A carbon nanotube/graphene nanoplatelet pressure sensor prepared by combining 3D printing and freeze-drying method

With the development of wearable electronic devices, flexible sensors have received widespread attention, especially for high sensitivity sensors. However, sensors prepared by conventional processes such as hot pressing, vacuum filtration and so forth are not sensitive enough to meet the needs of healthy detection. In order to solve this problem, we proposed an hydrogel-based carbon nanotube/graphene nanoplatelet/ polydimethylsiloxane (CNT/GNP/PDMS are named as CGP) pressure sensor prepared by combining direct ink writing three-dimensional (DIW 3D) printing and freeze-drying method. The effect of number of matrix infiltration treatment on mechanical properties is also discussed. By utilizing the designability of the 3D printing, multiple CGP sensor samples can be prepared simultaneously, saving time cost in preparation process. The CGP sensors with 6 mm thickness have excellent sensitivity (The maximum gauge factor (GF) is 18.49), which is higher than that of 4 mm thicknesses and other preparation method like mold method. Meanwhile, we find that CGP sensor with 6 mm thickness has good cycling performance in a 5000-cycled test. Furthermore, a series of performance tests are also systematically conducted. Consequently, prepared CGP sensor has the potential to be applied in human motion and healthy detection due to high sensitivity, having excellent performance.