A Highly Sensitive Toluene Gas Sensor Based on Pd/PdO Decorated SnO₂ Prepared by Electrospinning

Lung cancer is the most commonly diagnosed cancer and is the leading cause of death worldwide. Recently, the diagnosis of diseases using the exhaled breath analysis method has attracted more and more attention. Although the breath diagnosis of lung cancer has already been realized using organic (carbon) material based gas sensor arrays, more stable and more sensitive metal oxide semiconductor based gas sensors applied to lung cancer diagnosis are still needed. Toluene is one of the main biomarkers of lung cancer in exhaled breath. The concentration difference in breath toluene between lung cancer patients and healthy people is about 50 ppb. Here, we have fabricated an ultrasensitive toluene gas sensor based on Pd/PdO decorated SnO2 nanofibers prepared by electrospinning. It has a detection limit of 50 ppb at the optimal operating temperature of 285 °C, which meets the detection limit requirement for the lung cancer diagnosis. The sensor has good linear response, repeatability, selectivity (toward 20 kinds of common VOCs), long-term stability (>105 days), and batch-to-batch reproducibility, where 10 sensors fabricated from 10 different batches of sensing materials have almost the same gas sensing performance. It also has a good discrimination ability toward the ppb level of toluene contained in the breath, which is verified by using the breath as the diluting background gas. The sensor has great potential to be used in the breath diagnosis of lung cancer.