Statocyst is the balancing and sensing organ of the cephalopods (octopus, squid and cuttlefish). Previous studies have shown the macula/statolith part of the statocyst is the linear acceleration sensing system of the water particle motion. Although a few differences primarily in gross morphology exist, the macula/statolith part of the statocyst shows a striking number of similarities in structure and function among different cephalopods. In this study, the macula/statolith part of the statocyst is investigated by means of mechanics method. Specifically, based on the geometry and material property of macula/statolith from three cephalopod species (Octopus vulgaris, Sepia officinalis and Loligo vulgaris), a second order dynamic oscillator model was used to simulate its frequency response to the water particle motion. The acceleration detection threshold spectra comparison between the modeling analysis and the experiment data verifies that the cephalopods are sensitive to the water particle motion (acceleration) in the low (infrasound) frequency range.

As an integral part of this research, the characteristics of kinocilia bundle which is the mechanoreceptive part of macula/statolith are also studied by interpreting the interaction between kinocilia bundle and statolith in a fluid-structure-interaction (FSI) numerical model. A parametric study of the kinocilia/statolith numerical model is conducted to improve the understanding of the sensing mechanism of the kinocilia bundle interaction with the statolith. Inspired by this interaction phenomenon, a bio-inspired vibration sensor and a bio-inspired isolation element are conceptually developed and numerically studied. The numerical simulation result implies that the frequency response behavior observed in the kinocilia bundle model from FSI analysis is also seen in both engineering designs, and this behavior could be equivalently described by the Maxwell model and SLS model for these two designs, respectively.

Lastly, by taking advantage of 3D printing technology, a prototype bio-inspired vibration sensor was fabricated in the lab and subsequently tested to characterize its sensing behavior. A comparison between the experimental data and predictions from a theoretical model suggests that the frequency response of the bio-inspired sensor design is equivalent to the convolution of the frequency response of a 2nd-order oscillator and the sensor's inner beam. This unique feature enables the development of two potential motion sensor designs (jerk sensor and velocity sensor).