Molecules are excited objects, subject to movements that are constant over time, but random in space.These fluctuations are usually called “noise”, and affect the movement of fluids, the intensity of electromagnetic fields, chemical reactions etc..But, like any movement, this agitation of the molecules is a source of energy.
Scientists at the University of Berlin, Germany, have now shown for the first time that nanotechnology is about to allow exploitation of this energy practice.Jose Ignacio Pascual and his team were able to use the random and spontaneous movement of a single hydrogen molecule (H2) to move a macroscopic object, a bar oscillating in an electron microscope.
The researchers placed the hydrogen molecule in a very small space between a flat surface and the tip of an ultrasensitive atomic force microscope.This type of microscope uses the movement of a tip attached to the end of a highly sensitive mechanical oscillator in order to “feel” the forces which prevail in the nanometer range.
The hydrogen molecule with its random, chaotic motion, reaches the tip of the microscope by inducing on it a force that is enough to move the rocker arm of the microscope.
Of course, the lever also modulates the motion of the molecule, resulting in a “dance” orchestrated between the microscope tip and the molecule, but generating a movement which can be observed at macroscale.
“The result is that the smaller molecule which is a molecule of hydrogen, ‘push’ the rocker bar which has a mass 10 19 times – ten trillion times – higher! ” Pascual explained.
Molecular electric motor
The principle behind the experiment is known as stochastic resonance, which describes how random movements of energy are channeled in the form of periodic movements.“In our experiment, the ‘noise’ of the molecule is generated by injecting an electric current, temperature, and not through the molecule. Therefore it functions as a mechanism for converting electric energy into mechanical,” said Pascual. That is, the apparatus is essentially a molecular electric motor.
The researcher adds that one of the most promising aspects of this demonstration is that the principle can be applied to the creation of artificial molecules, complex molecules that are designed to oscillate or rotate in a single direction.
It also does not rule out that this molecular fluctuation may be produced by other sources such as light, or be performed with a greater number of molecules, even with different chemical compositions.