WO2022119471A1 - Field effect nanosized electrical potential sensor - Google Patents

Field effect nanosized electrical potential sensor Download PDF

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Publication number
WO2022119471A1
WO2022119471A1 PCT/RU2020/000663 RU2020000663W WO2022119471A1 WO 2022119471 A1 WO2022119471 A1 WO 2022119471A1 RU 2020000663 W RU2020000663 W RU 2020000663W WO 2022119471 A1 WO2022119471 A1 WO 2022119471A1
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WIPO (PCT)
Prior art keywords
nanopipette
sensor
electrical potential
measuring electrodes
layer
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Application number
PCT/RU2020/000663
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French (fr)
Other versions
WO2022119471A9 (en
Inventor
Ilya Viktorovich KUBASOV
Aleksandr Mikhajlovich KISLYUK
Aleksandr Anatol'evich TEMIROV
Andrei Vladimirovich TURUTIN
Mikhail Davy'dovich MALINKOVICH
Yuriy Nikolaevich PARKHOMENKO
Sergej Vladimirovich SALIKHOV
Yuri Evgen'evich KORCHEV
Alexandr Sergeevich EROFEEV
Petr Vladimirovich GORELKIN
Aleksandra Olegovna PRELOVSKAIA
Alexandr Nikolaevich VANEEV
Vasilii Sergeevich KOLMOGOROV
Roman Viktorovich TIMOSHENKO
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National University Of Science And Technology "Misis"
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Application filed by National University Of Science And Technology "Misis" filed Critical National University Of Science And Technology "Misis"
Priority to PCT/RU2020/000663 priority Critical patent/WO2022119471A1/en
Publication of WO2022119471A1 publication Critical patent/WO2022119471A1/en
Publication of WO2022119471A9 publication Critical patent/WO2022119471A9/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/414—Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS
    • G01N27/4146—Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS involving nanosized elements, e.g. nanotubes, nanowires
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/414—Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS
    • G01N27/4145—Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS specially adapted for biomolecules, e.g. gate electrode with immobilised receptors

Definitions

  • This invention relates to semiconductor devices, more specifically, to semiconductor electrical potential sensors which provide for high spatial resolution measurements on surfaces of solids and liquids, as well as in the bulk of liquids, including liquids contained inside living bodies and other biological structures.
  • the tips of the capillaries are coated with a polymer mixture of poly(3,4-ethylene dioxythiophene) / poly(styrene suilfate) (PEDOT7PSS) as the semiconducting material.
  • PEDOT7PSS poly(styrene suilfate)
  • Drawbacks of this technical solution include the necessity of using two probing capillaries and the impossibility of measuring the electrical potential with a high spatial resolution.
  • the prototype of this invention is a polypyrrole based nanosized field effect transistor for the detection of biological molecules [R. Ren, Y. Zhang, B. P. Nadappuram, B. Akpinar, D. Klenerman, A. P. Ivanov, J. B. Edel, Y. Korchev. Nanopore extended field-effect transistor for selective single-molecule biosensing Nature Communications, 2017, vol. 8, p. 586], which is in the form of a needle-shaped quartz capillary with a tip diameter of approx. 400 nm and two insulated empty barrels. One of said barrels is filled with pyrolytic carbon and acts as the contact for the field effect transistor gate.
  • the capillary tip is coated with a thin polypyrrole layer such that the pyrolytic carbon filled barrel is completely closed while the other barrel has an output to the environment and acts as the transistor drain and source.
  • a thin polypyrrole layer such that the pyrolytic carbon filled barrel is completely closed while the other barrel has an output to the environment and acts as the transistor drain and source.
  • Drawbacks of said prototype include the low measurement accuracy, non-reproducible measurement results as well as rapid degradation in the solution because polypyrrole acting as the sensing material is deposited using an electrochemical method and is not protected from the environment. Disclosure of the Invention.
  • the technical object of the invention disclosed herein is to provide for measurement and mapping of local electrical potentials on surfaces of solids and liquids, as well as in the bulk of liquids, including liquids contained inside living bodies and other biological structures, with a high spatial resolution and sensitivity.
  • the technical result of the invention disclosed herein is an increase in the stability of parameters, chemical neutrality and sensitivity of the sensor due to the formation of a field effect transistor structure for electrical potential measurement.
  • the field effect nanosized electrical potential sensor is in the form of a quartz or glass needle-shaped nanopipette comprising two longitudinal barrels which is narrowed at one of its tips to a diameter of 20 to 500 nm.
  • the narrow tip of the nanopipette is in the form of a flat pad orthogonal to the nanopipette axis and has a sensing element in the form of sequentially deposited semiconducting material layer and protective dielectric layer which is chemically neutral to the test environment.
  • Two measuring electrodes are connected to said semiconductor layer, said measuring electrodes being in the form of carbon layers deposited onto the inner walls of the longitudinal barrels inside the nanopipette, galvanically insulated from each other with a dielectric wall and connected to an external electrical resistivity meter.
  • said semiconductor material layer is in the form of a 10 to 100 nm thick silicon film and said dielectric layer is a continuous silicon oxide film 5 to 30 nm in thickness.
  • said semiconductor material layer is in the form of a 10 to 100 nm thick germanium film and said dielectric layer is a continuous amorphous silicon-carbon film 5 to 30 nm in thickness.
  • the length of said needle-shaped nanopipette is at least 10 mm.
  • Fig. 1 is a general schematic of the narrow sensing tip of the nanosized electrical potential sensor and Fig. 2 is a section schematic view of the sensing part of the nanosized electrical potential sensor in the narrow tip.
  • the device comprises a sensing element 1 provided on the flat narrow tip of the needle-shaped nanopipette 2 and comprising a protective dielectric layer 3 and a semiconducting material layer 4 that interconnects galvanically insulated electrodes 5 and 6 deposited onto the inner surfaces of the barrels 7 and 8 of the sensor. Between the electrodes 5 and 6 there is a thin dielectric wall 9 which insulates the electrodes from each other. The electrodes 5 and 6 are connected to an external electrical resistivity meter 10.
  • the field effect nanosized electrical potential sensor is in the form of a quartz or glass needle-shaped nanopipette which is narrowed at one of its tips to a diameter of 20 to 500 nm.
  • the choice of tip sizes within this range depends on the desired spatial resolution of the sensor and the quality of the process equipment to be used. Experiments have shown that sensors with a narrow tip diameter of less than 20 nm fail to provide reproducible sensor performance, while for a narrow tip diameter of greater than 500 nm the spatial resolution of solid and liquid surface mapping degrades significantly.
  • the sensor comprises two measuring electrodes 5 and 6 that are located in the barrels of the needle-shaped nanopipette 2 and are galvanically insulated from each other by the dielectric wall 9 and from the test environment by the walls of the nanopipette 2.
  • the measuring electrodes 5 and 6 are at the minimal distance from each other at the narrow sensing tip of the nanosized electrical potential sensor where they are connected to the sensing element 1.
  • the narrow sensing tip of the nanosized electrical potential sensor is pre- processed so its surface that is orthogonal to the axis of the needle-shaped nanopipette 2 is in the form of a flat pad.
  • the sensing element 1 is in the form of the semiconducting material layer 4 made from, e.g. silicon, deposited onto the flat pad and coated with the protective dielectric layer 3.
  • the external electrical resistivity meter 10 is connected to the measuring electrodes 5 and 6 at the other tip of the nanosized electrical potential sensor which is not sensing and has a diameter equal to that of the source quartz or glass nanopipette (typically 1 to 5 mm).
  • the semiconductor layer 4 jointly with the protective dielectric layer 3 form a transistor structure where the electrodes 5 and 6 act as the drain and the source and the environment is the gate.
  • the sensing element 1 of the sensor is brought closer to an object having a finite surface or bulk local electrical potential the electrical conductivity of the semiconductor layer changes due to the field effect, i.e., change in the electrophysical properties of materials due to exposure to an external electric field component that is normal to the surface.
  • a charge is brought closer to the sensing element 1 of the sensor a local inhomogeneity of carrier concentration is produced in the semiconductor layer 4, resulting in a change in its electrical conductivity.
  • a change in the electrical conductivity of the semiconductor layer 4 can be detected with the external meter 10, e.g. by a change in the current passing between the measuring electrodes 5 and 6 at a constant difference of potentials between them, or by a change in said difference of potentials at a constant current passing between the measuring electrodes 5 and 6.
  • the semiconductor layer 4 is coated with the thin protective dielectric layer 3 that is chemically neutral to the test environment.
  • the material of the protective layer 3 can be e.g. silicon oxide if the semiconductor layer 4 is silicon, or silicon-carbon diamond-like amorphous film for this or other compositions of the semiconductor layer 4.
  • the field effect nanosized electrical potential sensor operates as follows. As the sensor is brought closer to an object having an electrical charge the electrical conductivity of the semiconductor layer 4 connecting the electrodes 5 and 6 changes due to the field effect. A change in the electrical conductivity of the semiconductor layer can be detected by a change in the current passing between the measuring electrodes at a constant difference of potentials between them, or by a change in said difference of potentials at a constant current passing between the measuring electrodes as indicated by the external electrical resistivity meter 10.
  • the protective dielectric film 3 protects the structure from degradation, provides for its electrical insulation from the environment and acts as a separating dielectric layer for the field effect.
  • the conductivity of the portion of the semiconductor layer 4 between the measuring electrodes 5 and 6 is controlled by the electrical potential of the narrow sensing tip of the sensor. This provides for high accuracy and high spatial resolution measurements and mapping of the electrical potential.
  • the field effect nanosized electrical potential sensor disclosed herein can be produced as follows.
  • the blank piece is a thin quartz or glass nanopipette at least 20 mm in length comprising two longitudinal barrels.
  • the maximum length of the blank piece is chosen taking into account its suitability for mounting into the test device. Practice has shown that the reproducibility of the sensors decreases if blank nanopipettes less than 20 mm in length are used.
  • the blank nanopipette is locally heated to the melting point in its middle, longitudinally stretched until fracture and cooled.
  • Each of the half nanopipettes so produced are in the form of a needle-shaped nanopipette at least 10 mm in length and comprise two through barrels 7 and 8 the diameters of which decrease to decades of nanometers in the fracture area, the nanopipette diameter in the fracture area being within decades of nanometers.
  • the barrels 7 and 8 are insulated from each other with the wall 9.
  • the barrels 7 and 8 are filled with propane gas and heated to the pyrolytic decomposition point of the gas followed by carbon deposition on the inner walls of the barrels, the carbon layers so produced further acting as the measuring electrodes 5 and 6.
  • the narrow sensing tip of the quartz or glass nanopipette 2 is processed, e.g. with a focused gallium ion beam, to form a flat pad 20 to 500 nm in diameter.
  • said pad is sequentially coated with the semiconductor layer 4, e.g. germanium, to act as the channel with a variable electrical conductivity due to the field effect, and the protective dielectric layer 3, e.g. a silicon-carbon amorphous film.
  • the layers 3 and 4 can be deposited using one of the thin film synthesis methods used in microelectronics, e.g. by magnetron sputtering or chemical vapor deposition.
  • the thickness of said semiconductor layer should be not less than 10 nm in order to reduce the undesired quantum size effects but not greater than 100 nm so to avoid spatial resolution degradation.
  • Said protective dielectric layer should be sufficiently thin for the electric field to be localized in the semiconductor layer and for the field effect to be the strongest, and said dielectric should be chemically neutral to the test object.
  • said protective dielectric layer is silicon oxide or silicon-carbon amorphous film, the best protection performance without any significant compromise in the field effect is achieved for a protective dielectric layer thickness of 5 to 30 nm.
  • the so produced sensing element 1 of said sensor is located on the tip of said glass or quartz nanopipette 2 with a length of at least 10 mm and a narrow sensing tip diameter of 20 to 500 nm.
  • the nanosized electrical potential sensor disclosed herein provides for a change in the current between said measuring electrodes from 190 nA to 60 nA for a voltage of 0.8 V between said electrodes, and for a change in the electrical potential near the narrow sensing tip from 0 to 500 mV, which corresponds to a change in the electrical resistivity from 4.2 MOhm to 13.3 MOhm.
  • This provides the possibility of measurements and mapping of local electrical potentials on surfaces of solids and liquids, as well as in the bulk of liquids, including liquids contained inside living bodies and other biological structures, with a high spatial resolution and a sensitivity of not worse than 10 mV.

Abstract

This invention relates to semiconductor electrical potential sensors. The sensor is in the form of a quartz or glass needle-shaped nanopipette comprising two longitudinal barrels which is narrowed at one of its tips to a diameter of 20 to 500 nm. The narrow tip of the nanopipette is in the form of a flat pad orthogonal to the nanopipette axis and has a sensing element in the form of sequentially deposited semiconducting material layer and protective dielectric layer which is chemically neutral to the test environment. Two measuring electrodes are connected to said semiconductor layer, said measuring electrodes being in the form of carbon layers deposited onto the inner walls of the longitudinal barrels inside the nanopipette, galvanically insulated from each other with a dielectric wall and connected to an external electrical resistivity meter. The technical result is an increase in the stability of parameters, chemical neutrality and sensitivity of the sensor.

Description

Field Effect Nanosized Electrical Potential Sensor
Field of Invention. This invention relates to semiconductor devices, more specifically, to semiconductor electrical potential sensors which provide for high spatial resolution measurements on surfaces of solids and liquids, as well as in the bulk of liquids, including liquids contained inside living bodies and other biological structures.
Prior Art. One of the most important development trends in sensor engineering is increasing the spatial resolution of sensors. The possibility of local studies into various physical properties of objects and mapping the distributions of their properties delivers information on processes taking place at microscopic and nanoscale levels and allows controlling these processes. The electrophysical properties of liquids including biological ones as well as living bodies and their cells are largely controlled by local electrical potential. Local measurements of electrical potential are available with the aid of microscopic and nanosized semiconductor sensors wherein the resistivity of the conducting channel connecting the two measuring electrodes may vary due to external electrical potentials through the field effect.
Known is an electrochemical transistor for spatial mapping of dopamine molecules [F. Mariani, T. Quast, C. Andronescu, I. Gualandi, B. Fraboni, D. Tonelli, E. Scavetta, W. Schuhmann. Needle-type organic electrochemical transistor for spatially resolved detection of dopamine, Microchimica Acta, 2020, vol. 187, p. 378], which is in the form of two needle-shaped quartz capillaries with a tip diameter of approx. 400 nm wherein one of said capillaries comprises one barrel filled with pyrolytic carbon and acting as the transistor gate and the other one of said capillaries comprises two insulated barrels also filled with pyrolytic carbon and acting as the transistor drain and source. The tips of the capillaries are coated with a polymer mixture of poly(3,4-ethylene dioxythiophene) / poly(styrene suilfate) (PEDOT7PSS) as the semiconducting material. A change in the electrical potential of the gate relative to that of the source changes the size of the region with preferential oxidation of dopamine molecules (at the gate or in the drain/source region), and this can be used for local dopamine concentration measurements in the solution over a wide range of concentrations.
Drawbacks of this technical solution include the necessity of using two probing capillaries and the impossibility of measuring the electrical potential with a high spatial resolution.
The prototype of this invention is a polypyrrole based nanosized field effect transistor for the detection of biological molecules [R. Ren, Y. Zhang, B. P. Nadappuram, B. Akpinar, D. Klenerman, A. P. Ivanov, J. B. Edel, Y. Korchev. Nanopore extended field-effect transistor for selective single-molecule biosensing Nature Communications, 2017, vol. 8, p. 586], which is in the form of a needle-shaped quartz capillary with a tip diameter of approx. 400 nm and two insulated empty barrels. One of said barrels is filled with pyrolytic carbon and acts as the contact for the field effect transistor gate. The capillary tip is coated with a thin polypyrrole layer such that the pyrolytic carbon filled barrel is completely closed while the other barrel has an output to the environment and acts as the transistor drain and source. By controlling the gate voltage one can control the molecular transport properties of the open barrel, and the number of molecules passing via the drain-source channel can be controlled accurate to single molecules.
Drawbacks of said prototype include the low measurement accuracy, non-reproducible measurement results as well as rapid degradation in the solution because polypyrrole acting as the sensing material is deposited using an electrochemical method and is not protected from the environment. Disclosure of the Invention. The technical object of the invention disclosed herein is to provide for measurement and mapping of local electrical potentials on surfaces of solids and liquids, as well as in the bulk of liquids, including liquids contained inside living bodies and other biological structures, with a high spatial resolution and sensitivity.
The technical result of the invention disclosed herein is an increase in the stability of parameters, chemical neutrality and sensitivity of the sensor due to the formation of a field effect transistor structure for electrical potential measurement.
The technical result of the invention disclosed herein is achieved as follows.
The field effect nanosized electrical potential sensor is in the form of a quartz or glass needle-shaped nanopipette comprising two longitudinal barrels which is narrowed at one of its tips to a diameter of 20 to 500 nm. The narrow tip of the nanopipette is in the form of a flat pad orthogonal to the nanopipette axis and has a sensing element in the form of sequentially deposited semiconducting material layer and protective dielectric layer which is chemically neutral to the test environment. Two measuring electrodes are connected to said semiconductor layer, said measuring electrodes being in the form of carbon layers deposited onto the inner walls of the longitudinal barrels inside the nanopipette, galvanically insulated from each other with a dielectric wall and connected to an external electrical resistivity meter.
Furthermore said semiconductor material layer is in the form of a 10 to 100 nm thick silicon film and said dielectric layer is a continuous silicon oxide film 5 to 30 nm in thickness.
Moreover said semiconductor material layer is in the form of a 10 to 100 nm thick germanium film and said dielectric layer is a continuous amorphous silicon-carbon film 5 to 30 nm in thickness. The length of said needle-shaped nanopipette is at least 10 mm.
Brief Description of the Drawings. The invention will be illustrated hereinbelow with drawings wherein Fig. 1 is a general schematic of the narrow sensing tip of the nanosized electrical potential sensor and Fig. 2 is a section schematic view of the sensing part of the nanosized electrical potential sensor in the narrow tip.
The device comprises a sensing element 1 provided on the flat narrow tip of the needle-shaped nanopipette 2 and comprising a protective dielectric layer 3 and a semiconducting material layer 4 that interconnects galvanically insulated electrodes 5 and 6 deposited onto the inner surfaces of the barrels 7 and 8 of the sensor. Between the electrodes 5 and 6 there is a thin dielectric wall 9 which insulates the electrodes from each other. The electrodes 5 and 6 are connected to an external electrical resistivity meter 10.
Embodiments of the Invention. The field effect nanosized electrical potential sensor is in the form of a quartz or glass needle-shaped nanopipette which is narrowed at one of its tips to a diameter of 20 to 500 nm. The choice of tip sizes within this range depends on the desired spatial resolution of the sensor and the quality of the process equipment to be used. Experiments have shown that sensors with a narrow tip diameter of less than 20 nm fail to provide reproducible sensor performance, while for a narrow tip diameter of greater than 500 nm the spatial resolution of solid and liquid surface mapping degrades significantly.
The sensor comprises two measuring electrodes 5 and 6 that are located in the barrels of the needle-shaped nanopipette 2 and are galvanically insulated from each other by the dielectric wall 9 and from the test environment by the walls of the nanopipette 2. The measuring electrodes 5 and 6 are at the minimal distance from each other at the narrow sensing tip of the nanosized electrical potential sensor where they are connected to the sensing element 1. The narrow sensing tip of the nanosized electrical potential sensor is pre- processed so its surface that is orthogonal to the axis of the needle-shaped nanopipette 2 is in the form of a flat pad.
The sensing element 1 is in the form of the semiconducting material layer 4 made from, e.g. silicon, deposited onto the flat pad and coated with the protective dielectric layer 3.
The external electrical resistivity meter 10 is connected to the measuring electrodes 5 and 6 at the other tip of the nanosized electrical potential sensor which is not sensing and has a diameter equal to that of the source quartz or glass nanopipette (typically 1 to 5 mm).
The semiconductor layer 4 jointly with the protective dielectric layer 3 form a transistor structure where the electrodes 5 and 6 act as the drain and the source and the environment is the gate. As the sensing element 1 of the sensor is brought closer to an object having a finite surface or bulk local electrical potential the electrical conductivity of the semiconductor layer changes due to the field effect, i.e., change in the electrophysical properties of materials due to exposure to an external electric field component that is normal to the surface. As a charge is brought closer to the sensing element 1 of the sensor a local inhomogeneity of carrier concentration is produced in the semiconductor layer 4, resulting in a change in its electrical conductivity.
A change in the electrical conductivity of the semiconductor layer 4 can be detected with the external meter 10, e.g. by a change in the current passing between the measuring electrodes 5 and 6 at a constant difference of potentials between them, or by a change in said difference of potentials at a constant current passing between the measuring electrodes 5 and 6.
For protecting said sensitive element 1 and providing the field effect, the semiconductor layer 4 is coated with the thin protective dielectric layer 3 that is chemically neutral to the test environment. The material of the protective layer 3 can be e.g. silicon oxide if the semiconductor layer 4 is silicon, or silicon-carbon diamond-like amorphous film for this or other compositions of the semiconductor layer 4.
The field effect nanosized electrical potential sensor operates as follows. As the sensor is brought closer to an object having an electrical charge the electrical conductivity of the semiconductor layer 4 connecting the electrodes 5 and 6 changes due to the field effect. A change in the electrical conductivity of the semiconductor layer can be detected by a change in the current passing between the measuring electrodes at a constant difference of potentials between them, or by a change in said difference of potentials at a constant current passing between the measuring electrodes as indicated by the external electrical resistivity meter 10.
The protective dielectric film 3 protects the structure from degradation, provides for its electrical insulation from the environment and acts as a separating dielectric layer for the field effect.
When the sensor is brought into the test environment the conductivity of the portion of the semiconductor layer 4 between the measuring electrodes 5 and 6 is controlled by the electrical potential of the narrow sensing tip of the sensor. This provides for high accuracy and high spatial resolution measurements and mapping of the electrical potential.
The field effect nanosized electrical potential sensor disclosed herein can be produced as follows. The blank piece is a thin quartz or glass nanopipette at least 20 mm in length comprising two longitudinal barrels. The maximum length of the blank piece is chosen taking into account its suitability for mounting into the test device. Practice has shown that the reproducibility of the sensors decreases if blank nanopipettes less than 20 mm in length are used.
The blank nanopipette is locally heated to the melting point in its middle, longitudinally stretched until fracture and cooled. Each of the half nanopipettes so produced are in the form of a needle-shaped nanopipette at least 10 mm in length and comprise two through barrels 7 and 8 the diameters of which decrease to decades of nanometers in the fracture area, the nanopipette diameter in the fracture area being within decades of nanometers. The barrels 7 and 8 are insulated from each other with the wall 9.
Then the barrels 7 and 8 are filled with propane gas and heated to the pyrolytic decomposition point of the gas followed by carbon deposition on the inner walls of the barrels, the carbon layers so produced further acting as the measuring electrodes 5 and 6.
Then the narrow sensing tip of the quartz or glass nanopipette 2 is processed, e.g. with a focused gallium ion beam, to form a flat pad 20 to 500 nm in diameter.
Then said pad is sequentially coated with the semiconductor layer 4, e.g. germanium, to act as the channel with a variable electrical conductivity due to the field effect, and the protective dielectric layer 3, e.g. a silicon-carbon amorphous film. The layers 3 and 4 can be deposited using one of the thin film synthesis methods used in microelectronics, e.g. by magnetron sputtering or chemical vapor deposition.
The thickness of said semiconductor layer should be not less than 10 nm in order to reduce the undesired quantum size effects but not greater than 100 nm so to avoid spatial resolution degradation. Said protective dielectric layer should be sufficiently thin for the electric field to be localized in the semiconductor layer and for the field effect to be the strongest, and said dielectric should be chemically neutral to the test object. Experiments have shown that if said protective dielectric layer is silicon oxide or silicon-carbon amorphous film, the best protection performance without any significant compromise in the field effect is achieved for a protective dielectric layer thickness of 5 to 30 nm. The so produced sensing element 1 of said sensor is located on the tip of said glass or quartz nanopipette 2 with a length of at least 10 mm and a narrow sensing tip diameter of 20 to 500 nm.
Experiments have shown that the nanosized electrical potential sensor disclosed herein provides for a change in the current between said measuring electrodes from 190 nA to 60 nA for a voltage of 0.8 V between said electrodes, and for a change in the electrical potential near the narrow sensing tip from 0 to 500 mV, which corresponds to a change in the electrical resistivity from 4.2 MOhm to 13.3 MOhm. This provides the possibility of measurements and mapping of local electrical potentials on surfaces of solids and liquids, as well as in the bulk of liquids, including liquids contained inside living bodies and other biological structures, with a high spatial resolution and a sensitivity of not worse than 10 mV.

Claims

9 What is claimed is a
1. Field effect nanosized electrical potential sensor is in the form of a quartz or glass needle-shaped nanopipette comprising two longitudinal barrels which is narrowed at one of its tips to a diameter of 20 to 500 nm, wherein the narrow tip of the nanopipette is in the form of a flat pad orthogonal to the nanopipette axis and has a sensing element in the form of sequentially deposited semiconducting material layer and protective dielectric layer which is chemically neutral to the test environment, further wherein two measuring electrodes are connected to said semiconductor layer, said measuring electrodes being in the form of carbon layers deposited onto the inner walls of the longitudinal barrels inside the nanopipette, galvanically insulated from each other with a dielectric wall and connected to an external electrical resistivity meter.
2. Sensor of Claim 1 wherein said semiconductor material layer is in the form of a 10 to 100 nm thick silicon film and said dielectric layer is a continuous silicon oxide film 5 to 30 nm in thickness.
3. Sensor of Claim 1 wherein said semiconductor material layer is in the form of a 10 to 100 nm thick germanium film and said dielectric layer is a continuous amorphous silicon-carbon film 5 to 30 nm in thickness.
4. Sensor of Claim 1 wherein the length of said needle-shaped nanopipette is at least 10 mm.
PCT/RU2020/000663 2020-12-04 2020-12-04 Field effect nanosized electrical potential sensor WO2022119471A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006024023A2 (en) * 2004-08-24 2006-03-02 Nanomix, Inc. Nanotube sensor devices for dna detection
RU2349542C1 (en) * 2007-06-22 2009-03-20 Станислав Викторович Хартов Nanoelectromechanical structure (versions) and method of its production (versions)
KR20120071463A (en) * 2010-12-23 2012-07-03 한남대학교 산학협력단 Electrochemical dna sensor for diagnosis of infectious respiratory disease and method for preparing the same

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006024023A2 (en) * 2004-08-24 2006-03-02 Nanomix, Inc. Nanotube sensor devices for dna detection
RU2349542C1 (en) * 2007-06-22 2009-03-20 Станислав Викторович Хартов Nanoelectromechanical structure (versions) and method of its production (versions)
KR20120071463A (en) * 2010-12-23 2012-07-03 한남대학교 산학협력단 Electrochemical dna sensor for diagnosis of infectious respiratory disease and method for preparing the same

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