Patent Application
20240249771
Embodiments of the present disclosure relate generally to the field of information storage. More particularly, embodiments of the disclosure relate to a method for storing data and an optical storage.
With the growing demand for digital information storage, the optical storage that stores information in optically readable media has attracted great interests. The information is recorded by making designed marks in a substrate that can be read out via optical methods. Due to the limit of storage density in a planar or 2D fashion, 3D optical storage that volumetrically stores the data is generally believed to be the next-generation data storage solution.
In an aspect of the disclosure, a method of optically writing, encrypting, and storing data is provided. The method includes: patterning a hydrogel by illuminating a laser on the hydrogel; and shrinking the patterned hydrogel to encrypt and store the data.
In another aspect of the disclosure, an optical storage is provided. The optical storage includes a hydrogel with a pattern, where the hydrogel is expandable.
Embodiments of the disclosure are illustrated by way of example and not limitation in the figures of the accompanying drawings in which like references indicate similar elements.
Various embodiments and aspects of the disclosures will be described with reference to details discussed below, and the accompanying drawings will illustrate the various embodiments. The following description and drawings are illustrative of the disclosure and are not to be construed as limiting the disclosure. Numerous specific details are described to provide a thorough understanding of various embodiments of the present disclosure. However, in certain instances, well-known or conventional details are not described in order to provide a concise discussion of embodiments of the present disclosures.
It should also be noted that the embodiments in the present disclosure and the features in the embodiments may be combined with each other on a non-conflict basis. The present disclosure will be described below in detail with reference to the accompanying drawings and in combination with the embodiments.
In the related art, the high peak intensity of a fs laser can induce nonlinear interactions within a hard transparent material, such as multiphoton absorption, multiphoton ionization, avalanche ionization, etc. These interactions can be exploited to generate nanopores or nano-gratings in the substrate, which exhibit optical contrast (i.e., modified refractive index (RI)) to the surrounding medium. Thus, designed information can be optically stored. Various hard transparent materials have been used as the storage medium with a maximum storage density of 500 Gbit/cm3, e.g., polymers, silica, quartz, sapphire, and glasses. The method according to some embodiments of the disclosure can achieve a high optical storage density (i.e., >100 Pbit/cm3). Due to the requirement for fs-laser pulse accumulation (>10 pulses) to induce local defects such as nanopores or nano-gratings, the write-in speeds of methods in related art are typically slow. In contrast, by combining with suitable optical system, the method according to some embodiments of the disclosure could directly write a large 2D information pattern of ˜104 μm2 m with a single fs pulse, which speeds up the writing speed by over three orders of magnitude. In terms of lifetime, some of the hard storage mediums may have shrinkage-induced performance reductions during long-term storage. In addition, such storage media cannot be directly encrypted, which greatly reduces the safety of the stored information. The method according to some embodiments of the disclosure can effectively resolve these problems.
In the related art, besides modifying RI, using fluorescent materials as the storage media for elevated reading accuracy is another adopted approach, such as multi-photon modification of dye doped polymers, rare-earth doped glasses, and photo-bleaching/reduction/enhancement of fluorescent materials, etc. The methods in the related art essentially use a laser to selectively activate fluorescent materials for data write-in, and then read out the information by imaging the fluorescent pattern. Despite the improved reading accuracy by combining with super-resolution microscopies, the use of fluorescent materials does not solve the problem of storage density, in which the write-in resolution is still limited by optical diffraction. Comparing with the method according to some embodiments of the disclosure, the writing and reading processes are performed in the expanded hydrogel, while the high storage density is achieved in the shrunk state. This means there is no trade-off between high read-out accuracy and high storage density. In addition, due to the limited lifetime of fluorescent materials, signal degradation and information loss during long-term storage are often observed. In comparison, as the fluorescent materials are only presented in the reading step of the method according to some embodiments of the disclosure, it is expected to have no signal degradation during long-term storage. In other words, the method according to some embodiments of the disclosure can take the advantage of high reading accuracy of fluorescent materials, but effectively avoid its drawbacks.
In the related art, newly developed materials with special optical properties have been applied as the storage media for 3D optical storage to elevate the storage time, reading accuracy, or storage density, e.g., surface-plasmon resonances of metallic nanoparticles, photon up-conversion of rare-earth-doped nanocrystals, and photostimulated luminescence (PSL) materials, etc. Yet, optical storage based on these materials are still in the preliminary stage of development. The achieved density is still far below the theoretical limit. For example, PSL has a storage density of ˜130 Tbit/cm3, but the achieved density is limited to several Tbit/cm3, which is three orders of magnitude lower than the method according to some embodiments of the disclosure. Furthermore, the applications of such storage methods are typically limited by the high cost, low production efficiency, and limited stability of the storage mediums. In comparison, the method according to some embodiments of the disclosure uses low-cost hydrogel as the medium, which allows rapid information writing and reading by combining with high-throughput optical systems. The fully shrunk and dehydrated hydrogel is chemically stable, and can bear long term storage for years.
In the related art, the field of 3D optical storage faces three critical challenges that limit its applications and further development: (1) limited storage density and capacity due to the optical diffraction limit, where a storage density over 10 Tbit/cm3 has rarely been realized; (2) limited writing and reading speeds due to the conventional point-by-point scanning optical system; and (3) the stored data are directly readable upon storage, which potentially compromises its security.
The method according to some embodiments of the disclosure can effectively address the above issues. Comparing with the 3D optical storage techniques (e.g., holographic storage, nanomaterial/DNA-based storage, or glass-based storage) in the related art, the method according to some embodiments of the disclosure has the following advantages: (1) substantially improving storage density beyond the optical diffraction limit (up to 180 Pbit/cm3) via shrinking the storage media (i.e., hydrogel substrate) to create features down to 10 nm; (2) high writing/reading speed and accuracy by combining with suitable optical patterning/imaging systems; (3) enhancing storage security enabled by physically shrinking the substrate to nanometer level; and (4) the storage media are low cost.
Referring to
In some embodiments, polyacrylate-based hydrogels are synthesized with modified concentrations of reactant solution. In some embodiments, the hydrogel is a crosslinked hydrophilic polymer. In some embodiments, a mixed solution of monomers (sodium acrylate (SA), acrylamide (AA), and bisacrylamide (Bis)) is prepared. The initiator, ammonium persulfate (APS), is added to a final concentration of 0.2% (w/w). In some embodiments, a gelling chamber is constructed by using 2 glass slides with two pieces of coverslips spacer (0.3 mm) at each end of the slide. The mixture is added to the gelling chamber, sealed with parafilm, and incubated overnight at 40-45° C. to produce the final hydrogel.
In some embodiments, a piece of hydrogel is trimmed to proper sizes and soaked in DI water or an aqueous solution of base (e.g., 0.1-100 mM NaOH solution) for expansion. After an incubation of 10-120 min at room temperature, the remaining solution is removed. The gel is then placed on a coverslip (which also serves as a window for laser patterning), and sealed in a chamber to minimize evaporation. Finally, a fs laser (e.g.,10-200 fs, 1 kHz-100 MHz, peak intensity: 0.1-50 TW/cm2) is illuminated to the gel to write the designed patterns of information. When combined with high throughput optical patterning systems (e.g., fs light sheet patterning system.), the method can achieve a write-in speed up to 160 Mbit/s. For long-term storage, the patterned gel can be stored in DI water in a refrigerator at 4° C.
In some embodiments, after information writing, physical encryption is realized by shrinking the patterned gel for up to 27,000 folds in volume. In the encrypted state, the optical storage device has a storage density of up to 180 Pbit/cm3, which corresponds to a feature size of ˜10 nm. As hydrogels are chemically stable after complete shrinking and dehydration, such devices can bear long-term storage for years.
In some embodiments, as acrylic acid-based hydrogels shrink in acid, the patterned gel is pre-shrunk in hydrochloric acid (4 mM or 4 mmol/L) before material deposition and then air-dried for long-time storage.
In some embodiments, hydrogels with different compositions can be shrunk for up to 30 folds in each dimension via any of the following methods:
In some embodiments, after the shrinking, the hydrogel is air-dried via any of the following methods:
In some embodiments, besides steps 1 and 2 (the same as steps 101 and 102), The method further includes step 3.
Step 3 includes: expanding the shrunk hydrogel to obtain an expanded hydrogel; depositing a contrast-generation material on the expanded hydrogel; and reading the pattern of the expanded hydrogel deposited with the contrast-generation material by using an optical imaging system.
In some embodiments, for decryption, the encrypted gel is re-expanded and deposited with fluorescent materials; and after that a high-speed fluorescent imaging system is applied to read out the stored information
In some embodiments, for decryption, the dehydrated gel is first expanded in water or NaOH solution (0.01-100 mM) for 10-60 min, and then transferred into an aqueous solution of fluorescent materials to read the stored information. Applicable materials include but not limit to nanoparticles, quantum dots, fluorescent dyes, fluorescent biomaterials, etc. After 0.1-2 hours of incubation at room temperature, the remaining solution is removed. Finally, the information can be read out via an optical microscope. When a high-speed microscope is used (e.g., a temporal focusing microscope), an optical reading speed of up to 160 Mbit/s can be realized.
In some embodiments, an optical storage including a hydrogel with a pattern is provided. The hydrogel is expandable.
Part A of
Parts A to C of
The method and the optical storage according to some embodiments of the disclosure can provide an effective tool to reduce the physical volume of storing data. With the shrinkage of the storage medium, i.e., hydrogel substrate, the volume for storing the same amount of information is three orders of magnitude smaller than the solutions in the related art. More importantly, it serves as a practical solution for industrial application by combining with ultrafast writing and reading optical systems, which would be three orders of magnitude faster than the point-by-point scanning systems in the related art.
The foregoing is only a description of the preferred embodiments of the present disclosure and the applied technical principles. It should be appreciated by those skilled in the art that the inventive scope of the present disclosure is not limited to the technical solutions formed by the particular combinations of the above technical features. The inventive scope should also cover other technical solutions formed by any combinations of the above technical features or equivalent features thereof without departing from the concept of the invention, such as, technical solutions formed by replacing the features as disclosed in the present disclosure with (but not limited to), technical features with similar functions.
