Brownian motor
Brownian motors operate specifically to utilise this high level of random noise to achieve directed motion, and as such are only viable on the nanoscale.
[3] The Brownian motor, like the phenomenon of Brownian motion that underpinned its underlying theory, was also named after 19th century Scottish botanist Robert Brown, who, while looking through a microscope at pollen of the plant Clarkia pulchella immersed in water, famously described the random motion of pollen particles in water in 1827.
In 1905, almost eighty years later, theoretical physicist Albert Einstein published a paper where he modeled the motion of the pollen as being moved by individual water molecules,[6] and this was verified experimentally by Jean Perrin in 1908, who was awarded the Nobel Prize in Physics in 1926 "for his work on the discontinuous structure of matter".
There, they proposed the then novel concept of Brownian motors and posited that "thermal motion combined with input energy gives rise to a channeling of chance that can be used to exercise control over microscopic systems".
Astumian and Hänggi provide in their paper a copy of Wallace Stevens' 1919 poem "The Place of the Solitaires" to elegantly illustrate, from an abstract perspective, the ceaseless nature of noise.Inspired by the fascinating mechanism by which proteins move in the face of thermal noise, many physicists are working to understand molecular motors at a mesoscopic scale.
An important insight from this work is that, in some cases, thermal noise can assist directed motion by providing a mechanism for overcoming energy barriers.
[11] Specifically, an energy landscape was created by accurately shaping a nanofluidic slit, and alternate potentials and an oscillating electric field were then used to "rock" nanoparticles to produce directed motion.
Interdisciplinary collaboration between different branches of science and institutions is thus a key element of the SNI's day-to-day work.The thermal noise on the nanoscale is so great that moving in a particular direction is as difficult as "walking in a hurricane" or "swimming in molasses".
In the biological sense and in the extent to which this phenomenon appears in nature, this exists as chemical energy is sourced from the molecule adenosine triphosphate (ATP).
The Brownian ratchet is an apparent perpetual motion machine that appears to violate the second law of thermodynamics, but was later debunked upon more detailed analysis by Richard Feynman and other physicists.
[13] Similar motor proteins include kinesin and dynein, which all convert chemical energy into mechanical work by the hydrolysis of ATP.
These photomotors, in contrast to their natural counterpartsˇ, are inorganic and possess greater efficiency and average velocity, and are thus better suited to human use than existing alternatives, such as organic protein motors.
This will enable us to see inside even the narrowest blood vessels, to detect the fatty deposits (atherosclerotic plaque) that signal the start of arterial blockage and allow treatment before the disease progresses.
