Fabrication of high-aspect-ratio pillars by Proton Beam Writing and Application to DEP-devices

Scanning electron microscopy (SEM) images show that 21 mum thick SU-8 pillars on silicon develop after proton beam writing (PBW). These data demonstrate a capability of PBW to fabricate vertical pillars with a height of 21.0 mum and a width of as small as 1.1 mum with a high aspect ratio of 20, and with a uniformity over 700 mum square area. An optical microscope image shows a part of a dielectrophoretic (DEP) device, where the high-aspect-ratio SU-8 pillars with a 12 mum pitch are formed in the gap between the two surface electrodes. Preliminary investigation shows that Escherichia coli can be trapped at pillar structures under AC bias (3 volts, 100 kHz) of the two electrodes. The trapping behavior of DEP device with different structures and sizes are examined.