Mechatronic Design of a Thigh-Buttock Analogue and Instrumented Soft Pad for Pressure Injury Prevention

Pressure injuries in immobilized patients pose a global healthcare problem, imposing substantial economic burdens and affecting health and quality of life of those patients. While specialized pressure-redistributing mattresses and contoured foam cushions have been investigated, challenges persist. In this paper, we present mechatronic designs of (i) thighbuttock (TB) analogue and (ii) instrumented soft pad to study the contact interactions and mechanisms of pressure injury formation in a simulated human body environment. Developed full-scale TB analogue is equipped with embedded vasculature, pressure sensors, and flow sensors, designed to emulate vein collapse dynamics under normal loads. The soft pad is an actively controlled, dynamic, soft support surface discretized into multiple individual actuators with integrated pressure, temperature, and humidity sensors. The integrated sensors allow for continuous monitoring of the contact interactions and environmental conditions at the analogue-pad interface. Effects of developed normalizing pressure distribution algorithm on vein flow at various locations under bony and soft tissues, as well as monitoring of temperature and humidity that are known pressure injury formation factors are demonstrated through extensive experiments. The presented mechatronic design enables controlled physiological simulations contributing towards better understanding of pressure injury mechanisms and potentially leading towards improved pressure injury prevention.