A new method for storing and pumping media on a nanoscale could have a significant effect on a wide range of technologies including: hydrogen energetics, nano-robotics, nano-scale printing, atom optics, quantum computing, semiconductors, forensic and nucleotide analysis, chemical process control, cell biology, medical drug delivery, and molecular medicine.
The United States of America as represented by the United States Department of Energy (Washington, DC) received U.S. Patent 7,632,482 for a new method for nano-pumping using carbon nanotubes. According to inventors Zeke Insepov (Darien, IL) and Ahmed Hassanein (Bolingbrook, IL) their discovery includes methods for nano-pumping gaseous, liquid, solid, or other media through carbon nanotubes.
Surface waves transform the nanotubes into a nano-scale pump capable of pumping media. The driving force behind the nano-pump is the friction between the media (i.e. gas, liquid) and the nanotube walls. Gas atoms inside the carbon nanotube move almost freely along ballistic trajectories when surface waves are created on the nanotubes. The gas atoms are easily accelerated to a very high axial velocity along the direction of the traveling wave. The increase in acceleration is a result of multiple synchronous collisions with the moving nanotube walls (resulting from the surface waves). The surface waves cause the media to be pumped through the nanotube in the direction of the traveling surface wave.
A salient aspect of the carbon nanotube nano-pump is the creation of surface waves on the surface of the nanotubes. The surface waves are preferably transverse longitudinal waves. The waves are more preferably Raleigh waves. The induced surface waves can have a wide range of frequencies. The preferred frequency is dependent on the length of the carbon nanotubes being used. For shorter carbon nanotubes, the preferred range is generally less than about 60 THz, and more preferably between about 10 and 60 THz. However, for longer carbon nanotubes the frequency could be much smaller
A salient aspect of the carbon nanotube nano-pump is the creation of surface waves on the surface of the nanotubes. The surface waves are preferably transverse longitudinal waves. The waves are more preferably Raleigh waves. The induced surface waves can have a wide range of frequencies. The preferred frequency is dependent on the length of the carbon nanotubes being used. For shorter carbon nanotubes, the preferred range is generally less than about 60 THz, and more preferably between about 10 and 60 THz. However, for longer carbon nanotubes the frequency could be much smaller
Insepov's and Hassanein's invention generally comprises the following steps: (1) providing a plurality of carbon nanotubes, each carbon nanotube having a first and second end with the first end in contact with a gaseous, liquid, or solid media; and (2) creating surface waves along the carbon nanotubes which pumps media through the tube(s). There are at least two known methods of creating surface waves on carbon nanotubes. One method uses short laser pulses to generate thermo-acoustic waves on carbon nanotubes. Another way is to send ultra-sound waves through a liquid or dense gaseous media to carbon nanotubes.
The study of narrow channels has become a popular area of research since the discovery of carbon nanotubes by Sumio Ijima in 1991. Ijima found that carbon fibers, which were already known to exist, were in fact hollow. Part of the fullerene structural family (which also includes buckyballs), carbon nanotubes can be generally described as rolled-up sheets of graphite with diameters on the order of several nanometers. There are two common types of carbon nanotubes: single-walled carbon nanotubes and multi-walled carbon nanotubes. Single-walled carbon nanotubes consist of one rolled sheet of one-atom-thick graphite (called graphene). Multi-walled carbon nanotubes are made of concentric cylinders of graphene (e.g., a single-walled carbon nanotube within a larger single-walled carbon nanotube). Despite their small size, carbon nanotubes are known to exhibit remarkable strength and have other unexpected electrical and structural properties.
In recent years the study of fluid control in narrow channels has become a hot area of research. Current research has centered on microflow systems including liquid flows in narrow slit-pores, very thin liquid film on solid surfaces, flows in micropumps, microarrays and membranes. Although fluid flow dynamics in carbon nanotubes has been studied to some degree, research in this area has focused on: laser driven atomic transport using electric current which drives ions using drag forces (citation) and nano-pipette systems for dragging metal ions through a multi-walled CNT using electromigration forces. There is a need in the art for a new method of pumping non-ionic media on a nanoscale.
Nanotubes have also been studied for their energy storage capabilities. Of particular importance is the issue of how to store and release hydrogen in a safe and practical manner. The energy storage capabilities of carbon nanotubes have been explored through the two forms of adsorption: chemisorption and physisorption. Adsorption, in general, is where a gas or liquid accumulates on the surface of a solid or liquid and forms a molecular or atomic film. Chemisorption is a form of adsorption where molecules attach to the surface of the carbon nanotube by forming a chemical bond.
In recent years the study of fluid control in narrow channels has become a hot area of research. Current research has centered on microflow systems including liquid flows in narrow slit-pores, very thin liquid film on solid surfaces, flows in micropumps, microarrays and membranes. Although fluid flow dynamics in carbon nanotubes has been studied to some degree, research in this area has focused on: laser driven atomic transport using electric current which drives ions using drag forces (citation) and nano-pipette systems for dragging metal ions through a multi-walled CNT using electromigration forces. There is a need in the art for a new method of pumping non-ionic media on a nanoscale.
Nanotubes have also been studied for their energy storage capabilities. Of particular importance is the issue of how to store and release hydrogen in a safe and practical manner. The energy storage capabilities of carbon nanotubes have been explored through the two forms of adsorption: chemisorption and physisorption. Adsorption, in general, is where a gas or liquid accumulates on the surface of a solid or liquid and forms a molecular or atomic film. Chemisorption is a form of adsorption where molecules attach to the surface of the carbon nanotube by forming a chemical bond.
The use of nano-pumping for hydrogen storage could provide an efficient means for storing and subsequently releasing hydrogen for use in fuel cells and other uses. The use of nano-pumping in nano-robotics provides a means for movement of nano-robots by providing a nano-hydraulics system.
