서강대학교

초록/요약

In order to find how to fabricate and develop easily, quickly and costly a 3D structural tactile pressure sensor in 4 x 4 array form, the method of comprehensive integration of three printing techniques has been investigated: Contact pads and line electrodes, supporter and piezoresistive pattering structure have been deposited separately by using inkjet printing, plotter printing and stereolithography (STL) 3D printing, respectably. Elastic piezoresistive nanocomposite was formulated with a mixture of piezoresistive multiwalled carbon nanotube percolated in elastomer polydimethylsiloxane (MWCNT/PDMS) dissolved in tetrahydrofuran solution which is a moderate polar solvent. These mixture composite matrix in a range of 2.0 – 4.0 wt% showed not only the highest sensitivity of 0.070 kPa with empty pyramid shape MWCNT/PDMS composites, but also satisfied the fluidic conditions for ink formulation of STL 3D printing with pneumatic 3D printing method. Five different shaped piezoresistive pressure sensors have been fabricated by the STL printing: i.e., the filled cylinder, the empty cylinder, the filled pyramid, the empty pyramid and the spiral structural composites. Strain-stress tests for electromechanical properties revealed that two hard empty structure, empty cylinder and spiral shape composites showed high strain response, 0.52 for spiral composites and 0.57 for empty pyramid composites at 100 kPa stress, under same stress compare to other three shapes. The empty pyramid and the spiral shape composites also showed the low Young’s modulus relatively. For the resistive response via I-V, the empty pyramid and the spiral shapes showed relatively high than other three shapes. Particularly, we found that this tendency was more strengthen with high pressure condition. For 4 x 4 array sensor of the cylindrical shape connected to the mutiplexing data acquisition system (NI-DAQ, USB-6255), the spatial sensing distribution with piezoresistive sensing within 0.25 – 50 kPa has been achieved within 5 ms. We represented these areal tactile sensing in contour graph by performing the image processing of signal positions and intensities, to show the capability of the detection of size of an object successfully. If the physical engine to process the dynamic motion of signal is supplemented into the LabVIEW coding, the slip sensing could be also possible, which is left to the future work.