Publications by Andrew Turberfield

Holographic fabrication of photonic crystals

P SOC PHOTO-OPT INS 5720 (2005) 1-8

DN Sharp, ER Dedman, J Scrimgeour, OM Roche, CF Blanford, JC Saunders, RG Denning, AJ Turberfield

Holographic lithography is well-adapted to the production of three-dimensional photonic crystals for applications in the technologically important optical regime. We illustrate the flexibility of this approach by considering the design and fabrication of photonic crystals with symmetries that favour the formation of a complete photonic band gap. One of them, a structure with diamond symmetry, is calculated to have a complete gap at a refractive index contrast equal to the lowest yet reported.

Registration of single quantum dots for solid state cavity quantum electrodynamics

(2005) 113-114

KH Lee, AM Green, FSF Brossard, RA Taylor, AJ Turberfield, DA Williams, GAD Briggs

Design of an autonomous DNA nanomechanical device capable of universal computation and universal translational motion

LECT NOTES COMPUT SC 3384 (2005) 426-444

P Yin, AJ Turberfield, S Sahu, JH Reif

Intelligent nanomechanical devices that operate in an autonomous fashion are of great theoretical and practical interest. Recent successes in building large scale DNA nano-structures, in constructing DNA mechanical devices, and in DNA computing provide a solid foundation for the next step forward: designing autonomous DNA mechanical devices capable of arbitrarily complex behavior. One prototype system towards this goal can be an autonomous DNA mechanical device capable of universal computation, by mimicking the operation of a universal Turing machine. Building on our prior theoretical design and prototype experimental construction of an autonomous unidirectional DNA walking device moving along a linear track, we present here the design of a nanomechanical DNA device that autonomously mimics the operation of a 2-state 5-color universal Turing machine. Our autonomous nanomechanical device, called an Autonomous DNA Turing Machine (ADTM), is thus capable of universal computation and hence complex translational motion, which we define as universal translational motion.

DNA scaffolds and electron crystallography: a method for protein structure determination

BIOPHYS J 86 (2004) 80A-80A

J Malo, JC Mitchell, C Venien-Bryan, JR Harris, LN Johnson, DJ Sherratt, AJ Turberfield

The single-step synthesis of a DNA tetrahedron.

Chem Commun (Camb) (2004) 1372-1373

RP Goodman, RM Berry, AJ Turberfield

A tetrahedral nanostructure whose edges are DNA double helices self-assembles spontaneously when four appropriately designed oligonucleotides are annealed together in solution; the ease of synthesis, rigidity, and adaptability of this construct make it a promising candidate as a cage for other large molecules and as a building block for more complicated nanostructures.

Self-assembly of chiral DNA nanotubes.

J Am Chem Soc 126 (2004) 16342-16343

JC Mitchell, JR Harris, J Malo, J Bath, AJ Turberfield

A system of DNA "tiles" that is designed to assemble to form two-dimensional arrays is observed to form narrow ribbons several micrometers in length. The uniform width of the ribbons and lack of frayed edges lead us to propose that they are arrays that have curled and closed on themselves to form tubes. This proposal is confirmed by the observation of tubes with helical order.

Self assembled DNA monolayers as a mechanism for redox probe control

BIOPHYS J 86 (2004) 596A-596A

RP Goodman, JJ Davis, AJ Turberfield

A unidirectional DNA walker that moves autonomously along a track.

Angew Chem Int Ed Engl 43 (2004) 4906-4911

P Yin, H Yan, XG Daniell, AJ Turberfield, JH Reif

DNA fuel for free-running nanomachines

Physical Review Letters 90 (2003) article 118102 4pp-

AJ Turberfield, J. C. Mitchell, B. Yurke, A. P. Mills

Sol-gel organic-inorganic composites for 3-D holographic lithography of photonic crystals with submicron periodicity

Chemistry of Materials 15 (2003) 2301-2304

K Saravanamuttu, CF Blanford, DN Sharp, ER Dedman, AJ Turberfield, RG Denning

We demonstrate that silica-acrylate materials doped with transition metal (Zr, Ti) oxide nanoparticles are suitable for the three-dimensional holographic lithography of photonic crystals with submicron periodicity and large inorganic contents. By careful choice of inorganic components, such composites could provide a route to the template-free, direct lithography of three-dimensionally ordered structures with high refractive-index contrast, submicron periodicity, and band gaps in the visible and infrared regions.

Holographic photonic crystals with diamond symmetry

Physical Review B - Condensed Matter and Materials Physics 68 (2003)

DN Sharp, AJ Turberfield, RG Denning

We explore the analytical design of high-symmetry photonic crystals made by holographic lithography. We show how holographic lithography may be used to produce diamond-like photonic crystals that have a full, three-dimensional photonic band gap at a refractive index contrast equal to the lowest yet published. © 2003 The American Physical Society.

DNA as an engineering material

PHYSICS WORLD 16 (2003) 43-46

A Turberfield

Photonic crystals for the visible spectrum by holographic lithography


DN Sharp, M Campbell, ER Dedman, MT Harrison, RG Denning, AJ Turberfield

Diamond-like photonic crystals by holographic lithography

Technical Digest - Summaries of Papers Presented at the Quantum Electronics and Laser Science Conference, QELS 2001 (2001) 13-

AJ Turberfield

© 2001 Optical Soc. Of America. Summary form only given. Holographic lithography is a general and flexible technique for the fabrication of three-dimensional photonic crystals. Three-dimensional microstructure is generated when a four-beam laser interference pattern is used to expose a thick layer of photoresist. Highly exposed regions in the resulting three-dimensional intensity grating are rendered insoluble; unexposed areas are then dissolved away to produce a three-dimensional photonic crystal formed of cross-linked polymer with air-filled voids. The polymeric structure may be used as a template for the production of photonic crystals with higher refractive index contrast. This technique is particularly well adapted to the production of structures with the sub-micron periodicity required for applications in the visible optical spectrum.

Holographic definition of photonic crystal structures.


RG Denning, CF Blanford, DN Sharp, AJ Turberfield

Photonic crystals made by holographic lithography

MRS BULLETIN 26 (2001) 632-636

AJ Turberfield

Photonic crystals made by holographic lithography

MRS Bulletin 26 (2001) 632-636

AJ Turberfield

Fabrication of photonic crystals for the visible spectrum by holographic lithography

Nature 404 (2000) 53-56

M Campbell, DN Sharp, MT Harrison, RG Denning, AJ Turberfield

The term 'photonics' describes a technology whereby data transmission and processing occurs largely or entirely by means of photons. Photonic crystals are microstructured materials in which the dielectric constant is periodically modulated on a length scale comparable to the desired wavelength of operation. Multiple interference between waves scattered from each unit cell of the structure may open a 'photonic bandgap'--a range of frequencies, analogous to the electronic bandgap of a semiconductor, within which no propagating electromagnetic modes exist. Numerous device principles that exploit this property have been identified. Considerable progress has now been made in constructing two-dimensional structures using conventional lithography, but the fabrication of three-dimensional photonic crystal structures for the visible spectrum remains a considerable challenge. Here we describe a technique--three-dimensional holographic lithography--that is well suited to the production of three-dimensional structures with sub-micrometre periodicity. With this technique we have made microperiodic polymeric structures, and we have used these as templates to create complementary structures with higher refractive-index contrast.

A DNA-fuelled molecular machine made of DNA.

Nature 406 (2000) 605-608

B Yurke, AJ Turberfield, AP Mills, FC Simmel, JL Neumann

Molecular recognition between complementary strands of DNA allows construction on a nanometre length scale. For example, DNA tags may be used to organize the assembly of colloidal particles, and DNA templates can direct the growth of semiconductor nanocrystals and metal wires. As a structural material in its own right, DNA can be used to make ordered static arrays of tiles, linked rings and polyhedra. The construction of active devices is also possible--for example, a nanomechanical switch, whose conformation is changed by inducing a transition in the chirality of the DNA double helix. Melting of chemically modified DNA has been induced by optical absorption, and conformational changes caused by the binding of oligonucleotides or other small groups have been shown to change the enzymatic activity of ribozymes. Here we report the construction of a DNA machine in which the DNA is used not only as a structural material, but also as 'fuel'. The machine, made from three strands of DNA, has the form of a pair of tweezers. It may be closed and opened by addition of auxiliary strands of 'fuel' DNA; each cycle produces a duplex DNA waste product.

Photonic crystals for the visible spectrum by holographic lithography

Conference on Lasers and Electro-Optics Europe - Technical Digest (2000) 68-

DN Sharp, AJ Turberfield, M Campbell, RG Denning

The fabrication of three-dimensional photonic crystal structures with sub-micron periodicity was performed by holographic lithography. The photonic crystals of titanium dioxide and polymeric materials were characterized by scanning electron microscopy and optical diffraction measurements. The interference pattern generated at the intersection of four beams from a neodymium laser was employed for the exposure of the photoresist.