Precise Alignment of Individual Single-Walled Carbon Nanotube Using Dielectrophoresis Method for Development and Fabrication of pH Sensor (original) (raw)
Free related PDFsRelated papers
Development and fabrication of single-walled carbon nanotube (SWNT) based pH sensor were reported. The precise alignment of individual SWNT using dielectrophoresis method between the two microgap electrodes was conducted, and the effects of precise alignment of individual SWNT on impedance, long term stability, and capacitance of the sensor were studied. The pH sensor was fabricated using conventional photolithography and wet etching process. The impedance values were found to decrease in the order of distilled water > pH 10 > pH 5 > pH 3 > air. Without the alignment of SWNT, the capacitances values decreased with increasing of pH values at low frequency. All the impedance and capacitance results were highly repeatable.
Free PDF
TOPICAL REVIEW: Recent progress in carbon nanotube-based gas sensors
Nanotechnol, 2008
The development of carbon nanotube-(CNTs-)based gas sensors and sensor arrays has attracted intensive research interest in the last several years because of their potential for the selective and rapid detection of various gaseous species by novel nanostructures integrated in miniature and low-power consuming electronics. Chemiresistors and chemical field effect transistors are probably the most promising types of gas nanosensors. In these sensors, the electrical properties of nanostructures are dramatically changed when exposed to the target gas analytes. In this review, recent progress on the development of different types of CNT-based nanosensors is summarized. The focus was placed on the means used by various researchers to improve the sensing performance (sensitivity, selectivity and response time) through the rational functionalization of CNTs with different methods (covalent and non-covalent) and with different materials (polymers and metals).
Free PDF
This paper presents the development and fabrication of carbon nanotube (CNT) based sensor devices through morphological and electrical characterization. The silicon oxide (SiO 2) as insulator is formed by dry oxidation process and Aurum (Au) layer is deposited using thermal evaporator. Then, the electrodes pattern is transferred by photolithography process. The single-walled carbon nanotubes (SWNTs) were mixed with isopropyl alcohol (IPA) for dispersion process. The suspended SWNT was aligned between the electrodes gap by using AC dielectrophoresis method. The composition of SWNT aligned was determined by The conductivity of SWNT aligned on devices was decreases as pH buffer solution increases. Capacitances value for pre-SWNT aligned is much higher than post-SWNT aligned.
Free PDF
Free PDF
Free PDF
Free PDF
Free PDF
Integration of nanosensors into a sealed microchannel in a hybrid lab-on-a-chip device
Commonly used assembly methods for microfluidic devices rely heavily on direct, manual bonding of different components with limited visual aids. The manual operation is likely to cause damage to existing structures, especially to nanoscale sensors on the substrate. Here we report a novel approach to integrate nanosensors into a lab-on-a-chip device with total elimination of operational errors from the manual bonding process. The microfluidic components are composed of an ultraviolet (UV) light-defined, cross-linked SU-8 microchannel and a polydimethylsiloxane (PDMS) top cover. The hybrid microfluidic structure provides a fully sealed microchannel and precisely positioned features. Well-organized single-walled carbon nanotube (SWNT) thin films are deposited and aligned across the electrodes on a silicon substrate with dielectrophoresis. The assembly of SWNTs is carried out in a sealed microchannel which eliminates the potential damage of the nanosensors during the bonding process. The SWNT devices are configured as two-terminal resistor-type sensors with the metal electrodes as the probing pads and the dielectrophoretically captured SWNTs as the sensing elements. To demonstrate the feasibility of this integration approach, an assembled SWNT device is measured as an integrated flow sensor to monitor the flow rate in the microchannel. This lab-on-a-chip device is designed as a platform that can be expanded for more applications. For example, with minimal modifications, the device can be used in chemical sensing, biosensing, and medical research.
Free PDF
Free PDF
Free PDF
