A High-Load Stress Sensor for Scoliosis Surgery Application

The design of a stress sensor for a scoliosis surgery application is presented. Designed specifically for detecting forces and moments placed on spinal hooks and screws used in scoliosis correction, the sensor is less 2mm in the largest dimension and less than 0.5mm in thickness. The operative range is approximately 1000MPa in shear and normal stress directions. Preliminary FEA simulation of a piezoresistive sensor incorporating these design constraints demonstrates that different output signals are produced as the sensor is subjected to shear and normal stresses. When the separate signal patterns from several sensors are combined, the hooks and screws will be able to resolve forces and moments in three dimensions.