DATA STORAGE USING DNA
W.A. Germishuizen†, C. Wälti‡, R. Wirtz‡, M.B. Johnston‡, A.G. Davies‡,
M. Pepper‡ and A.P.J. Middelberg†
University of Cambridge, UK
†: Department of Chemical Engineering
‡: Semiconductor Physics Group, Cavendish Laboratory
Data storage requirements are increasing dramatically and therefore much attention is being given to nextgeneration data storage media. However, in optical data storage devices the storage density is limited by the
wavelength of light. This limitation can be avoided by an alternative data addressing mechanism using
electric fields between nanoelectrodes with smaller dimensions than the wavelength of commercially
available lasers. It has been shown that DNA of a range of lengths can be aligned in an electric field [1, 2]. In
this study we demonstrate the use of an ac electric field to address DNA as a data storage technique.
λ-DNA, immobilised on an array of electrodes utilising its self-assembling properties, serves as a scaffold
for fluorescent molecules. The DNA is immobilised onto gold electrodes in a multi-step procedure ensuring
a controlled surface coverage of the molecules onto specific electrodes. To minimise background
fluorescence and to enable reversible stretching, the substrate surface is silanised prior to DNA
immobilisation. Using a strong, spatially confined ac electric field (1MV/m, 400kHz) the DNA molecules on
each electrode are individually and reversibly stretched into a focused Argon laser beam. The fluorophores
(YOYO1, Molecular Probes) are rapidly photobleached when the power density of the beam is increased,
allowing for data storage when associating a photobleached data point with a binary 1 and an intact data
point with a binary 0 (Figure 1). The resulting pattern of high/low fluorescence intensities is read by
measuring the fluorescence intensity, using the same dielectrophoretic addressing mechanism, but in
conjunction with a much reduced power beam. Although this concept of data storage has been demonstrated
only on the micrometre scale, it is a promising candidate for miniaturisation, potentially to the molecular
scale.
Figure 1. A pattern of selectively stretched λ-DNA on an array of 4 gold electrodes. Photobleaching the stretched DNA
in this configuration will result in a 1, 0, 1, 0 signal when reading back by sequentially stretching the DNA on each
electrode into a reduced power beam. The DNA is being stretched in a 1 MV/m, 400 kHz ac field. The electrodes are 10
μm in width and 15 μm apart.
[1] M. Wasizu, and O. Kurosawa, IEEE T. Ind. Appl, 1990, 26, 1165.
[2] M. Wasizu, O. Kurosawa, I. Arai, S. Suzuki, and N. Shimamoto, IEEE T. Ind. Appl, 1995, 31, 447.
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