Fig. 3: The effects of PDMS thickness and viscosity on the local de-insulation method and the effectiveness of the local de-insulation method.
From: A local de-insulation method and its application in neural microneedle array
a Variation of PDMS thickness with spin coating speed. b Comparison of capillary phenomena when electrode array tips are inserted into PDMS of different viscosities (the noticeable capillary phenomena have been outlined with yellow lines). When the electrodes are inserted immediately after the PDMS has been spun, noticeable capillary action is observed. As the curing time increases to 5 min, the capillary effect becomes less discernible under an optical microscope. SEM reveals a slight capillary action still present at 7 min. At 8 min, the tips of the silicon-based microelectrode arrays are easily inserted and encapsulated by the PDMS without any capillary action occurring. c The average tip exposure length after the local de-insulation process for four electrode arrays (each has 10 × 10 array, totaling 400 recording sites) from the same batch. The average tip exposure length for the 400 recording sites is 50 ± 0.77 μm. d, e Tip exposure effects after the local de-insulation method process
