Characterization of the 2-Phase Turning Response of Madagascar Hissing Cockroach Biobots to Antennal Stimulation

Biobots are living insects that are controlled via neurostimulation applied through implanted electrodes and have a variety of potential applications such as search and rescue operations. Madagascar Hissing Cockroaches (MHCs) are commonly used as biobots; however, their use remains under investigation due to lack of a comprehensive motion profile in response to neurostimulation, which makes consistent control a challenge. MHC biobots often exhibit a 2-phase turning response to antennal stimulation, with an initial turn (primary) in the desired direction followed by a “corrective” turn (secondary) in the undesired direction. The purpose of this research is to characterize the 2-phase turning response of MHC biobots to antennal stimulation. Electrodes were implanted into the antennae of MHC biobots (n=20), and antennae of each subject were stimulated 40 times using a duty cycle of 50%, frequency of 125 Hz, and four sets of stimulus voltages and durations: 1 V and 0.5 s, 3 V and 0.5 s, 1 V and 1.5 s, and 3 V and 1.5 s. Modulation of stimulation voltage and duration did not significantly affect the responsiveness, direction of, or magnitude of turn angles. The direction of primary turns were found to be controlled in 88% of subjects, while the direction of secondary turns were able to be controlled in only 53% of subjects, which demonstrates that MHC biobots are able to be consistently controlled during the primary turn but not during the secondary turn. A histogram of the magnitude of secondary turns is centered approximately at 0°, which demonstrates that the secondary turn is likely when the cockroach regains control of its motion rather than a “corrective” turn as noted in previous studies. To improve MHC biobot technology, researchers could limit the amount of time between stimuli or introduce a feedback system where actual turn angle is measured, and stimuli are applied when the MHC biobot begins turning in the undesired direction