WO2024048422A1

WO2024048422A1 - Molecular memory, method for manufacturing molecular memory, method for decoding molecular memory, and device for decoding molecular memory

Info

Publication number: WO2024048422A1
Application number: PCT/JP2023/030588
Authority: WO
Inventors: 正輝谷口; 敬人大城
Original assignee: 国立大学法人大阪大学
Priority date: 2022-08-29
Filing date: 2023-08-24
Publication date: 2024-03-07

Abstract

The present invention addresses the problem of providing a molecular memory suitable for reading in a unit of a single molecule, a method for manufacturing the molecular memory, a method for decoding the molecular memory, and a device for decoding the molecular memory.　Said problem is solved by a molecular memory comprising: an address region; and a memory region linked to the address region. The address region and the memory region are formed of molecules that generate tunnel current. The memory region is formed of four or more types of molecules selected from a first molecule group. The address region is composed of four or more types of molecules selected from a second molecule group. The molecules included in the first molecule group are either of types totally different from the types of molecules included in the second molecule group, or include both types that are the same and different with respect to the types of molecules included in the second molecule group. As a result, the molecules forming the address region and the molecules forming the memory regions are partially of different types.

Description

Molecular memory, method for manufacturing molecular memory, method for decoding molecular memory, and device for decoding molecular memory

The disclosure in this application relates to a molecular memory, a method for manufacturing a molecular memory, a method for decoding a molecular memory, and a device for decoding a molecular memory.

With the rapid development of the information society and AI, an explosive amount of data is being produced around the world. In the future, when quantum computers are put into practical use, the amount of data generated will accelerate explosively. However, about 70 to 80% of the data that is produced in large quantities is cold data that is rarely used after it is produced. Since cold data is used for document management such as contracts, it is essential to store it for a certain period of time or more, but a large amount of electricity and storage materials are used to store cold data.

In order to solve the above problems, the development of DNA memory that does not require electricity and can be stored for a long time is underway. In order to obtain the information stored in DNA memory, it is necessary to read the DNA sequence. PCR is generally used as a method for reading DNA sequences. However, reading a DNA sequence using the PCR method requires a preprocessing step such as PCR. Furthermore, if A (adenosine), G (guanosine), C (cytidine), and T (thymidine) that make up DNA are used, the recording density per base is 2 bits/nt, but in reality, considering the replication error caused by PCR, It is known that the amount of information is limited to 1.57 bits/nt per base (see Patent Document 1). Therefore, Patent Document 1 discloses that by immobilizing oligonucleotides on a substrate and labeling the oligonucleotides with labeled atoms that can be identified by imaging mass spectrometry or imaging X-ray photoelectron spectroscopy, the It is stated that sequences can be analyzed and information can be read.

Another known method for reading DNA sequences is to measure the tunneling current when DNA passes between nanogap electrodes, and to read DNA sequences based on the differences in conductance of DNA molecules ( (See Non-Patent Document 1).

JP 2019-132588 Publication

The DNA reading method described in Non-Patent Document 1 is capable of identifying single molecules with different electronic states. However, the method described in Non-Patent Document 1 is related to general DNA sequence reading. A desirable arrangement of molecules when reading molecules constituting a molecular memory in units of molecules is not known.

The disclosure in this application has been made in order to solve the above-mentioned conventional problems. The present inventor conducted intensive research and found that (1) molecules that generate a tunnel current form an address region and a memory region connected to the address region, and (2) molecules that constitute the address region and the memory region. We have newly discovered that the capacity of molecular memory can be increased by making at least some of the types different.

That is, the purpose of the disclosure of the present application is to provide a molecular memory suitable for reading in units of molecules, a method for manufacturing the molecular memory, a method for decoding the molecular memory, and a device for decoding the molecular memory.

The disclosure of the present application relates to a molecular memory, a method for manufacturing a molecular memory, a method for decoding a molecular memory, and a device for decoding a molecular memory, as shown below.

(1) A molecular memory including an address area and a memory area connected to the address area,
The address area and memory area are composed of molecules that generate tunnel current,
The memory area is composed of molecules selected from a first molecule group of four or more types,
The address area is composed of molecules selected from a second molecule group of four or more types,
The molecules included in the first molecule group are:
The types of molecules contained in the second molecule group are all different types, or
Including the same types and different types of molecules contained in the second molecule group,
By that,
At least some of the molecules constituting the address area and the memory area are of different types,
molecular memory.
(2) When the first molecule group includes molecules of the same type as molecules included in the second molecule group, the molecules of the same type included in the first molecule group and the second molecule group are
It is not located at the end of the address area on the memory area side and at the end of the address area side of the memory area.
The molecular memory described in (1) above.
(3) The molecule with the smallest conductance among the molecules included in the first molecule group is not placed at the end of the memory area on the opposite side from the address area side,
The molecule with the smallest conductance among the molecules included in the second molecule group is not placed at the end of the address area on the opposite side to the memory area side.
The molecular memory described in (1) above.
(4) The types of molecules included in the first molecule group are all different from the types of molecules included in the second molecule group.
The molecular memory described in (1) above.
(5) The types of molecules included in the first molecule group are all different from the types of molecules included in the second molecule group.
The molecular memory described in (3) above.
(6) One of the first molecular group or the second molecular group is
4 or more molecules selected from the group consisting of
The other of the first molecular group or the second molecular group is
4 or more molecules selected from the group consisting of
The molecular memory described in (4) above.
(7) The first conductance range is the minimum and maximum conductance range of molecules included in the first molecule group, and the first conductance range is the range between the minimum and maximum conductance of molecules included in the second molecule group. 2 conductance ranges do not overlap,
The molecular memory described in (1) above.
(8) The first conductance range is the minimum and maximum conductance range of molecules included in the first molecule group, and the first conductance range is the range between the minimum and maximum conductance of molecules included in the second molecule group. 2 conductance ranges do not overlap,
The molecular memory described in (6) above.
(9) The address area is
a first address area connected to one end of the memory area;
a second address area connected to the other end of the memory area;
including;
The first address area is composed of molecules selected from four or more types of 2a molecule groups,
The second address area is composed of molecules selected from four or more types of second b molecule groups,
The molecules included in the first molecule group are:
The types of molecules contained in the 2a molecule group are all different types, or
It includes the same types and different types of molecules as those included in the molecule group 2a, and is all different types from the types of molecules included in the molecule group 2b, or
Including the same types and different types of molecules contained in the second b molecule group,
Molecules included in the 2b molecule group are:
The types of molecules contained in the 2a molecule group are all different types, or
Including the same types and different types of molecules contained in the 2a molecule group,
The molecular memory described in (1) above.
(10) The types of molecules included in the first molecule group, the types of molecules included in the 2a molecule group, and the molecule types included in the 2b molecule group are all different,
One of the 2a molecular group and the 2b molecular group,
4 or more molecules selected from the group consisting of
The other of the 2a molecule group and the 2b molecule group is
4 or more molecules selected from the group consisting of
The molecular memory described in (9) above.
(11) A redundant area is connected between the address area and the memory area,
The redundant area is
Consists of redundant region molecules that generate tunnel current,
The conductance of the redundant area molecules is smaller than the conductance of the molecules composing the address area and memory area.
The molecular memory described in (1) above.
(12) a first redundant area is connected between the first address area and the memory area;
a second redundant area is connected between the second address area and the memory area;
The first redundant area and the second redundant area are
Consists of redundant region molecules that generate tunnel current,
The conductance of the redundant area molecules is smaller than the conductance of molecules forming the first address area, the second address area, and the memory area.
The molecular memory described in (9) above.
(13) A method for manufacturing a molecular memory according to any one of (1) to (12) above, comprising:
an information preparation step for preparing information to be encoded;
a molecular sequencing step of converting the prepared information into molecules constituting the molecular memory and determining the arrangement of the molecular memory;
a synthesis step of synthesizing molecules constituting the molecular memory based on the determined sequence;
including,
Production method.
(14) A device for decoding the molecular memory according to any one of (1) to (12) above, the device comprising:
base material and
A flow path formed in the base material,
a pair of measurement electrodes for measuring tunneling current when the molecular memory passes;
a control unit;
including;
The flow path is
a molecular memory input channel;
a molecular memory measurement channel in which measurement electrodes are arranged;
a first tapered channel that is disposed between the molecular memory input channel and the molecular memory measurement channel, and whose channel width becomes narrower from the molecular memory input channel to the molecular memory measurement channel;
a molecular memory recovery channel for recovering the molecular memory that has passed through the molecular memory measurement channel;
including;
The width of the connecting portion between the first taper channel and the molecular memory measurement channel is 20 nm to 200 nm,
The analysis department is
Identifying the direction in which the molecular memory passes through the measurement electrode based on the conductance of the molecules forming the address area and the conductance of the molecules forming the memory area, or
identifying the direction in which the molecular memory passes through the measurement electrode based on the conductance of the molecules forming the first address area and the conductance of the molecules forming the second address area;
device.
(15) A method for decoding the molecular memory according to any one of (1) to (12) above using the device according to (14) above,
The molecular memory decoding method includes a molecular memory electrophoresis step, a measurement step, an analysis step, and a molecular memory passage direction identification step,
The molecular memory electrophoresis process is
By applying a voltage to the molecular memory input channel and the molecular memory recovery channel, the molecular memory in the molecular memory input channel is electrophoresed towards the molecular memory recovery channel,
The measurement process is
Measure the tunneling current when the molecular memory passes through the gap between a pair of measurement electrodes placed in the molecular memory measurement channel,
The analysis process is
Based on the measured tunnel current, we analyze the arrangement of the molecules that make up the molecular memory.
The molecular memory passing direction identification process is
Identifying the direction in which the molecular memory passes through the measurement electrode based on the conductance of the molecules forming the address area and the conductance of the molecules forming the memory area, or
identifying the direction in which the molecular memory passes through the measurement electrode based on the conductance of the molecules forming the first address area and the conductance of the molecules forming the second address area;
How to decode molecular memory.

The molecular memory disclosed in this application can read constituent molecules in units of molecules. Therefore, by designing the types of at least some of the molecules constituting the address area and the memory area to be different, the address area and the memory area can be distinguished and the capacity can be increased.

FIG. 1 is a schematic diagram showing an outline of a molecular memory 100. FIG. 2 is a schematic diagram showing the outline of the molecular memory 100a. FIG. 3 is a schematic diagram showing the outline of the molecular memories 100', 100a'. FIG. 4 is a schematic diagram showing the outline of the device 1. FIG. 5A is a top view for explaining the relationship between the flow paths of the device 1. FIG. 5B is a sectional view taken along the line XX in FIG. 5A. FIG. 5C is a sectional view taken along the YY arrow in FIG. 5A. FIG. 6 is a schematic diagram showing an example of a procedure for producing a flow path and a measurement electrode on a base material. FIG. 7 is a flowchart illustrating an example of a decoding method.

Hereinafter, a molecular memory, a method for manufacturing a molecular memory, a method for decoding a molecular memory, and a device for decoding a molecular memory will be described in detail with reference to the drawings.

In this specification, members having the same type of function are given the same or similar symbols. Further, repeated descriptions of members labeled with the same or similar symbols may be omitted.

In this specification, a numerical range expressed using "~" means a range that includes the numerical values written before and after "~" as lower and upper limits. Numerical values, numerical ranges, and qualitative expressions (e.g., expressions such as "same", "omitted", etc.) are intended to indicate numerical values, numerical ranges, and properties including errors generally accepted in the technical field. shall be subject to interpretation.

Additionally, the position, size, range, etc. of each component shown in the drawings may not represent the actual position, size, range, etc. for ease of understanding. Therefore, the disclosure in this application is not necessarily limited to the position, size, range, etc. disclosed in the drawings.

(Embodiment of molecular memory)
An embodiment of the molecular memory 100 will be described with reference to FIGS. 1 to 3. 1 to 3 are schematic diagrams showing the outline of a molecular memory 100.

The molecular memory 100 includes an address area 101 and a memory area 102 connected to the address area 101. Address area 101 and memory area 102 are composed of molecules that generate tunnel current. The memory area 102 is made up of molecules selected from four or more types of first molecule groups, and the molecules forming the address area 101 are made up of molecules selected from four or more types of second molecule groups. Furthermore, the molecules included in the first molecule group may be of different types from the molecules included in the second molecule group, or may be of the same type and different types as the molecules included in the second molecule group. May include. Therefore, the molecular memory 100 according to the embodiment is configured such that at least some of the molecules forming the address area 101 and the memory area 102 are of different types.

The molecules constituting the molecular memory 100 can generate a tunnel current and are not particularly limited as long as the molecules can be connected to each other. Including, but not limited to, the following molecules:
(1) Nucleosides: A (Adenosine), T (Thymidine), G (Guanosine), C (Cytidine), U (Uridine), modified products of the above nucleosides, and artificial nucleosides.
(2) Organic semiconductor molecules: thiophene, pyridine, naphthalene, pentacene, anthracene, rubrene, phthalocyanine, perylene, Alq3, pyrrole, aniline, and derivatives of the above molecules.
(3) Amino acids: Ala, Arg, Asn, Asp, Cys, Gln, Glu, Gly, His, He, Leu, Lys Met, Phe, Pro, Ser, Thr, Trp, Tyr, Va, etc., acetylated amino acids, and , methylated amino acids.
(4) Sugar chains: α, β glucose and its isomers, pentoses, hexoses, amino sugars, etc.

The molecular memory 100 according to the embodiment can be identified in units of molecules based on the difference in conductance of the constituent molecules by a decoding method of the molecular memory 100 using a device for decoding molecular memory, which will be described later. By the way, the molecular memory 100 has an elongated shape, and when it is decoded using a device to be described later, there are cases in which it is decoded from the address area 101 side of the elongated molecular memory 100 and cases where it is decoded from the memory area 102 side. do. However, if the types of molecules included in the first molecule group are all different from the types of molecules included in the second molecule group, the types of molecules making up the address area 101 will be different from the types of molecules making up the memory area 102. All different. In that case, the address area 101 and the memory area 102 can be easily identified based on the type of molecule read.

Next, the molecules included in the first molecule group and the molecules included in the second molecule group include the same type and different types, and as a result, the type of molecules constituting the address area 101 is different from that of the molecules constituting the memory area 102. Cases in which the same type and different types are included will be explained. When designing the molecular memory 100, the length of the address area 101 and the length of the memory area 102 can be set in advance. Therefore, when reading the molecule memory 100 in units of molecules, the position where the molecule contained only in the address area 101 and/or the molecule contained only in the memory area 102 is read, the length of the address area 101, and the memory Based on the length of the area 102, the address area 101 and the memory area 102 can be specified.

Note that when the molecules included in the first molecule group and the molecules included in the second molecule group include molecules of the same type, the end of the address area 101 on the memory area 102 side and the address area of the memory area 102 may be optionally added. The end on the 101 side may be designed so that molecules of the same type are not placed. If molecules of the same type are not placed in the connection between the address area 101 and the memory area 102, the address area 101 and the memory area 102 can be easily identified.

The molecular memory 100 disclosed in this application is identified by conductance. By the way, the present inventors have newly discovered through experiments that when measuring elongated molecules using tunneling current, the accuracy of reading is slightly lower at the end portions of the elongated molecules than at the central portion. The reason for this is thought to be that the end portions of elongated molecules are affected by thermal motion, but the central portion is less affected by thermal motion. Additionally, through experiments we discovered that the electrical noise of the device affects the accuracy of reading molecules when reading molecules using conductance.

Based on the knowledge obtained from the above experiment, the molecule with the smallest conductance among the molecules included in the first molecule group is optionally placed at the end of the memory area 102 on the opposite side from the address area 101 side. Alternatively, the molecule having the smallest conductance among the molecules included in the second molecule group may be designed so as not to be placed at the end of the address area 101 on the opposite side to the memory area 102 side. By not placing the molecule with the lowest conductance at the end of the molecular memory 100 among the molecule groups constituting each region, in other words, by placing the molecule with the highest conductance at the end of the molecule group, electrical noise can be reduced. The accuracy of reading molecules is increased even under the influence of thermal motion. Among the molecule groups constituting each region, it is most preferable to arrange the molecule with the highest conductance at the end of the molecular memory 100, but of course the molecule with the second highest conductance may be arranged at the end. By placing molecules other than those with the smallest conductance among the selectable molecules at the end of the molecular memory, the accuracy of reading molecules can be improved compared to the case where the conductance of the molecules that make up each region is not considered at all.

Examples of the first molecule group constituting the memory area 102 include molecules exemplified by <Molecular Group 1> below. It should be noted that the following molecules are merely examples and are not intended to be limiting. Further, the molecules exemplified in <Molecular Group 1> below may be used as the second molecule group.

Furthermore, examples of the second molecule group constituting the address area 101 include molecules exemplified by <Molecular Group 2> and <Molecular Group 3> below. It should be noted that the following molecules are merely examples and are not intended to be limiting. Furthermore, the molecules exemplified in <Molecular Group 2> and <Molecular Group 3> below may be used as the first molecule group.

Further, the values of Conductance and Relative G of the compounds exemplified in <Molecular Group 1>, <Molecular Group 2>, and <Molecular Group 3> are shown in Table 1 below. Note that Conductance and Relative G shown in Table 1 are values measured using Device 1, which will be described later. Further, the technical significance of Conductance and Relative G will be described later.

If the structure of the molecule differs, the conductance will also differ. Therefore, although the above-described molecular memory 100 can identify molecules based on conductance, it may optionally be designed so that the conductances of the molecules forming the address area 101 and the memory area 102 do not overlap. More specifically, the first conductance range is the range of the minimum and maximum conductance of molecules included in the first molecule group, and the range of the minimum and maximum conductance of molecules included in the second molecule group. Molecules included in each group may be selected so that the second conductance range does not overlap. If the design is such that the conductances of the molecules constituting the address area 101 and the memory area 102 do not overlap, it is possible to easily distinguish between the address area 101 and the memory area 102, and also to easily identify which area is being decoded. It has the effect of being able to do it.

If the first conductance range and the second conductance range are designed so as not to overlap, the first conductance range may be greater than the second conductance range, or the first conductance range may be less than the second conductance range.

Note that preventing the first conductance range and the second conductance range from overlapping is an optional additional design as described above. Even if the first conductance range and the second conductance range partially overlap, the type of molecule can be identified because different types of molecules have different conductances. For example, in the example shown in Table 1, the range of conductance of the first molecule group is 25.8 (FTD) to 123.0 (guanosine). On the other hand, the conductance of the second molecule group is 108.2 (AmdU) and 110.7 (m6A) to 270.6 (TTFdU). In the example shown in Table 1, when designing the molecules included in the second molecule group, they may be designed to include AmdU and/or m6A, or may be designed not to include AmdU and/or m6A. Even if the first conductance range and the second conductance range partially overlap, the conductance distribution will be different between the region made up of molecules in the first conductance range and the region made up of molecules in the second conductance range. . Therefore, compared to a design that does not consider the conductance range, it becomes easier to distinguish between the address area 101 and the memory area 102, and to specify which area side the decoding starts from.

The types of molecules constituting the address area 101 and the memory area 102 may be appropriately designed depending on the intended capacity. For example, 4 types, 8 types, 16 types, etc. may be selected from a large number of molecules included in the molecule groups constituting each region. Note that general memory is limited to a power of two. On the other hand, the molecular memory 100 disclosed in this application can read molecules composed of single molecules. Therefore, for example, you can identify the end of a region by placing a different type of molecule from the molecules in the same region only at the end of each region, or add a specific function even within the same region. Various designs are possible, such as arranging molecules of a different type than those in the same region. Therefore, the number of molecules constituting each area of the molecular memory 100 disclosed in this application may be 5 to 7 types, 9 to 15 types, or 17 or more types.

Note that the molecule memory 100 encodes desired information by combining constituent molecules. For example, assume that the types of molecules included in the first molecule group constituting the memory area 102 are four types, A, B, C, and D, and the length of the memory area 102 is L. In that case, the memory area 102 created by encoding information may be divided into four molecules A to D, depending on the content of the information to be encoded. The length of L includes various sequences, such as when all types are included. Therefore, the types of molecules included in the first molecule group and the second molecule group and the types of molecules constituting the actually produced molecular memory do not need to completely match.

The lengths of the address area 101 and the memory area 102 are not particularly limited as long as they are long enough to synthesize the molecules that make up the molecular memory 100. Note that the molecular memory 100 according to the embodiment can read constituent molecules in units of molecules and can use many types of molecules, so it can store a large amount of information in a short length.

For example, it is assumed that the address area 101 uses 16 types of molecules and has a length of 20 molecules, and the memory area 102 uses 4 types of molecules and has a length of 100 molecules. In that case, the total memory capacity will be as follows.
(1) Number of combinations of address areas 101 16 ²⁰ = 2 ⁸⁰
(2) Number of bytes in memory area 102 - 4 types of molecules → 4 = 2 ² → 2 bits - 2 bits x 100 = 200 bits - 200 ÷ 8 = 25 bytes (3) Total memory capacity - 25 bytes x 2 ⁸⁰
Here, since 2 ¹⁰ = 1024≒10 ³ , 25 bytes x 2 ⁸⁰ → 25 bytes x 10 ²⁴ → 25 yottabytes.

25 yottabytes is a memory capacity that exceeds the memory capacity that humans have ever produced.

The molecular memory 100 according to the embodiment has the following effects.
(a) Conventional DNA memory is a combination of four types of DNA, but in the molecular memory 100 according to the embodiment, the types of molecules forming the address area 101 and the molecules forming the memory area 102 do not completely match. I'm changing it like this. Therefore, since the number of combinations of molecules can be increased, a large amount of information can be stored even if the molecule memory 100 is short.
(b) The molecular memory 100 has an elongated shape. Therefore, the direction in which the molecular memory 100 passes through the measurement electrode of the device for decoding the molecular memory 100 is not constant. By designing so that the types of molecules forming the address area 101 and the molecules forming the memory area 102 do not completely match, the direction in which the molecular memory 100 passes through the measurement electrode can be easily identified.
(c) If the first conductance range and the second conductance range are designed so that they do not completely overlap or only partially overlap, the address area 101 and the memory area 102 can be distinguished when the molecular memory 100 is decoded. becomes easier. Therefore, the boundary between the address area 101 and the memory area 102 can be read with high precision, reducing storage errors.

Next, an optional additional configuration example that can be adopted by the molecular memory 100 will be described.
(First address area and second address area)
The molecular memory 100 shown in FIG. 1 has one address area 101, but as shown in FIG. 2, the molecular memory 100a may include two address areas. The example shown in FIG. 2 includes a first address area 101a connected to one end of the memory area 102, and a second address area 101b connected to the other end of the memory area 102.

The first address area 101a is made up of molecules selected from two or more types of second-a molecule groups, and the second address area 101b is made up of molecules selected from two or more types of second-b molecule groups. The relationship between the molecules forming the first address area 101a and the second address area 101b and the relationship between the molecules forming the memory area 102 are the same as the relationship between the address area 101 and the memory area 102 described above. Specifically, the molecules included in the first molecule group are all different types from the types of molecules included in the 2a molecule group, or the same types and different types of molecules are included in the 2a molecule group. and are all different types from the types of molecules included in the 2b molecule group, or include the same types and different types of molecules as the molecule types included in the 2b molecule group. In other words, the types of molecules forming the first address area 101a and the second address area 101b and the types of molecules forming the memory area 102 need not completely match.

Note that when the first address area 101a and the second address area 101b are included, it is necessary to distinguish between the first address area 101a and the second address area 101b. Therefore, the molecules included in the 2b molecule group are all different types from the molecules included in the 2a molecule group, or include the same types and different types of molecules as the 2a molecule group. It should be designed to.

Even when it includes the first address area 101a and the second address area 101b, the design concept of the molecular memory 100a is the same as that of the molecular memory 100 that includes the address area 101 and the memory area 102. Therefore, what has been described for molecular memory 100 is applicable to molecular memory 100a.

For example, if the first molecule group includes molecules of the same type as molecules included in the 2a molecule group and the 2b molecule group, the same molecule is present in both the connected portion of the first address area 101a and the memory area 102. It is preferable not to arrange it at the end of the area and at the end of both the areas where the second address area 101b and the memory area 102 are connected.

Furthermore, the molecule included in the 2a molecule group and the 2b molecule group and having the smallest conductance is the end of the first address area 101a on the opposite side to the memory area 102 and/or the end of the second address area 101b. Preferably, it is not located at the end.

Furthermore, the range of the minimum and maximum conductance of molecules included in the 2a molecule group is defined as the 2a conductance range, and the range of the minimum and maximum conductance of molecules included in the 2b molecule group is defined as the 2b conductance range. If
・1st conductance range>2nd a conductance range>2nd b conductance range・1st conductance range>2nd b conductance range>2nd a conductance range・2nd a conductance range>1st conductance range>2nd b conductance range・2nd a conductance range > 2nd b conductance range > 1st conductance range, 2nd b conductance range > 1st conductance range > 2nd a conductance range, 2nd b conductance range > 2nd a conductance range > 1st conductance range.

Furthermore, the first conductance range, the second a conductance range, and the second b conductance range may be designed so that the respective ranges do not completely overlap, or may partially overlap.

Note that, as described above, when measuring an elongated molecule using tunneling current, the accuracy of reading is slightly lower at the end portion of the elongated molecule than at the central portion. In terms of storing information, the memory area 102 is more important than the first address area 101a and the second address area 101b. Therefore, when providing the first address area 101a and the second address area 101b, considering reading accuracy,
- It is preferable to set it as 2nd a conductance range > 2nd b conductance range > 1st conductance range - 2nd b conductance range > 2nd a conductance range > 1st conductance range.

The 2-a molecular group is, for example, one of the groups exemplified by the above-mentioned <Molecular Group 2> and <Molecular Group 3>, and the 2-b Molecular Group is the other of the <Molecular Group 2> and <Molecular Group 3>. Note that the molecules are merely examples, and are not limited.

When two address areas are provided, in addition to the effects described in (a) to (d) above that the molecular memory 100 exhibits, the following effects are achieved.
(e) If two address areas are provided, the total length of the molecular memory becomes a little longer, but the same capacity as the molecular memory 100 can be obtained with fewer types of molecules. For example, it is assumed that the first address area 101a uses four types of molecules and has a length of 20 molecules, the memory area 102 uses four types of molecules and has a length of 100 molecules, and the second address area 101b uses four types of molecules and is assumed to have a length of 100 molecules. Assume that four types of molecules are used and the length is 20 molecules. In that case, the total memory capacity will be as follows.
(1) Number of combinations of first address area 101a 4 ²⁰ = 2 ⁴⁰
(2) Number of combinations of second address area 101b 4 ²⁰ = 2 ⁴⁰
(3) Number of bytes in memory area 102 - 4 types of molecules → 4 = 2 ² → 2 bits - 2 bits x 100 = 200 bits - 200 ÷ 8 = 25 bytes (4) Total memory capacity - 25 bytes x 2 ⁴⁰ x 2 ⁴⁰ = 25 bytes x 2 ⁸⁰
Here, since 2 ¹⁰ = 10 ²⁴ ≒ 10 ³ , 25 bytes x 2 ⁸⁰ → 25 bytes x 10 ²⁴ → 25 yottabytes.
The molecular memory 100 shown in FIG. 1 has a capacity of 25 yottabytes with a total of 20 types of molecules and a total length of 120 molecules. On the other hand, the molecular memory 100a shown in FIG. 2 has a capacity of 25 yottabytes with a total of 12 types of molecules and a total length of 140 molecules. By reducing the number of types of molecules, the degree of freedom in selecting molecules with different conductances increases. The greater the difference in conductance between molecules, the fewer errors occur when measuring tunnel current. Therefore, the molecule memory 100a shown in FIG. 2 can improve reading accuracy by selecting constituent molecules.
(f) As mentioned above, when measuring an elongated molecule using tunneling current, the accuracy of reading is slightly lower at the end portion of the elongated molecule than at the central portion. However, by arranging the memory area 102 that stores information between the first address area 101a and the second address area 101b, the reading accuracy of the memory area 102 that stores information can be increased compared to the molecular memory 100. .
(g) When the memory area 102 is sandwiched between a first address area 101a and a second address area 101b having a conductance larger than the conductance of the memory area 102, the division of the memory area 102 and the first address area 101a, Furthermore, the memory area 102 and the second address area 101b can be clearly distinguished.
(h) Furthermore, if the memory area 102 is sandwiched between the first address area 101a and the second address area 101b, which have a conductance larger than the conductance of the memory area 102, the conductance is higher at both ends of the molecular memory. Since the molecules are arranged, it is possible to prevent deterioration in reading accuracy due to the effects of thermal movement, etc.

(redundant area)
As shown in FIG. 3, in the molecular memory 100, a redundant area 103 may be connected between the address area and the memory area (molecular memory 100'). Further, in the molecular memory 100a, a first redundant area 103a is connected between the first address area 101a and the memory area 102, and a second redundant area 103b is connected between the second address area 101b and the memory area 102. (Molecular memory 100a'). The redundant regions 103, 103a, and 103b are composed of redundant region molecules that generate tunnel current, and the conductance of the redundant region molecules is smaller than the conductance of the molecules forming the (first and second) address region 101 and memory region 102. Design as follows.

The conductance of the redundant area molecules is smaller than the conductance of the molecules forming the (first and second) address areas 101 and the memory area 102, and there is no particular restriction as long as the molecules can be connected to each other. Examples include, but are not limited to, the following compounds.

The redundant areas 103, 103a, and 103b are provided to make it easier to distinguish between the (first and second) address area 101 and memory area 102. Therefore, the length of the redundant regions 103, 103a, and 103b may be short, for example, about 2 molecules, 3 molecules, 4 molecules, 5 molecules, 6 molecules, 7 molecules, or 8 molecules. In the example shown in FIG. 3, the redundant areas 103, 103a, and 103b are connected between the (first and second) address area 101 and the memory area 102. Although not shown, the redundant area is located not only at the position shown in FIG. and/or the right end of the second address area 101b). Further, in the case of the molecular memory 100', it may be connected to the other end of the memory area 102.

When the redundant regions 103, 103a, and 103b are provided, in addition to the effects described in (a) to (h) above provided by the molecular memories 100 and 100a, the following effects are achieved.
(i) By providing a redundant area, the (first and second) address areas 101 and memory area 102 can be more clearly distinguished.
(j) A sequence (sequence that becomes duplicate information) can be added to the redundant region to recover information even if molecules are skipped and read during decoding (for example, repeating the same sequence or adding an sequence with information increased by 1). (e.g. create). When this sequence is added, the reproducibility of information can be ensured.
(k) For information security, a sequence corresponding to an encryption code may be inserted into the redundant area (for example, the original information can be reconstructed using a decryption code). In that case, information leakage will be prevented.
(l) Also, the redundant area is defined as the edge of the address area (the left edge of the address area 101 in the case of the molecular memory 100', the left edge of the first address area 101a in the case of the molecular memory 100a', and/or If it is also connected to the right end of the second address area 101b, the effect described in (i) above can be obtained.

The above embodiment of the molecular memory is an example for ease of understanding. As long as it is within the scope of the technical idea disclosed in this application, changes such as combinations of various exemplified designs may be made.

(Embodiment of method for manufacturing molecular memory)
Next, an embodiment of a method for manufacturing a molecular memory will be described. Embodiments of the manufacturing method include an information preparation step, a molecular sequencing step, and a synthesis step.

The information preparation step prepares information to be encoded. For example, obtaining information and performing preliminary conversion of analog data into digital data.

The molecular sequencing step converts the prepared information into molecules that constitute a molecular memory, and determines the arrangement of the molecular memory when encoding the information. For example, the digital data stored in the memory area 102 is converted using 4 types of molecules in the case of 2-bit data, and 16 types of molecules in the case of 4-bit data, and the arrangement is determined. In addition, the (first and second) address areas 101, which are array tags for random access, are converted using 4 types of molecules in the case of 2-bit data and 16 types of molecules in the case of 4-bit data to create an array. decide. In addition, if a redundant area is provided, an arrangement including the redundant area is determined. Note that, in the following, description of redundant areas will be omitted to avoid complicating the description.

In the synthesis step, molecules constituting the molecular memory are synthesized based on the determined sequence. As the synthesis apparatus, a known synthesis apparatus may be used depending on the molecules constituting the molecular memories 100 and 100a. For example, when using nucleosides as molecules, a nucleic acid synthesizer may be used. When using amino acids as molecules, a protein synthesis apparatus may be used. Furthermore, when introducing an organic semiconductor in the form of a chain, a peptide nucleic acid may be used, and a protein synthesis apparatus may be used. Furthermore, when a nucleoside and an organic semiconductor are mixed, hydrogen in the base molecule of the nucleoside may be replaced with a semiconductor molecule, and the mixture may be synthesized using a nucleic acid synthesizer. Alternatively, a base molecule and an organic semiconductor may be introduced into a peptide nucleic acid and synthesized using a protein synthesis apparatus.

Note that during the molecule sequencing step, molecules included in the first molecule group and second molecule group (2a molecule group, 2b molecule group) described in the embodiment of the molecule memories 100 and 100a are used to sequence the molecules. Determine. In the synthesis step, the molecular memories 100 and 100a are synthesized using the molecules included in the first molecule group and the second molecule group (the 2a molecule group and the 2b molecule group). The molecular memories 100 and 100a use molecules included in a first molecular group and a second molecular group (a second molecular group and a second molecular group), and (first and second) address areas 101 and memory areas 102. It is a novel invention that at least some of the molecules constituting the molecule are of different types. Therefore, the molecular sequencing and synthesis steps are also novel steps.

(Embodiment of a device for decoding molecular memory)
An embodiment of a device 1 for decoding a molecular memory will now be described with reference to FIGS. 4, 5A-5C and 6. FIG. 4 is a schematic diagram showing the outline of the device 1. 5A is a top view for explaining the relationship of flow paths, FIG. 5B is a sectional view taken along the line XX in FIG. 5A, and FIG. 5C is a sectional view taken along the line YY in FIG. 5A. FIG. 6 is a schematic diagram showing an example of a procedure for producing a flow path and a measurement electrode on a base material.

In the example shown in FIGS. 4 and 5A to 5C, the device 1 includes a base material 2, a channel 3 formed in the base material 2, and a pair of channels for measuring tunneling current when the molecular memory passes through. It includes measurement electrodes 4 (4a and 4b) and an analysis section 9. In addition, below, the base material 2, the flow path 3, and the measurement electrode 4 part may be described as a "measuring part." Further, in FIG. 4, optionally, power supplies for electrophoresis 6, 6a, 6b, first electrode for electrophoresis 61, second electrode for electrophoresis 62, tunnel current detection unit 7, power supply for tunnel current measurement 8, An example including a display section 10, a program memory 11, and a control section 12 is shown. Any additional configuration may be added as necessary when implementing the molecular memory decoding method. Furthermore, in the following description, the molecular memory may be the embodiments indicated by reference numerals 100, 100a, 100', 100a', or other embodiments. In order to avoid complication, the reference numerals of the molecular memories will be omitted in the following description.

The flow path 3 includes a molecular memory input flow path 31 into which a solution containing molecular memory is input, a molecular memory measurement flow path 32 in which the measurement electrode 4 is arranged, and the molecular memory input flow path 31 and the molecular memory measurement flow path 32. A first tapered channel 33 is disposed between the molecular memory input channel 31 and the channel width narrows from the molecular memory measurement channel 32, and the molecular memory that has passed through the molecular memory measurement channel 32 is recovered. A molecular memory recovery channel 34 is included. The width W1 of the connecting portion between the first tapered channel 33 and the molecular memory measurement channel 32 is 20 nm to 200 nm.

Although the second tapered flow path 35 is illustrated in the example shown in FIG. 5A, the second tapered flow path 35 is an optional additional configuration. If the molecular memory flowing out from the molecular memory measurement channel 32 can be recovered, the molecular memory recovery channel 34 may be directly connected to the molecular memory measurement channel 32.

The measurement portion can be manufactured using, for example, a nanochannel-integrated mechanically controllable break junction method. Referring to FIG. 6, an example of the manufacturing procedure is shown. Regarding the mechanical breaking bonding method (MCBJ) for producing the pair of measurement electrodes 4, for example, Japanese Patent Publication No. 2019-525766, Patent Document 1 mentioned above, M. Tsutsui, K. , Shoji, M. Taniguchi, T. Kawai, Nano Lett. , 345 (2008), and M. Tsutsui, M. Taniguchi, T. Kawai, Appl. Phys. Lett. 93, 163115 (2008), etc.

(1) An insulating layer 2b is formed of an insulating material such as polyimide on a substrate 2a of silicon or the like.
(2) A metal layer for forming the measurement electrode 4 is deposited on the insulating layer 2b by electron beam lithography.
(3) Form a deposited layer 2c of SiO ₂ or the like by chemical vapor deposition. A resist layer 2d is laminated on the deposition tank 2c by spin coating.
(4) A pattern of the channel 3 including the molecular memory measurement channel 32 is formed by electron beam lithography so as to overlap the metal layer for forming the measurement electrode 4.
(5) Form the flow path 3 by dry etching. Thereafter, a measurement electrode 4 is formed by forming a gap (nanogap G) in the metal layer by MCBJ. In the example shown in FIG. 6, the molecular memory measurement flow path 32 is etched to the bottom of the measurement electrode 4, but the flow path below the measurement electrode 4 may not be provided. Further, in the example shown in FIG. 6, there is one measurement electrode 4, but two or more measurement electrodes 4 may be formed. Furthermore, during the electron beam lithography in (4) above, a pattern for constructing pillars (not shown in FIGS. 5A and 5C) may be formed in the channel 3 except for the molecular memory measurement channel 32. . By masking the portion forming the pillar so that it is not dry-etched, it is possible to form a pillar whose one end is connected to the bottom of the channel 3 except for the molecular memory measurement channel 32 and whose other end is open upward.
(6) Attach the cover member 5 in which holes are formed as necessary for introducing solutions, inserting electrodes for electrophoresis, etc. Note that the cover member 5 only needs to be attached at the time of tunnel current measurement.

The substrate 2a is not particularly limited as long as it is made of a material commonly used in the field of semiconductor manufacturing technology. Examples of the material of the substrate 2a include Si, SiO _x , SiN _x , Ge, Se, Te, GaAs, GaP, GaN, InSb, and InP. Note that if a pillar is provided in the flow path 3 except for the molecular memory measurement flow path 32, the contact area with the solution flowing through the flow path 3 can be expanded. Note that, as described later, when forming the measurement portion so as to be symmetrical with respect to the molecular memory measurement channel 32, pillars are also formed in the molecular memory recovery channel 34 and the second tapered channel 35. Good too.

The insulating layer 2b is also not particularly limited as long as it is made of a material commonly used in the field of semiconductor manufacturing technology. Examples of materials for the insulating layer 2b include insulating polymers such as polyimide, polypropylene, polyvinyl chloride, polystyrene, high density polyethylene (HDPE), polyacetal (POM), and polyepoxy; insulating materials such as SiO ₂ and aluminum oxide. Examples include oxidized semiconductor metal objects; and the like.

Materials for forming the deposited layer 2c include insulating polymers such as polyimide, polypropylene, polyvinyl chloride, polystyrene, high-density polyethylene (HDPE), polyacetal (POM), and polyepoxy; insulating materials such as SiO ₂ and aluminum oxide; Examples include oxidized semiconductor metal objects; and the like.

There is no particular restriction on the material for forming the measurement electrode 4 as long as it can measure tunnel current. Examples include gold, platinum, silver, palladium, tungsten, and alloys of the above metals.

The photoresist used in electron beam lithography and the reagents used in development, etching, etc. are not particularly limited as long as they are materials commonly used in the field of microfabrication technology. Furthermore, there are no particular limitations on the equipment used for spin coaters, etching, etc. as long as they are made of materials commonly used in the field of microfabrication technology.

The cover member 5 is not particularly limited as long as it can be attached to the base material 2 on which the flow path 3 is formed. Examples of the material for the cover member 5 include polymethyldisiloxane (PDMS). The cover member 5 and the base material 2 may be attached by, for example, ozone plasma treatment.

Note that in this specification, the "base material" refers to a material portion that becomes the basis for forming the flow path 3. In the example shown in FIG. 6, the base material 2 includes a substrate 2a, an insulating layer 2b, a deposited layer 2c, and a resist layer 2d. Note that FIG. 6 is only an example of the procedure for manufacturing a measurement part in which the measurement electrode 4 is arranged in the molecular memory measurement channel 32. Other steps may be added or deleted in the measurement part as long as the tunnel current when the molecular memory passes can be measured. For example, after forming the channel 3 by etching, the resist layer 2d may be removed. In that case, the base material 2 does not include the resist layer 2d. Further, the measurement portion may be produced by electron beam engraving, nanoprinting, or the like.

Further, in order to facilitate understanding, in the examples shown in FIGS. 5A to 5C, detailed descriptions of the substrate 2a, the insulating layer 2b, the deposited layer 2c, and the resist layer 2d are omitted, and they are referred to as the base material 2.

By applying a voltage to the molecular memory input channel 31 and the molecular memory recovery channel 34, an electrophoretic force is applied to the molecular memory, increasing the moving speed of the molecular memory. As a result, the measurement speed of molecular memory is improved compared to the case where no electrophoretic force is applied. On the other hand, when applying a voltage to the flow path 3 to impart an electrophoretic force to the molecular memory, the larger the cross-sectional area of the flow path 3, the greater the voltage required.

By the way, reading of molecular memory using tunnel current is performed by identifying differences in measured current values at the picoampere level. When a voltage at a level capable of imparting an electrophoretic force to a molecular memory placed in a flow channel on the order of μm is applied, there is a possibility that the measurement electrode 4 may detect noise caused by the voltage for electrophoresis. The measurement portion shown in FIGS. 5A to 5C can apply electrophoretic force to the molecular memory with a low voltage, and therefore can measure tunnel current with less noise caused by electrophoresis voltage.

The molecular memory input channel 31 needs to have a predetermined size in order to input a solution containing molecular memory. Therefore, in the measurement part, the width of the molecular memory measurement channel 32 in which the measurement electrode 4 is arranged is narrowed (reduced), and the molecular memory input channel 31 and the molecular memory measurement channel 32 are replaced by the first tapered channel 33. Adopts a connecting structure.

As mentioned above, in order to reduce noise caused by the voltage for electrophoresis, it is preferable that the width of the molecular memory measurement channel 32 is narrow. When the width W1 of the connecting portion between the first taper channel 33 and the molecular memory measurement channel 32 is specified, W1 is 200 nm or less, 180 nm or less, 160 nm or less, 140 nm or less, 120 nm or less, 100 nm or less, 90 nm or less, 80 nm or less , 70 nm or less, 60 nm or less, or 50 nm or less. On the other hand, the lower limit of W1 is not particularly limited as long as it is within a manufacturable range. Although not limited, the thickness may be, for example, 20 nm or more, 25 nm or more, or 30 nm or more.

The width of the molecular memory measurement channel 32 may be the same at any location, or may be different as long as it does not affect analysis of measurement results. In the example shown in FIG. 5A, when the end of the molecular memory measurement channel 32 opposite to W1 is defined as W1a, W1a may be the same as W1, or may be larger or smaller than W1. .

The gap between the pair of measurement electrodes 4a and 4b (gap G, see FIG. 5B) is not particularly limited as long as it is within a range where the tunneling current when the molecular memory passes can be measured. Although not limited, the thickness may be, for example, 0.1 nm or more, 0.3 nm or more, 0.5 nm or more, 0.7 nm or more, or 0.9 nm or more. On the other hand, the upper limit of the gap G is not limited, but may be, for example, 50 nm or less, 30 nm or less, 10 nm or less, 8 nm or less, 6 nm or less, 5 nm or less, 4 nm or less, 3 nm or less, 2 nm or less, 1 nm or less. good.

The length of the measurement electrode 4 (the length of the gap G in the same direction as L2 in FIG. 5A) is also not particularly limited as long as it is within the range in which the tunneling current when the molecular memory passes can be measured. Although not limited, it may be, for example, 1000 nm or less, 800 nm or less, 600 nm or less, 400 nm or less, 200 nm or less, 100 nm or less, 80 nm or less, or 60 nm or less.

In addition, in order to facilitate cutting in MCBJ, the amount of accumulation of the measurement electrode 4 (direction perpendicular to the length direction of the measurement electrode 4, or direction H in FIG. 5B; hereinafter referred to as "thickness") ) is preferably smaller. If the thickness of the measurement electrode 4 is increased, it becomes difficult to control the cutting location, and there is a possibility that the cut surface of the produced gap G may become disordered. Therefore, the thickness of the measurement electrode 4 is not limited, but may be, for example, 80 nm or less, 70 nm or less, 60 nm or less, or 50 nm or less. The lower limit of the thickness of the measurement electrode 4 is not particularly limited as long as the tunnel current can be measured, and is not limited, for example, 2 nm or more, 4 nm or more, 6 nm or more, 8 nm or more, 10 nm or more, 15 nm or more, 20 nm or more. And it is sufficient.

As mentioned above, in order to reduce the thickness of the measurement electrode 4 and form the gap G by MCBJ, it is preferable that the length of the measurement electrode 4 be larger than the thickness. For example, the length/thickness ratio may be 10 to 100, although it is not limited to this.

The length L2 of the molecular memory measurement channel 32 is not particularly limited as long as it is within a range where the tunnel current when the molecular memory passes can be measured. If it is too long, the entire flow path of the measurement portion will become long. On the other hand, if it is too short, it becomes difficult for the elongated molecular memory to maintain its extended state. Although not limited, L2 may be 20 nm or more, 25 nm or more, 30 nm or more, 35 nm or more, 40 nm or more, 45 nm or more, or 50 nm or more. Further, L2 may be 2000 nm or less, 1500 nm or less, 1000 nm or less, 800 nm or less, 600 nm or less, 400 nm or less, 200 nm or less, 180 nm or less, 160 nm or less, 140 nm or less, 120 nm or less, or 100 nm or less. Of course, the length L2 needs to be longer than the length of the gap G portion of the measurement electrode 4.

In order to reduce noise caused by voltage for electrophoresis, it is preferable that the depth H of the channel 3 is also small. The depth H of the channel 3 is not limited, but is, for example, 200 nm or less, 180 nm or less, 160 nm or less, 140 nm or less, 120 nm or less, 100 nm or less, 90 nm or less, 80 nm or less, 70 nm or less, 60 nm or less, 50 nm. The following may be used. On the other hand, the depth H of the channel 3 may be, for example, 20 nm or more, 25 nm or more, or 30 nm or more.

In the measurement portions shown in FIGS. 5A to 5C, the length of the first tapered channel 33 (L1 in FIG. 5A) and the width of the molecular memory input channel 31 (the connection part with the first tapered channel 33, Although W2) is not particularly limited, it is desirable to make the width of the flow path 3 as small as possible. Note that, in order to input a solution containing molecular memory, the molecular memory input channel 31 may have a wide portion wider than W2 as necessary.

In the measurement part, there are no particular restrictions on the width of the molecular memory recovery channel 34 and the length of the optionally additionally provided second tapered channel 35 (L1a in FIG. 5A), but the width of the channel 3 is within a possible range. It is desirable to make it small. Note that in order to recover the molecular memory, the molecular memory recovery channel 34 may have a wide portion wider than W2a as necessary.

In the measurement portion, the width of the connecting portion between the first taper channel 33 and the molecular memory measurement channel 32 is defined as W1, and the width of the connecting portion between the first taper channel 33 and the molecular memory input channel 31 is defined as W2. The lower limit of W2/W1 is 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, and the upper limit is 50 or less, 40 or less, 30 or less, 20 or less. You can also use it as Furthermore, when the length of the connecting portion W1 between the first taper flow path 33 and the molecular memory measurement flow path 32 and the length of the connection portion between the first taper flow path and the molecular memory input flow path is defined as L1, the lower limit of L1/W2 is defined as L1. It may be 0.3 or more, 0.4 or more, or 0.5 or more, and the upper limit may be 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, or 5 or less.

When the shape of the first tapered flow path 33 is set to the above ratio, the following effects are achieved.
(1) By setting the first tapered channel 33 to the above ratio, it is possible to easily linearize the molecular memory in the solution.
(2) When the flow channel is filled with a solvent and a voltage is applied, an electroosmotic flow (EOF) is generated within the flow channel, but reverse flow occurs in the region along the wall. When the first taper flow path 33 is set within the above range, the generation of EOF is easily suppressed, and the shape of the first taper flow path 33 provides an acceleration effect due to electric field reinforcement. Therefore, it becomes easier to straighten the molecular memory contained in the solution and then introduce it into the molecular memory measurement channel 32.

The measurement part is a second tapered flow which is disposed between the molecular memory measurement channel 32 and the molecular memory recovery channel 34, and the channel width increases from the molecular memory measurement channel 32 to the molecular memory recovery channel 34. A path 35 may also be included.

When the measurement portion includes the second tapered flow path 35, this has the effect of preventing the molecular memory from stacking at the exit of the molecular memory measurement flow path 32 and promoting passage of the molecular memory.

In the measurement portion, the width of the connecting portion between the molecular memory measurement channel 32 and the second tapered channel 35 is defined as W1a, and the width of the connecting portion between the second tapered channel 35 and the molecular memory recovery channel 34 is defined as W2a. When the length of the connection between the second taper flow path 35 and the molecular memory measurement flow path 32 and the length of the connection between the second taper flow path 35 and the molecular memory recovery flow path 32 is defined as L1a, W1=W1a, W2. =W2a and L1=L1a may be satisfied. In other words, the channel 3 may be formed to be symmetrical with respect to the molecular memory measurement channel 32.

The analysis unit 9 identifies the direction in which the molecular memory passes through the measurement electrode 4 based on the conductance of the molecules forming the address area 101 (101a, 101b) and the conductance of the molecules forming the memory area 102. Furthermore, the analysis unit 9 identifies the direction in which the molecular memory passes through the measurement electrode based on the conductance of the molecules forming the first address area 101a and the conductance of the molecules forming the second address area 101b. The molecular memory has an elongated shape and passes through the measurement electrode 4 while expanding. Therefore, the direction in which the molecular memory passes through the measurement electrode 4 is not constant. In other words, in the case of the molecular memory 100 shown in FIG. 1, there are cases where decoding is performed from the address area 101 and cases where decoding is performed from the memory area 102. Similarly, in the case of the molecular memory 100a shown in FIG. 2, there are cases in which data is decoded from the first address area 101a and cases where data is decoded from the second address area 101b. By specifying the passing direction of the molecular memory, the analysis unit 9 can correctly decode the information stored in the molecular memory.

(Embodiment of molecular memory decoding method) Next, an embodiment of a molecular memory decoding method (hereinafter sometimes simply referred to as "decoding method") will be described with reference to FIG. 7. It is a flowchart showing an example of the method.The decoding method is performed using the above-mentioned device 1.Moreover, the molecular memory is the above-mentioned molecular memory 100, 100a, 100', 100a' or the scope of the technical idea disclosed in this application. A molecular memory modified within can be used. Note that to avoid complication, the reference numerals of the molecular memory will be omitted in the following description.

The decoding method includes a molecular memory electrophoresis step (ST1), a measurement step (ST2), an analysis step (ST3), and a molecular memory passage direction identification step (ST4).

In the molecular memory electrophoresis step (ST1), the molecular memory in the molecular memory input channel 31 is directed toward the molecular memory recovery channel 34 by applying a voltage to the molecular memory input channel 31 and the molecular memory recovery channel 34. and perform electrophoresis. More specifically, a solution containing molecular memory is introduced into the molecular memory input channel 31, a solvent is introduced into the molecular memory recovery channel 34, and a voltage is applied to the first electrode 61 and the second electrode 62. Implemented. The introduced molecular memory or solvent permeates into the first tapered channel 33, the molecular memory measurement channel 32, and the second tapered channel 35 formed as necessary by capillary force, thereby creating a liquid junction. A solvent for producing a solution containing molecular memory only needs to conduct electricity. Examples include, but are not limited to, ultrapure water, buffer solutions, and the like. Ultrapure water can be produced using, for example, Milli-Q (registered trademark) Integral 3 (device name) manufactured by EMD Millipore (Milli-Q (registered trademark) Integral 33/5/1015 (catalog number)). Can be done. Examples of the buffer include known electrophoresis buffers such as TE buffer and TBE buffer. The concentration of the buffer is not limited, but may be adjusted as appropriate within a range that allows electrophoresis, such as 1 μM or less. In addition, in addition to surfactants such as polyvinyl-pyrrolidone (PVP), amphiphilic chemicals may be added to the solution containing molecular memory as necessary to reduce the effects of electroosmotic flow (EOF). It's okay.

In the example shown in FIG. 4, the molecular memory measurement channel 32 and a pair of measurement electrodes 4a and 4b arranged in the molecular memory measurement channel 32 form a measurement section. Then, a first electrode for electrophoresis (hereinafter sometimes referred to as "first electrode") 61 is formed at a location in contact with the solution containing molecular memory in the molecular memory input channel 31, and a molecular memory recovery channel A second electrode for electrophoresis (hereinafter sometimes referred to as "second electrode") 62 is formed at a location in the channel 34 that comes into contact with the solvent. Then, by applying a voltage across the measurement electrodes 4a and 4b using the first power supply 6a connected to the first electrode 61 and the first power supply 6b connected to the second electrode 62, the molecular memory undergoes electrophoresis. It passes through the measurement electrodes 4a and 4b. Although FIG. 4 shows an example in which the voltage for electrophoresis is applied using two first power supplies 6, the number of first power supplies 6 may be one.

The first electrode 61 and the second electrode 62 can be formed of a known conductive metal such as Ag/AgCl, aluminum, copper, platinum, gold, silver, or titanium. The first electrode 61 and the second electrode 62 may be formed on the base material 2 or may be made separate from the device 1 and inserted through a hole in the cover member 5.

If the voltage applied by the first power supply 6 is too small, the movement speed of the molecular memory will be slow and measurement will take time. Although not limited, the voltage may be, for example, 10 mV or more, 15 mV or more, 20 mV or more, 25 mV or more, or 30 mV or more. On the other hand, the upper limit of the voltage applied by the first power source 6 may be appropriately set in consideration of the accuracy of the analysis process, the width of the flow path 3, etc., which will be described later. Although not limited, the voltage may be, for example, 5V or less, 3V or less, 1V or less, 500mV or less, 300mV or less, 100mV or less, 90mV or less, 80mV or less, 70mV or less, 60mV or less, or 50mV or less.

In the measurement step (ST2), a tunnel current is measured when the molecular memory passes through the gap between the pair of measurement electrodes 4a and 4b arranged in the molecular memory measurement channel 32. In the example shown in FIG. 4, the measurement step (ST2) involves applying a voltage to the pair of measurement electrodes 4a and 4b by a tunnel current measurement power supply (hereinafter sometimes referred to as "second power supply") 8. The tunnel current detection unit 7 measures the change in tunnel current that occurs when the molecular memory passes through the gap between the pair of measurement electrodes 4a and 4b. Note that the example shown in FIG. 4 is an example of the measurement step (ST2), and is not limited thereto. Since the change in the tunnel current that occurs is at the picoampere level, the tunneling current detection section 7 may use a known ammeter that can measure current at the picoampere level. Alternatively, the current may be calculated from the voltage measured with a voltmeter. The tunnel current detection unit 7 may optionally include a current amplification amplifier, a noise removal device, an A/D converter, and the like. When the tunnel current detection unit 7 includes a current amplification amplifier, a noise removal device, an A/D converter, etc., data that is easy to analyze can be provided instead of raw data of the measured tunnel current value. Alternatively, the tunnel current detection section 7 may be configured only to be able to measure changes in tunnel current, and the current amplification amplifier, noise removal device, A/D converter, etc. may be configured in the analysis section 9.

The second power supply 8 applies a voltage to the pair of measurement electrodes 4a and 4b. The voltage applied by the second electrode 8 is not particularly limited as long as tunnel current can be measured. Although not limited, for example, the lower limit may be set to 20 mV or more, 50 mV or more, or 100 mV or more, and the upper limit may be set to 750 mV or less, 500 mV or less, 250 mV or less, etc. The specific configuration of the second power source 8 is not particularly limited, and any known power source device may be used. In the example shown in FIG. 4, the device 1 can reduce the voltage required for electrophoresis of the molecular memory by making the width of the channel 3, particularly the molecular memory measurement channel 32, very small. Therefore, when measuring the tunnel current when the molecular memory passes through the gap between the measurement electrodes 4, the tunnel current detection unit 7 can obtain a measured value of the tunnel current with a small noise component. In the tunnel current measurement step, when the molecular memory passes through the gap between the pair of measurement electrodes 4a and 4b, the tunnel current can be measured for each molecule making up the molecular memory.

In the analysis step (ST3), the arrangement of molecules constituting the molecular memory is analyzed from the results of the measured tunnel current. In the example shown in FIG. 4, the analysis step (ST3) is performed in the analysis section 9 (hereinafter, the analysis step performed in the analysis section may be simply referred to as "analysis section"). More specifically, the analysis unit 9 calculates conductance from the measured value of tunnel current. The conductance can be calculated by dividing the measured value of the tunnel current by the voltage applied to the pair of measurement electrodes 4a and 4b. The conductance calculated from the tunnel current generated when molecules pass through the pair of measurement electrodes 4a and 4b differs depending on the type of molecule. The reason for this is that, for example, the ease with which electricity flows differs due to differences in base structure in the case of nucleosides, and differences in constituent structures in the case of amino acids. Therefore, by comparing the conductance of various molecules measured and calculated in advance with the measured conductance of molecules and analyzing the measured values of tunnel current in time series, it is possible to read the molecular arrangement that constitutes the molecular memory. Note that the above description is only an example of the analysis section 9. As long as the molecular arrangement can be analyzed from the measured tunnel current, analysis methods other than conductance may be used. Note that since conductance is an absolute value obtained from measurement data, it is a value that includes noise and fluctuations of the measurement system. If necessary, the influence of system noise etc. may be reduced by normalizing (Relative G) using the conductance of guanine.

In the molecular memory passage direction identification step (ST4), the molecular memory determines the measurement electrodes 4a and 4b based on the conductance of the molecules constituting the (first and second) address areas 101 and the conductance of the molecules constituting the memory area 102. Determine the direction of passage. The molecular memories 100 and 100a disclosed in this application are designed so that the types of at least some of the molecules forming the (first and second) address areas 101 and memory areas 102 are different. Therefore, based on the conductance depending on the type of molecule, in the case of the molecular memory 100, it is determined from which direction of the address area 101 or the memory area 102, and in the case of the molecular memory 100a, it is determined whether the decoding is from the first address area 101a or the first address area 101a. It is possible to specify from which direction of the 2-address area 101b the decoding is performed.

The decoding method may optionally include an information restoration step after the molecular memory passage direction identification step (ST4). For example, a molecular sequence table corresponding to the ASCII code table may be prepared, and the encoded information may be restored using this molecular sequence table.

Further, as shown in FIG. 4, as an example of a device that implements the decoding method, a display section 10 for displaying information provided in the analysis step (ST3) and the passing direction identification step (ST4), an analysis section 9 It may also include a program memory 11 storing a program for operating the display unit 10, and a control unit 12 for reading and executing the program stored in the program memory 11. The program may be stored in the program memory 11 in advance, or may be recorded on a recording medium and stored in the program memory 11 using an installation means.

For the display unit 10, a known display device such as a liquid crystal display, a plasma display, an organic EL display, etc. may be used.

A large-capacity molecular memory can be provided by using the molecular memory, the method for manufacturing the molecular memory, the method for decoding the molecular memory, and the device for decoding the molecular memory disclosed in this application. Therefore, it is useful for the information industry.

DESCRIPTION OF SYMBOLS 1... Device, 2... Base material, 2a... Substrate, 2b... Insulating layer, 2c... Deposition layer, 2d... Resist layer, 3... Channel, 31... Molecular memory input channel, 32... Molecular memory measurement channel, 33 ...First taper channel, 34...Molecular memory recovery channel, 35...Second taper channel, 4, 4a, 4b...Measurement electrode, 5...Cover member, 6, 6a, 6b...Power source for electrophoresis, 61 ...First electrode for electrophoresis, 62... Second electrode for electrophoresis, 7... Tunnel current detection unit, 8... Power supply for tunnel current measurement, 9... Analysis unit, 10... Display unit, 11... Program memory, 12... Control Part, 100...Molecular memory, 101...Address area, 101a...First address area, 101b...Second address area, 102...Memory area, 103, 103a, 103b...Redundant area

Claims

A molecular memory comprising an address area and a memory area connected to the address area,
The address area and memory area are composed of molecules that generate tunnel current,
The memory area is composed of molecules selected from a first molecule group of four or more types,
The address area is composed of molecules selected from a second molecule group of four or more types,
The molecules included in the first molecule group are:
The types of molecules contained in the second molecule group are all different types, or
Including the same types and different types of molecules contained in the second molecule group,
By that,
At least some of the molecules constituting the address area and the memory area are of different types,
molecular memory.
When the first molecule group includes molecules of the same type as molecules included in the second molecule group, the molecules of the same type included in the first molecule group and the second molecule group are
It is not located at the end of the address area on the memory area side and at the end of the address area side of the memory area.
The molecular memory according to claim 1.
The molecule with the smallest conductance among the molecules included in the first molecule group is not placed at the end of the memory area on the opposite side from the address area side,
The molecule with the smallest conductance among the molecules included in the second molecule group is not placed at the end of the address area on the opposite side to the memory area side.
The molecular memory according to claim 1.
The types of molecules included in the first molecule group are all different from the types of molecules included in the second molecule group,
The molecular memory according to claim 1.
The types of molecules included in the first molecule group are all different from the types of molecules included in the second molecule group,
The molecular memory according to claim 3.
One of the first molecular group or the second molecular group is
4 or more molecules selected from the group consisting of
The other of the first molecular group or the second molecular group is
4 or more molecules selected from the group consisting of
The molecular memory according to claim 4.
A first conductance range that is the range of minimum and maximum conductance values of molecules included in the first molecule group, and a second conductance range that is a range of minimum and maximum conductance values of molecules included in the second molecule group. do not overlap,
The molecular memory according to claim 1.
A first conductance range that is the range of minimum and maximum conductance values of molecules included in the first molecule group, and a second conductance range that is a range of minimum and maximum conductance values of molecules included in the second molecule group. do not overlap,
The molecular memory according to claim 6.
The address area is
a first address area connected to one end of the memory area;
a second address area connected to the other end of the memory area;
including;
The first address area is composed of molecules selected from four or more types of 2a molecule groups,
The second address area is composed of molecules selected from four or more types of second b molecule groups,
The molecules included in the first molecule group are:
The types of molecules contained in the 2a molecule group are all different types, or
It includes the same types and different types of molecules as those included in the molecule group 2a, and is all different types from the types of molecules included in the molecule group 2b, or
Including the same types and different types of molecules contained in the second b molecule group,
Molecules included in the 2b molecule group are:
The types of molecules contained in the 2a molecule group are all different types, or
Including the same types and different types of molecules contained in the 2a molecule group,
The molecular memory according to claim 1.
The types of molecules included in the first molecule group, the types of molecules included in the second a molecule group, and the types of molecules included in the second b molecule group are all different,
One of the 2a molecular group and the 2b molecular group,
4 or more molecules selected from the group consisting of
The other of the 2a molecule group and the 2b molecule group is
4 or more molecules selected from the group consisting of
The molecular memory according to claim 9.
A redundant area is connected between the address area and the memory area,
The redundant area is
Consists of redundant region molecules that generate tunnel current,
The conductance of the redundant area molecules is smaller than the conductance of the molecules composing the address area and memory area.
The molecular memory according to claim 1.
a first redundant area is connected between the first address area and the memory area;
a second redundant area is connected between the second address area and the memory area;
The first redundant area and the second redundant area are
Consists of redundant region molecules that generate tunnel current,
The conductance of the redundant area molecules is smaller than the conductance of molecules forming the first address area, the second address area, and the memory area.
The molecular memory according to claim 9.
A method for manufacturing a molecular memory according to any one of claims 1 to 12, comprising:
an information preparation step for preparing information to be encoded;
a molecular sequencing step of converting the prepared information into molecules constituting the molecular memory and determining the arrangement of the molecular memory;
a synthesis step of synthesizing molecules constituting the molecular memory based on the determined sequence;
including,
Production method.
A device for decoding a molecular memory according to any one of claims 1 to 12, comprising:
base material and
A flow path formed in the base material,
a pair of measurement electrodes for measuring tunneling current when the molecular memory passes;
a control unit;
including;
The flow path is
a molecular memory input channel;
a molecular memory measurement channel in which measurement electrodes are arranged;
a first tapered channel that is disposed between the molecular memory input channel and the molecular memory measurement channel, and whose channel width becomes narrower from the molecular memory input channel to the molecular memory measurement channel;
a molecular memory recovery channel for recovering the molecular memory that has passed through the molecular memory measurement channel;
including;
The width of the connecting portion between the first taper channel and the molecular memory measurement channel is 20 nm to 200 nm,
The analysis department is
Identifying the direction in which the molecular memory passes through the measurement electrode based on the conductance of the molecules forming the address area and the conductance of the molecules forming the memory area, or
identifying the direction in which the molecular memory passes through the measurement electrode based on the conductance of the molecules forming the first address area and the conductance of the molecules forming the second address area;
device.
A method for decoding a molecular memory according to any one of claims 1 to 12 using the device according to claim 14,
The molecular memory decoding method includes a molecular memory electrophoresis step, a measurement step, an analysis step, and a molecular memory passage direction identification step,
The molecular memory electrophoresis process is
By applying a voltage to the molecular memory input channel and the molecular memory recovery channel, the molecular memory in the molecular memory input channel is electrophoresed towards the molecular memory recovery channel,
The measurement process is
Measure the tunneling current when the molecular memory passes through the gap between a pair of measurement electrodes placed in the molecular memory measurement channel,
The analysis process is
Based on the measured tunnel current, we analyze the arrangement of the molecules that make up the molecular memory.
The molecular memory passing direction identification process is
Identifying the direction in which the molecular memory passes through the measurement electrode based on the conductance of the molecules forming the address area and the conductance of the molecules forming the memory area, or
identifying the direction in which the molecular memory passes through the measurement electrode based on the conductance of the molecules forming the first address area and the conductance of the molecules forming the second address area;
How to decode molecular memory.