Microfluidic machines, self-assembled and yet reconfigurable, have
been created by a collaboration of Northwestern, ProChimia Poland and
The machines consist largely of patterns of rotors which perform a
variety of tasks in a liquid environment---manipulation or sorting of
floating particles and microreactors in which mixing of reagents, and
microcrystallization can be performed.
The rotors are made in tiny molds and then loosed onto a liquid-air
interface, where they are guided into place and set spinning by electromagnets
positioned beneath the interface. By changing the magnet activity, the
overlying rotors can be put into new arrangements for carrying out new
a new job (see figure).
The rotors are at the millimeter scale but can be made much smaller.
Unlike conventional machines the rotor arrays have no fixed axles and
are virtually friction free. (Grzybowski
et al., Applied Physics Letters, 8 March 2004, contact
Bartosz Grzybowski, firstname.lastname@example.org or George Whitesides, email@example.com.)