Fiber-optic stress sensor array for diabetic foot ulcers

DESCRIPTION (provided by applicant): Foot ulceration is a diabetic complication that is difficult to treat. This condition results in significant morbidity and in many cases precedes limb amputation. It has been reported that 20% of all diabetic patient hospital admissions have been due to foot problems. Previous research has established the significance of nerve damage and a compromised vascular system in the etiology of diabetic foot ulcers. In recent years, the importance of mechanical factors such as pressure and frictional forces due to shear stress has also been established but to date, these two loading conditions have never been quantified simultaneously. The rationale behind the current proposal is that by developing a compact, high-resolution load cell array, quantifying localized skin loads factors leading to diabetic skin ulceration will be more fully understood. The operating principal of the proposed sensor array is based on the change in optical properties at the molecular level with loading of a pre-stressed polymer or crystalline material, which acts as a linkage to which a force would be applied either in compression or tension in any direction. The molecular deformation of the polymer linkage will be analyzed using miniature optical components arranged as an array of fiber-optic, phase-modulated polarization state load sensor arrays. The overall aim of this research is to develop an optical sensor array capable of determining true skin loading conditions (pressure and frictional forces) acting on the sole of the foot during gait. This will be accomplished by developing a fiber-optic coupled matrix of load transducers that are based on optical polarization-state modulation and heterodyning signal analysis techniques. Preliminary data indicate that pressure and stress measurements can be achieved with errors of less than 1% of the actual forces.