Curvature Characterization of Flex Sensors for Human Posture Recognition

Resistive flex sensors have been increasingly used in different areas for their interesting property to change their resistance when bent. They can be employed in those systems where a joint rotation has to be measured, in particular biomedical systems, to measure human joint static and dynamic postures. In spite of their interesting properties, such as robustness, low price and long life, to date commercial flex sensors have been only characterized against the variation of the bend angle with small fixed curvature radius mostly around the device center, so limiting the application to the measure of human joints. Here we aimed to investigate the flex sensor’s response when there is a change in curvature radius as it is, for instance, for the measure of the postures of the human torso. So, we designed a novel automated test process to obtain resistances vs. curvature radius pairs. Results demonstrated the usability of flex sensors to other parts of the human body rather than “simply” joints, differently as it is currently done.