Chemical vapor sensors respond to changes in ambient vapor composition with changes in conductivity. Ideally, this change is a simple function of the concentration change and rapidly tracks those changes. More importantly, the sensor is at least somewhat selective, not only responding differently to different compounds but also rejecting benign interferents while responding strongly to compounds of interest (TICs/TIMs/CWAs). Characterization of the sensor response to a wide range of challenges is needed to develop better performing sensors. An understanding of adsorption models and the electronic structure of low dimensional materials (e.g., graphene, MoS2, CNT) and molecules will be helpful for this.