Nanopore forming method and uses thereof

Abstract

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.

What is claimed is: 
     
         1 . A method for forming a nanopore with a prescribed diameter (dr) in a membrane of transition metal dichalcogenide (TMDC) crystals comprising:
 providing at least one TMDC thin layer having from 0.3 nm to 5 nm thickness (H m ) suspended in an electrically conducting liquid;   applying a transmembrane voltage (V) at a value higher than the oxidation potential of the transition metal of the said at least one TMDC thin layer configured for an electrochemical atomic etching of said at least one TMDC thin layer;   measuring an ionic current (L) in the said electrically conducting liquid; and   turning off the transmembrane voltage once the ionic current (I i ) has reached a value (I p ) corresponding to an electrical conductance of a pore within the said TMDC thin layer having the prescribed diameter (d p ).   
     
     
         2 . A method according to  claim 1 , wherein the TMDC is of chemical formula is MX 2 , where M is a transition metal atom and X is a chalcogen. 
     
     
         3 . A method according to  claim 1 , wherein the TMDC is selected from the group consisting of MoS 2 , SnSe 2 , WS 2 , TaS 2 , MoSe 2 , WSe 2 , and TaSe 2 . 
     
     
         4 . A method according to  claim 1 , wherein the TMDC is NbS 2  or NbSe 2 . 
     
     
         5 . A method according  claim 1 , wherein the at least one TMDC thin layer is a single or double layer. 
     
     
         6 . A method according to  claim 1 , wherein the TMDC layer comprises MoS 2  thin layers or is a MoS 2  monolayer. 
     
     
         7 . A method according to  claim 6 , wherein the applied transmembrane voltage is from 800 mV to 1,000 mV. 
     
     
         8 . A method according to  claim 1 , wherein the transmembrane voltage is an essentially constant DC manner. 
     
     
         9 . A method according to  claim 1 , wherein the ionic current is measured in an ionic current circuit comprising a pair of electrodes, one of the pair of electrodes is located in the electrically conducting liquid on one side of the membrane, and the other of the pair of electrodes is located in the electrically conducting liquid on the other side of the membrane. 
     
     
         10 . A method according to  claim 1 , wherein the electrically conducting liquid comprises an aqueous liquid comprising an electrolyte. 
     
     
         11 . A method according to  claim 1 , wherein the TMDC thin layer is a sensing membrane already integrated in a biosensing device. 
     
     
         12 . A method according to  claim 1 , wherein the size of the pore is from 1 nm to 5 nm. 
     
     
         13 . A method according to  claim 1 , wherein the electrically conducting liquid is an aqueous ionic solution comprising KCl, LiCl, NaCl, MgCl 2 , or CaCl 2 ). 
     
     
         14 . A method according to  claim 1 , wherein the turning off the transmembrane voltage comprises switching off the transmembrane voltage. 
     
     
         15 . A method according to  claim 1 , wherein the turning off of the transmembrane voltage is achieved by an automatic switch which is activated through a feed-back control circuit when said electrical conductance current is reached. 
     
     
         16 . A method according to  claim 1 , wherein the turning off of the transmembrane voltage comprises decreasing the transmembrane voltage to a value (V d ) which is 50% or less of the voltage at which an electrochemical reaction occurs for a given pore and experimental condition. 
     
     
         17 . A method according to  claim 16 , wherein the transmembrane voltage is decreased to a value (V d ) from 800 mV to 2V. 
     
     
         18 . A method according to  claim 1 , wherein the at least one TMDC thin layer comprises a plurality of TMDC thin layers, and the transmembrane voltage is applied to each of the plurality of TMDC thin layers in parallel. 
     
     
         19 . A method for forming a nanopore with a prescribed diameter (d p ) in an electrochemically etchable 2D material comprising:
 providing at least one thin layer of said electrochemically etchable 2D material having from 0.3 nm to 5 nm thickness (H m ) suspended in an electrically conducting liquid;   applying a transmembrane voltage (V) at a value higher than the oxidation potential of a transition metal of said at least one electrochemically etchable thin layer configured for an electrochemical atomic etching of said thin layer;   measuring an ionic current (I i ) in the said electrically conducting liquid; and   turning off the transmembrane voltage once the ionic current (I i ) has reached a value (I p ) corresponding to an electrical conductance of a pore within the said at least one thin layer having the prescribed diameter (d p ).   
     
     
         20 . A method according to  claim 19 , wherein the electrochemically etchable 2D material is a membrane of hBn silicene, transition metal trichalcogenides, metal halides, or transition metal oxides.