Precise Electrokinetic Position and 3D Orientation Control of a Nanowire Bioprobe in Solution

Micro- and nanostructures are promising tools in biomedical research, but it remains challenging to manipulate individual particles with precision in solution due to Brownian effects. Nanomanipulation techniques therefore attach particles to cantilevers to enable their use as nanoprobes. Here, we demonstrate a versatile electrokinetic trap that simultaneously controls both the 2D-position and the 3D-orientation of an untethered particle or nanowire with high accuracy and speed. A precision of 20 nm in the 2D-position and 0.5° in the 3D-orientation is achieved. A nanowire as small as 300 nm in length can be successfully controlled. The method permits active transport of nanowires while allowing for their synchronous 3D-alignment and rotation along complex trajectories. We use the electrokinetic trap to accurately move a nanoprobe and stably position it on the surface of single bacterial cells for extended periods to record the secretion of metabolites. The controlled 3D-manipulation of individual nanowire-probes paves the way to develop nanorobotic tools for assembly, micromanipulation, and biological measurements with subcellular resolution. The experimental data are provided here.