Chemical Sensor Using Dielectrophoretically Assembled Carbon Nanotube on Micro-Trenches

This paper presents a novel carbon nanotube (CNT) sensor, where the micro-trench was designed to enhance the sensing performance. Device designs for suspending CNTs have provided enhanced sensing performance due to the higher surface area of the CNTs. However, previously reported sensors for the suspended CNTs were primarily involved in complicating the fabrication and delicate process of CNT transfer, resulting in a low device yield rate. We designed a micro-trench structure between gold electrodes using conventional photolithography. In addition, we adopted post-assembly of the CNTs based on dielectrophoresis, enabling single-step chemiresistor fabrication while protecting the CNTs from further damage or contamination. The CNT sensor with the micro-trench exhibited improved sensitivity and signal-to-noise ratio in detecting isopropyl alcohol (IPA) by 33 % and 125 %, respectively, compared to the non-trenched device. In addition, the present CNT sensor detected IPA as low as 0.3 ppm.