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 voltage at a first voltage level across the first electrode and the second electrode and across the layer of transition metal dichalcogenide crystals such that an aperture is created in the layer of transition metal dichalcogenide crystals, wherein the voltage is an alternating current voltage;
maintaining the voltage at the first voltage level for a specified amount of time, the specified amount of time corresponding to the aperture widening to have at least a specified diameter; and
after the specified amount of time, reducing the applied voltage to a second voltage level to inhibit the widening of the aperture.
2. The method of claim 1 , wherein:
the transition metal of the transition metal dichalcogenide crystals has an oxidation potential, and
the first voltage level is higher than the oxidation potential.
3. The method of claim 1 , further comprising measuring a current between the first electrode and the second electrode, and
wherein reducing the applied voltage comprises reducing the applied voltage after the current reaches a current level corresponding to the specified diameter of the aperture.
4. The method of claim 3 , wherein reducing the voltage comprises activating a switch through a feedback control circuit when the current level is reached.
5. The method of claim 4 , wherein the activation of the switch turns off the applied voltage.
6. The method of claim 1 , wherein the first voltage level is in a range from 800 mV to 1,000 mV.
7. 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 a group consisting of sulfur, selenium, and tellurium.
8. 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 .
9. The method of claim 1 , wherein the layer of transition metal dichalcogenide crystals is disposed on an insulating material.
10. 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.
11. 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.
12. The method of claim 1 , wherein the layer of transition metal dichalcogenide crystals is one monolayer thick.
13. The method of claim 1 , wherein the layer of transition metal dichalcogenide crystals is two monolayers thick.
14. The method of claim 1 , wherein the specified diameter is in a range from 1 nm to 5 nm.
15. 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.
16. The method of claim 1 , wherein the specified amount of time is based on average times for apertures to be created with the specified diameter in previous samples.
17. The method of claim 1 , wherein the second voltage level is non-zero.
18. 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 voltage at a first voltage level across the first electrode and the second electrode and across the layer of transition metal dichalcogenide crystals such that an aperture is created in the layer of transition metal dichalcogenide crystals, wherein the first voltage level is in a range from 800 mV to 1,000 mV;
maintaining the voltage at the first voltage level for a specified amount of time, the specified amount of time corresponding to the aperture widening to have at least a specified diameter; and
after the specified amount of time, reducing the applied voltage to a second voltage level to inhibit the widening of the aperture.