A smart orthopedic compression device based on a polymeric stress memory actuator

• An application of thermal-sensitive memory polyurethane for orthopedic applications
• It utilizes the stress memory phenomena for smart compression management.
• First attempt in the designing of a smart orthopedic device with the benefit of both static and dynamic compressions
• Theoretical modeling using phase transition approach to predict the pressure or stress results

In current practice of compression therapy, there has been a challenge of compression controlling and need for multiple devices to achieve different functions. Herein, the potential of a thermal-sensitive memory polymer, namely, polyurethane (MPU), is explored in designing a prototype that acts as a flexible bandage system to provide dual benefits (heat and pressure) simultaneously for a desired compression. After preconditioning, the thermomechanical behavior of the MPU becomes repeatable and consistent, which can be programmed to remember (store) and retrieve reversibly a prescribed internal stress, responsive to an external stimulus around its transition temperature (Ttrans). The smart bandage system is then built using the MPU actuator which integrates electric resistive wires as both a heat source for thermal therapy and stimulus for trigger control. The compression can also be easily switched between static and dynamic (massage) modes using a pro-set thermal stimulus. This paper also addresses several challenging issues and design considerations for the prototype. Theoretical analyses have been applied to predict the device performance, showing excellent agreement with experimental results. This work sheds insights for broadening the applications of stress memory and for engineering smart products needing stimulus responsive forces such as dynamic cushions, pressure garment and electronic actuators.

Figure optionsDownload as PowerPoint slide