The characteristics of this sensor is analysed. It is concluded that for a certain refractive index range, the index of fibrecore, the radius of core and bending radius need to be optimized.
Dr Hess envisages a ray of light travelling down an optical fibre made from two materials: a core with a negative refractive index and an outer sheath with a positive one.
The material choice is simple: the shoe is a laminate with Carbon fibre for the core which gives the shoe its spring and strength, leather on the foot side and rubber on the walking wearing side.