壁碳纳米管（MWCNT）溶液中SDS表面活性剂的浓度。使用动态光散射（DLS）和紫外可见光谱（UV-Vis）分析对溶液进行表征。我们发现，对于成功进行MWCNT的DEP操控而言，MWCNT溶液中的最佳SDS浓度在0.1 wt%至0.01 wt%之间。然后采用一种新颖的DEP配置将MWCNT组装在透明电极上。该配置基于顶部沉积，电极位于液滴上方。新提出的配置降低了拖曳速度，并防止了大尺寸MWCNT束的组装。MWCNT成功地在叉指电极（IDE）上进行了组装和排列。从水溶液中在透明电极上组装MWCNT在未来的透明电子器件和传感器设备中具有潜在应用。
