Chemical Source Localization Using Electronic Nose Robotics


Experimental Overview
Experimental Setup
Data Acquisition
Data Processing
Discussion and Future
About Us

The goal of this project is to understand the responses of electronic chemical sensors when exposed isopropyl alcohol. In order to achieve this, we built an experimental setup consisting of an array of six chemical sensors, their corresponding signal conditioning circuitry, and a data acquisition device.  For acquiring and processing the data, we implemented a graphical user interface (GUI) in Labview. Algorithms were then developed to characterize the peaks and valleys for each signal and compare their location to corresponding peaks and valleys in the sensor's pair signal. This provides us with information of which sensor within each sensor pair sensed the odor first. Our end goal is implementing our model on an actual robot. When the sensors are exposed to an odor, the program will measure the delay as the odor passes each sensor pair and using our algorithm will be able to locate the source of the odor. 


Electronic sensing technology is a developing field of study that has greatly advanced over the last decade in technical and consumer applications. Electronic noses are already being introduced in research laboratories, manufacturing processing technology, home and workplace safety monitoring and quality control. We initially attempted using a concentration gradient to locate the source of an odor, but after puzzling results and the publication of  "The Function of Bilateral Odor Arrival Time Differences in Olfactory Orientation of Sharks," by Jayne M. Gardiner and Jelle Atema, in Current Biology this summer. Prior to the release of this article, animals were believed to orient themselves towards an odor by comparing bilateral odor concentration differences, turning toward higher concentrations. However, in the article, a small shark species, 
Mustelus canis, was presented with with carefully timed and measured odor pulses directly into their nares. They turned toward the side stimulated first, even with delayed pulses of higher concentration. This is the first conclusive evidence that under semi-natural conditions and without training, bilateral time differences trump odor concentration differences. We are now using a chemical sensor array and using the delay between peaks and valleys of corresponding sensors to find which sensor sensed the odor first. 

Potential Applications:

The designed GUI and experimental setup can be used as a starting point for future research exploring chemical array signal processing applications, such as chemical source localization and  specific compound detection.