Background: The relationship between utricle diseases and structural lesions is not very clear in the clinic due to the complexity and delicacy of the utricle structure. Therefore, it is necessary to study the perception mechanism of the utricle. Methods: Imitating the sensory cells in the macula of the utricle, a symmetrical metal core PVDF fiber (SMPF) was designed as a bionic hair sensor to fabricate a bionic macula (BM), a bionic macula with sand (BMS) and a bionic utricle (BU). Then experiments were carried out on them. Results: This indicated the SMPF sensor can sense its bending deformation, which was similar to the sensory cell. The amplitude of the output charges of the SMPF in BMS and BU were significantly improved. The SMPF, whose electrode boundary was perpendicular to the impact direction, exhibited the largest output charges. Conclusion: The presence of otoliths and endolymph can improve the sensing ability of the utricle. The human brain can judge the direction of head linear accelerations based on the location of the sensory cell in the macula that produces the largest nerve signals. This provides a possibility of studying utricle abnormal functions in vitro in the future.

Canalithiasis is a common vestibular system disorder, which may lead to a specific form of vertigo known as BPPV or top-shelf vertigo. In this paper, based on the actual geometric parameters of the human semicircular canal, we designed a 4-fold in vitro one-dimensional semicircular canal model using technologies such as 3D printing, image processing, and target tracking. We investigated the essential characteristics of the semicircular canal, such as the time constant of the cupula and the relationship between the number, density, and size of the canalith and the cupular deformation during canalith settlement. The results showed a linear relationship between the number and size of the canalith and the amount of cupular deformation. We also found that when the number of canaliths reached a particular scale, the interaction between the canaliths exerted an additional disturbance on the cupular deformation (‘Z’ twist). In addition, we explored the latency time of the cupula during canalith settlement. Finally, we verified that the canaliths had little effect on the frequency characteristics of the semicircular canal by a sinusoidal swing experiment. All the results validate the reliability of our 4-fold in vitro one-dimensional semicircular canal model.

To date, there are three main hypotheses explaining why the human semicircular canals (HSCCs) cannot sense linear accelerations. To further study this issue, we designed a bionic ampulla (BA) instrumented with a symmetrical metal core polyvinylidene fluoride fiber as a bionic sensor, which imitates the structure and function of the human ampulla. The BA was confirmed to have a good sensing ability in experiments with a straight tube. Additionally, we designed a bionic semicircular canal model, a blocking model, and a square model. We compared the perception performance of these three models to test the “density hypothesis,” the “closed loop hypothesis,” and the “circular hypothesis.” The outcomes of these experiments verified the “density hypothesis” and “circular hypothesis,” but did not support the “closed loop hypothesis,” shedding light on why the HSCC is sensitive to angular acceleration, but not to linear acceleration.

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