When you buy a new computer today, there is one thing you can be sure of: in just a year’s time it will be obsolete! The speed of progress in computer technology today is truly breathtaking. To give just a single example – more and more data can be packed onto smaller and smaller areas. Can this trend to miniaturization continue endlessly? Will the nanometer scale –which has already been reached – turn out to be the ultimate limit?

Even dyed-in-the-wool nanotechnologists doubt that this pace of development can continue for ever! Magnetic storage media, at least, are already pushing up against physical boundaries. The so-called super-paramagnetic limit causes problems resulting in bits being lost from memory. This happens because with very tiny, nanometer-scale structures, where a single bit is represented by just a few atoms, the magnetic orientation can spontaneously flip due to thermal excitation. As in a compass, which is shaken hard, the orientation becomes more or less random. The result is the loss of data on a computer’s hard drive.

The millipede that saves data mechanically

The market for data storage products is enormous, so it is no surprise that the battle for the next generation of hard drives has already begun. The IBM Research Laboratory in Rueschlikon, near Zurich, is relying on a millipede to make the breakthrough. The data is scribed onto a suitable substrate using a force microscope with 1024 tips – hence the name. A hole represents a "1" and no hole represents a "0" – simple binary code. The data is read back using the same microscope with which it was written. The IBM researchers hope to achieve a data density of ten times higher than available with conventional media.

Red and blue dots instead of holes

EMPA scientists are also searching for the switching element for the storage medium of the future. In a cooperative project with the ETH Zurich, they are investigating the use of the mechanical-optical properties of Langmuir-Blodgett films (LB films) made of polydiacetylene (PDA). The films change color from blue to red when subjected to mechanical load. Individual dots of film could therefore be used as switches, with information being saved in a red-blue pattern. The binary-coded color pattern could then be read out using optical near field technology. The supramolecular structure of the nanoswitch has a minimum dimension of about 550 nm. It is therefore located in the wavelength range of optical absorption. (Vs)

The development of the nanoswitch has become possible through the financial support of the Swiss National Foundation within the research project "Supramolecular Functional Materials".

Chemische Flexibilität macht geringe Speicherkapazität wett

Die gegenwärtig erreichbare Speicherdichte liegt beim Empa-System bei 0.9 Mbits/cm². Im Vergleich dazu erreichen heutige Speichermedien auf Siliziumbasis einen Wert von 0.9 Gbits/cm². Ein beachtlicher Unterschied. Doch unser Ziel ist es, nicht die etablierte Siliziumtechnologie zu konkurrieren, sondern ein System zu entwickeln, das die Flexibilität des organisch-chemischen Aufbaus des Nanoschalters nutzt, um ihn entsprechend seines Einsatzgebietes zu optimieren. Anwendungen sind denkbar in den Bereichen der molekularen Erkennung, der Sensortechnologie sowie beim Einsatz unter speziellen Bedinigungen, z.B. in biologischer oder chemisch aggressiver Umgebung.

Your contact:

Dr Beat Keller, Laboratory Organic Chemistry, Phone +41 1 823 46 52, E-mail: beat.keller@empa.ch

E. Geiger, P. Hug, B.A. Keller: Chromatic Transitions in Polydiacetylene Langmuir-Blodgett Films due to Molecular Recognition at the Film Surface Studied by Spectroscopic Methods and Surface Analysis. Macromol. Chem. Phys. 203, No. 17 (2002)

More expert articles written by Beat Keller