Using Insect Electroantennogram Sensors on Autonomous Robots for Olfactory Searches

Abstract

Robots designed to track chemical leaks in hazardous industrial facilities 1 or explosive traces in landmine fields 2 face the same problem as insects foraging for food or searching for mates 3 : the olfactory search is constrained by the physics of turbulent transport 4. The concentration landscape of wind borne odors is discontinuous and consists of sporadically located patches. A pre-requisite to olfactory search is that intermittent odor patches are detected. Because of its high speed and sensitivity [5][6] , the olfactory organ of insects provides a unique opportunity for detection. Insect antennae have been used in the past to detect not only sex pheromones 7 but also chemicals that are relevant to humans, e.g., volatile compounds emanating from cancer cells 8 or toxic and illicit substances [9][10][11] . We describe here a protocol for using insect antennae on autonomous robots and present a proof of concept for tracking odor plumes to their source. The global response of olfactory neurons is recorded in situ in the form of electroantennograms (EAGs). Our experimental design, based on a whole insect preparation, allows stable recordings within a working day. In comparison, EAGs on excised antennae have a lifetime of 2 hr. A custom hardware/software interface was developed between the EAG electrodes and a robot. The measurement system resolves individual odor patches up to 10 Hz, which exceeds the time scale of artificial chemical sensors 12. The efficiency of EAG sensors for olfactory searches is further demonstrated in driving the robot toward a source of pheromone. By using identical olfactory stimuli and sensors as in real animals, our robotic platform provides a direct means for testing biological hypotheses about olfactory coding and search strategies 13

Explosive sensing with insect-based biorobots

“…Prior works have demonstrated that neural signals such as electroantennogram, which monitors the total activity of the all ORNs [37,38], or behavioral read-outs such as proboscis extension reflex [39], can be used for achieving chemical sensing with invertebrates. We note that the electroantennagram signals, while experimentally easy to acquire, tend to be less discriminatory overall.…”

Reactive Searching and Infotaxis in Odor Source Localization

“…A graphical user interface (written in Qt/C++) visualized both EAG input and neuron output. For more details see [22] , [53] .…”

New electroantennography method on a marine shrimp in water

“…In Lepidoptera, EAG is typically performed from whole insect preparations by cutting the tip of the antenna and inserting it in a glass electrode filled with electrolyte, with the reference electrode inserted in the insect body. Excised antenna can also be used but they have a shorter lifetime (Martinez et al, 2014). In Coleoptera, the recording electrode is inserted in the antenna (Roelofs, 1984).…”