CN117699737A - Large-stroke nanoscale distance adjusting method and system for constructing single-molecule junction - Google Patents
Large-stroke nanoscale distance adjusting method and system for constructing single-molecule junction Download PDFInfo
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Abstract
The invention relates to a large-stroke nanoscale distance adjusting method and a large-stroke nanoscale distance adjusting system for constructing a single-molecule junction, wherein the telescopic end of a stepping motor is connected with a probe through piezoelectric ceramics, and the stepping motor and the piezoelectric ceramics cooperatively drive the probe to be close to or far from a substrate; the nanoscale distance adjusting method comprises the following steps: s1, applying and maintaining a maximum stroke voltage to the piezoelectric ceramic to enable the piezoelectric ceramic to maintain a maximum stroke; s2, driving the piezoelectric ceramic and the probe to rapidly approach the substrate through the stepping motor; s3, when the probe is in contact with the substrate, the voltage applied to the piezoelectric ceramic is gradually reduced to 0V from the maximum stroke voltage, and if the probe and the substrate cannot be disconnected, the stepping motor is controlled to drive the piezoelectric ceramic and the probe to be far away from the substrate and then return to S2; and S4, applying voltage to the piezoelectric ceramic to enable the probe and the substrate to be contacted and disconnected for a plurality of times, so as to construct a single-molecule junction.
Description
Technical Field
The invention relates to the field of nanoscale distance adjustment, in particular to a large-stroke nanoscale distance adjustment method and system for constructing a single-molecule junction.
Background
With the development of single-molecule electrical measurement technology, researchers can realize the rapid characterization of single-molecule electrical transport behavior directly at normal temperature and normal pressure. Single molecule electrical measurement techniques are capable of revealing, at the single molecule level, the rich information underlying between molecular structure and function. By utilizing the technical advantage of single molecule manipulation, the single molecule electrical measurement technology provides a potential application platform for single molecule sensing and recognition, single molecule electrochemical behavior, single molecule scale chemical reaction, single molecule scale material thermoelectric potential research and other front direction and fields. Currently, the main methods of measuring single-molecule junction thermoelectric potential are the common mechanically controllable cleavage technology (Mechanically Controllable Break Junction, MCBJ) method or scanning tunneling cleavage technology (Scanning Tunneling Microscope Break junction, STM-BJ) and the like.
The single molecular size is normally between 0.1nm and 10nm, and the nano-scale displacement can be controlled by piezoelectric ceramics. Because the displacement distance of the piezoelectric ceramics is limited, as shown in fig. 1 in the prior art, probes are connected to the bottom ends of the piezoelectric ceramic groups by superposing a plurality of piezoelectric ceramics, and the probes and the substrate are contacted and disconnected by applying voltage to the piezoelectric ceramic groups. However, compared with a single piezoelectric ceramic, the step distance of the stacked piezoelectric ceramic group is multiplied, the precision is reduced, the cost is increased, and meanwhile, the distance between the probe and the substrate is very close when the piezoelectric ceramic group is not loaded with voltage, so that the sample to be measured is difficult to place or replace on the substrate.
The invention aims at solving the problems existing in the prior art and designing a large-stroke nanoscale distance adjusting method and system for constructing a single-molecule junction.
Disclosure of Invention
The invention aims to solve at least one problem existing in the prior art by providing a large-stroke nanoscale distance adjusting method and system for constructing a single-molecule junction.
The technical scheme of the invention is as follows:
a large-travel nanoscale distance-adjusting method for constructing a single-molecule junction, which is characterized by comprising the following steps of: the nanoscale distance adjusting method is based on a single-molecule measuring instrument, the single-molecule measuring instrument comprises a substrate, a stepping motor and a probe, the probe and the substrate are respectively used as test electrodes of the single-molecule measuring instrument, the substrate is fixedly arranged, the telescopic end of the stepping motor is connected with the probe through piezoelectric ceramics, and the stepping motor and the piezoelectric ceramics cooperatively drive the probe to be close to or far away from the substrate;
the nanoscale distance adjusting method comprises the following steps:
s1, applying and maintaining a maximum stroke voltage to the piezoelectric ceramic to enable the piezoelectric ceramic to maintain a maximum stroke;
s2, driving the piezoelectric ceramic and the probe to rapidly approach the substrate through the stepping motor;
s3, when the probe is in contact with the substrate, controlling the stepping motor to stop running, gradually reducing the voltage applied to the piezoelectric ceramic from the maximum travel voltage to 0V, entering S4 if the probe and the substrate can be disconnected, and controlling the stepping motor to drive the piezoelectric ceramic and the probe to return to S2 after the probe and the substrate can not be disconnected;
s4, applying voltage to the piezoelectric ceramic to enable the probe and the substrate to be contacted and disconnected for a plurality of times, wherein the method comprises the following steps of:
s41, applying a voltage which is reduced from the maximum travel voltage to the piezoelectric ceramic at an initial voltage change speed for a plurality of times, so that the probe and the substrate are contacted and disconnected for a plurality of times;
the initial voltage change speed is related to the length of a molecule to be detected, and the length of the molecule to be detected is more than 2nm or less than 0.5nm, so that the initial voltage change speed is reduced;
s42, after each contact and disconnection between the probe and the substrate, performing: cycling several times: applying voltage to the piezoelectric ceramic to enable the probe to be in contact with the substrate, reducing the applied voltage to the piezoelectric ceramic, and applying one or more combined voltages of sine waves, square waves, triangular waves and irregular waves to the piezoelectric ceramic after the probe and the substrate are disconnected, so that the probe shakes and drops a sample to be detected remained on the surface of the probe;
s43, detecting whether a single molecule is captured between the probe and the substrate, if so, constructing to obtain a single molecule junction, and measuring a molecular signal; if not, the voltage change speed is reduced and the process returns to S41;
s5, measuring the molecular electrical signals.
Further, in step S2, bias voltages are applied to the probe and the substrate during the process of the probe approaching the substrate, and the current change between the probe and the substrate is monitored;
in step S3, when a current occurs between the probe and the substrate, it is determined that the probe is in contact with the substrate, and when the current between the probe and the substrate is lost, it is determined that the probe is disconnected from the substrate.
Further, it is detected whether a single molecule is captured between the probe and the substrate by:
and in the process of repeatedly contacting and disconnecting the probe and the substrate, measuring the conductance between the probe and the substrate to generate a conductance change curve, and analyzing the image of the conductance change curve, wherein if the conductance change curve is stepped after suddenly falling for a short time, the single molecule is captured between the probe and the substrate.
Further, the initial voltage change rate is positively correlated with the affinity of the test molecule to the probe.
Further, step S2 includes:
the piezoelectric ceramic and the probe are driven by the stepping motor to approach the substrate at a first speed and then approach the substrate at a second speed, and the first speed is greater than the second speed.
Further, before the molecular signal measurement is performed, performing:
the applied voltage of the current piezoelectric ceramic is maintained.
The large-stroke nanoscale distance adjusting system for constructing the single-molecule junction comprises a substrate, a stepping motor, a probe and a control system, wherein the probe and the substrate are respectively used as test electrodes for single-molecule measurement, the substrate is fixedly arranged, the telescopic end of the stepping motor is connected with the probe through piezoelectric ceramics, and the stepping motor and the piezoelectric ceramics cooperatively drive the probe to be close to or far away from the substrate;
the control system executes the large-travel nanoscale distance adjusting method for constructing the single-molecule junction during operation.
Accordingly, the present invention provides the following effects and/or advantages:
according to the method, the piezoelectric ceramic is arranged between the stepping motor and the probe, the probe is driven to contact with the substrate through the stepping motor in a full stroke state of the piezoelectric ceramic, so that the working mode that whether the probe can contact with the substrate or not is explored through the piezoelectric ceramic after the stepping motor drives the piezoelectric ceramic to construct a millimeter-micron-sized gap firstly in the prior art is changed, the probe is directly disconnected with the substrate through the shrinkage of the piezoelectric ceramic after the driving probe contacts with the substrate, the probe is ensured to contact with the substrate, whether the probe and the substrate can be disconnected through the piezoelectric ceramic or not is explored, and the speed of constructing a molecular node is improved.
According to the method, the voltage waveform enabling the probe to shake is increased after the probe breaks off the substrate, the residual sample on the surface of the probe is thrown away through the probe shake, the probe is kept in a clean state to be contacted with the sample to be tested and the substrate again, the sample to be tested is prevented from being adhered on the surface of the probe and being difficult to separate, and the efficiency of constructing molecular nodes is improved.
According to the method, different initial voltage change rates are adopted according to the physicochemical properties of the sample to be tested, so that the method is suitable for different samples to be tested, the fastest initial change rate which can be used for constructing and obtaining a single molecular junction is selected, and the efficiency of constructing the molecular junction can be improved.
It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
Drawings
Fig. 1 is a schematic diagram of a prior art structure.
Fig. 2 is a flow chart of an embodiment of the present invention.
Fig. 3 is a schematic structural diagram of an embodiment of the present invention.
Fig. 4 is a schematic diagram of a conductance variation.
Reference numerals illustrate:
a substrate 1, a stepping motor 2, a probe 3 and piezoelectric ceramics 4.
Detailed Description
For the convenience of understanding by those skilled in the art, the structure of the present invention will now be described in further detail with reference to the accompanying drawings:
a large-stroke nanoscale distance adjusting method for constructing a single-molecule junction, the nanoscale distance adjusting method is based on a single-molecule measuring instrument, referring to fig. 3, the single-molecule measuring instrument comprises a substrate 1, a stepping motor 2 and a probe 3, the probe 3 and the substrate 1 are respectively used as test electrodes of the single-molecule measuring instrument, the substrate 1 is fixedly arranged, the telescopic end of the stepping motor 2 is connected with the probe 3 through piezoelectric ceramics 4, and the stepping motor 2 and the piezoelectric ceramics 4 cooperatively drive the probe 3 to be close to or far from the substrate 1;
in the present embodiment, the number of piezoelectric ceramics 4 is 1.
In this embodiment, the working principle of the single molecule measuring instrument is the prior art, such as the scanning tunneling microscope technology. The working principle is that the probe 3 is driven to contact and disconnect the substrate 1, so that single molecules are captured between the probe 3 and the substrate 1, and a single molecule junction consisting of probe molecules, single molecules to be detected and substrate molecules is constructed. After single molecules are captured between the probe 3 and the substrate 1 by taking the probe 3 and the substrate 1 as a test motor, a voltage is applied between the probe 3 and the substrate 1 to obtain a tunnel current corresponding to a single molecule junction, so that the electrical information of the single molecules is observed and measured.
In the prior art, it is generally necessary to first keep the distance between the probe and the sample to be about several millimeters or several hundred micrometers by placing the piezoelectric ceramic 4 in a state where no voltage is applied, then driving the piezoelectric ceramic 4 and the probe 3 together to approach the substrate 1 by the stepping motor 2, and then searching whether the probe 3 can be brought into contact with the substrate 1 by the stacked piezoelectric ceramic 4. Each time the piezoelectric ceramic 4 and the probe 3 are driven by the stepper motor 2 to approach the substrate 1 together, the distance between the probe 3 and the substrate 1 is difficult to control at the nanometer level, so that multiple searches are required to enable the probe 3 and the substrate 1 to be contacted under the driving of the stacked piezoelectric ceramic 4.
The nanoscale distance adjusting method comprises the following steps: with reference to figure 2 of the drawings,
s1, applying and maintaining a maximum stroke voltage to the piezoelectric ceramic 4 to enable the piezoelectric ceramic 4 to maintain a maximum stroke;
in this embodiment, a voltage is applied to the piezoelectric ceramic 4 so as to be maintained at the maximum stroke, that is, the maximum deformation of the piezoelectric ceramic 4. For example, if the maximum stroke of the piezoelectric ceramic 4 is 5 μm and the corresponding maximum stroke voltage is 10V, in this step, 10V is applied to and held by the piezoelectric ceramic 4, so that the piezoelectric ceramic 4 is held at 5 μm;
s2, driving the piezoelectric ceramic 4 and the probe 3 to rapidly approach the substrate 1 through the stepping motor 2;
in this step, the piezoelectric ceramic 4 is kept in a state of maximum stroke, the distance between the probe 3 and the substrate 1 is roughly adjusted by driving the stepping motor 2, and the driving speed of the stepping motor 2 is high, so that the probe 3 and the substrate can be quickly moved closer to each other.
S3, when the probe 3 is in contact with the substrate 1, the stepping motor 2 is controlled to stop running, the voltage applied to the piezoelectric ceramic 4 is gradually reduced to 0V from the maximum stroke voltage, if the probe 3 and the substrate 1 can be disconnected, the step S4 is started, and if the probe 3 and the substrate 1 can not be disconnected, the stepping motor 2 is controlled to drive the piezoelectric ceramic 4 and the probe 3 to be far away from the substrate 1 and then the step S2 is started;
in this step, the piezoelectric ceramic 4 is kept in a state of maximum stroke to make the probe 3 contact with the substrate 1, and since the probe 3 is of a metal elongated structure, and the process of making the probe 3 and the substrate 1 by the stepper motor 2 is rough-regulated, there is a slight delay after the probe 3 contacts the substrate 1 to stop the operation of the stepper motor 2, and the slight delay of the stepper motor 2 is difficult to precisely control, the probe 3 is extruded by the substrate 1 and forms a slight bend. Then, the voltage applied to the piezoelectric ceramic 4 gradually decreases to 0V, and after decreasing to 0V, the stroke of the piezoelectric ceramic 4 also becomes 0 μm, and at this time, if the shrinkage of the piezoelectric ceramic 4 can offset the change of the bending portion of the probe 3, so that the probe 3 is completely separated from the substrate 1, the probe 3 can be disconnected from the substrate 1, which indicates that the piezoelectric ceramic 4 cannot complete the contact and disconnection between the substrate 1 and the probe 3 for a plurality of times required for constructing the single-molecule junction in this state, and it is necessary to re-contact the probe 3 with the substrate by moving the stepping motor 2 away from the substrate 1 again. If the contraction of the piezoelectric ceramic 4 can counteract the change in the bending portion of the probe 3, the construction of a single molecular node can begin.
S4, applying voltage to the piezoelectric ceramic 4 to enable the probe 3 and the substrate 1 to be contacted and disconnected for a plurality of times;
s5, measuring the molecular electrical signals.
The principles and manner of constructing single molecular junctions and performing molecular signal measurements may be referenced to the prior art and do not relate to the actual point of improvement of the present application.
Further, in step S2, during the process of approaching the probe 3 to the substrate 1, applying a bias voltage to the probe 3 and the substrate 1, and monitoring the current change between the probe 3 and the substrate 1;
in step S3, when a current occurs between the probe 3 and the substrate 1, it is determined that the probe 3 is in contact with the substrate 1, and when a current between the probe 3 and the substrate 1 disappears, it is determined that the probe 3 is disconnected from the substrate 1.
In this step, the probe 3 and the substrate 1 are made of metal, and a voltage, a measurement current, or the like can be applied as a test electrode of the measuring instrument. In this step, the bias voltage may be a constant voltage of 0.1V. When the probe 3 contacts the substrate 1, there is a current flow between the two, whereas there is no current flow. In this way, the contact/disconnection between the probe 3 and the substrate 1 is determined.
Further, step S4 includes:
s41 of applying a voltage decreasing from the maximum stroke voltage to the piezoelectric ceramic 4 at an initial voltage change rate a plurality of times to contact and disconnect the probe 3 and the substrate 1 a plurality of times;
s42, after each contact and disconnection between the probe and the substrate, performing: cycling several times: and applying voltage to the piezoelectric ceramic 4 to enable the probe 3 to be in contact with the substrate 1, reducing the applied voltage to the piezoelectric ceramic 4, enabling the probe 3 to be disconnected from the substrate 1, and then applying voltage of one or more of sine waves, square waves, triangular waves and irregular waves to the piezoelectric ceramic 4 to enable the probe 3 to shake and drop a sample to be detected remained on the surface of the probe 3.
Because the probe 3 and the sample to be measured are contacted, the sample to be measured may be adhered to the surface of the probe 3, and when the probe 3 contacts the substrate 1 again, the sample to be measured on the surface of the probe 3 is difficult to fall off the probe, thereby reducing the probability of constructing a single molecular junction. In this step, the piezoelectric ceramic 4 is applied with voltage to drive the probe 3 to shake up and down, so that the sample to be tested on the surface of the probe 3 falls off, and the probe 3 keeps a clean state to be contacted with the sample to be tested and the substrate 1 again.
S42, detecting whether a single molecule is captured between the probe 3 and the substrate 1, if so, constructing a single molecule junction, and measuring a molecular signal; if not, the voltage change speed is reduced and the process returns to S41.
The step is performed by first setting an initial voltage change speed, for example, 1V/s, then driving the piezoelectric ceramic 4 at the initial voltage change speed to drive the probe 3 gradually away from the substrate 1, if a single-molecule junction can be constructed, starting molecular signal measurement, if a single-molecule junction cannot be constructed, reducing the voltage change speed, for example, to 0.8V/s, and then re-monitoring whether the single-molecule junction is constructed.
The principle of this is that, according to the characteristics of the shape, structure, etc. of the molecules to be measured, some substances to be measured are not easily attached to the surface of the probe 3 and are pulled upwards by the attractive force of the probe 3, or some molecules of the substances to be measured are long and are not easily captured to a single molecule, at this time, if an excessively fast voltage change speed is adopted, it is difficult to capture a single molecule, and it is necessary to reduce the voltage change speed. The voltage change speed is gradually reduced through repeated exploration, so that the detection can be performed under the condition that the physicochemical property of the substance to be detected is unknown.
Further, it is detected whether a single molecule is captured between the probe 3 and the substrate 1 by:
and in the process of contacting and disconnecting the probe 3 and the substrate 1 for a plurality of times, measuring the conductance between the probe 3 and the substrate 1 to generate a conductance change curve, and analyzing the image of the conductance change curve, wherein if the conductance change curve is stepped after suddenly falling and is maintained for a short time, the capturing of single molecules between the probe 3 and the substrate 1 is indicated.
Referring to fig. 4, the stepwise maintenance of the conductance profile for a short period of time after the sudden drop in the conductance profile may refer to the profile change within the dashed box in fig. 4. In the above, the measurement of the current and voltage can be performed by the probe 3 and the substrate 1, and if the case of fig. 4 is present, it can be determined that a single molecule is trapped between the probe 3 and the substrate 1. Whether or not a curve change within the dashed box in fig. 4 occurs can be detected by means of image recognition, image analysis, or the like of the related art.
Further, the initial voltage change speed is related to the length of the molecule to be detected, and if the length of the molecule to be detected is greater than 2nm or less than 0.5nm, the initial voltage change speed is reduced.
In this embodiment, if the length of the molecule to be measured is shorter (less than 0.5 nm), the voltage change speed needs to be lower, the length of the molecule to be measured is medium (greater than 0.5nm and less than 2 nm), the voltage change speed can be faster, the molecule to be measured is too long (greater than 2 nm), and the voltage change speed is slow. Through the corresponding initial speed setting, the measurement efficiency can be improved, samples to be measured with different physicochemical properties are adapted, the time required for the initial voltage change speed to reach the correct voltage change speed is reduced, and the time required for capturing single molecules is shortened.
Further, the initial voltage change rate is positively correlated with the affinity of the molecule to be detected with the probe 3.
In this embodiment, if the affinity between the molecule to be detected and the probe 3 is high, a faster voltage change speed may be selected as the initial value, whereas if the affinity between the molecule to be detected and the probe 3 is low, a slower voltage change speed may be selected as the initial value.
Further, step S2 includes:
the piezoelectric ceramic 4 and the probe 3 are driven by the stepping motor 2 to approach the substrate 1 at a first speed and then approach the substrate 1 at a second speed, the first speed being greater than the second speed.
This step reduces the time required for the probe 3 to contact the substrate 1 by driving the piezoelectric ceramic 4 and the probe 3 by the stepper motor 2 to approach the substrate 1 at a faster speed and then approach the substrate 1 at a slower speed. In particular, the stepper motor 2 may be controlled by a PWM waveform, with the period of PWM corresponding to the first speed being shorter. PWM is a pulse width modulated waveform.
Further, before the molecular signal measurement is performed, performing:
the applied voltage of the piezoelectric ceramic 4 is maintained at the present time.
After the single-molecule junction is constructed, the displacement of the piezoelectric ceramic 4 enables exactly one molecule to exist between the probe 3 and the substrate 1, the displacement of the piezoelectric ceramic 4 is kept free from bridging by keeping voltage, and then different voltages, such as square waves, sine waves and the like, can be applied on the substrate 1 to see the electrical change characteristics of the molecule.
The system comprises a substrate 1, a stepping motor 2, a probe 3 and a control system (not shown), wherein the probe 3 and the substrate 1 are respectively used as test electrodes for single-molecule measurement, the substrate 1 is fixedly arranged, the telescopic end of the stepping motor 2 is connected with the probe 3 through piezoelectric ceramics 4, and the stepping motor 2 and the piezoelectric ceramics 4 cooperatively drive the probe 3 to be close to or far away from the substrate 1;
the control system is operated by the large-stroke nanoscale distance adjusting method for constructing the single-molecule junction.
The working principle of the nanoscale distance-adjusting system is the same as that of the nanoscale distance-adjusting method.
Experimental data
The single-molecule junction is built several times by the nanoscale distance-adjusting method or the nanoscale distance-adjusting system provided by the embodiment, the time required for building the single-molecule junction is 1.15 seconds/time on average, the single-molecule junction is built several times by the distance-adjusting method of the motor driving probe provided with a plurality of stacked piezoelectric ceramics, and the time required for building the single-molecule junction is 10.39 seconds/time on average.
It can be seen that the time required to construct a molecular moiety can be greatly reduced by the methods or systems provided herein.
It should be noted that in the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The use of the words first, second, third, etc. do not denote any order. These words may be interpreted as names.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms should not be understood as necessarily being directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
Claims (7)
1. A large-travel nanoscale distance-adjusting method for constructing a single-molecule junction, which is characterized by comprising the following steps of: the nanoscale distance adjusting method is based on a single-molecule measuring instrument, the single-molecule measuring instrument comprises a substrate, a stepping motor and a probe, the probe and the substrate are respectively used as test electrodes of the single-molecule measuring instrument, the substrate is fixedly arranged, the telescopic end of the stepping motor is connected with the probe through piezoelectric ceramics, and the stepping motor and the piezoelectric ceramics cooperatively drive the probe to be close to or far away from the substrate;
the nanoscale distance adjusting method comprises the following steps:
s1, applying and maintaining a maximum stroke voltage to the piezoelectric ceramic to enable the piezoelectric ceramic to maintain a maximum stroke;
s2, driving the piezoelectric ceramic and the probe to rapidly approach the substrate through the stepping motor;
s3, when the probe is in contact with the substrate, controlling the stepping motor to stop running, gradually reducing the voltage applied to the piezoelectric ceramic from the maximum travel voltage to 0V, entering S4 if the probe and the substrate can be disconnected, and controlling the stepping motor to drive the piezoelectric ceramic and the probe to return to S2 after the probe and the substrate can not be disconnected;
s4, applying voltage to the piezoelectric ceramic to enable the probe and the substrate to be contacted and disconnected for a plurality of times, wherein the method comprises the following steps of:
s41, applying a voltage which is reduced from the maximum travel voltage to the piezoelectric ceramic at an initial voltage change speed for a plurality of times, so that the probe and the substrate are contacted and disconnected for a plurality of times;
the initial voltage change speed is related to the length of a molecule to be detected, and the length of the molecule to be detected is more than 2nm or less than 0.5nm, so that the initial voltage change speed is reduced;
s42, after each contact and disconnection between the probe and the substrate, performing: cycling several times: applying voltage to the piezoelectric ceramic to enable the probe to be in contact with the substrate, reducing the applied voltage to the piezoelectric ceramic, and applying one or more combined voltages of sine waves, square waves, triangular waves and irregular waves to the piezoelectric ceramic after the probe and the substrate are disconnected, so that the probe shakes and drops a sample to be detected remained on the surface of the probe;
s43, detecting whether a single molecule is captured between the probe and the substrate, if so, constructing to obtain a single molecule junction, and measuring a molecular signal; if not, the voltage change speed is reduced and the process returns to S41;
s5, measuring the molecular electrical signals.
2. A long-travel nanoscale pitch method for constructing a single-molecule junction as claimed in claim 1, wherein: in step S2, during the process of the probe approaching to the substrate, applying a bias voltage to the probe and the substrate, and monitoring the current change condition between the probe and the substrate;
in step S3, when a current occurs between the probe and the substrate, it is determined that the probe is in contact with the substrate, and when the current between the probe and the substrate is lost, it is determined that the probe is disconnected from the substrate.
3. A long-travel nanoscale pitch method for constructing a single-molecule junction as claimed in claim 1, wherein: detecting whether a single molecule is captured between the probe and the substrate by:
and in the process of repeatedly contacting and disconnecting the probe and the substrate, measuring the conductance between the probe and the substrate to generate a conductance change curve, and analyzing the image of the conductance change curve, wherein if the conductance change curve is stepped after suddenly falling for a short time, the single molecule is captured between the probe and the substrate.
4. A long-travel nanoscale pitch method for constructing a single-molecule junction as claimed in claim 1, wherein: the initial voltage change speed is positively correlated with the affinity of the molecule to be detected with the probe.
5. A long-travel nanoscale pitch method for constructing a single-molecule junction as claimed in claim 1, wherein: the step S2 comprises the following steps:
the piezoelectric ceramic and the probe are driven by the stepping motor to approach the substrate at a first speed and then approach the substrate at a second speed, and the first speed is greater than the second speed.
6. A long-travel nanoscale pitch method for constructing a single-molecule junction as claimed in claim 1, wherein: prior to performing molecular signal measurements, performing:
the applied voltage of the current piezoelectric ceramic is maintained.
7. A long-travel nanoscale pitch system for constructing single-molecule junctions, characterized by: the device comprises a substrate, a stepping motor, a probe and a control system, wherein the probe and the substrate are respectively used as test electrodes for single-molecule measurement, the substrate is fixedly arranged, the telescopic end of the stepping motor is connected with the probe through piezoelectric ceramics, and the stepping motor and the piezoelectric ceramics cooperatively drive the probe to be close to or far away from the substrate;
the control system is operative to perform a long-stroke nanoscale pitch method for constructing a single-molecule junction as claimed in any one of claims 1-6.
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| US5205147A (en) * | 1989-05-12 | 1993-04-27 | Fuji Electric Co., Ltd. | Pre-loaded actuator using piezoelectric element |
| CN1845443A (en) * | 2006-03-16 | 2006-10-11 | 中国科学技术大学 | High-precision linear driver with arbitrary distance of run |
| CN102788889A (en) * | 2012-07-27 | 2012-11-21 | 中国科学院电工研究所 | Needle inserting method for atomic force microscope |
| US20140336479A1 (en) * | 2013-05-07 | 2014-11-13 | Hideo Ando | Detection method of life activity, measuring device of life activity, transmission method of life activity detection signal, or service based on life activity information |
| CN107064639A (en) * | 2017-05-15 | 2017-08-18 | 武汉科技大学 | It is a kind of to split system and its application method that connection measures unimolecule electric property |
| CN108088359A (en) * | 2016-11-21 | 2018-05-29 | 清华大学 | Portable contourgraph and profile scan microscope and system |
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| US5205147A (en) * | 1989-05-12 | 1993-04-27 | Fuji Electric Co., Ltd. | Pre-loaded actuator using piezoelectric element |
| CN1845443A (en) * | 2006-03-16 | 2006-10-11 | 中国科学技术大学 | High-precision linear driver with arbitrary distance of run |
| CN102788889A (en) * | 2012-07-27 | 2012-11-21 | 中国科学院电工研究所 | Needle inserting method for atomic force microscope |
| US20140336479A1 (en) * | 2013-05-07 | 2014-11-13 | Hideo Ando | Detection method of life activity, measuring device of life activity, transmission method of life activity detection signal, or service based on life activity information |
| CN108088359A (en) * | 2016-11-21 | 2018-05-29 | 清华大学 | Portable contourgraph and profile scan microscope and system |
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