Transcript Presentation Renugopalakrishnan

BIONANOTECHNOLOGY AT FLORIDA INTERNATIONAL
UNIVERSITY, MIAMI, FLORIDA, USA
Dr. V. Renugopalakrishnan
HARVARD UNIVERSITY
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CURRENT STORAGE TECHNOLOGY –
LIMITATIONS
THE SUPER PARA-MAGNETIC LIMIT.
• The data held in the positively and the negatively charged
concentric magnetic tracks become so small that they will
cease to work.
• The energy required to maintain each tiny magnetic section
will be equaled and cancelled out by the surrounding heat
energy inside the drive.
• Super Para-magnetic limit at 100 gigabits per square inch.
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ATTRIBUTES OF AN IDEAL OPTICAL
STORAGE MEDIUM
TWO GENERAL ATTRIBUTES DESCRIBE
CHARACTERISTICS OF AN IDEAL OPTICAL
STORAGE DEVICE
1.
Optical media should be physically capable of manifesting at least
two steady states. If there are two states, this corresponds to one bit
of digital information. If there are more then two stable states, this
corresponds to information capacity of more then one bit.
2.
The thermal stability of the optical medium is very important. For
any given optical medium, a fundamental requirement is the
availability of methods for writing, reading, and erasing information.
These methods are specific for the optical medium. Selection of a
suitable method is dependent upon optical properties and spectral
characteristics of the optical medium.
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QUEST FOR AN IDEAL STORAGE MEDIUM:
GENETICALLY ENGINEERED
BACTERIORHODOPSINS
PROTEIN-BASED SYSTEMS OFFER NUMEROUS
ADVANTAGES
STRUCTURE
The chromophoric group of br consists of the retinylidene residue and an inner
shell of interacting amino acids that influences the absorption properties and
controls the photochemical pathways of the retinylidene residue. The rest of the
protein moiety carries the proton conduction pathway and shields the photochromic
inner group from influences from the outer environment.
MOLECULAR FUNCTION
The molecular function of br is that of a light-driven proton pump. The wild-type
molecule needs about 10 ms for a complete photochemical cycle. As br does not
have any refractory period after completing a photocycle under light saturating
conditions, 100 protons per second could be transported by a single molecule from
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the inner area of the cell to the outer medium
SECONDARY STRUCTURE
Eight residues in w-br
(D85,W86,L93,D96,D115,W182,
W189,D212) were systematically
mutated to enhance Tm and life
times, 50, of M and O photointermediates.
8 of these residues are shown in
red and retinal binding site,
Lys216, is shown in blue Arg and
Tyr residues were the chosen
residues whenever possible as the
choice for the above 8 residues in
the rational site-directed
mutations, since these residues
occur much more frequently in
thermophilic proteins.
The overall -helicity of br was
retained.
VECTOR FOR BR EXPRESSION IN PICHIA PASTORIS
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3D Strcture of Bacteriorhodopsin
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3D structure of [D96-N] bR
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bR [D96-N] in Dimyristoyl Phosphatidyl Choline
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MOLECULAR PROCESSES INVOLVED IN
BACTERIORHODOPSIN’S UNIQUE FUNCTION
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Photocycle of br 192 switching between M and Br state.
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Calculation of Delta Cp of a protein
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Goal is to demonstrate the feasibility of recording/storing/retrieving information
on/from photochromic proteins at areal densities of above 1 Terabit/in2 and data
rates of above 10 Gigahertz.
Approach is
1) to take advantage of the 2-D stability of BR media to record on one surface at
a single-molecule level or/and use a stack of layers to record in 3-D and
2) take advantage of the most advanced nanoscale recording system – so
called heat-assisted magnetic recording (HAMR) based on the near-field
optical recording transducer
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Earlier Proposed Protein Memory*
Parallel Data Access (page by page via positioning of the green light)
Drawback: Uncorrelated beams resulted in
substantial noise (limits data density)!
*R. R. Birge, Scientific American, 90-95, March 1995
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The Proposed Solution to Demonstrate the Feasibility of Protein Based Storage
All the above-described methods of recording/retrieving data are quite complicated and it is
hard to see whether they will be implemented and if yes, when. In fact, so far no physical
demonstration of ultra-high density recording (with a bit size of smaller than 100 nm) has
been made!
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first, to use a bit-by-bit type of recording to demonstrate the feasibility
of the protein-based storage;
then, to apply one of the available parallel data recording/retrieving
mechanism (e.g. holographic).
To accomplish this goal, the PIs use the transducer design earlier developed for heat-assisted magnetic
recording (HAMR). HAMR is the most advanced recording mechanism proposed so far. The PIs have
pioneered one of the most efficient design of the transducer for HAMR
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Holographic Type of Data Recording/Retrieving
The problem of uncorrelated beams to position information in the medium can be
solved through using a holography-type system.
However, from the perspective of achievable areal densities, a holographic system
is still substantially more inferior to any conventional data recording system (for
example, magnetic hard-drive)
Advantages
•Volume recording (data redundancy)
•Ultra-fast due to parallel write/read
•Multiplexing (by changing reference angle)
•No moving parts
Challenges
•Re-writable media
•Unstable media (data decay)
•Inter-symbol interference
•Slow recording (rates of 31 KB/sec 10
GB/sec during writing and read-out,
respectively. Access time is 2 sec)
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Novel Recording Transducer for Areal Densities Above 1 Terabit/in2
Note: Focused ion beam (FIB) is used to fabricate “apertureless” transducers
(with aperture dimensions of less than 100 nm << than the wavelength)
Air-bearing-surface (ABS) view of
laser diode with a thin layer of Al
with FIB-etched "C" shape
aperture
Electron Image of FIB-fabricated
Apertureless Transducer
< 90 nm
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Experimental setup to record and read information on/from proteins
Schematic Diagram
Near-field Optical System by DI
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Thin-film Protein Media Fabrication
AFM Image of a 2-D Pattern with
a 2.4-nm Period
Note: Patented approach to immobilize
proteins Into stable thin-film recording
media
Optical Spectra of a Gelatinmixed BR Film for Two States,
Ground (blue) and M-state (red)
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Early Results: Reading Tracks from Photochromic BR Media
Near-field Optical Readback Signal
Narrowest track is ~ 100 nm
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Note: The signal is the absorbed power in the detector system in the reflection mode
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COMPARISON OF DVD MEMORY CAPACITY
DVD-5 TO DVD-18 WILL
STORE UP TO 17 GBYTES OF
DATA
ONE LAYER TO ONE SIDE FOR DVD-5
TWO LAYERS TO TWO SIDES FOR DVD18
PROTEIN-BASED
TECHNOLOGY WILL HOLD
THE SAME FOR THE SAME
SPACE AND THE USAGE OF
THE SAME TECHNOLOGY.
ONE LAYER TO ONE SIDE FOR SAME
FORMAT AS DVD-5. 4.9 GBYTES
TWO LAYERS TO TWO SIDES FOR SAME
FORMAT AS DVD-10, 9.8 GBYTES
PROTEIN-BASED
TECHNOLOGY IS
CONDUCIVE TO
MULTILAYER USAGE.
MULTI LAYER TECHNOLOGY, 100
LAYERS WILL CREATE A STORAGE
CAPACITY OF 9.4 GIGBYTES TIME X 100
= 940 GBYTES.
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GLOBAL MARKET
$12B - worldwide sales of optical and removable disk drives
$208B - market size of the enterprise storage disk arrays (hard drive segment)
$50B+ - hard drive sales
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