Energy harvesting system in which two-terminal lif memristor device and mosfet are combined

Abstract

The present invention relates to an energy harvesting system. More specifically, the energy harvesting system comprises: an energy conversion unit for generating an AC voltage using external energy; a rectification circuit unit connected in parallel with the energy conversion unit and converting the AC voltage into a DC voltage; and a conversion circuit unit connected in parallel with the rectification circuit unit, generating an output voltage and an output current on the basis of the converted DC voltage, and controlling driving of an electronic element, wherein the conversion circuit unit comprises: first and second capacitors connected in series with each other; a transistor having a drain terminal connected to the first capacitor and a source terminal connected to the electronic element; and a switching element having one end connected between the first and second capacitors and the other end connected to a gate terminal of the transistor.

Description

Energy harvesting system combining a 2-terminal LIF memristor and a MOSFET

[0001] The present invention relates to an energy harvesting system, and more specifically, to an energy harvesting system in which a two-terminal LIF memristor device and a MOSFET are combined.

[0002] This invention is the result of research conducted with funding from the government (Ministry of Education) and supported by the Early Employment Contract Department Leading University (Graduate School) Development Project through the Korea Institute for Industrial Technology Promotion.

[0003]

[0004] Energy harvesting technology is a technique that collects energy that is unused and wasted in the external environment and converts it into useful electrical energy. It can utilize various energy sources generated in daily life, such as mechanical, optical, magnetic, RF, and thermal energy. In particular, the method utilizing triboelectric nanogenerators (TENGs) for converting mechanical energy into electrical energy is attracting attention.

[0005] Triboelectric nanogenerators (TENGs) are energy conversion devices that generate electric charge through the friction of two materials with different electrical properties, utilizing this charge to produce voltage. Due to their relatively simple structure, miniaturization potential, and low cost, these triboelectric nanogenerators are being utilized in various energy harvesting applications.

[0006] However, one of the biggest limitations of triboelectric nanogenerators is their low output current. While triboelectric nanogenerators can generate high output voltages (hundreds of volts or more), their very low output current makes it difficult to directly drive most electronic devices or loads that consume relatively large amounts of current. For example, electronic devices such as LEDs, sensors, and wireless transmitters require a certain level of current, but the low output current of triboelectric nanogenerators often prevents them from being driven directly.

[0007] To address this, it is necessary to use an auxiliary circuit capable of rectifying and accumulating low output current and releasing it when needed. A commonly used method involves rectifying the AC output of a triboelectric nanogenerator into DC, accumulating charge in an energy storage device such as a capacitor, and then releasing it when the voltage exceeds a certain level. This allows for the instantaneous generation of high current to drive the device.

[0008] However, several technical challenges arise in the process of implementing these auxiliary circuits. First, the Under Voltage Lock Out (UVLO) circuit can contribute to voltage maintenance and stabilization by blocking the output below a certain voltage and outputting only when sufficient voltage is secured. However, UVLO circuits require the use of additional components and complex designs, which can hinder the simple and miniaturized structure of triboelectric nanogenerators.

[0009] Furthermore, when using voltage regulation circuits such as Buck converters, high-frequency switching and additional components like inductors and capacitors are required, which complicates the circuit, increases manufacturing costs, and can expand the overall system size. Such complex power conversion circuits present problems that conflict with the advantages of triboelectric nanogenerators, such as low cost, miniaturization, and simple structure.

[0010] In conclusion, while voltage conversion circuits such as UVLOs and Buck converters can be used to address the low output current issue of conventional triboelectric nanogenerators, this entails problems such as increased circuit complexity, higher costs, and hindered miniaturization. Therefore, there is a growing need for a new type of energy harvesting system that can compensate for low current more simply and efficiently to solve these problems.

[0011] [Prior Art Literature]

[0012] [Patent Literature]

[0013] Korean Registered Patent Publication No. 10-2723658 (“Method for controlling an application using power from an energy harvesting device and apparatus for performing the same.” Registration date: Oct. 25, 2024.)

[0014]

[0015] The present invention was devised to solve the problems described above. The objective of the energy harvesting system combined with a two-terminal LIF memristor device and a MOSFET according to the present invention is to provide an energy harvesting system capable of operating an application without directly allowing the current flowing to the application to flow through the LIF device by positioning the LIF device at the gate terminal of the MOSFET and turning the MOSFET device on and off according to the voltage applied to the LIF device.

[0016]

[0017] An energy harvesting system according to various embodiments of the present invention for solving the problems described above comprises an energy conversion unit that generates an alternating current voltage using external energy, a rectifier circuit unit connected in parallel with the energy conversion unit and converting the alternating current voltage into a direct current voltage, and a conversion circuit unit connected in parallel with the rectifier circuit unit and generating an output voltage and an output current based on the converted direct current voltage and controlling the driving of an electronic device, wherein the conversion circuit unit comprises first and second capacitors connected in series with each other, a transistor having a drain terminal connected to the first capacitor and a source terminal connected to the electronic device, and a switching device having one end connected between the first and second capacitors and the other end connected to the gate terminal of the transistor.

[0018] In addition, the transistor and switching element are characterized by being integrated on a single flexible substrate.

[0019] In addition, the switching element is characterized by being integrated on the gate stack of the transistor.

[0020] In addition, the switching element is characterized as being one of a volatile memristor, a biristor, or a thyristor.

[0021] In addition, the switching element includes the volatile memristor and is characterized by using a lower electrode formed on the gate stack of the transistor, which uses the gate material of the transistor directly as the lower electrode or uses a lower electrode comprising a heterogeneous combination of a platinum (Pt) electrode and a gate material.

[0022] In addition, the above volatile memristor is a Leaky-Integrate and Fire memristor (LIF memristor), and the lower electrode of the LIF memristor is characterized by being composed of a heterogeneous film of a platinum (Pt) electrode and a gate material.

[0023] In addition, the above LIF memristor is characterized by operating in an IMT (Insulator-Metal Transition) manner using niobium oxide (NbOx).

[0024] In addition, the above LIF memristor is characterized by operating in an OTS (Ovonic Transition Switching) manner using telluride (B-Te).

[0025] In addition, the above LIF memristor is characterized by operating in a manner utilizing the redox and migration of the Ag electrode.

[0026] In addition, the energy conversion unit is characterized as being a triboelectric nanogenerator.

[0027] In addition, it is characterized by further including a resistor, one end of which is connected between the first and second capacitors and the other end of which is connected to one end of the switching element.

[0028] In addition, the output voltage is the driving voltage of the transistor, and the output current is the driving current of the transistor.

[0029]

[0030] According to an energy harvesting system combining a two-terminal LIF memristor device and a MOSFET according to various embodiments of the present invention as described above, the problem of low output current of triboelectric nanogenerators can be solved.

[0031] In addition, high-output discharge can be enabled by utilizing the characteristics of the LIF memristor.

[0032] In addition, it can be implemented with a simple circuit without a complex power conversion circuit.

[0033] In addition, efficient energy utilization is possible by minimizing energy loss through a voltage accumulation and discharge method.

[0034] In addition, the ability to use various electrode materials provides high design flexibility.

[0035] In addition, the energy conversion efficiency of triboelectric nanogenerators can be maximized.

[0036] In addition, manufacturing costs can be reduced by decreasing the number of parts and simplifying the process.

[0037]

[0038] Figure 1 is a circuit diagram illustrating a conventional energy harvesting system.

[0039] FIG. 2 is a circuit diagram illustrating an energy harvesting system according to the present invention.

[0040] Figure 3 is a graph showing the simulation results of an energy harvesting system according to the present invention.

[0041]

[0042] In order to explain the present invention, the operational advantages of the present invention, and the objectives achieved by the implementation of the present invention, preferred embodiments of the present invention are illustrated below and examined with reference thereto.

[0043] First, the terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention; singular expressions may include plural expressions unless the context clearly indicates otherwise. Furthermore, in this application, terms such as "comprising" or "having" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0044] In describing the present invention, if it is determined that a detailed description of related known components or functions may obscure the essence of the invention, such detailed description is omitted.

[0045] Figure 1 is a circuit diagram illustrating a conventional energy harvesting system (1).

[0046] As illustrated in FIG. 1, a conventional energy harvesting system (1) may include an energy conversion unit (10), a rectification circuit unit (20), and a conversion circuit unit (30).

[0047] The energy conversion unit (10) may be composed of a device that generates current using various principles. These include photoelectric conversion in which a metal or the like absorbs high-energy sunlight and emits electrons, piezoelectric conversion in which current flows as positive and negative charges are separated by dielectric polarization when mechanical pressure is applied, electromagnetic wave conversion that generates electricity by collecting electromagnetic waves, thermoelectric conversion utilizing the Seebeck effect that converts a temperature difference into a potential difference, and triboelectric nanogenerators (TENGs) that collect electricity generated by friction.

[0048] The rectifier circuit (20) may include an AC-DC rectifier circuit that converts the voltage waveform of a triboelectric nanogenerator, which generates a pulse-shaped alternating current (AC) voltage, into a direct current (DC) form.

[0049] The conversion circuit section (30) may include a DC-DC converter, a capacitor, a switch, and an intermittent power transfer section for converting the input voltage that has passed through the rectifier into a specific output voltage. The DC-DC converter is generally composed of a switch, a diode, an inductor, a capacitor, a load, etc., and can control the output voltage by turning it ON when the voltage applied to the switch through the power transfer section is above a preset voltage and turning it OFF when it is below the preset voltage. Such a switch may be an automatic control switch, such as a power semiconductor switch, or a mechanical switch. Additionally, the conversion circuit section (30) may include a capacitor that performs the role of regulating the input voltage ripple of the DC-DC converter between the rectifier circuit section (20) and the conversion circuit section (30). In some cases, it may have a structure that directly transfers the accumulated current to the load by being composed only of an intermittent power transfer section without a step-down converter, a step-up converter, or a step-down converter.

[0050] Since the DC-DC converter has a complex circuit structure and there are limitations to circuit miniaturization due to the inductor, there is a problem that the existing conversion circuit section (30) containing it is difficult to integrate on the same substrate as the energy conversion section (10) or the rectification circuit section (20). In addition, even if the conversion circuit section (30) is composed only of UVLO (UV Lockout) or intermittent power transfer section, there is a problem that it is difficult to integrate on the same substrate as the energy harvesting element.

[0051] The energy harvesting system (1) may additionally include a battery unit (not shown), and the battery unit may be composed of a capacitor or secondary battery capable of storing energy to drive a specific application through a conversion circuit unit (30). Depending on the type of specific application, the battery unit may be omitted.

[0052] FIG. 2 is a circuit diagram illustrating an energy harvesting system according to the present invention.

[0053] As illustrated in FIG. 2, the energy harvesting system (1000) according to the present invention may include an energy conversion unit (100), a rectification circuit unit (200), and a conversion circuit unit (300).

[0054] The energy conversion unit (100) is a device that converts various forms of energy generated externally into electrical energy. Although there are no restrictions on the type, it is described here based on a triboelectric nanogenerator as an example. The triboelectric nanogenerator utilizes the triboelectric charging phenomenon and the electrostatic induction phenomenon as its driving principles. The triboelectric charging phenomenon refers to the electrical charging phenomenon that occurs when different materials come into contact and then separate. Depending on the charging method, such triboelectric nanogenerators can be classified into a method utilizing the action of separation after contact, a method utilizing the action of sliding against each other, a method inducing the charging phenomenon based on a single electrode, or a method inducing the charging phenomenon in an independent structure. In the present invention, the same effect can be obtained regardless of the difference between each method.

[0055] The rectifier circuit section (200) may include a rectifier circuit for converting pulsed AC voltage and current waveforms generated from a triboelectric nanogenerator into a DC form. The rectifier circuit may be implemented by configuring diodes in a bridge form to convert the negative voltage component of the input voltage into a positive voltage and convert it into DC, or by using a single diode to remove the negative voltage component of the input voltage and convert it into DC. Additionally, the diode used in the rectifier circuit may be configured with a flexible structure using a polymer conductive material such as PEDOT:PSS or an inorganic thin film material so that it can be fabricated on a flexible substrate and at a low temperature using printed electronics technology.

[0056] The conversion circuit unit (300) is connected in parallel with the rectifier circuit unit (200) and can generate an output voltage and an output current based on the DC voltage converted by the rectifier circuit unit (200). Accordingly, the output of an electronic device (application) connected to the conversion circuit unit (300) can be controlled.

[0057] Specifically, the conversion circuit (300) may include first and second capacitors (C1, C2), a transistor (MOSFET), and a switching element (S).

[0058] The first and second capacitors (C1, C2) can be connected in series with each other.

[0059] The transistor may include a MOSFET, the drain terminal may be connected to a first capacitor (C1), and the source terminal may be connected to an electronic device.

[0060] One end of the switching element (S) may be connected between the first and second capacitors (C1, C2), and the other end may be connected to the gate terminal of the MOSFET.

[0061] More specifically, the first and second capacitors (C1, C2) store charge and regulate voltage using the DC voltage provided from the TENG (triboelectric nanogenerator) and the rectifier circuit (200). The DC voltage converted through the rectifier circuit is accumulated in the capacitors (C1, C2), and the first and second capacitors (C1, C2) are connected in series to perform the function of distributing voltage. As an energy storage element, the capacitor limits the flow of current until the voltage generated by the external energy conversion unit rises sufficiently, and operates as an electrical charging element capable of discharging above a specific voltage. The first capacitor (C1) collects the initial charge, and the second capacitor (C2) can contribute to forming a threshold voltage to regulate the operation of the switching element while additionally storing charge.

[0062] The switching element (S) can be composed of a device that discharges current when a specific threshold voltage is reached, such as an LIF (Leaky-Integrate and Fire) memristor. When sufficient charge is accumulated in the capacitors (C1, C2), the switching element (S) switches to an electrically conductive state the moment it reaches that threshold voltage and applies voltage to the gate electrode of the MOSFET. The switching element (S) is connected to the gate terminal of the MOSFET and serves to block the flow of current to the gate until the voltage generated in the capacitor becomes sufficiently high. The LIF memristor is a volatile memristor that rapidly discharges current and delivers voltage when a certain threshold voltage is exceeded, and is used directly to drive the gate of the MOSFET.

[0063] Here, the LIF (Leaky-Integrate and Fire) memristor is a device that maintains a high-resistance state up to a specific voltage and switches to a low-resistance state to rapidly release current once the threshold voltage is exceeded. This device mimics the firing mechanism of biological neurons, operating by suppressing current flow until the voltage reaches a certain level, but rapidly releasing current the moment the voltage reaches the critical point.

[0064] The LIF memristor follows three main operating stages. First, in the leakage stage, only a minute current flows when voltage is applied to the device, and voltage slowly accumulates internally. At this stage, almost no current flows, but the voltage gradually rises. In the second stage, integration, the applied voltage continuously rises while current flow is minimized, and the voltage is stored until the device voltage reaches a specific threshold. In the third stage, fire, the moment the accumulated voltage exceeds the threshold, the device's resistance decreases sharply, transitioning to a state where a strong current flows. During this process, a rapid current release occurs, which can be used to drive a MOSFET.

[0065] LIF memristors can use various electrode materials depending on the configuration of the bottom electrode. For example, the platinum (Pt) electrode and the gate electrode of the MOSFET can be configured as heterogeneous films, or materials such as niobium oxide (NbOx), boron telluride (B-Te), or silver (Ag) can be used to enhance specific operating mechanisms. When niobium oxide is used, the principle of Insulator-Metal Transition (IMT), which switches from an insulator to a metal in response to external stimuli such as temperature and an electric field, is utilized; in the case of boron telluride, the Ovonic Transition Switching (OTS) method converts from an insulating state to a metallic state and releases current when a threshold voltage is exceeded. When using a silver (Ag) electrode, when a positive voltage is applied, the upper silver electrode is oxidized and then reduced at the lower electrode, forming a conductive filament to switch to a low-resistance state and release current. When the voltage is lowered due to the release of current, the silver aggregates to minimize interfacial energy, and filament rupture occurs, returning to a high-resistance state.

[0066] LIF memristors can be used to solve the problem of low output current in energy harvesting systems, such as triboelectric nanogenerators (TENGs), which makes it difficult to drive devices directly. They operate by converting the AC voltage of the TENG into DC through a rectifier circuit, storing it in a capacitor, and then discharging it via an LIF memristor when the voltage reaches a critical threshold. In this process, the LIF memristor is connected to the gate of a MOSFET, where the discharge current acts as a trigger signal, switching the MOSFET to the ON state and allowing the stored energy to be released to electronic devices.

[0067] The characteristics of such an LIF memristor enable simple and effective current discharge in energy harvesting systems without complex power conversion circuits, thereby solving the problem of low output current while ensuring the operational stability of the device.

[0068] In addition, the switching element (S) may include a biristor or a thyristor.

[0069] Biristors and thyristors are devices similar to Leaky-Integrate and Fire (LIF) memristors that release current or induce switching when specific voltage conditions are met. A biristor consists of two PN junction diodes connected back-to-back and possesses the characteristic of flowing current when a specific threshold voltage (breakdown voltage) is exceeded. When the voltage is below the threshold, almost no current flows; however, when the threshold voltage is exceeded, current flows momentarily, and the device returns to a high-resistance state once the voltage is removed, exhibiting the characteristics of a volatile device. These characteristics make it suitable for controlling energy harvesting circuits, such as triboelectric nanogenerators (TENGs), to accumulate current for a certain period and then instantaneously release it when the threshold voltage is reached.

[0070] A thyristor is a semiconductor device with a 4-layer PNPN structure and is a non-volatile switching device capable of receiving a trigger signal through its gate electrode. When a trigger signal is applied to the gate, the thyristor switches to a conducting state and releases current. Unlike biristors, thyristors have the characteristic that once conduction begins, current continues to flow until it is completely cut off. Therefore, thyristors can be controlled via trigger signals and can be used to reliably transfer charge stored in a capacitor to the gate of a MOSFET.

[0071] An LIF memristor is a device that suppresses current flow until a specific voltage is accumulated and rapidly releases current upon reaching a threshold voltage, based on a three-stage operation of leakage, integration, and fire. Biristors and thyristors can replace the function of such LIF memristors, and each device shares the common characteristic of releasing current above a specific voltage. However, while LIF memristors have strong analog characteristics involving voltage accumulation and leakage processes, biristors and thyristors are switching devices closer to digital methods.

[0072] In the energy harvesting system (1000), the role of the switching element is to utilize the low current and high voltage generated from the TENG (triboelectric nanogenerator) to block the current flow until sufficient voltage is accumulated, and to switch the MOSFET to the ON state to release the current when the threshold voltage is reached. This mode of operation is consistent with the characteristics of biristors and thyristors, and in particular, in the case of thyristors, it has the advantage of enabling precise trigger signal control through the gate electrode.

[0073] In conclusion, in addition to the LIF memristor, the biristor and thyristor can discharge current when a specific threshold voltage is reached or control the flow of current through a gate trigger signal, so they can be used as switching elements in an energy harvesting system (1000). Since the biristor utilizes a simple voltage breakdown principle and the thyristor provides a current maintenance function through gate control, each element can be selected and utilized as needed.

[0074] The energy conversion unit (100), rectification circuit unit (200), and conversion circuit unit (300) constituting the energy harvesting system (1000) can be integrated on a single substrate. Additionally, the single substrate may be a flexible substrate.

[0075] For example, by forming an LIF memristor among the switching elements (S) described above directly on the gate stack of a MOSFET, the accumulation and release of current within the energy harvesting system (1000) can be precisely controlled. The alternating current voltage generated by the triboelectric nanogenerator is converted into a direct current voltage through a bridge rectifier, and then charge is accumulated in a capacitor connected in series. When the voltage accumulates above a certain threshold value, the resistance state of the LIF memristor changes rapidly, and current is applied to the gate of the MOSFET, and as the MOSFET is switched to the ON state, the stored charge can be released to an external electronic device.

[0076] The LIF memristor can directly utilize the gate material of a MOSFET as the bottom electrode, or it can be used in combination with a heterogeneous film of the gate material and a platinum (Pt) electrode. This not only improves the electrical reliability of the device but also ensures the stability of gate driving and enables more precise control of current release timing. In particular, by directly forming the LIF memristor on the MOSFET gate stack, the current accumulation and release processes are integrated, allowing for stable power management without the need for additional power conversion circuits.

[0077] This circuit configuration allows for the omission of complex voltage regulation circuits, such as UVLO (Under Voltage Lock Out) and Buck converters, and enables the output of high current while compensating for the low output current of triboelectric nanogenerators. Consequently, a power management device incorporating an LIF memristor on top of a MOSFET gate stack can realize a miniaturized, simplified, and highly efficient energy harvesting circuit, offering the advantage of supplying stable current to various electronic devices.

[0078] In addition, the energy harvesting system (1000) according to the present invention may further include a resistor (R1).

[0079] One end of the resistor (R1) may be connected between the first and second capacitors (C1, C2), and the other end may be connected to one end of the switching element (S). This is to ensure that the current flowing through the switching element (S) does not flow excessively depending on the operation of the circuit, and this can be selected or replaced as needed.

[0080] In addition, the energy harvesting system (1000) may additionally include a battery unit (not shown), and the battery unit refers to a capacitor capable of storing energy to drive an electronic device to be driven through a conversion circuit unit (300), and may be composed of a secondary battery, etc. Also, depending on the type of electronic device to be driven, the battery unit may not be provided.

[0081] Figure 3 is a graph showing the simulation results of an energy harvesting system according to the present invention.

[0082] As shown in Fig. 3, the alternating current generated by the triboelectric nanogenerator (TENG) is converted into direct current through a bridge rectifier circuit and accumulated in a capacitor, exhibiting a gradual increase in voltage. At this time, the voltage accumulated in the capacitor is applied to the LIF memristor device, and the current flow is limited until the voltage reaches the threshold voltage of the LIF memristor. When the threshold voltage is exceeded, the resistance state of the LIF memristor changes rapidly, and the current is discharged to the gate of the MOSFET.

[0083] Due to the current discharge from the LIF memristor, the gate of the MOSFET turns on, and the MOSFET switches to conduction mode. When the MOSFET conducts, the charge accumulated in the capacitor is discharged, and current flows through the 10 kΩ resistor (the load element in the simulation). During this process, energy discharge occurs repeatedly, and the energy conversion of the TENG and the charging and discharge operations of the capacitor take place periodically.

[0084] The simulation results reveal a periodic pattern in which the capacitor voltage gradually increases over time, and when the threshold voltage of the LIF memristor is exceeded, the MOSFET switches to the ON state, releasing the stored current to an external electronic (load) device. Through this circuit simulation, it can be confirmed that the circuit accumulates the low current generated by the triboelectric nanogenerator in the capacitor and stably releases a high-output current when the threshold voltage is reached.

[0085] Although preferred embodiments of the present invention have been described above, the present invention is not limited to the specific embodiments described above. That is, those skilled in the art to which the present invention pertains can make numerous changes and modifications to the present invention without departing from the spirit and scope of the appended claims, and all such appropriate changes and modifications should be deemed to fall within the scope of the present invention as equivalents.

[0086] The present invention is an invention carried out with the support of a research project supported by the Ministry of Education and managed by the Korea Institute for Industrial Technology Advancement (KIAT) (Project No.: 2023-Jochi-Graduate-03, Research Project Name: National Hanbat University Early Employment Type Contract Department Leading University (Graduate) Development Project, Research Name: (202502220001)(2025 Early Employment Type Contract Department Industry-Academic R&D Project)).

[0087] [Explanation of the symbol]

[0088] 1, 1000 : Energy harvesting system

[0089] 10, 100: Energy conversion unit

[0090] 20, 200 : Rectifier circuit section

[0091] 30, 300 : Conversion circuit section

Claims

1. An energy conversion unit that generates alternating current voltage using external energy; A rectifier circuit connected in parallel with the energy conversion unit and converting the AC voltage into a DC voltage; and A conversion circuit unit connected in parallel with the above rectifier circuit unit, generating an output voltage and an output current based on the converted DC voltage, and controlling the driving of an electronic device; is included. The above conversion circuit section is, First and second capacitors connected in series with each other; A transistor having a drain terminal connected to the first capacitor and a source terminal connected to the electronic element; and An energy harvesting system comprising: a switching element, one end of which is connected between the first and second capacitors and the other end of which is connected to the gate terminal of the transistor.

2. In Paragraph 1, The above transistor and switching element are integrated on a single flexible substrate, forming an energy harvesting system.

3. In Paragraph 2, The above switching element is an energy harvesting system integrated on the gate stack of the above transistor.

4. In Paragraph 3, The above switching element is an energy harvesting system that is any one of a volatile memristor, a biristor, or a thyristor.

5. In Paragraph 4, The above switching element is, Includes the above-mentioned volatile memristor, An energy harvesting system having a lower electrode formed on the gate stack of the above-mentioned transistor, wherein the gate material of the above-mentioned transistor is used directly as the lower electrode, or a lower electrode comprising a heterogeneous combination of a platinum (Pt) electrode and a gate material is used.

6. In Paragraph 5, The above volatile memristor is a LIF memristor (Leaky-Integrate and Fire memristor), and The lower electrode of the above LIF memristor is an energy harvesting system composed of a platinum (Pt) electrode and a heterogeneous film of a gate material.

7. In Paragraph 6, The above LIF memristor is an energy harvesting system that operates using an Insulator-Metal Transition (IMT) method with niobium oxide (NbOx).

8. In Paragraph 6, The above LIF memristor is an energy harvesting system that operates using an OTS (Ovonic Transition Switching) method with boron telluride (B-Te).

9. In Paragraph 1, The above energy conversion unit is an energy harvesting system, which is a triboelectric nanogenerator.

10. In Paragraph 1, An energy harvesting system further comprising a resistor, one end of which is connected between the first and second capacitors and the other end of which is connected to one end of the switching element.

11. In Paragraph 1, The above output voltage is the driving voltage of the transistor, and An energy harvesting system characterized in that the above output current is the driving current of the transistor.

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