UV-Illumination Induced Desorption of CNT Sensors

This paper presents a chemical sensor employing electronic-grade CNTs (EG-CNTs) as the active sensing element for sodium hypochlorite (NaOCl) detection and the-desorption phenomenon of the sensing element by applying UV illumination. By using AC dielectrophoretic (DEP) technique, EG-CNTs are aligned between the microelectrodes fabricated on a glass substrate with a gap distance of 2 mum. A microfluidic chamber is created by bonding a PDMS microchannel of 1mm width onto the glass substrate on which pairs of microelectrodes are fabricated. This microfluidic chamber encloses the EG-CNTs sensing elements and ensures that they are submerged in a chemical solution of certain volume during experimental tests. We demonstrate the electrical response of the sensor to NaOCl solution of different concentrations at room temperature as well as to other chemical reagents for comparison. After the measurement the response, UV illumination with 3 UV light tubes of 15W each is applied to the sensor for desorption of NaOCl molecules. Preliminary experiments show that the response of CNT sensor to NaOCl is intense and varies with concentration of the solution. UV illumination significantly shortens the otherwise long recovery period, thus improves reversibility and repeatability of the CNT-based chemical sensors.