Device for ambient thermal and vibration energy harvesting

Abstract

The integrated circuit on the chip may include a plurality of capacitors connected in series to generate an AC noise signal. A selected bandwidth of the AC noise signal is transmitted through the series of capacitors as a first AC power signal. Each rectifier is positioned to receive a positive cycle of the first AC power signal and a negative cycle of the first AC power signal. Output terminals are connected to each rectifier and configured to be connected to off-chip circuitry. The capacitors may be fixed capacitors or variable gap capacitors.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and incorporates by reference U.S. Provisional Patent Application No. 63 / 013,631, filed April 22, 2020, and entitled "Ambient Thermal and Vibration Energy Harvesting."

[0002] The disclosed technology relates generally to systems, devices, and methods for harvesting thermal and vibrational energy.

[0003] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH The work presented in this disclosure did not rely on government funding during the development work. [Background technology]

[0004] Energy harvesting is the practice of obtaining traditional electrical power from external sources, but also utilizes emerging technologies to capture energy generated from thermal energy sources, vibration sources (e.g., vehicle, machine, building, and human motion), and kinetic sources. This harvested energy can then be used for a variety of applications. For example, while capacitors have long been standard devices in energy storage, new technologies enable additional approaches to energy harvesting.

[0005] In newer embodiments, the plates of the capacitor can be variable gap capacitors that can actually generate alternating current that can be rectified for power storage. See U.S. Patent Publication No. 2019 / 0386584 ("Energy Harvesting Devices and Sensors and Methods of Making and Use Thereof"), which is incorporated by reference as if fully set forth herein. In the co-owned '584 publication, the plates (optionally graphene films) are fixed at one end and, when excited by applied energy, ambient energy, vibration, heat, light, etc., will oscillate up and down between two extremes. The strain / stress induced on the surface of the plates by bending and oscillating between the two extremes can be used to harvest energy.

[0006] In one example, atomic-scale vibrations are ubiquitous even in mechanically quiet environments, due to materials being held at temperatures above absolute zero, referred to as thermal vibrations. The various embodiments described below are presented with respect to these and other considerations.

[0007] Thermal energy, such as that which induces the vibrations described above, also induces electrical responses in many other circuits. However, the signal generated by the thermal energy must not only be acquired, but must also be converted into a reliable and consistent power signal if the energy is to be harvested for use in other applications. Currently, there is a need in the energy field for circuits, methods, and systems that can be used to harvest electrical energy produced by thermal systems, even under ambient temperature conditions. Summary of the Invention

[0008] In one embodiment, an energy harvesting system includes a DC voltage source connected to at least one capacitor that generates an AC noise signal, a selected bandwidth of the AC noise signal that is transmitted through the capacitor as a first AC power signal, and respective diodes that rectify the first power signal to charge a positive cycle storage capacitor and a negative cycle storage capacitor with the first AC power signal.

[0009] In another embodiment, the AC noise signal is a thermal noise signal and the at least one capacitor is a plurality of capacitors connected in series.

[0010] In another embodiment, the capacitor is configured to have a storage capacitance of 1 picofarad.

[0011] In another embodiment, the first AC power signal is rectified through a forward biased diode during a positive cycle of the first AC power signal to produce the output power signal.

[0012] In another embodiment, the first AC power signal is rectified through a reverse-biased diode during a negative cycle of the first AC power signal to produce the output power signal.

[0013] In another embodiment, the diodes are paired as subunits, the subunits are connected to positive cycle metal trace connections and negative cycle metal trace connections, and the subunits are repeated with their respective connections to the positive cycle metal trace connections and negative cycle metal trace connections.

[0014] In another embodiment, the forward base diode and the reverse biased diode are connected to an additional diode in a Cockcroft-Walton full wave rectifier circuit and a multiplier circuit.

[0015] In another embodiment, the plurality of capacitors in the energy harvesting system comprises a variable gap capacitor that generates both a first AC power signal from an AC noise signal and a second AC power signal from a variable gap capacitor discharge cycle.

[0016] In another embodiment, the capacitor is fully charged to a steady state by a DC voltage source.

[0017] In another embodiment, the diode is selected based on its conductance rating to match the capacitor as a noise source.

[0018] In another embodiment, the AC noise signal comprises conductivity due to conductive carrier defect hopping through a capacitor.

[0019] In another embodiment, the DC voltage source provides a voltage corresponding to the turn-on voltage of the diode.

[0020] Another embodiment of the present disclosure is an integrated circuit on a chip, the integrated circuit including at least one capacitor connected to a circuit for generating an AC noise signal. A selected bandwidth of the AC noise signal is transmitted through the capacitor as a first AC power signal. Respective rectifiers receive a positive cycle of the first AC power signal and a negative cycle of the first AC power signal. Output terminals are connected to each rectifier and configured to connect to off-chip circuitry. In another embodiment, the AC noise signal in the circuit results from ambient thermal energy.

[0021] In another embodiment, the integrated circuit is configured to connect to an off-chip circuit having a DC voltage source connected to a plurality of capacitors, and a positive cycle storage capacitor and a negative cycle storage capacitor that are charged with the first AC power signal.

[0022] In another embodiment, the integrated circuit has a first diode configured as a first respective rectifier of the first AC power signal to produce a first output power signal from a positive cycle of the first AC power signal.

[0023] In another embodiment, the second diode is configured as a second respective rectifier of the first AC power signal to produce a second output power signal from the negative cycle of the first AC power signal.

[0024] In another embodiment of the integrated circuit, the integrated circuit includes at least one capacitor for generating an AC noise signal. A selected bandwidth of the AC noise signal is transmitted through the capacitor as a first AC power signal. A forward-biased transistor and a reverse-biased transistor rectify corresponding positive and negative cycles of the AC noise signal, respectively. An output terminal is connected to the transistor and configured to connect to off-chip circuitry for harvesting energy from the output signal.

[0025] In a method embodiment, a method of assembling an energy harvesting circuit includes connecting at least one capacitor in the energy harvesting circuit; forming a capacitive region in the energy harvesting circuit by defining the at least one capacitor with a first capacitor plate having an initial separation distance relative to a first surface of a free-standing membrane, the first surface of the free-standing membrane defining a second capacitor plate; exposing the free-standing membrane to ambient thermal energy to induce charge accumulation in the capacitive region, the ambient thermal energy also inducing a thermal AC noise signal; selecting a capacitance of the capacitor to select a bandwidth of the AC noise signal to transmit through the capacitor; and rectifying the first AC power signal to charge a positive cycle storage capacitor and a negative cycle storage capacitor with the first AC power signal.

[0026] Another embodiment of the method includes positioning a membrane relative to a first capacitor plate such that the membrane vibrates freely and unimpeded in response to ambient energy, wherein the vibration of the membrane defines periodic ripple formations along the first surface, each ripple formation alternating between a peak and a valley relative to the first capacitor plate to vary the initial separation distance in a variable gap capacitor.

[0027] In another embodiment, the method includes discharging a capacitive region across each rectifier to direct the stored charge to add a second power signal to the energy harvesting circuit. [Brief explanation of the drawings]

[0028] Reference will now be made to the accompanying drawings, which are not necessarily drawn to scale.

[0029] [Figure 1A] FIG. 1 is a schematic, illustrative diagram of an energy harvesting circuit according to an embodiment of the present disclosure. [Figure 1B] FIG. 1B is a schematic, illustrative diagram of an off-chip circuit compatible with the energy harvesting circuit according to FIG. 1A for storing energy according to an embodiment of the present disclosure. [Figure 2] FIG. 1B is a schematic illustration of Nyquist noise signal power plotted along voltage versus average power of a rectified noise signal from the energy harvesting circuit according to FIG. 1A; [Figure 3A] FIG. 10 is a schematic, illustrative diagram of an energy harvesting circuit that utilizes a multiplier circuit to achieve a DC output in accordance with another embodiment of the present disclosure. [Figure 3B] FIG. 1 is a schematic, illustrative diagram of an exemplary energy harvesting circuit that establishes a variable gap capacitor and in which a flexible membrane receives ripples from an ambient energy source. [Figure 3C] FIG. 3C is a cross-sectional schematic diagram of one section of the energy harvesting circuit of FIG. 3B. [Figure 4] 4 is a schematic illustration of a test setup for measuring an output power signal from an AC noise signal applied to a rectifier circuit according to FIG. 3. [Figure 5] 1B is a plot of reverse capacitance values ​​versus effective voltage for the DC voltage source shown in FIG. 1A with reverse capacitance values ​​added according to the series of capacitors shown in FIG. 1A. [Figure 6] FIG. 1 is a schematic, illustrative diagram of a computing environment in which the disclosed methods and systems may operate. [Figure 7] 1 is a plot of test results showing the noise voltage from a resistor and a 10 pF capacitor connected in parallel with each other. The noise voltage is highest when the source resistance is 100 MΩ, matching the load resistance. [Figure 8] 10 is a graph illustrating gain versus input voltage for both 18-stage and 24-stage Schottky-Cockcroft-Walton circuits in accordance with the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0030] Although exemplary embodiments of the disclosed technology are described in detail herein, it should be understood that other embodiments are contemplated. Accordingly, the disclosed technology is not limited in scope to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The disclosed technology is capable of other embodiments and of being practiced or carried out in various ways.

[0031] In the following description, references are made to the accompanying drawings that form a part hereof and that show, by way of illustration, specific embodiments or examples.

[0032] It should also be noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from "about" or "approximately" one particular value and / or to "about" or "approximately" another particular value. When such a range is expressed, other exemplary embodiments include from the one particular value and / or to the other particular value.

[0033] In describing exemplary embodiments, technical terminology is used for the sake of clarity. Each term is intended to have its broadest meaning as understood by one of ordinary skill in the art and to include all technical equivalents that operate in a similar manner to accomplish a similar purpose. It should also be understood that the reference to one or more steps of a method does not exclude the presence of additional or intervening method steps between those steps that are explicitly identified. Method steps may be performed in a different order than described herein without departing from the scope of the disclosed technology. Similarly, it should also be understood that the reference to one or more components in a device or system does not exclude the presence of additional or intervening components between those components that are explicitly identified.

[0034] This disclosure illustrates hardware and associated methods that can direct noise energy present in all circuits to a power harvesting circuit for use in other applications. A device for harvesting energy from ambient charge fluctuations can be based on this disclosure of the recent discovery that output power can be significantly amplified by the rate of change in conductance to charge and / or voltage. The noise energy can be a planned signal of a previously predicted frequency and amplitude generated from selected hardware. In one non-limiting embodiment, a single noise energy source is used to provide a noise signal to a rectifier circuit for power supply. The single source can be a series of capacitors as shown in the accompanying drawings.

[0035] One non-limiting example of a single noise energy source can be illustrated in connection with the disclosure of previously published, commonly owned U.S. Patent Publication No. 2019 / 0386584 (“Energy Harvesting Devices and Sensors and Methods of Making and Use Thereof”) and is shown for illustrative purposes in FIGS. 3B and 3C herein. FIGS. 3A and 3B are schematic, illustrative diagrams of a silicon-based integrated circuit 400 with potentially millions of energy harvesting elements 225. While this design has only one power source 200 and one storage capacitor 275, these are not limiting factors. The first path (denoted by shading and dashed lines “----”) is when current is adding charge to the graphene film, and the second path (denoted by circles “xxx”) is when current is adding charge to the fixed storage capacitor 275. The silicon has an array of diode pairs 250A-250n, with a respective metal contact 225A-225n between each diode pair. Metal contact 225 serves as the energy harvesting element of the system. On top of metal contact 225 is free-standing graphene 265, which is in constant motion, forming peaks and troughs in response to ambient energy, vibrations, etc., as described above. Each small electrode 225A-225n is used to transfer charge back to the graphene and / or battery or storage capacitor 275 as the graphene film oscillates. This is one way to harvest energy at the nanoscale using millions of graphene ripples, each of which imparts charge to a capacitor.

[0036] For illustrative purposes and without limiting the present disclosure to any one configuration, the embodiment of Figures 3A and 3B is notable in that contacts 225A-225I (or up to 225n, where n is any number of contacts) serve as traffic direction points for variable capacitors that are charged and discharged according to the previously described embodiments. A flexible plate, shown as a graphene membrane 265 covering the essential components, can be used as the first capacitor plate 335, and metal contacts 225 can be used as the second capacitor plates 235A-235n to form a variable capacitor (i.e., the distance between the plates varies according to membrane ripples with peaks and troughs). These types of variable capacitors can be used as the respective capacitors represented in the set of capacitors 105A, 105B, and 105C in Figure 1A. The membrane can cover the entire circuit as shown, or at least the metal contacts 225 to form a variable capacitor. This variable capacitor operates in the same manner as the previous embodiment, with ripples in the membrane 265 generated by ambient thermal and vibrational kinetic energy displacing and then returning the membrane 265, and thus one of the capacitor plates (discharging and storing charge in cycles). The cycling causes a corresponding change in charge on the metal contact 225, so that when the capacitive area distance between the metal plate 225 and the membrane 265 increases between the plates, the collected charge on the metal contact is moved toward the storage capacitor for collection. When the capacitive area between the plates 235, 335 of the variable capacitor 120 is minimum (i.e., the plates are closest to each other during the ripple trough), the capacitive charge is at Cmax, along with the charge collected on the metal contact 235. In the example shown for the integrated circuit 400, during the peak ripple time in the window region of the graphene membrane 265, the positive charge carriers collected on the metal contact are directed toward the storage capacitor (i.e., charging the fixed storage capacitor 275), causing current to flow in the direction of the upward arrow. During the trough ripple time in the window region of the graphene film 265, the positive charge carriers are further collected on the metal contacts (i.e., charging the voltage source 200) with negative carriers directed towards the graphene film 265 so that current flows in the direction of the downward arrow.

[0037] FIG. 3C shows a side view of the cross section of the integrated circuit shown in FIG. 3B. The layered integrated circuit 400 includes the voltage source or battery 200 described above, a fixed storage capacitor 275, and an acquisition circuit formed in a substrate, such as, but not limited to, a silicon wafer 205. A free-standing membrane 265 is formed on the structure; in this non-limiting example, the membrane is made of graphene. A diode 250 is formed in the silicon wafer substrate 205. Standoff supports 210 ensure proper isolation and are a source of thermal and kinetic ambient energy. The free-standing graphene membrane 265 has a first surface 125A and a second surface 125B, with the first surface serving as a capacitor plate 335. The silicon wafer includes a metal contact 225, which is another capacitor plate 235 as discussed above. In certain non-limiting embodiments of the present disclosure, the free-standing graphene membrane 265 can be incorporated into a grid 258 that defines a window area for pairing with a metal contact to form a variable capacitor as disclosed herein.

[0038] In another exemplary, preliminary embodiment, an energy harvesting device with a power source for ambient heat and vibration energy harvesting is disclosed, which includes an atomic two-dimensional membrane that buckles at a relatively low frequency. In a non-limiting embodiment, the active component of the membrane can be carbon from isolated graphite. In a specific embodiment, the source can be free-standing graphene, which has a substantially large velocity component in its velocity probability distribution. The vibrating membrane is a noise signal source, but can also be another source of AC power released during the discharge cycle of a capacitor attached to the membrane. See U.S. Patent Publication No. 2019 / 0386584, cited above.

[0039] Devices according to embodiments of the disclosed technology can be incorporated into a variety of systems, devices, and methods for extracting energy, including discharge sensors, force and mass sensors, and self-powered devices with longer charge life.

[0040] Devices according to embodiments of the disclosed technology are also contemplated for use as mass detection devices or flowing charge sensors. For example, in certain embodiments, an analytical computer component operatively connected to the two-dimensional membrane will have a predetermined sensitivity operable to sense and exploit relatively low frequency vibrations from the membrane. As such, the two-dimensional membrane will undergo a buckling frequency, and upon detection of a predetermined change based on the presence of a mass proximate the membrane, an output related to the detection of the mass will be determined and transmitted due to the sensitivity of the membrane of the device to vibrations caused by forces arising from the mass.

[0041] The origin or source of the energy harvested in the above non-limiting examples is primarily thermal energy. In some non-limiting embodiments, the technology used to harvest this energy will be a custom-designed silicon-based integrated circuit. Once designed, the circuit can be built by a commercial semiconductor foundry service. The present disclosure also makes it suitable for manufacturers to work directly with multi-project wafer (MPW) third-party services.

[0042] One non-limiting design discussed below is shown in FIG. 1A and referenced in FIGS. 3B and 3C. As shown in FIGS. 3B and 3C and described in detail in co-pending U.S. Patent Application Publication No. 2019 / 0386584, there is a series of capacitors connected to two diodes, which is an energy harvesting circuit. In one non-limiting example, the set of capacitors 105A, 105B, 105C in FIG. 1A can be variable-gap capacitors, as shown in FIGS. 3B and 3C discussed above and below, which create an AC voltage as the capacitor plates move. The diodes in FIG. 1A then rectify this AC voltage signal.

[0043] At the top of FIG. 1A are three contact pads labeled D1, C, and D2. They provide access to the chip. D1 connects only to the left line of diodes, D2 connects only to the right line of diodes, and C connects only to the series of capacitors. The terms "right," "left," "top," "bottom," "vertical," and horizontal are used as example orientations for the schematic illustrations of FIGS. 1A and 1B and are not intended to limit the present disclosure. One example design is therefore made up of vertically consecutive subunits, illustrated for illustrative purposes as repeating groups of series diode pairs and capacitor sets. 1A, the first subunit 102A includes a first diode pair 110A, 120A and a first set of series capacitors 105A, the second subunit 102B includes a second diode pair 110B, 120B and a second set of series capacitors 105B, and the third subunit 102C includes a third diode pair 110C, 120C and a third set of series capacitors 105C. In the exemplary embodiment, each subunit thus has two diodes 110A, 120A, 110B, 120B, 110C, 120C connected to each other and aligned to pass current in the same direction. In FIG. 1A, the positive cycle of the circuit current flows from right to left.

[0044] Continuing to refer to FIG. 1A , the outputs of the leftmost diodes 110A, 110B, and 110C are connected together by a common metal trace called the diode 1 (D1) trace 141. The D1 trace 141 is also connected to a first contact pad 130 associated with D1 near the top left of the chip in the representation of FIG. 1A , which is used for off-chip access. Similarly, the input signals of the rightmost diodes 120A, 120B, and 120C in the non-limiting illustration are connected together by a common metal trace called the diode 2 (D2) trace 143. The D2 trace 143 is also connected to a second contact pad 140 labeled D2 near the top right of FIG. 1A , which is also used for off-chip access. In each subunit, a respective intermediate metal trace 145A, 145B, and 145C connects two diodes together and has a respective third metal trace 131A, 131B, and 131C extending vertically in the illustration. This third metal trace 131A, 131B, 131C connects each series of capacitors 105A, 105B, 105C at the first end of the capacitors. At the second end of the series of capacitors, there is a common metal trace, called capacitor (C) trace 142. C trace 142 connects all of the second ends of the capacitors together and connects the capacitors to a contact pad near the top, labeled C135, used for off-chip access. In an exemplary assembly, the pattern of diode and capacitor subunits is then repeated thousands of times across the chip, similar to the pattern shown in FIG. 3B, moving downward. The chip will have a limited number of connections for off-chip access. The minimum number of off-chip contacts is three (D1, D2, and C). As discussed further below, instead of power depending only on conductance, this device output shows that power also depends on the rate of change of conductance. This allows for a significant increase in output power.

[0045] Instead of using the diodes described above, the present disclosure also includes using active rectification MOSFETs, which provide a lower "turn-on" voltage and therefore lower losses. If active rectification were used, additional metal traces and metal contact pads would be required for off-chip access. These contacts allow power to be delivered to the chip MOSFET components.

[0046] The capacitance of the capacitors used above will be as small as possible, and in a non-limiting embodiment, may generally be less than 1 picofarad (pF). By adding capacitors in series as shown in FIG. 1A (i.e., by using a series of capacitors 105A, 105B, 105C for each of the single variable capacitors 225A-225n in FIG. 3B), the design reduces the capacitance by a series number. In other words, for each of the variable capacitors 225A-225n in FIG. 3B, one non-limiting configuration incorporates several variable capacitors 105A, 105B, 105C in series, as shown in FIG. 1A, and uses the thermal noise of these series capacitances to increase the power output of the circuit. For example, by having ten 1 pF capacitors in series, the total series capacitance is 0.1 pF. The thermal voltage created by the capacitors can be considered a power source (i.e., the noise power source discussed above). Matching this voltage to the diode performance will help minimize losses and maximize output power.

[0047] Recent theoretical findings disclosed herein demonstrate a power increase over traditional Nyquist theory, as shown in Figure 2. This power increase occurs when nonlinear devices such as diodes and series capacitors are used. Figure 2 illustrates a comparison of accurate theoretical models that predict output power increase from the disclosed designs over Nyquist theory when nonlinear devices such as diodes are used. Equation 1 represents the historical Nyquist result.

number

[0048] The angle brackets <> indicate that the values ​​plotted in FIG. 2 are average values. Within the brackets, T represents temperature, and R represents the load resistance (i.e., the device or application connected to and drawing power from the circuit of FIG. 1A). R has a constant value. C is a capacitance value, such as, but not limited to, the variable capacitance of a plate-graphene junction as described in U.S. Patent Publication No. 2019 / 0386584 and shown in FIG. 3B. R_E, in this exemplary embodiment, is the equivalent resistance of two opposing diodes as shown in FIG. 3C. The value of R_E is not constant but depends on the current flowing in the circuit. After all, current is the time rate of change of charge. The Nyquist plot 215 in FIG. 2 is the average power output at D2 140 versus the voltage at D2 140 in FIG. 1.

[0049] Equation 2 illustrates at least one advancement disclosed herein.

number

[0050] Here, the new term has a variable H in it. H is the total energy of one plate of one variable capacitor, such as graphene 265 in FIGS. 3B and 3C (i.e., the Hamiltonian value of the system). In the non-limiting example of FIGS. 3A and 3B, the energy of the graphene film depends on the charge q. Thus, if the change (delta) is d, then dH / dq = q / C. If R_E is constant, then d / dq (dH / dq) = 1 / C, yielding the Nyquist equation. However, the d / dq term also represents the rate of change of the diode's resistance as charge changes (changing charge is current). Because the calculation cannot be written in a simple form, the value of the equation is plotted as the exact output 208 to graphically illustrate the enhancement to the Nyquist equation. A test setup 405 plotting these results 410, 412 from test circuits 418, 422 monitored by computer 427 is shown in FIG. 4. Numerous computerized components may be incorporated into all embodiments of the present disclosure.

[0051] The graph in Figure 5 shows the output noise voltage of various capacitors tested in accordance with the present disclosure. Plot 505 shows the output voltage versus 1 / C. Note that the larger the value of 1 / C, the larger the output voltage. The minimum capacitance shown at 515 is 10~12 Farads (1 pF), although this is not a limitation of the present disclosure.

[0052] 1A and 1B are described above as illustrating a first, non-limiting embodiment. The energy harvesting system shown in FIG. 1B includes an on-chip circuit 100 (detailed in FIG. 1A) and an off-chip circuit 102 (which, for purposes of discussion, may be equivalent to, but is not limited to, the circuitry of FIGS. 3A and 3B). The off-chip circuit 102 includes a DC voltage source 150 connected to a plurality of capacitors 105A, 105B, and 105C within the on-chip circuit 100, which are connected in series as discussed above to generate an AC noise signal on lines 131A, 131B, and 131C. This connection is shown in FIG. 1B at the contact pad labeled C135, which connects the C trace 142 of FIG. 1 as the AC voltage source. By selecting capacitors with a specified design specification, a selected bandwidth of the AC noise signal is transmitted through the series of capacitors 105A, 105B, and 105C as a first AC power signal. The capacitors take into account noise response, such as a measurement of the noise signal standard deviation. In one non-limiting theory of operation, the AC noise signal includes at least conductivity due to conductive carrier defect hopping through the capacitors. The first AC noise signal 131A, 131B, 131C is directed to respective diodes 110A, 110B, 110C, 120A, 120B, 120C, which rectify the first power signal to charge positive-cycle storage capacitor 160 and negative-cycle storage capacitor 170 with the first AC power signal. The series of capacitors collectively reduces the overall series capacitance due to the additive nature of the exemplary series mutual capacitance. In one non-limiting embodiment, the capacitors are configured to have a storage capacitance of 1 picofarad (1 pF).

[0053] FIG. 1 utilizes AC noise signals 131A, 131B, and 131C present across a series of capacitors; in one non-limiting embodiment, the noise signals are thermal noise. The thermal noise can be controlled, at least in part, by the ambient conditions of a chip having the circuit of FIGS. 1A and 1B. For example, the circuit of FIG. 1A can be exposed to a heated environment to increase the amplitude of the thermal noise. First AC noise signals 131A, 131B, and 131C are a subset of the frequencies of the ambient noise signal transmitting through the capacitors. The first AC noise signal is rectified through forward-biased diodes 110A, 110B, and 110C during the positive cycle of the first AC noise signal to produce an output power signal. The first AC noise signal is further rectified through reverse-biased diodes 120A, 120B, and 120C during the negative cycle of the first AC power signal to produce a corresponding output power signal. The diodes may be paired as part of a subunit, which is connected to a positive cycle metal trace connection 141 and a negative cycle metal trace connection 143. The subunits are repeated with their respective connections to the positive cycle metal trace connection and the negative cycle metal trace connection.

[0054] In some non-limiting versions of the embodiment shown in Figures 1A and 1B, the capacitors are fully charged to a steady state by a DC voltage source (similar to Figure 3B reference numeral 200) located either off-chip (Figure 1B) or on-chip, as needed. The DC voltage source 200 provides a voltage corresponding to the turn-on voltage of the diode or other non-linear circuit component being used. The diode is selected based on its conductance rating to match the capacitors as a noise source.

[0055] In another embodiment, the forward base diode and reverse biased diode are connected to additional diodes in a Cockcroft-Walton full-wave rectifier and multiplier circuit, as shown in Figure 3A. The AC noise signals 131A, 131B, and 131C, shown in Figure 1A as outputs from a series of capacitors 105A, 105B, and 105C, can be connected to the positive and negative terminals 308A and 308B. The full-wave rectifier establishes multiple input power signals in stages with forward-biased diodes 310 and reverse-biased diodes 320, and the rectified power signal is directed to the DC output 365.

[0056] The circuitry of the corresponding figures herein may use multiple capacitors 305 with variable gap capacitors generating both a first AC power signal from the AC noise signal and a second AC power signal from the variable gap capacitor discharge. Variable gap capacitor technology is discussed above, and U.S. Patent Publication No. 2019 / 0386584 ("Energy Harvesting Devices and Sensors and Methods of Making and Use Thereof") discusses the technology in detail, and this patent application is incorporated by reference as if fully set forth herein.

[0057] As shown in FIGS. 1A and 1B, the energy harvesting circuit can be implemented as an integrated circuit on a chip. FIG. 1A illustrates an on-chip circuit having multiple capacitors connected in series and generating the AC noise signal described above. A selected bandwidth of the AC noise signal is transmitted through a series of capacitors as a first AC power signal. Respective rectifiers receive a positive cycle of the first AC power signal and a negative cycle of the first AC power signal. Output terminals are connected to each rectifier and configured for connection to off-chip circuitry. In one non-limiting embodiment shown in FIG. 1B, the off-chip circuitry can include a companion circuit, including, but not limited to, a DC voltage source connected to multiple capacitors, namely, a positive-cycle storage capacitor and a negative-cycle storage capacitor, which are charged with the first AC power signal. When the off-chip circuitry is configured as shown in FIGS. 3B and 3C, normal operation of discharging the capacitive field across each rectifier also directs the stored charge to add a second power signal to the energy harvesting circuit. In other words, the rectified thermal noise signals 131A, 131B, 131C of the present disclosure are the first power signals, and in some embodiments, conventional variable capacitor energy harvesting as shown in FIGS. 3B and 3C is the second power signal for energy harvesting.

[0058] The variable-gap capacitor technology discussed above is suitable for efficient energy harvesting circuits. The method steps may include at least connecting a series of capacitors within the energy harvesting circuit and, for each capacitor in the series, defining a first capacitor plate having an initial separation distance relative to a first surface of a free-standing membrane to form a capacitive region within the energy harvesting circuit. The first surface of the free-standing membrane defines a second capacitor plate. Exposing the free-standing membrane to ambient thermal energy induces charge accumulation in the capacitive region, and the ambient thermal energy also induces a thermal AC noise signal. The method includes selecting the capacitance of the capacitors to select a bandwidth of the AC noise signal to transmit through the series of capacitors as a first AC power signal. In accordance with the remainder of the disclosure, the method includes rectifying the first AC power signal to charge a positive-cycle storage capacitor and a negative-cycle storage capacitor with the first AC power signal. Implementing the method, in a non-limiting embodiment, includes positioning the membrane relative to the first capacitor plate so that the membrane vibrates freely and unhindered in response to ambient thermal energy. The vibration of the membrane defines periodic ripple formations along the first surface, each ripple forming an alternating peak and a valley relative to the first capacitor plate to vary the initial separation distance in the variable gap capacitor. Discharging the capacitive region across each rectifier directs the stored charge to add a second power signal to the energy harvesting circuit.

[0059] Experiment disclosure As discussed in the above-referenced patent application publication on energy harvesting, U.S. Patent Publication No. 2019 / 0386584 ("Energy Harvesting Devices and Sensors and Methods of Making and Use Thereof"), the linear power formula found from the model for output power is similar to the Nyquist equation P = kBT / RC, where C is the average capacitance of the fluctuating graphene. Under certain modeling conditions, the total movement of the graphene can be made smaller, but the formula remains the same. This means that if the fixed capacitance is the average capacitance, a fixed capacitor should also work and give the same formula. Tests have shown that output power is enhanced at lower frequencies. The mechanism in the primary, but non-limiting, model used herein is a slowing of the rate at which graphene reverses its curvature due to strain accumulation. One non-limiting theory of operation believes that the conduction mechanism (barrier crossing rate) is the origin of all 1 / f noise.

[0060] The conclusion is that 1 / f noise exists in all electronic devices, including fixed capacitors (thought to be due to defect hopping). This means that fixed capacitors will provide enhanced power even at lower frequencies. The voltage fluctuation across the output of the variable-gap capacitor (Vrms) for the graphene experiments is small, approximately 30 mV. Because one goal is to rectify the signal, it is best to set this voltage above the "turn-on" diode voltage (200 mV for Schottky diodes). Silicon diodes (700 mV turn-on) have also been tested for active rectification using MOSFET technology. While these devices require a small amount of power to operate, their turn-on voltage is only 10 mV. Comparing applications in the photovoltaic industry, the electrical resistance losses when using silicon were much greater than the power used to drive the MOSFET. This allows for the full use of the amplifier benefits provided by transistors.

[0061] To test this, one test example, as shown in FIG. 4, was constructed in the form of a full-wave rectifier 418 to which a 10x multiplier circuit from passive diodes and capacitors was added. While the noise signal actually originates from a series of capacitors, recall that a simulated test input noise signals 410, 412 with a Vrms of 200 mV (average zero) resulted in an output 422 of 2 VDC, as shown for the experiment on multimeter 427. Since this worked for Schottky (and silicon at 700 mV), this same theory of operation would work for MOSFETs at 10 mV. The low voltage is not a problem. While the voltage is lower for fixed capacitors than for graphene, fixed capacitors have been demonstrated in the lab to increase the output voltage by a factor of four when, for example, 16 capacitors are connected in series. This disclosure and related test results demonstrate that by designing related integrated circuits, users can have them built using known foundry resources. In one non-limiting embodiment, the circuit can be laid out in any desired manner, typically having over 10,000 circuit elements on a 2.5 mm x 2 mm chip. In one example, the smallest capacitance capacitor made by an exemplary foundry is 0.2 pF, which is small enough (and takes up a small area). This leads to the conclusion that we can design an array of these capacitors, followed by an active rectifier / multiplier circuit, to create a power generation chip with current technology. This chip is low-risk, low-cost, and will help us in our research toward more powerful graphene chips.

[0062] Additionally, as further discovered in the research model, when a capacitor is placed with a diode and resistor in a particular circuit layout, the output power increases beyond known formulas for Nyquist comparison.

[0063] As shown in Figure 7, this disclosure successfully develops a detailed physical understanding of Nyquist noise voltage. The noise voltage increases with decreasing capacitance, as originally predicted. This disclosure also illustrates an approximately tenfold increase in noise power when a test circuit adds a specific resistor value in parallel with a series of capacitors 105A, 105B, and 105C. The resistor value must match the resistance of the circuit used to measure the noise power. The data for this discovery is shown in Figure 7, where the noise voltage generated by a 10 pF capacitor is plotted as a function of the resistance of the resistor connected in parallel with the 10 pF capacitor. The noise voltage is greatest when the parallel resistance is 100 MΩ, the same resistance as the measurement circuit. Without the resistor added in parallel, the noise voltage drops tenfold. Adding no resistor is equivalent to adding a very large resistor in parallel. The trend line for adding too large a resistor is shown in Figure 7 as a square.

[0064] As shown in Figure 8, this disclosure tested three rectifier-multiplier circuit topologies on a breadboard and then tested them using a noise power input source. The topologies are known as differential drive, charge pump, and Schottky-Cockcroft-Walton. Unfortunately, differential drive actually divides the signal instead of multiplying it. While the other two topologies multiply the signal, Schottky-Cockcroft-Walton offers the best performance. Figure 8 shows the gain of both the 18-stage and 24-stage Schottky-Cockcroft-Walton rectifier-multiplier circuits as a function of input noise voltage. When the input noise voltage has an effective value of 10 mV, the output voltage is approximately five times larger, or 50 mV DC. On a silicon wafer chip, the results show that the input effective noise voltage is 100 mV, and in this case, the output voltage is a very significant 3.5 volts DC.

[0065] Figure 6 of the present disclosure illustrates that the computerized systems described herein can be used in conjunction with equipment that monitors or assists in energy harvesting. New models / functions can be pushed to various servers and cloud-based servers as needed.

[0066] The implementations described above in connection with Figures 1-6 may be used with an apparatus implementing a computerized method initiated by an electronic control unit ("ECU") 600. In particular, the described apparatus, including a computer used as part of the system, communicates with a computer processor configured to process one or more characteristics and / or profiles of received electrical signals. By way of example, and without limiting the disclosure to any particular hardware or software, Figure 6 illustrates a block diagram of a system herein according to one implementation.

[0067] The ECU 600 may include a computing unit 606, a system clock 608, an output module 610, and communication hardware 612. In its most basic form, the computing unit 606 may include a processor 604 and a system memory 610. The processor 602 may be a standard programmable processor that performs arithmetic and logical operations necessary for the operation of the sensor system 600. The processor 602 may be configured to execute program code encoded on a tangible computer-readable medium. For example, the processor 602 may execute program code stored in a system memory 604, which may be volatile or non-volatile memory. The system memory 604 is only one example of a tangible computer-readable medium. In one aspect, the computing unit 606 may be considered an integrated device, such as firmware. Other examples of tangible computer-readable media include a floppy disk, a CD-ROM, a DVD, a hard drive, a flash memory, or any other machine-readable storage medium; when program code is loaded into and executed by a machine, such as the processor 602, the machine becomes an apparatus for implementing the disclosed subject matter.

[0068] Any combination of one or more computer-readable media may be utilized. The computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. The computer-readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the above. More specific examples (non-exhaustive list) of computer-readable storage media include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the context of this specification, a computer-readable storage medium may be any tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device.

[0069] A computer-readable signal medium may include a propagated data signal in which computer-readable program code is embodied, for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electromagnetic, optical, or any suitable combination thereof. A computer-readable signal medium is not a computer-readable storage medium but may be any computer-readable medium that can communicate, propagate, or transfer a program for use by or in connection with an instruction execution system, apparatus, or device.

[0070] The program code embodied on the computer readable medium may be transmitted using any suitable medium, including, but not limited to, wireless, wireline, fiber optic cable, RF, etc., or any suitable combination of the above.

[0071] Computer program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages ​​such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter scenario, the remote computer may be connected to the vehicle computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or a connection may be made to an external computer (e.g., through the Internet using an Internet Service Provider).

[0072] These computer program instructions may also be stored in a computer-readable memory that can direct a computer, other programmable data processing apparatus, or other device to function in a particular manner, such that the instructions stored in the computer-readable memory create an article of manufacture that includes instructions that implement the functions / acts specified in one or more blocks of the flowcharts and / or block diagrams.

[0073] Computer program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus, or other device, creating a computer-implemented process such that the instructions executing on the computer or other programmable apparatus provide a process for implementing the functions / acts specified in one or more blocks of the flowcharts and / or block diagrams.

Claims

1. 1. An energy harvesting system, comprising: a DC voltage source connected to at least one capacitor that generates an AC noise signal having a pre-determined frequency and amplitude; a selected bandwidth of the AC noise signal for transmission through the capacitor as a first AC power signal; a diode for rectifying the first AC power signal to charge a positive cycle storage capacitor and a negative cycle storage capacitor with the first AC power signal, respectively; A system comprising:

2. The system of claim 1 , wherein the AC noise signal is a thermal noise signal and the at least one capacitor is a plurality of capacitors connected in series.

3. The system of claim 1 , wherein the capacitor is configured to have a storage capacitance of 1 picofarad.

4. 10. The system of claim 1, further comprising the first AC power signal rectified through a forward biased diode during a positive cycle of the first AC power signal to produce an output power signal.

5. 5. The system of claim 4, further comprising the first AC power signal rectified through a reverse-biased diode during a negative cycle of the first AC power signal to produce an output power signal.

6. 6. The system of claim 5, wherein the diodes are paired as subunits, the subunits are connected to a positive cycle metal trace connection and a negative cycle metal trace connection, and the subunits are repeated in their respective connections to the positive cycle metal trace connection and the negative cycle metal trace connection.

7. 6. The system of claim 5, wherein the forward biased diode and the reverse biased diode are connected to additional diodes in a Cockcroft-Walton full-wave rectifier circuit and a multiplier circuit.

8. 2. The system of claim 1, wherein the at least one capacitor comprises a variable gap capacitor that generates both the first AC power signal from the AC noise signal and a second AC power signal from a variable gap capacitor discharge cycle.

9. The system of claim 1 , wherein the capacitor is fully charged to a steady state by the DC voltage source.

10. The system of claim 1 , wherein the diode is selected based on a conductance rating to match the capacitor as a noise source.

11. 2. The system of claim 1, wherein the AC noise signal comprises conductivity due to conductive carrier defect hopping through the capacitor.

12. The system of claim 1 , wherein the DC voltage source provides a voltage corresponding to a turn-on voltage of the diode.

13. 1. An integrated circuit on a chip, comprising: at least one capacitor connected to the integrated circuit for generating an AC noise signal having a predetermined frequency and amplitude; a selected bandwidth of the AC noise signal for transmission through the capacitor as a first AC power signal; a rectifier receiving a positive cycle of the first AC power signal and a negative cycle of the first AC power signal; an output terminal connected to each of the rectifiers and configured for connection to off-chip circuitry; and 1. An integrated circuit comprising:

14. The integrated circuit of claim 13 , wherein the AC noise signal results from ambient thermal energy.

15. The integrated circuit of claim 13, configured to connect to the off-chip circuitry having a DC voltage source connected to the at least one capacitor including a positive cycle storage capacitor and a negative cycle storage capacitor that are charged by the first AC power signal.

16. 14. The integrated circuit of claim 13, further comprising: a first diode configured as a first respective rectifier of the first AC power signal to produce a first output power signal from a positive cycle of the first AC power signal.

17. 17. The integrated circuit of claim 16, further comprising: a second diode configured as a second respective rectifier of the first AC power signal to produce a second output power signal from a negative cycle of the first AC power signal.

18. 1. An integrated circuit comprising: at least one capacitor for generating an AC noise signal having a predetermined frequency and amplitude; a selected bandwidth of the AC noise signal for transmission through the capacitor as a first AC power signal; forward-biased and reverse-biased transistors for rectifying corresponding positive and negative cycles of the AC noise signal, respectively; an output terminal connected to the forward biased transistor and the reverse biased transistor, respectively, and configured to connect to off-chip circuitry for harvesting energy from the output signal; and 1. An integrated circuit comprising:

19. 1. A method of assembling an energy harvesting circuit, comprising: connecting at least one capacitor in the energy harvesting circuit; forming a capacitive region within the energy harvesting circuit by defining the at least one capacitor with a first capacitor plate having an initial separation distance relative to a first surface of a free-standing membrane, the first surface of the free-standing membrane defining a second capacitor plate; exposing the free-standing membrane to ambient thermal energy to induce charge accumulation in the capacitive regions, the ambient thermal energy also inducing a thermal AC noise signal; selecting a capacitance of the capacitor to select a bandwidth of the thermal AC noise signal for transmission through the capacitor as a first AC power signal having a predetermined frequency and amplitude; rectifying the first AC power signal to charge a positive cycle storage capacitor and a negative cycle storage capacitor with the first AC power signal; A method comprising:

20. 20. The method of claim 19, further comprising positioning the free-standing membrane relative to the first capacitor plate so that the free-standing membrane vibrates unhindered and freely in response to ambient thermal energy, the vibration of the free-standing membrane defining periodic ripple formations along the first surface, each ripple formation alternating between a peak and a valley relative to the first capacitor plate to vary the initial separation distance in a variable gap capacitor.

21. 21. The method of claim 20, further comprising discharging the capacitive region across each rectifier to direct stored charge to add a second power signal to the energy harvesting circuit.

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