A Highly Sensitive\nToluene Gas Sensor Based on Pd/PdO\nDecorated SnO<sub>2</sub> Prepared by Electrospinning

Lung cancer is the most commonly diagnosed cancer and\nis the leading\ncause of death worldwide. Recently, the diagnosis of diseases using\nthe exhaled breath analysis method has attracted more and more attention.\nAlthough the breath diagnosis of lung cancer has already been realized\nusing organic (carbon) material based gas sensor arrays, more stable\nand more sensitive metal oxide semiconductor based gas sensors applied\nto lung cancer diagnosis are still needed. Toluene is one of the main\nbiomarkers of lung cancer in exhaled breath. The concentration difference\nin breath toluene between lung cancer patients and healthy people\nis about 50 ppb. Here, we have fabricated an ultrasensitive toluene\ngas sensor based on Pd/PdO decorated SnO<sub>2</sub> nanofibers prepared\nby electrospinning. It has a detection limit of 50 ppb at the optimal\noperating temperature of 285 °C, which meets the detection limit\nrequirement for the lung cancer diagnosis. The sensor has good linear\nresponse, repeatability, selectivity (toward 20 kinds of common VOCs),\nlong-term stability (>105 days), and batch-to-batch reproducibility,\nwhere 10 sensors fabricated from 10 different batches of sensing materials\nhave almost the same gas sensing performance. It also has a good discrimination\nability toward the ppb level of toluene contained in the breath, which\nis verified by using the breath as the diluting background gas. The\nsensor has great potential to be used in the breath diagnosis of lung\ncancer.