Transforming 'noise' into mechanical energy at nanometric level

A team of researchers at the Freie Universität Berlin, co-ordinated by José Ignacio Pascual*, have developed a method that enables efficiently using the random movement of a molecule in order to make a macroscopic-scale lever oscillate.

In nature, processes such as the movement of fluids, the intensity of electromagnetic signals, chemical compositions, etc., are subject to random fluctuations which normally are called 'noise'. This noise is a source of energy and its utilisation for undertaking a task is a paradigm that nature has shown to be possible in certain cases.

The research led by José Ignacio Pascual and published in Science, focused on a molecule of hydrogen (H2). The researchers placed the molecule within a very small space between a flat surface and the sharp point of an ultra-sensitive atomic force microscope. This microscope used the periodic movement of the point located at the end of a highly sensitive mechanical oscillator in order to 'feel' the forces that exist at a nanoscale level. The molecule of hydrogen moves randomly and chaotically and, when the point of the microscope approaches it, the point hits the molecule, making the oscillator or lever move. But this lever, at the same time, modulates the movement of the molecule, resulting in an orchestrated 'dance' between the point and the 'noisy' molecule. "The result is that the smallest molecule that exists, a molecule of hydrogen, 'pushes' the lever, that has a mass 1019 greater; ten trillion time greater!," explained José Ignacio Pascual.