Abstract
Swarms of insects instrumented with wireless electronic backpacks have previously been proposed for potential use in search and rescue operations. Before deploying such biobot swarms, an effective long-term neural-electric stimulus interface must be established, and the locomotion response to various stimuli quantified. To this end, we studied a variety of pulse types (mono- vs. bipolar; voltage- vs. current-controlled) and shapes (amplitude, frequency, duration) to parameters that are most effective for evoking locomotion along a desired path in the Madagascar hissing cockroach (G. portentosa) in response to antennal and cercal stimulation. We identified bipolar, 2 V, 50 Hz, 0.5 s voltage controlled pulses as being optimal for evoking forward motion and turns in the expected contraversive direction without habituation in ≈50% of test subjects, a substantial increase over ≈10% success rates previously reported. Larger amplitudes for voltage (1–4 V) and current (50–150 μA) pulses generally evoked larger forward walking (15.6–25.6 cm; 3.9–5.6 cm/s) but smaller concomitant turning responses (149 to 80.0 deg; 62.8 to 41.2 deg/s). Thus, the radius of curvature of the initial turn-then-run locomotor response (≈10–25 cm) could be controlled in a graded manner by varying the stimulus amplitude. These findings could be used to help optimize stimulus protocols for swarms of cockroach biobots navigating unknown terrain.
Highlights
Insects outfitted with miniature neural-electric stimulation units, so-called biobots, could potentially be utilized as a swarm of mobile agents in a search and rescue operation or other hazardous environment [1]
We investigated the efficacy of voltage-controlled stimuli (VCS) and current-controlled stimuli (CCS), as each offers potential advantages
Our results suggest that it may be possible to achieve a much higher success rate than the %10% previously reported by others [11, 12] in driving a Madagascar hissing cockroach (MHC) biobot along a desired path in a free-ranging arena, with electric stimuli to cerci and antenna delivered by a miniature wireless backpack mounted on the animal’s dorsal surface
Summary
Insects outfitted with miniature neural-electric stimulation units, so-called biobots, could potentially be utilized as a swarm of mobile agents in a search and rescue operation or other hazardous environment [1]. Various insects have been considered for their aerial and terrestrial biobot potential, including the hawk moth M. sexta [6], rhinoceros beetle M. torquata [3, 5], American grasshopper S. americana [7], and American cockroach P. americana [8]. Another attractive candidate for biobot applications is the Madagascar hissing cockroach (MHC) G. portentosa. They are excellent climbers, reared in the lab, and have a long lifespan (3–24 months). The time scale and speed of MHC maneuvers are sufficiently slow such that a human “pilot” or computer-automated system can interact in real-time, sending a sequence of commands to steer it along a desired path
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