Using low-cost alcohol sensors to monitor real-time olfactory information during odor-guided navigation

Olfaction -- an evolutionarily conserved chemosensory modality -- guides navigation and decision-making in organisms from multiple phyla within the animal kingdom. However, using olfactory cues to guide navigation is a complicated problem. This is because the spread of odor molecules from the source is governed by turbulent and chaotic air currents, resulting in intermittent and spatiotemporally varying sensory cues as odor plumes. Precisely correlating olfactory information with behavior and neurophysiology from freely behaving animals has thus been a challenging avenue due to the dynamic nature of the odor plumes. Current technologies for chemical quantification are cumbersome and not feasible for monitoring the olfactory information at the temporal and spatial scales relevant for plume and odor tracking in animals. Here we present an alternate method for real-time monitoring of olfactory information using low-cost, lightweight sensors that robustly detect common solvent molecules, like alcohols. Paired recordings were made from these ethanol sensors with a Photoionization detector (PID) to precisely controlled ethanol stimuli. The ethanol sensor recordings were then deconvolved using a double exponential kernel, showing robust correlations with the PID recordings at behaviorally relevant time, frequency and spatial scales. Furthermore, the light weight of these sensors allows us to mount them on the heads of freely behaving rodents engaged in odor-guided navigation. Our preliminary experiments in mice show robust behavioral and neurophysiological responses correlated with ethanol plume contacts detected by these sensors.