Robert W. Cohn (University of Louisville)

Professor of Electrical and Computer Engineering 

and Director of the ElectroOptics Institute and Nanotechnology Center at the

Fluid mechanical forces can be used to naturally induce polymeric

liquids to self-assemble into suspended fibers, membranes and

air-bridges that have nanoscale features and aspect ratios exceeding

10,000:1. The fabrication process is quite robust, enabling defect-free

arrays of identical structures to be produced with even crude hand

application. Nanofiber air-bridges have been produced in seconds with

numerous types of organic polymers, nanomaterial-polymer composites, and

biopolymers—including with fibrin and DNA.

Most recently we have assembled an ultraflexible air-bridge in the form

of a micron-scale bead on a 50 to 200 nanometer diameter string. The

relatively large bead enables both simple observation and

nanomanipulation of the structure under a light microscope. Force

detection limits of under a piconewton are estimated, making visual

sensing under a light microscope a possible alternative to traditional

atomic force microscopy and laser trapping for detection of biomolecular

forces. This talk will present the self-assembly method, measurements of

resulting magneto-mechanical properties of the beaded fibers, and new

ideas for using the magnetic nanorods to further control and modify the

process of self-assembly.