Printing of high concentration nanocomposites (MWNTs/PDMS) using 3D-printed shadow masks

This paper presents an attractive and feasible approach for developing large area flexible pressure sensors by using high concentration nanocomposites of multiwall carbon nanotubes (MWNTs) mixed in poly (dimethyl-siloxane) (PDMS). A shadow mask is prepared by using 3D printer and employed for the patterned deposition of nanocomposites on 25 μm thick flexible polyethylene terephthalate (PET) substrate. Sensors are developed in the form of 4 modules in single step, each containing arrays of 4×4 interconnected sensors. A parallel plate capacitive structure is followed, whereby, MWNTs/PDMS nanocomposites layers are packed in two printed silver plates of 1×1 mm² area each. An encapsulation layer of another pet substrate is adhered on top of these printed sensors, containing top electrodes and force concentrated structures on each side respectively. Three different (by wt. %) nanocomposite solutions are prepared which are finally printed by using a shadow mask developed by 3D printer. An investigative study has been carried out in this research in which an easy and cost-effective technique for patterned deposition of nonhomogeneous nanocomposites with high percolation ratios is developed. Here the change in resistance values upon application of normal compressive forces is investigated to monitor the applied stress. The modular expansion of this type of sensor could be advanced for possible application as a tactile sensor in an electronic skin for robots and general purpose applications.