Pristine and Pd doped Carbon Nanotube as a Lung Cancer Biomarker for CO₂ and Rn gas: A DFT Analysis

Lung cancer has the highest mortality rate over the years. According to the American Cancer Society, around 1,620 individuals were predicted to die of cancer every day in the United States in 2015 this is roughly equivalent to nearly 590,000 individuals. The death level of lung cancer among males has fallen by 29% over the previous 39 years, while it has risen by 102% among females. There are many methods to sense lung cancer early, but they all are very costly and not user friendly. We develop a carbon nano tube (CNT) based pristine and palladium (Pd) doped sensors for lung cancer pre-diagnosis. There are carbon dioxide (CO₂) and radon (Rn) two leading lung cancer gases. To improve the sensing behavior of pristine CNT, Pd is used as a doping agent. The performance of the sensor is evaluated by using DFT based quantum ATK method, in terms of band gap, density of state (DOS), adsorption energy (E_ads), recovery time (τ), charge transfer, conductance, and sensitivity. The calculated negative adsorption energy confirms the stability of pristine and pd doped CNT and observes the type of interaction with CO₂ and Rn, as physical adsorption, that also confirms the reusability of the sensor and its low operational temperature. It has also been observed that the pd-doped CNT has favorable stability with and without presence of CO₂ and Rn gas molecules in comparison to pristine CNT, whereas the pd-doped CNT has a better recovery time, sensitivity, and better range of detection.