Patterned MWCNT/polydimethylsiloxane (PDMS) nanocomposite strain sensors were achieved by a microelectromechanical system assisted electrophoretic deposition (EPD) technique. With the combined effect of superior intrinsic piezoresistivity of the individual MWCNT and the tunneling effect of the MWCNT network, the stretchable composite demonstrates high sensitivity to the tensile strain. The gauge factor shows a strong dependence on both the initial resistance of the CNT/PDMS composite and the applied strain level. The mechanism is elucidated by analyzing the structure-property-function of patterned CNT networks. When the entanglement of a MWCNT network allows effective load transfer, the sensitivity is primarily dominated by the intrinsic piezoresistivity of individual MWCNTs. Conversely, when the MWCNTs interpenetrate loosely, the tunneling effect prevails. The sensitivity of the device can be tailored by the proposed technique since MWCNT film thickness/density can be readily controlled by means of the patterning parameters of the EPD process. The work provides useful guidance for design and development of strain/stress sensors with targeted sensitivity for flexible electronics applications. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1505-1512