Then trioctylamine was added, followed by the crosslinkable PDMS. The inks were sonicated in an ultrasonic bath at 50°C for 1 h until the ink became homogenous and printed directly after preparation. Scanning Electron Microscopy: SEM was performed using a field-emission scanning electron microscope (Ultra 55, Carl Zeiss Microscopy) at a primary electron energy of 3 keV. Prior to imaging, the 3D printed microstructures were sputter coated with a 12 nm layer of Pt/Pd (80:20).