Highly stable flex sensors fabricated through mass production roll-to-roll micro-gravure printing system

A highly stable low cost flex sensor has been fabricated in this research work using micro-gravure mass production roll-to-roll printing system. The active layer was fabricated on PET substrate using composite of Activated Carbon with PVDF. PVDF has been added as a binding agent to improve the mechanical stability of the active layer. Protective coating of PVAc was deposited on top of active layer using the same system. The sensors' electrical and morphological characterizations were performed to find out the surface characteristics and response of the sensors towards various bending angles. Results show promising response of both the protected and un-protected sensors towards positive and negative bending. Sensors with different lengths and widths were tested for both types and the best recorded response for protected sensors was 2.3 MΩ to 3 MΩ to 3.6 MΩ for −120° to 0° to 120° bend while for non-protected sensors was 0.25 MΩ to 0.4 MΩ to 0.55 MΩ for −120° to 0° to 120° bend. Protective coating caused increase in the overall sensor resistance thus reducing the operating power of the device. Also, increasing the sensor width decreases the resistance and so does reducing the length. The sensors were mounted on a glove and the results indicate stable and accurate operation.