Nanopore forming method and uses thereof
The invention relates to a method for making nanopores in thin layers or monolayers of transition metal dichalcogenides that enables accurate and controllable formation of pore within those thin layer(s) with sub-nanometer precision.
1. A method of forming a nanopore in a layer of transition metal dichalcogenide crystals residing between a first electrode on a first side of the layer of transition metal dichalcogenide crystals and a second electrode on a second side of the layer of transition metal dichalcogenide crystals, wherein a first liquid is disposed on the first side and a second liquid is disposed on the second side, the method comprising:
applying a variable voltage across the first electrode and the second electrode such that an aperture is created in the layer of transition metal dichalcogenide crystals;
varying the variable voltage as the aperture widens such that a current having a constant average current level exists between the first electrode to the second electrode, the constant average current level corresponding to a specified diameter of the aperture to be formed in the layer of transition metal dichalcogenide crystals; and
maintaining the current at the constant average current level such that the aperture widens to have the specified diameter, thereby forming the nanopore.
2. The method of claim 1 , wherein the current is an alternating current.
3. The method of claim 1 , wherein the current is a direct current.
4. The method of claim 1 , further comprising decreasing a voltage level of the variable voltage to maintain the current at the constant average current level.
5. The method of claim 4 , wherein decreasing the voltage level of the variable voltage includes a decrease after the aperture widens to have the specified diameter.
6. The method of claim 1 , wherein the transition metal dichalcogenide crystals comprise a compound having a chemical formula MX2, wherein M is a transition metal atom, and wherein X is selected from the group consisting of sulfur, selenium, and tellurium.
7. The method of claim 1 , wherein the transition metal dichalcogenide crystals comprises a compound selected from the group consisting of MoS 2 , SnSe 2 , WS 2 , TeS 2 , MoSe 2 , WSe 2 , TeSe 2 NbS 2 , NbSe 2 , TiS 2 , TiSe 2 , ReS 2 , and ReSe 2 .
8. The method of claim 1 , wherein the layer of transition metal dichalcogenide crystals is disposed on an insulating material.
9. The method of claim 1 , wherein:
the first electrode is disposed in the first liquid, and
the second electrode is disposed in the second liquid.
10. The method of claim 1 , wherein the first liquid comprises aqueous, organic, or ionic liquid.
11. The method of claim 1 , wherein the first liquid has a composition different from a composition of the second liquid.
12. The method of claim 1 , wherein the layer of transition metal dichalcogenide crystals has a thickness in a range from 0.3 nm to 5 nm.
13. The method of claim 1 , wherein the layer of transition metal dichalcogenide crystals is one monolayer thick.
14. The method of claim 1 , wherein the layer of transition metal dichalcogenide crystals is two monolayers thick.
15. The method of claim 1 , wherein the specified diameter is in a range from 1 nm to 5 nm.
16. The method of claim 1 , further comprising detecting a subunit of a polymer molecule in the nanopore based on electrical signals detected by at least one of the first electrode and the second electrode.
17. The method of claim 1 , wherein:
the transition metal of the transition metal dichalcogenide crystals has an oxidation potential, and
the variable voltage is applied at a voltage level that is higher than the oxidation potential.