Electrostatically actuated dip pen nanolithography probe arrays

Dip pen nanolithography (DPN) is a method of creating nanoscale chemical patterns on surfaces using an atomic force microscope (AFM) probe. Until now, efforts to increase the process throughput have focused on passive multi-probe arrays and active arrays based on thermal bimetallic actuation. This paper describes the first use of electrostatic actuation to create an active DPN probe array. Electrostatic actuation offers the benefit of actuation without the probe heating required for thermal bimetallic actuation. Actuator cross talk between neighboring probes is also reduced, permitting more densely spaced probe arrays. The array presented here consists of 10 cantilever probes, where each is 120 μm long and 20 μm wide. Each cantilever probe is actuated by the electrostatic force between the probe and a built-in counter electrode with a 20–25 μm gap. The tip-to-tip probe spacing, also called the array pitch, is 30 μm. Patterns of 1-octadecanethiol were created on gold surfaces to demonstrate single-probe actuation, simultaneous multi-probe actuation, and overlap of patterns from adjacent probes. The minimum line width was 25 nm with an average line width of 30–40 nm.