(LR-043) Sacral Soft-Tissue Deformation Under Wearable Devices: Effects of Contact Geometry and Tissue Mechanical Variability

Friday, April 10, 2026

Aleksei Orlov, PhD; Anastasiia Simonova, MSc

Introduction: Medical device related pressure injuries are common in the sacral region, where soft tissues vary in thickness and mechanical behavior across individuals. These differences influence how stresses and strains develop beneath wearable devices such as sensors and cables. Device skin-contact geometry may further affect tissue loading, yet the combined effects of device contact shape and tissue mechanical variability are not well defined under varying loads. We used computational modeling to evaluate how device geometry and tissue stiffness influence sacral soft-tissue exposure to loads.

Methods:

A multilayer sacral finite element model was developed in Abaqus/CAE 2024 that included epidermis, dermis, adipose tissue, and muscle with literature-based thicknesses and mechanical properties [1,2]. Tissue stiffness was varied between softer tissues, associated with aging or degeneration, and stiffer tissue states. Two device geometries were simulated: a round, flat sensor and a narrow, elongated cable. Uniform pressures of 2-10 kPa were applied beneath each device. Stress and strain distributions were evaluated within a 30-mm region of interest, and the top quartile of strain values was used to compare tissue exposure across device types and tissue conditions.

Results:

The two device geometries produced distinct tissue deformation patterns. Under 10 kPa loading, the flat, round sensor generated relatively uniform strain fields, while the narrow cable created localized regions of concentrated strain. This resulted in 1.25-fold more tissue being in the highest strain quartile for the cable compared with the sensor. Softened tissues increased tissues exposed to high strain 1.4-fold for the sensor and 1.6-fold for the cable. Stiffened tissues decreased the amount of tissue in the highest strain quartile by 1.1-fold for the sensor and 1.3-fold for the cable.

Discussion:

Device geometry and tissue stiffness together influence mechanical loading effects in sacral soft tissues. The cable exposed more tissue to high strains than the flat sensor, and this effect increased with tissue softening. Stiffened tissues reduced tissue exposed to high strain for both device types. This highlights the importance of considering tissue variability and device geometry when assessing medical device related pressure injury risk and in design of wearable technologies.