Sensing Passive Eye Response to Impact Induced Head Acceleration Using MEMS IMUs

Abstract

The eye may act as a surrogate for the brain in response to head acceleration during an impact. Passive eye movements in a dynamic system are sensed by microelectromechanical systems (MEMS) inertial measurement units (IMU) in this paper. The technique is validated using a three-dimensional printed scaled human skull model and on human volunteers by performing drop-and-impact experiments with ribbon-style flexible printed circuit board IMUs inserted in the eyes and reference IMUs on the heads. Data are captured by a microcontroller unit and processed using data fusion. Displacements are thus estimated and match the measured parameters. Relative accelerations and displacements of the eye to the head are computed indicating the influence of the concussion causing impacts.

Correlating the passive response of eye and brain to head impact using MEMS IMUs on 3D-printed human head phantom

“…Five of the IMUs were mounted on ribbon-style flexible PCBs made of 25.4-µm-thick DuPont TM Pyralux, coated with silicone conformal coating, and connected to interface PCBs as seen in figure 1. As an improvement compared to the design in Meng et al (2017), the polyimide substrate material was trimmed into a half-moon shape designed to fit the sensor to the surface of the eyeball in the lower eyelid, and better couple the motions of the eye and sensor at the position of the IMU. The sensor's silicone conformal coating created a moisture barrier to protect the circuits and made the sensor less likely to scratch the eye.…”

“…All the sensing data, including temperature readings from the six IMUs, were buffered in the 256 KB RAM of each MCU before being logged to its micro SD card. The overall sampling rate was 1 kHz which was sufficient for this application (Meng et al 2017).…”

“…A number of drop-and-impact experiments on this skull-brain-eye system were performed with the testing apparatus. Relative accelerations of the eye and brain IMUs to the phantom skull along the impact direction were calculated applying the data fusion technique developed in Meng et al (2017). Instead of relative displacements, only relative accelerations were computed to further diminish errors introduced by integration.…”