Molecular memory is a term for

data storage Data storage is the recording (storing) of information (data) in a storage medium. Handwriting, phonographic recording, magnetic tape, and optical discs are all examples of storage media. Biological molecules such as RNA and DNA are conside ...

technologies that use molecular species as the data storage element, rather than e.g. circuits,

magnetics Magnetism is the class of physical attributes that are mediated by a magnetic field, which refers to the capacity to induce attractive and repulsive phenomena in other entities. Electric currents and the magnetic moments of elementary particle ...

inorganic In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...

materials or physical shapes. The molecular component can be described as a

molecular switch A molecular switch is a molecule that can be reversibly shifted between two or more stable states. The molecules may be shifted between the states in response to environmental stimuli, such as changes in pH, light, temperature, an electric curren ...

, and may perform this function by any of several mechanisms, including

charge Charge or charged may refer to: Arts, entertainment, and media Films * '' Charge, Zero Emissions/Maximum Speed'', a 2011 documentary Music * ''Charge'' (David Ford album) * ''Charge'' (Machel Montano album) * ''Charge!!'', an album by The Aqu ...

storage,

photochromism Photochromism is the reversible transformation of a chemical species (photoswitch) between two forms by the absorption of electromagnetic radiation (photoisomerization), where the two forms have different absorption spectra. In plain language, th ...

, or changes in

capacitance Capacitance is the capability of a material object or device to store electric charge. It is measured by the change in charge in response to a difference in electric potential, expressed as the ratio of those quantities. Commonly recognized are ...

. In a perfect molecular memory device, each individual molecule contains a

bit The bit is the most basic unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represente ...

of data, leading to massive data capacity. However, practical devices are more likely to use large numbers of molecules for each bit, in the manner of 3D optical data storage (many examples of which can be considered molecular memory devices). The term "molecular memory" is most often used to mean very fast, electronically addressed solid-state data storage, as is the term

computer memory In computing, memory is a device or system that is used to store information for immediate use in a computer or related computer hardware and digital electronic devices. The term ''memory'' is often synonymous with the term ''primary storage ...

. At present, molecular memories are still found only in laboratories.

Examples

One approach to molecular memories is based on special compounds such as

porphyrin Porphyrins ( ) are a group of heterocyclic macrocycle organic compounds, composed of four modified pyrrole subunits interconnected at their α carbon atoms via methine bridges (=CH−). The parent of porphyrin is porphine, a rare chemical com ...

-based

polymer A polymer (; Greek '' poly-'', "many" + ''-mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...

s which are capable of storing

electric charge Electric charge is the physical property of matter that causes charged matter to experience a force when placed in an electromagnetic field. Electric charge can be ''positive'' or ''negative'' (commonly carried by protons and electrons respe ...

. Once a certain voltage threshold is achieved the material oxidizes, releasing an electric charge. The process is reversible, in effect creating an electric

capacitor A capacitor is a device that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. It is a passive electronic component with two terminals. The effect of ...

. The properties of the material allow for a much greater capacitance per unit area than with conventional DRAM memory, thus potentially leading to smaller and cheaper

integrated circuit An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny ...

s. Several universities and a number of companies (

Hewlett Packard The Hewlett-Packard Company, commonly shortened to Hewlett-Packard ( ) or HP, was an American multinational information technology company headquartered in Palo Alto, California. HP developed and provided a wide variety of hardware components ...

, ZettaCore) have announced work on molecular memories, which some hope will supplant

DRAM Dynamic random-access memory (dynamic RAM or DRAM) is a type of random-access semiconductor memory that stores each bit of data in a memory cell, usually consisting of a tiny capacitor and a transistor, both typically based on metal-oxid ...

memory as the lowest cost technology for high-speed

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

is also supporting research on non-volatile molecular memories. In 2018, researches from the

University of Jyväskylä The University of Jyväskylä ( fi, Jyväskylän yliopisto) is a research university in Jyväskylä, Finland. It has its origins in the first Finnish-speaking Teacher Training College (the so-called Teacher Seminary), founded in 1863. Ar ...

in Finland, developed a molecular memory which can memorize the direction of a magnetic field for long periods of time after being switched off at extremely low temperatures, which would aid in enhancing the storage capacity of

hard disk drives A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating hard disk platter, platters ...

without enlarging their physical size.

References

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External links

Nonvolatile Molecular Memory
-

Molecular memory a game-changer
- article from

Phys.Org Phys.org is an online science, research and technology news aggregator offering briefs from press releases and reports from news agencies (a form of journalism sometimes pejoratively called churnalism). The website also produces its own science jo ...

DNA-interfaced Molecular Memory
- article from Acs.org
Graphene flash memory
nanowerk Computer memory Molecular electronics Nanoelectronics