Electrostatic Force Microscopy (EFM): Imaging electric charge using microbial nanowires: Breakthrough in protein based nanoelectronics

Recent study carried out by UMass Amherst researchers has showed that electric charges propagate along microbial nanowires of the microbe Geobacter just as they do in carbon nanotubes.

Physicists affirmed that injection of electrons at one end in the microbial nanowires lit up the whole filament as the electrons propagated through the nanowire, similar to the other highly conductive materials. The technique applied here is known as electrostatic force microscopy (EFM). This technique has immense environment implications as conversion of waste to biogas is possible by conducting electricity through these wires. The nanowires permit Geobacter to live on iron and other metals in the soil, significantly changing soil chemistry and playing an important role in environmental cleanup. Microbial nanowires are also key components in the ability of Geobacter to produce electricity, a novel capability that is being adapted to engineer microbial sensors and biological computing devices.

In biological materials, electrons typically move by hopping along discrete biochemical stepping-stones that can hold the individual electrons. By contrast, electrons in microbial nanowires are delocalized, not associated with just one molecule, leading to metallic-like conductivity phenomena.

This investigation not only brings up an important new principle in biology but also in materials science. Natural amino acids, when arranged correctly, can propagate charges similar to molecular conductors. It opens exciting opportunities for protein-based nanoelectronics due to the fact that manipulating microbes for electrical application seems feasible. Efforts are also directed towards building electronic sensors to detect environmental contaminants and microbiological computers using Geobacter.

Mechanosensation device by molybdenum disulfide (MoS2)

In a breakthrough invention, scientists have successfully executed an experiment of piezoelectricity and the piezotronic effect in an atomically thin material, molybdenum disulfide (MoS₂), resulting in a unique electric generator and mechanosensation devices; although the piezoelectric effect in this material had already been predicted theoretically.

Piezoelectricity is defined as a phenomenon in which pressure generates an electrical voltage in a material or vice-versa. But no experimental observation of piezoelectricity has been made yet for few atom thickness material. The observation of molybdenum disulfide material has unfolded the potential for new types of mechanically controlled electronic devices.

In an interesting application of this phenomenon, this material could be made as a wearable device, integrated into clothing, to convert energy from your body movement to electricity and power wearable sensors or medical devices, or perhaps supply enough energy to charge cell phone.

There are two keys to using molybdenum disulfide for generating current: using an odd number of layers and flexing it in the proper direction. The material is highly polar, but an even number of layers cancels out the piezoelectric effect. The material's crystalline structure also is piezoelectric in only certain crystalline orientations.

Group of researchers placed thin flakes of MoS₂ on flexible plastic substrates and determined how their crystal lattices were oriented using optical techniques. They then patterned metal electrodes onto the flakes and measure current flow as the samples were mechanically deformed. They monitored the conversion of mechanical to electrical energy, and observed voltage and current outputs.

The researchers also noted that the output voltage reversed sign when they changed the direction of applied strain, and that it disappeared in samples with an even number of atomic layers, confirming theoretical predictions published last year. The presence of piezotronic effect in odd layered MoS₂ was also observed for the first time.

To be piezoelectric, a material must break central symmetry. A single atomic layer of MoS₂ has such a structure, and should be piezoelectric. However, in bulk MoS₂, successive layers are oriented in opposite directions, and generate positive and negative voltages that cancel each other out and give zero net piezoelectric effect.

In fact, MoS₂ is just one of a group of 2D semiconducting materials known as transition metal dichalcogenides, all of which are predicted to have similar piezoelectric properties. These are part of an even larger family of 2D materials whose piezoelectric materials remain unexplored. The research could lead to complete atomic-thick nanosystems that are self-powered by harvesting mechanical energy from the environment. This study also reveals the piezotronic effect in two-dimensional materials for the first time, which greatly expands the application of layered materials for human-machine interfacing, robotics, MEMS, and active flexible electronics.

Fullerene spheres: as nano-bearing

About 3500 years ago, man invented the wheel to make life easier. Then, thanks to Leonardo Da Vinci's, the wheel was made smaller to obtain ball bearings. Today we are trying to get even smaller: scientists are thinking about nano-bearings. In the future we'll have many nano-machines capable of carrying out the most diverse tasks, for example transporting medicines inside the human body. In order to save energy, many of these vehicles will have to able to move efficiently, using as little energy as possible, and nano-sized ball bearings may help achieve this goal.

Nanomechanical devices will need tiny devices to reduce friction and make movement possible. Fullerene or buckyballs (C60 molecule) seemed to be an excellent candidate for nano-bearings. Scientists thought they could use C60, a hollow carbon nano-sphere as a nano-bearing. Preliminary studies suggested that C60 molecules suddenly become free to rotate at a particular temperature, which hopefully has a role in friction. However, experimental results yielded conflicting results and yet to be verified in which temperature the friction becomes less. 

Simulation has been carried out using tiny tip of an electron microscope bearing a C60 flake, which was dragged over a surface also made of C60. It has been found that when the flake was attached in such a way that it couldn't rotate and the friction did not decrease, even if the temperature is raised. It's as if the bearings making up the flake interlocked with the substrate, with no nano-bearing effect. However, when the flake was free to rotate there was a dramatic drop in friction and the flake could slide over the surface far more smoothly.

Modulated Nanostructure: Nanowire bridging transistors: The new Buzz word for next-generation electronics

Silicon has been established as one of the widely used material in the integrated circuit since approximately 60 years. It is used to fabricate transistors using conventional method, where etching of the layers was done to formulate some structures. However, circuit based on silicon reach its operational speed limit and does not work above certain temperature. In addition to that, ever increasing demand of miniaturization has led to the development of advanced manufacturing technique where nanostructure material plays significant roles along with the addition of other semiconducting material such as gallium nitride. It does not only show promise for a new generation of fast, robust electronic and photonic devices, but also opens up the scope of innovation for the researchers. Such is the case of three dimensional nanowire transistors, developed by scientists of University of California.

 

 One of the technical problem silicon substrate is facing over the years is the lattice parameter mismatch with other materials. Match is necessary due to the growth technique associated with integrated circuit, which in turn faces major limitation as far as the growth material is concerned. To overcome these challenges, nanowire made of semiconductor materials was made on top of silicon surfaces. Due to the lower surface area of nanowire which acquires the place of silicon, problem of lattice mismatch does not arise. The new technology could be used, for example, to build sensors that can operate under high temperatures, for example inside aircraft engines. In the near future, machine will be dependent on a variety of sensors and control systems that operate in extreme environments, such as motor vehicles, boats, airplanes, terrestrial oil and ore extraction, rockets, spacecraft, and bodily implants.

 

The researchers have been able to make these nanowires operate as transistors, and combine them into more complex circuits as well as devices that are responsive to light. They have developed techniques to control the number of nanowires, their physical characteristics and consistency. The technology also leverages the well-established technology for manufacturing silicon integrated circuits.

New nanomaterial for longer battery life

An architecture nanostructured material has been recently developed by researchers at the University of California using nanocrystalline ruthenium oxide coupled with graphene. This technology could improve the quality of the supercapacitors leading to long lasting battery life in portable electronics.

 

The present study showed that two times more energy and power can be achieved with this material compared to commercial supercapacitors. The electrode and/or supercapacitors made with above mentioned nanomaterial can be cycled over 8000 times without any fatigue because of its high energy density. Nanostructured materials also rendered large surface area, high electrical conductivity, short ion diffusion pathways and excellent interfacial integrity, making these high energy supercapacitor electrodes ideal for future energy storage applications.

Self assembled nanostructure through field assisted phase transition

In the year of 2012, scientist developed the idea of using nanoparticles as building block of functional material which can be engineered to make a computer chip that can assemble itself.

The research carried out by researchers of NASA and University of Delware reported an article about the self assembled with specific structures, built by nanomaterials.

They have observed transition of paramagnetic colloids from random structures to organised crystalline structures when an external magnetic field with desired frequency and field strength was applied into it. This kind of phase separation/transition provides the opportunity to build crystals using magnetic field. It is also useful in understanding the phenomena/mechanisms through which the materials are turned into crystalline.

This new phenomenon could prove worthy for manufacturing new nanoscale self assembled components due to a definite relationship between applied electric field and the conversion of disorder to order structure.

For further reading regarding field assisted phase transition:

http://www.pnas.org/content/109/40/16023.full.pdf+html?sid=d4c55815-5d87-4419-b4da-dd7cc0eaeb9c

Discovery of EIGHTH colour in the rainbow using Carbon nano tube

Scientists have recently “observed” an invisible eighth colour in the rainbow, a discovery that could have wide-ranging implications in the field of military camouflage and modern surveillance.

The invention of the new basic colour in the spectrum of light was made by physicists at the Randall Monroe University in West Virginia, who were investigating packets of photons that are fired through a cloud of ultracold sodium atoms, colliding with the light and slowing it down. This light was then passed through a series of carbon nanotubes in which the incident angle was enough to bounce the photons back on themselves.

The eighth colour can be thought of as the first addition to the traditional spectrum since Isaac Newton first successfully split white light using a triangular prism in 1671.

There is a possibility that this new colour could be the pioneer in the invention of a invisible cover. While current designs rely on physically bending light around an object or shielding it from a small portion of the spectrum, scientists suggest that simply bathing the target in this previously unseen colour could have dramatic results. 
 

The relative simplicity of the new technology could also have impact on the consumer market, as researchers claim, accessing the colour would not be expensive.

Manipulation of Cells and molecules by biomolecular mechanical tweezers

A new type of biomolecular tweezers could help researchers to study how mechanical forces affect the biochemical activity of cells and proteins. The devices, too small to see without a microscope, use opposing magnetic and electrophoretic forces to precisely stretch the cells and molecules, holding them in position so that the activity of receptors and other biochemical activity can be studied.

Arrays of the tweezers could be combined to study multiple molecules and cells simultaneously, providing a high-throughput capability for assessing the effects of mechanical forces on a broad scale.

For example, a cell that's binding the extracellular matrix may bind with one receptor while the matrix is being stretched, and a different receptor when it's not under stress. Those binding differences could drive changes in cell phenotype and affect processes such as cell differentiation. A device like this will allow us to interrogate what the specific binding sites are and what the specific binding triggers are.

Scientists have been able to study how single cells or proteins are affected by mechanical forces, but their activity can vary considerably from cell-to-cell and among molecules. The new tweezers, which are built using nanolithography, can facilitate studying thousands or more cells and proteins in aggregate.

At the center of the tweezers are few micron polystyrene microbeads that contain superparamagnetic nanoparticles. The tiny beads are engineered to adhere to a sample being studied. That sample is attached to a bead on one side, and to a magnetic pad on the other. The magnet draws the bead toward it, while an electrophoretic force created by current flowing through a gold wiring pattern pushes the bead away. The device simultaneously pushes and pulls on the same particle.

Because the forces can be varied, the tweezers can be used to study structures of widely different size scales, from protein molecules to cells. Absolute forces in the nano-Newton range applied by the two sources overcome the much smaller effects of Brownian motion and thermal energy, allowing the tweezers to hold the cells or molecules without constant adjustment.

As a proof of principle for the system, the researchers demonstrated its ability to distinguish between antigen binding to loaded magnetic beads coated with different antibodies. When a sufficient upward force is applied, non-specific antibody coated beads are displaced from the antigen-coated device surface, while beads coated with the specific antibody are more strongly attracted to the surface and retained on it.

Nanotechnology Breakthroughs by International Business Machines Corporation (IBM)

Source : http://www-03.ibm.com/press/attachments/28488.pdf

 

In chronological order:

 

1981 - IBM scientists invent the  Scanning Tunneling Microscope, giving ready access for the first time to the nanoscale world of individual atoms and molecules on electrically conducting substrates.

1986 -The  Atomic Force Microscope is invented by IBM and Stanford University scientists, quickly becoming the workhorse of nanoscience, providing general purpose imaging and manipulation in the nanometer realm.

1986 - IBM scientists Gerd Binnig and Heinrich Rohrer win the  Nobel Prize in Physics for the Scanning Tunneling Microscope.

1988 - IBM scientists observe  photon emission from local nanometer-sizes areas stimulated by a scanning tunneling microscope, allowing phenomena such as luminescence and fluorescence to be studied on the nanometer scale.

1989 - IBM Fellow Don Eigler is the  first to controllably manipulate individual atoms on  a surface, using the STM to spell out "I-B-M" by positioning 35 xenon atoms, and in the process, perhaps creating the world’s smallest corporate logo.

1991 -IBM scientists demonstrate an  atomic switch, a significant milestone on the road to the eventual design of electronic devices of atomic dimensions.

1993 – Scientists at IBM and NEC  independently discover single-wall carbon nanotubes and the methods to produce them using metal catalysts.

1996 - IBM scientists extend STM manipulation techniques to  position individual  molecules at room temperature for the first time.

1996 - The  world's smallest abacus is created out of 10 atoms by scientists at IBM, another major milestone in engineering at the nanoscale.

1998 -  IBM scientists and partners discover a molecular wheel, which shows promise for making nanoscale mechanical gears and motors.

 2000 - IBM and university researchers develop nanomechanical sensors using  tiny silicon  fingers to detect minute quantities of biochemical substances and to recognize specific patterns of DNA.

2001 - IBM's "constructive destruction" method overcomes major hurdle for building computer chips beyond silicon with a  method to separate semiconducting and metallic  nanotubes to form a working transistor on the nanoscale

2001 - IBM scientists unveil the  world's first single-molecule computer circuit, carbon nanotube transistors transformed into logic-performing integrated circuits, a major step toward molecular computers.

 

2002 - IBM researchers build world's smallest operating computing circuits using a  molecule cascade, wherein molecules move in a manner analogous to falling dominos.

2003 -- Scientists from IBM, Columbia University and the University of New Orleans demonstrate the first  three-dimensional self assembly of magnetic and semiconducting nanoparticles, a modular assembly method that enables scientists to bring almost any materials together.

2003 - IBM scientists demonstrate the  world's smallest solid-state light emitter, suggesting that carbon nanotubes may be suitable for optoelectroinics.

2004 -- IBM scientists develop a new technique called “spin-flip spectroscopy” to study the properties of atomic-scale magnetic structures. They use this technique to measure  a  fundamental magnetic property of a single atom -- the energy required to flip its magnetic  orientation.

2004 – IBM scientists measure the tiny  magnetic force from a single electron spin using an ultra sensitive magnetic resonance force microscope, showing the potential of vastly extending the sensitivity of magnetic resonance imaging (MRI).

2004 -- IBM scientists  manipulate and control the charge state of individual atoms. This ability to add or remove an electron charge to or from an individual atom can help expand the scope of atom-scale research. Switching between different charge states of an individual atom could enable unprecedented control in the study of chemical reactivity, optical properties, or magnetic moment.

2004 -- IBM scientists make breakthrough in  nanoscale imaging -- the ability to detect the faint magnetic signal from a single electron buried inside a solid sample is a major milestone toward creating a microscope that can make three-dimensional images of molecules with atomic resolution.

2005 -- Using nanoelectronic fabrication technologies, IBM researchers create a tiny device that  slows the speed of light, representing a big advance toward the eventual use of light in place of electricity in the connection of electronic components, potentially leading to vast improvements in the performance of computers and other electronic systems.

2006 -- IBM researchers build the  first complete electronic integrated circuit around a  single “carbon nanotube” molecule, a new material that shows promise for providing enhanced performance over today’s standard silicon semiconductors. The achievement is significant because the circuit was built using standard semiconductor processes and used a single molecule as the base for all components in the circuit, rather than linking together individually-constructed components. This can simplify manufacturing and provide the consistency needed to more thoroughly test and adjust the material for use in these applications.

2006 -- IBM scientists develop a powerful new technique for  exploring and controlling  atomic magnetism, an important tool in the quest not only to understand the operation of future computer circuit and data-storage elements as they shrink toward atomic dimensions, but also to lay the foundation for new materials and computing devices that leverage atom-scale magnetic phenomena.

2006 – In a study investigating the fundamentals of molecular electronics, the  quantum  mechanical effects of attaching gold atoms to a molecule were elucidated. The work demonstrated that it is not only possible to control the atomic-scale geometry of a metal-molecule contact, but also its coupling strength and the phase of the orbital wave function at the contact point.

2007 -- IBM demonstrates the first-ever manufacturing application of "self assembly" used to create a vacuum -- the ultimate insulator -- around nanowires for next-generation microprocessors for its  airgap chip technique.

2007 - IBM researchers in collaboration with scientists from the ETH Zurich demonstrate a new, efficient and precise technique to  “print” at the nanoscale.

2007 - IBM unveils two  nanotechnology breakthroughs as building blocks for atomic structures and devices: Magnetic atom milestone brings single-atom data storage closer to reality; single-molecule switching could lead to molecular computers.

2007 - IBM researchers develop magnetic resonance imaging (MRI) techniques to visualize nanoscale objects. This technique brings  MRI capability to the nanoscale level  for the first time.

2008 - IBM scientists, in collaboration with the University of Regensburg in Germany, are the first ever to measure  the force it takes to move individual atoms on a surface.

2009 – IBM Research builds  microscope with 100 million times finer resolution than current MRI, extending three-dimensional MRI to the nanoscale.

 2009 - IBM scientists reach a landmark in the field of nanoelectronics: the development and demonstration of novel techniques to  measure the distribution of energy and heat in  powered carbon nanotube devices. By employing these techniques, IBM researchers have determined how the energy of electrical currents running through nanotubes is converted into heat and dissipated into collective vibrations of the nanotube's atoms, as well as surface vibrations of the substrate beneath it.

2009 - IBM scientists in collaboration with the University of Regensburg, Germany, and Utrecht University, Netherlands, for the first time demonstrate the ability  to measure the  charge state of individual atoms using non contact atomic force microscopy.

2009 - In an effort to achieve energy-aware computing, the Swiss Federal Institute of Technology Zurich (ETH) and IBM plan to build a  first-of-a-kind water-cooled  supercomputer that will directly repurpose excess heat for the university buildings. The system is expected to save up to 30 tons of CO2 per year, compared to a similar system using today's cooling technologies.

 

2009 – IBM launches new research effort for  next generation electric energy storage, exploring battery technologies to drive electric vehicle adoption and make energy grids more efficient.