Static and Dynamic Evaluation of Biophysical Properties of Footwear: The Jozef Stefan Institute Sweating Thermal Foot Manikin System

摘要

Freezing and non-freezing cold injury occurs predominantly in the extremities, with the feet being at greatest risk. Inappropriate footwear is the main cause for cold injury of the feet. Ensuring that footwear meets minimal biophysical standards is therefore essential in preventing cold injury. The Thermal Foot Manikin System comprises a sweating thermal foot manikin, a gait simulator and a control unit. The foot manikin has 10 segments constructed of a silver-copper alloy. Each segment is heated and the temperature of each segment is monitored. Water is delivered to 6 sweat glands in each of the 10 segments, distributed over the segment surface by a thin cotton layer. Each segment is covered by a water impermeable, but water vapor permeable membrane, ensuring that only water vapor crosses the membrane. In this manner, the resistance to water vapor may be determined from each of the 10 segments. By disconnecting the sweat gland activity, the same analysis provides a value of insulation for each segment. The manikin is attached to a gait simulator, which can simulate different stride magnitudes and walking paces. The gait simulator simulates the heel-to-toe action of walking and also simulates the ground reaction forces. The manikin also allows biomechanical analysis of footwear during simulated gait. The thermal foot manikin is able to analyze the static and dynamic biophysical properties of footwear in sub-zero environments. The differences in the results obtained in the static and simulated gait mode are due to friction between the foot manikin and footwear, and due to footwear design. In the biomechanical mode, the foot manikin allows the assessment of wear, as well as how such wear affects biophysical properties. The developed thermal foot manikin gives industry the capability to develop footwear with biophysical properties specified by the customer. Such a strategy will reduce the risk of cold injury.