A range of methods employing optical tweezers or scanned probes have been used for directly manipulating and measuring the mechanical properties of individual biomolecules. These are powerful methods for studying the forces that lead to biopolymer confirmation and structure. For some time we have been studying simple nanostructures that can be used to exert controlled forces on molecules and exploring nanostructures for isolation of individual molecules for study. In nanofluidic systems with dimensions less than the size of a biopolymer, for example, we can use applied electric fields to control the confirmation and precise position of a molecule. This enables a method for sorting molecules and also can be used to deliver molecules in a controlled fashion for individual analysis by optical or electrical approaches. For the design of analytical systems it is necessary to understand the forces and interactions that control the motion of molecules in these confined geometries. We have therefore been exploring the effects on electrophoretic molecular mobility in nanostructures and studying forces in geometries of changing electric fields and confinement. Much of the work is done with DNA as both a simple model biopolymer and as a target for genetic analysis.