Tag: Keat Ghee Ong

Optical Based Sensing of Shear Strain using Reflective Color Patterns

Presenter: Maryam Shuaib – Human Physiology

Faculty Mentor(s): Mike McGeehan, Keat Ghee Ong

Session: (In-Person) Oral Panel—Stimuli and Response, Poster Presentation

There is an increasing need to measure shear force in biomedical applications. Many shear force sensors exist, but are often impractical as they can be bulky, require large amounts of power, and are sensitive to electromagnetic interference. The goal of this project is to apply new optoelectronic sensing principles to measure shear strain. Optoelectronic sensors have various advantages including a smaller design that is able to measure multi-axial shear strain. This particular sensor functions through optical coupling of an LED that emits red, green, and blue (RGB) light, which is then reflected off of an adjacent surface displaying a color pattern consisting of randomized color pixels (Figure 1A). Shearing between these surfaces is measured using a photodiode, which senses changes in the RGB light intensities due to the shifts in the color pattern’s position. The purpose of this study was to compare the efficacy of various color patterns and classification algorithms to determine multi-axial shear strain. The optimal sensor configuration was found to be Pattern 3 (Figure 1B) with a Weighted K-Nearest-Neighbor algorithm with an accuracy of 98%, and a misclassification cost of 0.07 millimeters. The accuracy and robustness of the sensor-derived measurements, along with the practical and scalable design, support the use of this sensor in a multitude of biomedical applications.

Femoral Fracture Fixation Device to Wirelessly Monitor Real Time, in Vivo Strain

Presenter: Noah Greenblatt – Human Physiology

Co-Presenter(s): Walker Rosenthal

Faculty Mentor(s): Keat Ghee Ong, Salil Karipott

Session: (In-Person) Oral Panel—Stimuli and Response, Poster Presentation

Strain, a primary measure of the dynamic mechanical environment, is important with regard to patient aimed orthopedic treatment especially in minimizing complications that arise after certain bone fracture injuries. Currently, methods aimed at assessing the mechanical environment include external stimulating devices that fail to measure strain during normal gait patterns, and estimated parameters computed from different computational models which lack real-time data. With these limitations in determining real time load condition in bone fracture healing, we aimed to fabricate a bone fixation device that provided adequate mechanical stability to a healing bone fracture and measured strain present on the device in a rodent femur. This device transmits measurements wirelessly to a nearby computer for quantification of strain. Our results showed the ability to successfully measure local axial strain during functional loading on a rodent with a femur fracture. This device facilitates the study of mechanical strain and its role in bone healing in preclinical rodent fracture models. Most importantly, this device allows for future rehabilitation protocols that are evidenced-based and patient specific.