Autonomous cricket biosensors for acoustic localization
Mulcahey, Thomas Ian
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The goal of this project was to design networked arrays of cricket biosensors capable of localizing sources such as footsteps within dangerous environments, with a possible application to earthquake detection. We utilize the cricket's natural ability to localize low frequency (5 Hz - 600 Hz) acoustic sources using hair-covered appendages called cerci. Whereas previous investigations explored crickets' neurological response to near field flows generated by single frequency steady-state sounds, we investigated the effects of transient waveforms, which better represent real world stimuli, and to which the cercal system appears to be most reactive. Extracellular recording electrodes are permanently implanted into a cricket's ventral nerve cord to record the action potentials emanating from the cerci. In order to calibrate this system, we attempt to find the relationships between the frequency and direction of acoustic stimuli and the neurological responses known as spike trains, which they elicit. The degree of habituation to repeated signals that exists in most neurological systems was also experimentally measured. We process the signals to estimate frequency and directionality of near field acoustic sources. The design goal is a bionic cricket-computer system design capable of localizing low frequency near field acoustic signals while going about its natural activities such as locomotion.