Development of highly sensitive optical sensor from carbon nanotube-alumina nanocomposite free-standing films: CNTs loading dependence sensor performance Analysis

We report a highly sensitive optical sensor based on free-standing thin films derived from multi-walled carbon nanotubes (MWCNTs)-Alumina nanocomposite by Gel-cast technique. The sensing principle involves the change in the resistance/conductance of the fabricated nanocomposite film on interaction with the optical stimulus. The performance of the sensor strongly depends − on loading and dispersion of MWCNTs in Alumina host matrix; wavelength; and power density of the laser beam. The optimized loading of CNTs to achieve maximum sensitivity was 1.5 wt%. The sensitivity of the sensor shows linear relationship with power density of the laser beam and found to be highly sensitive in Vis-NIR region. The maximum sensitivity of the sensor is found to be 13.2% at 635 nm wavelength, 3.5 mW/mm2 power density of laser beam and at 1.5 wt% MWCNTs loading in Alumina host matrix. At this loading, the response time and recovery time of the sensor are found to be 1.7 s and 2.1 s respectively. The additional advantage of the present sensor is that it is facile and cost-effective method to fabricate high performance optical sensors.