The Design and Validation of a Force and Bending Moment Sensing Device

Abstract

Shoulder dystocia (SD) is a serious obstetric emergency in which an infant’s shoulder becomes blocked by the mother’s pubic symphasis and the infant is unable to be delivered. In these instances, the infant must be delivered hastily, yet this hurried extraction may lead to an increase in clinician-applied forces. Injury risk is as high as 10% of all SD cases as it is shown that excessive force applied on the head and neck of the infant can lead to birthing injuries, specifically brachial plexus injuries (BPI) [2-4]. Several groups speculate that the direction of force applied to an infant head and neck is important in determining the amount of brachial plexus stretch of an infant [1, 5]. In this study we discuss the development and validation of a force and bending moment sensing glove that will be used to investigate clinician-applied forces. The developed glove uses an Arduino microcontroller, pressure sensors, inertial sensors, and magnetic sensors to determine orientation and forces sensed by the device. In order to ensure the glove system performed correctly, our device was validated against external systems to assess accuracy of the developed glove. The system was first validated for orientation by placing electromagnetic sensors from an external motion detection system (accuracy <0.5°) on a hand mannequin along with the inertial and magnetic sensors (IMUs) of the developed device. Inertial and electromagnetic sensors were placed on the back of each fingertip as well as the hand. After comparing 14 different hand orientations, the average root-mean-square error (RMSE) between calculated Euler angles from the glove device and electromagnetic sensors was less than 16° in any direction.