The elevator to success is out of order. You'll have to use the stairs... one step at a time.
- Joe Girard
Scientists spent years developing the tools needed to observe individual atoms or everyday housekeeping events occurring in the living cell. But the key challenge of nanoscience is not just how to observe these minuscule settings, but how to manipulate them to design nano-structures with novel applications.
In the early 1980s, the Institute’s Prof. Jacob Sagiv made a pioneering contribution to this field, with an approach known as planned or guided self-assembly. The idea is to allow atoms and molecules - the tiniest building blocks of matter - to self-assemble into functional structures. The approach introduces chemical changes to organic molecules, causing them to vertically bind additional molecules. Working with Dr. Rivka Maoz, Sagiv later expanded this approach to create 3-dimensional designs, in a strategy called constructive nanolithography.
Today, numerous groups around the world are pursuing the goal of self assembly. Some are turning to DNA, proteins and other biological compounds - master self-assemblers in the body - in the hope of incorporating them into transistors and other nanodevices.
Constructive nanolithography - The art of bottom-up
Prof. Jacob Sagiv aims to build data from the bottom up, out of atoms and molecules - much as a builder uses bricks to construct a brick wall. The key idea is that an artificial molecular system may control its own construction, similar to the way a biological system controls its development.
Beginning with a smooth silicon surface consisting of a one-molecule-thick layer in which the exposed ends of the molecules are rendered chemically inert, the team, headed by Sagiv and Dr. Rivka Maoz, has devised methods to chemically activate a select portion of these molecules. Since the properties of the activated molecules then differ from those of surrounding molecules, they can encode diverse data - from text to images or even music.
This kind of information can be inscribed using an atomic force microscope (AFM) as a pencil. Equipped with an ultrasharp needle probe that transmits electrical signals, the AFM writes the information by electrochemically modifying the ends of molecules it touches. These modified molecules are later detected by an AFM operating in its reading mode.
Once the molecular ends are activated, they are capable of binding other atoms and molecules, making possible the deposition of additional molecular floors.
Molecules in the first layer have binding sites to which the second layer adheres as it is added.
Unlike the "destructive" information development in conventional photo- and electron-beam lithographies, achieved by etching into the underlying substrate material, in this approach, named constructive nanolithography, the initial information stored in the first layer guides the assembly pattern of the higher data “floors.” Cashing in on this feature, the research team was able to create double-deck or even taller information packs, including a nanosized molecular replica of the Weizmann Institute’s logo tree with leaves one-thousandth the width of a human hair.
This novel bottom-up approach could offer precise control over the structure and chemical composition of future nano devices, paving the way to chemically synthesized electronics with significantly enhanced data density. For starters, we may enjoy a Beethoven symphony from a thumbnail-sized chip.
- Joe Girard
Scientists spent years developing the tools needed to observe individual atoms or everyday housekeeping events occurring in the living cell. But the key challenge of nanoscience is not just how to observe these minuscule settings, but how to manipulate them to design nano-structures with novel applications.
In the early 1980s, the Institute’s Prof. Jacob Sagiv made a pioneering contribution to this field, with an approach known as planned or guided self-assembly. The idea is to allow atoms and molecules - the tiniest building blocks of matter - to self-assemble into functional structures. The approach introduces chemical changes to organic molecules, causing them to vertically bind additional molecules. Working with Dr. Rivka Maoz, Sagiv later expanded this approach to create 3-dimensional designs, in a strategy called constructive nanolithography.
Today, numerous groups around the world are pursuing the goal of self assembly. Some are turning to DNA, proteins and other biological compounds - master self-assemblers in the body - in the hope of incorporating them into transistors and other nanodevices.
Constructive nanolithography - The art of bottom-up
Prof. Jacob Sagiv aims to build data from the bottom up, out of atoms and molecules - much as a builder uses bricks to construct a brick wall. The key idea is that an artificial molecular system may control its own construction, similar to the way a biological system controls its development.
Beginning with a smooth silicon surface consisting of a one-molecule-thick layer in which the exposed ends of the molecules are rendered chemically inert, the team, headed by Sagiv and Dr. Rivka Maoz, has devised methods to chemically activate a select portion of these molecules. Since the properties of the activated molecules then differ from those of surrounding molecules, they can encode diverse data - from text to images or even music.
This kind of information can be inscribed using an atomic force microscope (AFM) as a pencil. Equipped with an ultrasharp needle probe that transmits electrical signals, the AFM writes the information by electrochemically modifying the ends of molecules it touches. These modified molecules are later detected by an AFM operating in its reading mode.
Once the molecular ends are activated, they are capable of binding other atoms and molecules, making possible the deposition of additional molecular floors.
Molecules in the first layer have binding sites to which the second layer adheres as it is added.
Unlike the "destructive" information development in conventional photo- and electron-beam lithographies, achieved by etching into the underlying substrate material, in this approach, named constructive nanolithography, the initial information stored in the first layer guides the assembly pattern of the higher data “floors.”
Cashing in on this feature, the research team was able to create double-deck or even taller information packs, including a nanosized molecular replica of the Weizmann Institute’s logo tree with leaves one-thousandth the width of a human hair.
This novel bottom-up approach could offer precise control over the structure and chemical composition of future nano devices, paving the way to chemically synthesized electronics with significantly enhanced data density. For starters, we may enjoy a Beethoven symphony from a thumbnail-sized chip.
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