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List of very small things

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From Molecupedia, the encyclopedia of very small things
Sizes from 2 millimeters to 31 picometers, with the reason each one matters in nanopore work

This list of very small things runs from a 2 mm macropore down to a difference in radius of 31 pm. Nanopore work covers that range: a pore a few hundred micrometers wide counts cells, and one a few nanometers wide counts molecules. Sizes are diameters unless the entry says otherwise, and the values are typical figures with the source beside them.

At the bottom of the scale the unit of account is the elementary charge. A current of 1 pA is 6.2 million charges a second, and the 3.1 nA that a model predicts for a pore a few nanometers wide in 1 M potassium chloride at 200 mV is 19 billion ions a second.[1]

The list

Things from 2 mm to 31 pm
Size Thing Role in nanopore work
2 mm The macropore through which a knotted nylon string was drawn Knots passing through gave "downward (resistive) spikes", and the experiment tested a prototype amplifier. The founder's post calls the pore "not much fancier than the melted one" in an earlier demonstration. See Knot sequencing.[2]
200 µm The laser-drilled pore on the company's live stream About the aperture of a Coulter counter. The dips worth looking for come from cells and particles several micrometers across. See 200-micron laser-drilled pore.[1]
70 µm A human hair (reported range 17 to 181 µm) The live-stream pore is a little under three hairs wide.[3]
16.5 µm Contour length of one molecule of λ phage DNA, which is 2 nm wide The standard long test molecule: 48,502 base pairs at 0.34 nm each, a thread 16.5 µm long.[4] See Lambda phage DNA.
7.8 µm A human red blood cell (mean diameter 7.82 µm) The particle that the Coulter counter was built to count. About 26 fit across the live-stream pore.[5]
2 µm An Escherichia coli cell, about 0.5 to 1 µm wide Bacteria have been counted and sized with Coulter apertures since 1958.[6][7]
250 nm A polystyrene particle The particles in a multipass Coulter counter that measured a mean blocking current equivalent to resolving radii differing by 31 pm.[8][9] See Polystyrene bead.
200 nm The pore in a silicon chip behind the best afternoon of data at the company's first laboratory The founder describes it as "a beautiful, fully wet, stable 200 nm underpore", the result of a week or two of what he calls dumb problems. See Dumb problems.[10]
About 200 nm The finest detail a light microscope resolves (Abbe limit) For green light and a good objective the limit is near 200 nm. The company's essay on its machine-learning plans says that video of a flow cell shows bubbles and fouling and cannot show a molecule.[11][12]
100 nm (60 to 140 nm) A SARS-CoV-2 virion In the size range of the particles that solid-state pores and machine learning have been used to classify. See Virus detection with nanopores.[13]
50 nm Persistence length of double-stranded DNA A double helix is stiff on this scale, and a long molecule has to uncoil to enter a pore a few nanometers wide.[14]
15 nm The aperture below which the company's sliding pore is a stated target Apertures smaller than this are "a target, not yet a result". See Sliding occlusion.[15]
10 nm The edge of a cube that holds one zeptoliter The scale of the water bridge between two pores 20 nm apart in a dual-pore device, whose volume is about a zeptoliter, and the founder's "favorite unit of measurement". See Zeptoliter.[16]
5 nm A cylindrical pore 5 nm wide and 10 nm long In 1 M potassium chloride at 200 mV, a model that includes access resistance gives a conductance of 15.5 nS and a current of 3.1 nA, which is 19 billion ions a second.[a][17] See Pore conductance.
4.6 nm The widest part of the alpha-hemolysin channel, inside its cap The channel is 10 nm long and narrows from this width to 1.4 nm.[18]
2 nm The double helix of DNA, 20 Å across A pore a few nanometers wide admits one double helix at a time. See DNA.[19]
1.4 nm The narrowest point of alpha-hemolysin Wide enough for a single strand of DNA and too narrow for a double one, a fact that decided what the first experiments could measure.[18]
1.2 nm The constriction of MspA, no more than 0.6 nm long A shorter constriction puts fewer bases in the sensing region at once.[20]
0.9 nm The constriction of CsgG The pore of the R9 flow cells that Oxford Nanopore Technologies announced in 2016.[21][22]
0.68 nm The height of the slits in the 2019 "molecular streaming" experiment About one hydrated ion tall. See Molecular streaming (nanofluidics).[23]
0.66 nm A hydrated potassium or chloride ion The charge carriers in the potassium chloride solutions common in nanopore work.[24] See Potassium chloride.
0.34 nm The spacing of base pairs along DNA A strand passing at one base per microsecond moves at 0.34 mm/s; at 30 bases per microsecond, at 10 mm/s. See Speeding bullet problem.[19]
0.30 nm The Debye length in 1 M potassium chloride at 25 °C The potential of a charged pore wall falls to 1/e of its surface value over this distance in 1 M salt. See Debye length.[25]
0.276 nm A potassium ion without its water (ionic radius 138 pm) Less than half the width of the ion in solution.[26]
53 pm The Bohr radius, the most probable distance of the electron from the proton in a hydrogen atom A hydrogen atom has no edge; this is the distance at which its electron is most likely to be found. The next entry is 0.59 of it.[27]
31 pm The difference in radius between particles that a multipass Coulter counter was reported to resolve statistically About the covalent radius of hydrogen. The founder's comment on the paper was "smaller than a single hydrogen atom".[9][28][8]

The company's pores

The pores in the table that belong to the company are at the large end. A paragraph of its public guide begins "Honesty about scale: the pores we stream today are larger than a nanometer" and describes the plan as walking the family of pore-based sensing "from the big end toward the small".[29] The live-stream pore is 200 µm wide, 200,000 times the 1 nm that the sentence names. In a Coulter aperture of that size the dip in current is roughly proportional to the volume of the particle in it. In a pore a few nanometers wide the double layer on the walls fills a large share of the opening (see Electric double layer), and at 1 to 2 nm what matters is how many bases or amino acids lie in the narrowest part at once.

The Glossary of nanopore terms explains the vocabulary, and the List of unusual units used at Molecular Reality collects the company's less usual units.

See also

Notes

  1. ^ Calculated with the conductance formula G = σ[4L/(πd2) + 1/d]−1, σ = 11 S/m, d = 5 nm and L = 10 nm: the bracket is 5.09 × 108 + 2.00 × 108 = 7.09 × 108 m−1, so G = 15.5 nS and I = 15.5 nS × 0.2 V = 3.1 nA. Divided by the elementary charge, 1.6 × 10−19 C, that is 1.9 × 1010 charges a second.

References

  1. ^ a b Dr. Lenora Ashgrove (July 29, 2026). "Nineteen Billion Ions a Second, Live on the Internet". Signal & Noise.
  2. ^ Kemmishtree (March 29, 2026). "Sequencing a string". EQBio-OS.
  3. ^ Brian Ley (1999). "Diameter of a human hair". The Physics Factbook.
  4. ^ Sanger, F.; et al. (1982). "Nucleotide sequence of bacteriophage λ DNA". Journal of Molecular Biology 162 (4): 729-773. doi:10.1016/0022-2836(82)90546-0.
  5. ^ Evans, E.; Fung, Y.-C. (1972). "Improved measurements of the erythrocyte geometry". Microvascular Research 4 (4): 335-347. doi:10.1016/0026-2862(72)90069-6.
  6. ^ Kubitschek, H. E. (1958). "Electronic counting and sizing of bacteria". Nature 182 (4630): 234-235. doi:10.1038/182234a0.
  7. ^ Milo, R.; Phillips, R. (2015). Cell Biology by the Numbers. Garland Science. ISBN 978-0-8153-4537-4.
  8. ^ a b Kemmishtree (March 28, 2026). "Molecular Supreme". EQBio-OS.
  9. ^ a b Edwards, Martin A.; German, Sean R.; Dick, Jeffrey E.; Bard, Allen J.; White, Henry S. (2015). "High-speed multipass Coulter counter with ultrahigh resolution". ACS Nano 9 (12): 12274-12282. doi:10.1021/acsnano.5b05554.
  10. ^ Kemmishtree (March 29, 2026). "Focused Ion Beam pore". EQBio-OS.
  11. ^ "Keltar's Critique v2: The Nanopore World Model (Hardened)". Molecular Reality Corporation. June 2026.
  12. ^ Abbe, E. (1873). "Beiträge zur Theorie des Mikroskops und der mikroskopischen Wahrnehmung". Archiv für mikroskopische Anatomie 9 (1): 413-468. doi:10.1007/BF02956173.
  13. ^ Bar-On, Y. M.; et al. (2020). "SARS-CoV-2 (COVID-19) by the numbers". eLife 9: e57309. doi:10.7554/eLife.57309.
  14. ^ Hagerman, P. J. (1988). "Flexibility of DNA". Annual Review of Biophysics and Biophysical Chemistry 17: 265-286. doi:10.1146/annurev.bb.17.060188.001405.
  15. ^ "Company records". Molecular Reality Corporation. October 2026.
  16. ^ Kemmishtree (March 29, 2026). "Zeptoliter is My Favorite Unit of Measurement". EQBio-OS.
  17. ^ Kowalczyk, S. W.; et al. (2011). "Modeling the conductance and DNA blockade of solid-state nanopores". Nanotechnology 22 (31): 315101. doi:10.1088/0957-4484/22/31/315101.
  18. ^ a b Song, L.; et al. (1996). "Structure of staphylococcal α-hemolysin, a heptameric transmembrane pore". Science 274 (5294): 1859-1865. doi:10.1126/science.274.5294.1859.
  19. ^ a b Watson, J. D.; Crick, F. H. C. (1953). "Molecular structure of nucleic acids: a structure for deoxyribose nucleic acid". Nature 171 (4356): 737-738. doi:10.1038/171737a0.
  20. ^ Deamer, D.; Akeson, M.; Branton, D. (2016). "Three decades of nanopore sequencing". Nature Biotechnology 34 (5): 518-524. doi:10.1038/nbt.3423.
  21. ^ "Update: New "R9" nanopore for faster, more accurate sequencing, and new ten minute preparation kit". Oxford Nanopore Technologies. May 26, 2016. Retrieved October 25, 2026.
  22. ^ Goyal, P.; et al. (2014). "Structural and mechanistic insights into the bacterial amyloid secretion channel CsgG". Nature 516 (7530): 250-253. doi:10.1038/nature13768.
  23. ^ Mouterde, T.; Keerthi, A.; et al. (2019). "Molecular streaming and its voltage control in ångström-scale channels". Nature 567 (7746): 87-90. doi:10.1038/s41586-019-0961-5.
  24. ^ Esfandiar, A.; et al. (2017). "Size effect in ion transport through angstrom-scale slits". Science 358 (6362): 511-513. doi:10.1126/science.aan5275.
  25. ^ Israelachvili, J. N. (2011). Intermolecular and Surface Forces. 3rd ed. Academic Press. ISBN 978-0-12-375182-9.
  26. ^ Shannon, R. D. (1976). "Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides". Acta Crystallographica Section A 32 (5): 751-767. doi:10.1107/S0567739476001551.
  27. ^ Tiesinga, E.; et al. (2021). "CODATA recommended values of the fundamental physical constants: 2018". Reviews of Modern Physics 93 (2): 025010. doi:10.1103/RevModPhys.93.025010.
  28. ^ Cordero, B.; et al. (2008). "Covalent radii revisited". Dalton Transactions (21): 2832-2838. doi:10.1039/b801115j.
  29. ^ "Keltar's Field Guide to Molecular Reality". Molecular Reality Corporation. August 2026.
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