Highly sensitive porous PDMS-based piezoresistive sensors prepared by assembling CNTs in HIPE template

With the rapid development of the application in health-monitors and wearable devices, the demand for the piezoresistive sensors with both high flexibility and high sensitivity has been growing. In this work, a porous carbon nanotubes/polydimethylsiloxane (CNTs/PDMS) composite was prepared by high internal phase emulsion (HIPE) template. The PDMS foam with tens of micrometers of pores offered high flexibility and elasticity. Moreover, guided by cetyltrimethylammonium bromide (CTAB) in HIPE, CNTs were selectively distributed in inner pores' surface of the foam, and then the 3D conductive network was constructed. As a result, the stress of the foam was 107.1 kPa at 60 % compressive strain and the electrical conductivity reached 9.77 × 10−5 S m−1, when the volume fraction of CNTs was 1 vol%. Finally, the flexible conductive foam was applied for a piezoresistive sensor. The sensor exhibited a high gauge factor (GF = 24.15) and a wide working range (0∼60 %). Furthermore, the human movements, such as finger bending and walking, were detected by as-prepared piezoresistive sensor, and a good response was obtained.