Lower limb complications associated with diabetes include the development of plantar ulcers that can lead to infection and subsequent amputation. While it is known from force plate analyses that there are medial/lateral and anterior/posterior shear components of the ground reaction force, there is little known about the actual distribution of this force during daily activities, nor about the role that shear plays in causing plantar ulceration. Furthermore, one critical reason why these data have not been obtained previously is the lack of a validated, widely used, commercially available shear sensor, in part because of the various technical issues associated with shear measurement. The research proposal is aimed at developing, fabricating and implementing a polymer based Bragg grating sensor array that will be used in study plantar pressure and shear changes associated with diabetic patients. In order to significantly increase the number of multiplexed sensors, a hybrid of time domain multiplexing (TDM) and wavelength division multiplexing (WDM) techniques will be used. A simple micro-fabrication technique utilizing laser writing, laser holography and electron beam writing system will allow a rapid construction of complex optical gratings and waveguide system. Uniqueness of the system is in its single input and single output configuration. One other benefit of this research is the possibility of performing a long term prospective study of the effect of shear stress on ulcer development. The further application of sensor goes beyond measuring plantar pressure and shear. A wearable (in-shoe) or embedded (active shoe, or prosthesis) sensor can be derived from this sensor. Other sensors can also be incorporated into the polymer-based sheet to create a multi-parameter sensor system.
