Fueling controversy

Abstract

Artificial molecular machines now come in a dizzying variety of forms, including motors, pumps, and data-reading ratchets. While some machines are powered by light, a growing number are driven by chemical reactions with fuel molecules. Chemists are now learning how to fine-tune these chemical fuels to improve the machines’ performance and are building autonomous machines that keep ticking as long as they have a fuel supply. But the work is also fueling debate about the machines’ fundamental operating principles. As researchers grapple with the kinetics and thermodynamics of molecular machines, many believe that developing a more robust set of design principles for these nanosized devices will ultimately help the field. The workshops of molecular machinists seem to be growing louder by the year. You can almost hear the imaginary whirring of their nanoscale devices, accompanied by an anvil chorus of tiny but industrious hammers. Over the past couple of decades,