Omar Elsafty

Research Interests

Analysis of Partial-Thickness Skin Injuries from Non-Lethal High-Rate Impact

Cutaneous wounds have the highest incidence of all bodily injuries in survivors of blast debris. Even after survival, there is an increased risk of mortality due to wound infection, and a possible decline in a person’s well-being due scar formation which can have long lasting functional, aesthetic, and psychological effects on the wounded. These non-lethal cutaneous wounds are not only prevalent in military settings, but they are also often observed in civilian life due to natural disasters, broken glass injuries from car crashes, and construction accidents. However, while their significance is clear, there is a poor understanding of the damage processes involved in this impact sequence and the influence of projectile attributes, such as shape, size, and orientation at impact, on injury severity. Here we quantitatively characterize the damage mechanisms involved in partial-thickness cutaneous injuries and develop a three-dimensional multi-layered full-thickness cutaneous finite element (FE) damage model to accurately predict partial-thickness injuries at highly dynamic impact conditions.

Design and Fabrication of Protective Appliques

Cutaneous injuries in the face and joints can have significant implications on the wounded, as it can lead to scar formation which can have long lasting functional, aesthetic, and psychological effects. However, joint regions have high mobility, and facial regions are necessary for identification purposes, necessitating the need for light, stretchable, and flexible protective wearables as opposed to heavy armor that is more suitable for areas of less mobility such as the chest and torso. Using computational modeling and rapid prototyping, we design and manufacture protective thin film appliques that reduce and/or prevent cutaneous injuries caused by blast debris while allowing full natural motion of the protected regions.

Multi-Method Approaches for Assessing Full-Body Distributed Injuries

The most harmful effect of blast debris injuries is their widely distributed impact sites, as hundreds of fragments can impact the wounded at various locations on the body, each having variable mechanical behavior of skin damage due to differences in thickness and topography. In addition, the fragments are typically of different shapes and sizes, which creates an increased level of difficulty in analyzing these injuries. While finite element models have helped extract the damage mechanisms of single projectile impact of a fragment, it is too computationally costly to perform a full-body multi-impact analysis of blast debris impact. Here we develop a multi-method approach for assessing full-body distributed impact injuries using machine learning algorithms coupled with physics-based analysis using computer graphics tools in order to replicate these injuries with minimum computational cost and time. The machine learning algorithms are trained with computational and experimental results and the multi-method model is used to analyze the effect of distance, body orientation, alignment, and blast source shape and size on the predicted injury severity.

Computational Analysis of Tactile Perception

Understanding tactile perception is essential for the design and development of haptic devices and other human interface technologies. However, skin has a complex multi-layered structure where each layer performs specific functions and as such, they demonstrate different mechanical behavior that effects the mechanoreceptor responses to external stimuli. Here we develop structurally and topographically accurate 3D finite element models of the human skin to assess the role skin structure plays in adjusting the firing rate of the mechanoreceptors due to thermal and mechanical stimuli. Using silicone casts and/or digital imaging, we have generated accurate CAD models of the topography of the uppermost layer of the skin, the stratum corneum, and found that the primary lines play a significant role in enhancing our perception of touch.

Design Optimization of Substrates for Stretchable Electronics

Stretchable electronics are essential for the development of wearable electronics, epidermal and bio-implanted electronics, 3D surface compliable devices, bionics, and prosthesis. They can be used for energy harvesting, electronic display, health monitoring, and in various sensors. However, due to the need of conductive materials in these devices, which are typically of low stretchability and flexibility, they can fail due to the frequent motion and curvature of certain body regions such as fingers and other joint areas. Furthermore, if the device is too stiff, it will cause discomfort for the user. Here we design a metamaterial substrate that can reduce the maximum deformation required in thin film devices for specific body regions while also reducing stresses in the skin caused by its interaction with the device.

Publications

• C. Berkey, O.Elsafty, and R.H. Dauskardt, “The Mechanics of Partial-Thickness Cutaneous Injury from Debris-Simulating Kinetic Projectiles” Communications Engineering, July. 2022
• O. Elsafty, C. Berkey, and R.H. Dauskardt, “On the Characterization, Quantification, and Simulation of Partial-Thickness Cutaneous Injuries from High-Speed Fragment Impact” World Congress of Biomechanics, July. 2022

Conference Presentations

•  O. Elsafty, C. Berkey, and R.H. Dauskardt, “A Multi-Method Approach for Assessing Non-Lethal Cutaneous Impact Injuries" Summer Biomechanics, Bioengineering, and Biotransport Conference, June. 2022

Awards

• Mechanical Engineering PhD 1-year Fellowship | Stanford University (2018-2019)
• Outstanding Academic Achievement Scholarship | The American University in Cairo (2013-2018)
• Undergraduate Research Grant for the maximum amount of $1600 | The American University in Cairo (2016)
• Undergraduate Research Grant for the maximum amount of $2000 | The American University in Cairo (2015)