Pencil Graphite on Paper: Facile approach for Fabrication of Flexible Strain Sensors

The implementation of flexible electronics is expanding since it has been widely used, especially in the development of robotics and healthcare systems. Most of the developed strain sensors are made of brittle and hard materials, and the manufacturing process is difficult and complex. The use of metals in its manufacturing, the traditional strain sensor can only achieve high sensitivity but not great stretchability, resulting in modest flexing and bending capabilities. Therefore, the integration of pencil graphite as sensing material is conducted in this project to enhance the adaptability and the effectiveness of the sensor. This project uses four different pencils graphite to test the influence of graphite traces on the sensor's performance which includes pencil grades of HB, 2B, 4B, and 9B. To acquire the best pencil grade in this manufacturing, the performance will be tested in terms of resistance and sensitivity (gauge factor). Besides, the pencil-on-paper-based sensor has fulfilled the flexibility requirement as it is tested as the function of chord length. On the other hand, the highest strain detection is attainable by HB pencil with a gauge factor of 5.8MΩ/mm. Therefore, the implementation of pencil-on-paper-based strain sensors provides an attractive strategy to be applied for flexible electronics.