WO2019083899A1

WO2019083899A1 - Thin film self-switching device

Info

Publication number: WO2019083899A1
Application number: PCT/US2018/056927
Authority: WO
Inventors: Vera N. LOCKETT; Sri Harsha KOLLI; William J. Ray
Original assignee: Printed Energy Pty Ltd; Min, Kyu, S.
Priority date: 2017-10-23
Filing date: 2018-10-22
Publication date: 2019-05-02

Abstract

A self-switching device includes a thin film conductive line and a gap in the thin film conductive line having disposed therein a resistance change (RC) material. Upon application of a current across the gap, the RC material transitions from a low resistance state (LRS) to a high resistance state (HRS), and wherein upon attaining the HRS, the RC material transitions from the HRS to the LRS by self-switching.

Description

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application Number 62/575,925, filed October 23, 2017, entitled "THIN FILM INTERVAL TIMER," the content of which is hereby incorporated by reference herein in its entirety.

BACKGROUND

Field

[0002] The disclosed technology generally relates to switching devices, and more particularly to printed thin film self-switching devices, apparatuses incorporating the same and methods of fabricating the same.

Description of the Related Art

[0003] Recent advances in thin film-based electronic devices such as printed electronic devices have enabled various new forms of electronics that are adapted for internet of things (loT) and smart packaging, for potentially lower cost. Such thin film-based electronic devices include flexible displays and electronics on 3D structures, larger area electronics such as sensor arrays and higher performance devices such as organic light emitting displays, to name a few.

[0004] Electronic switching devices, such as timer devices, can enable new thin film-based electronic devices, including light emitting devices, sound-generating devices and sensor devices, among others. Traditionally, electronic switching devices have been implemented as integrated circuit (IC) devices based on bipolar junction transistor (BJT) and/or complementary metal oxide semiconductor (CMOS) technologies. For example, timer IC devices have been used in a variety of timer, pulse generation and oscillator applications. However, IC-based switching devices include relatively complex circuits, such as logic and clock circuits. Due to their complexity, switching device designs have remained difficult to implement using thin film technologies, e.g., printed thin film technologies. Thus, there is a need for thin-film based electronic switching devices, e.g., printed electronic switching devices, for further enabling various new devices, and enabling new device functionalities in existing thin film-based electronic devices.

SUMMARY

[0005] A self-switching device comprises a resistance change (RC) material that self-switches. The RC material switches from a first resistance state to a second resistance state upon application of a current thereacross. Upon attaining the second resistance state, the RC material self-switches to the first resistance state. The first resistance state may be a low resistance state and the second resistance state may be a high resistance state. The first resistance state may be a solid state and the second resistance state may be a liquid state. One or more layers of the self-switching device or the entire device may be printed.

[0006] An apparatus comprises a resistance change (RC) material that self- switches and one or both of a core device and an energy source. Upon being connected to the core device and the energy or power source, the RC material self-switches from a first resistance state to a second resistance state. The core device is configured to receive intermittent energy from the energy or power source. The energy source may be a primary battery (e.g., one-time use battery), a secondary batter}' (e.g., rechargeable battery), a fuel cell, a capacitor, and/or a super capacitor (e.g., a symmetric or asymmetric super capacitor including an electric double-layer capacitor (EDLC) and/or a pseudo capacitor). One or more layers of or the entire apparatus may be printed.

[0007] A device is configured to be a self-switching device upon activation. The device may be activated by disposing a resistance change (RC) material into a gap formed between conductors of the device. Upon activation, the RC material switches from a first resistance state to a second resistance state upon application of a current thereacross.

[0008] In a first aspect, a self-switching device includes a thin film conductive line and a gap in the thin film conductive line having disposed therein a resistive change (RC) material. Upon application of a current across the gap, the RC material transitions from a low resistance state (LRS) to a high resistance state (HRS), and wherein upon attaining the HRS, the RC material transitions from the HRS to the LRS by self-switching. The RC material may transition from the LRS to the HRS and from the HRS to the LRS without changing a voltage applied to the self-switching device. The RC material may transition from the LRS to the HRS and from the HRS to the LRS under a positive voltage or a negative voltage applied to the self- switching device. After transitioning from the HRS to the LRS by self-switching, the RC material may transition from the LRS to the HRS by self-switching. The transition from the HRS to the LRS by self-switching and the transition from the LRS to the HRS by self-switching may repeat cyclically. The application of the current across the gap may generate heat, and the generated heat may cause the transition from the LRS to the HRS. The transition from the LRS to the HRS may correspond to a first phase change of the RC material, and the transition from the HRS to the LRS may correspond to a second phase change of the RC material. The transition from the LRS to the HRS may correspond to a solid-to-liquid transition of the RC material, and the transition from the HRS to the LRS may correspond to a liquid-to-solid transition of the RC material. The RC material may have a melting temperature of about 40 °C to 80 °C. The transition from the LRS to the HRS and the transition from the HRS to the LRS may occur within an interval of about 0.1 second to about 10 minutes. The HRS may have a higher resistance value compared to the LRS by a factor between about 2 and about 000. The RC material in the LRS may have an electrical resistance that is substantially higher than an electrical resistance of the thin film conductive line, such that the transition from the LRS to the HRS is caused at least in part by self-heating of the RC material in the gap. The device may further comprise a resistive heating element electrically connected to the RC material and the thin film conductive line, wherein application of the current across the resistive heating element produces heat, and wherein the produced heat causes the transition of the RC material from the LRS to the HRS. The transition from the HRS to the LRS may- comprise conduction of heat away from the RC material to a surrounding environment. The device may further comprise a heat conductive element and a resistive heating element contacting the heat conductive element, wherein application of the current across the resistive heating element produces heat, and wherein the produced heat that is conducted through the heat conductive element causes the transition of RC material from the LRS to the HRS. The device may further have a thickness in a range of 1 micron to 2000 microns. The device may further comprise one or both of an electrically powered component and an energy source electrically coupled to the electrically powered component by the thin film conductive line. The device may further comprise a switch for activating the electrically powered component. The RC material may be between the switch and the electrically powered device. The thin film conductive line may be formed from a printed conductive ink. At least one of the electrically powered component and the energy source may be formed from a printed ink. The RC material may be exposed to air. The RC material may be enclosed to inhibit evaporation of the RC material. The gap may have a width and the RC material in the HRS is in a liquid state having a viscosity such that, when the RC material is in the liquid state, the RC material is held in the gap by a capillary force. The gap may have a width between about 10 um and about 1000 μιη. The RC material may comprise an organic material. The RC material may comprise a material selected from the group consisting of an ionic liquid, a polymeric material, an alcohol, an aldehyde, an amine, a carboxylic acid, an ester, a ketone, a phenol, or a combination thereof. The RC material may comprise a composite material comprising an organic material and a conductive additive. The RC material may comprise a composite material comprising an organic material and a carbon-based conductive additive selected from the group consisting of carbon, graphite, pyrolytic graphite, graphene, reduced graphene oxide, carbon nanotubes, carbon nanoonions, or a combination thereof. The RC material may comprise a composite material comprising an organic material and a metal -containing additive selected from the group consisting of silver, nickel, copper, copped coated with nickel, copper coated with silver, a plastic coated with a metal, a glass coated with a metal, or a combination thereof.

[0009] In a second aspect, a self-switching apparatus includes a core device and a power source configured to deliver power sufficient to activate the core device. The self- switching apparatus additionally includes a self-switching device electrically connected between the power source and the core device. The self-switching device includes a resistance change (RC) material, wherein, after the core device is activated by the power source, the RC material transitions from a low resistance state (LRS) to a high resistance state (HRS) by self- switching, thereby deactivating the core device. The transition from the LRS to the HRS by self-switching may be followed by a transition of the RC material from the HRS to the LRS by self-switching, thereby reactivating the core device. The deactivation and the self- reactivation may repeat cyclically. The core device may be a device selected from the group consisting of a light emitting device, a sound-generating device, or a sensor device. The one or more of the core device, the self-switching device and the power source may be printed devices having a thickness i a range of 1 |im to 2000 μτη. The self-switching device of the apparatus may comprise a thin film conductive line and a gap in the thin film conductive line having disposed therein the RC material. The RC material may transition from the LRS to the HRS by self-switching by a current applied across the gap. Upon deactivation of the core device, the RC material may transition from the HRS to the LRS by self-switching, thereby reactivating the core device. The self-switching device of the apparatus may be according to the device of any one of the configurations of the first aspect. The RC material may comprise an organic material. The RC material may comprise a material selected from the group consisting of an ionic liquid, a polymeric material, an alcohol, an aldehyde, an amine, a carboxylic acid, an ester, a ketone, a phenol, or a combination thereof. The RC material may comprise a composite material comprising an organic material and a conductive additive. The RC material may comprise a composite material comprising an organic material and a carbon- based conductive additive selected from the group consisting of carbon, graphite, pyrolytic graphite, graphene, reduced graphene oxide, carbon nanotubes, carbon nanoonions, or a combination thereof. The RC material may comprise a composite material comprising an organic material and a metal -containing additive selected from the group consisting of silver, nickel, copper, copped coated with nickel, copper coated with silver, a plastic coated with a metal, a glass coated with a metal, or a combination thereof.

[0010] In a third aspect, a self-switching device includes a thin film conductive line configured to be electrically biased thereacross and a gap in the thin film conductive line configured hold a resistance change (RC) material. The device additionally includes a reservoir containing the RC material, wherein the reservoir is in fluidic communication with the gap and configured to transfer the RC material in a liquid state to the gap. The reservoir may be configured to liquefy the RC material prior to transferring the RC material to the gap. The reservoir may be configured to liquefy the RC material by heating. The gap may have a spacing and the RC material in the liquid state has a viscosity such that upon being transferred to the gap, the RC material is held in the gap at least in part by capillary action. The reservoir may be configured to apply pressure to the RC in the liquid state to transfer the RC material into the gap. The device may be configured such that, after the RC material is transferred to the gap, the RC material cools to a solid state. The RC material in the solid state may- correspond to a low resistance state (LRS) and the RC material in the liquid state may correspond to a high resistance state (HRS). After the RC material cools to the solid state, upon application of a current across the gap having the RC material disposed therein, the RC material transitions from the LRS to the HRS, and wherein upon attaining the HRS, the RC material transitions from the HRS to the LRS by self-switching. The device may be according to the device of any one of configurations of the first aspect. The RC material may comprise an organic material. The RC material may comprise a material selected from the group consisting of an ionic liquid, a polymeric material, an alcohol, an aldehyde, an amine, a carboxylic acid, an ester, a ketone, a phenol, or a combination thereof. The RC material may comprise a composite material comprising an organic material and a conductive additive. The RC material may comprise a composite material comprising an organic material and a carbon- based conductive additive selected from the group consisting of carbon, graphite, pyrolytic graphite, graphene, reduced graphene oxide, carbon nanotubes, carbon nanoonions, or a combination thereof. The RC material may comprise a composite material comprising an organic material and a metal -containing additive selected from the group consisting of silver, nickel, copper, copped coated with nickel, copper coated with silver, a plastic coated with a metal, a glass coated with a metal, or a combination thereof.

[0011] For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages are described herein. Of course, it is to be understood that not necessarily all such objects or advantages need to be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the invention may be embodied or earned out in a manner that can achieve or optimize one advantage or a group of advantages without necessarily achieving other objects or advantages.

[0012] All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments will become readily apparent to those skilled in the art from the following detailed description having reference to the attached figures, the invention not being limited to any particular disclosed embodiment(s).

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 A schematically illustrates a plan view of an example self-switching device. [0014] FIG. IB schematically illustrates a side view of the self-switching device of FIG. 1A.

[0015] FIG. 2 schematically illustrates a side view of an example apparatus comprising a self-switching device having a resistance change (RC) material disposed in a gap formed in a conductive line, where the self-switchmg device is connected between a power source and a core device.

[0016] FIG. 3A schematically illustrates a plan view of an example self-switching device having a resistance change (RC) material disposed in a gap formed in a resistive heating element.

[0017] FIG. 3B schematically illustrates a side view of the self-switching device illustrated in FIG. 3 A in which the resistance change (RC) material completely fills or overfills the gap formed in a resistive heating element.

[0018] FIG. 3C schematically illustrates a side view of a self-switchmg device similar to the switching device illustrated in FIG. 3A, in which the resistance change (RC) material partially fills the gap formed in a resistive heating element.

[0019] FIG. 4 schematically illustrates a cross-sectional view of an example self- switching device having an encapsulated resistance change (RC) material disposed in a gap formed in a resistive heating element.

[0020] FIG. 5 A schematically illustrates a plan view of an example self-switching device having a resistance change (RC) material in thermal communication with a resistive heating element through a heat conductive element.

[0021] FIG. 5B schematically illustrates a side view of the self-switchmg device of FIG 5A,

[0022] FIG. 6A schematically illustrates a plan view of an example self-switching device having a gap formed in a resistive heating element and a reservoir containing a resistance change (RC) material that is in fluidic communication with the gap and configured to transfer the RC material in a liquid state to the gap.

[0023] FIG. 6B schematically illustrates the self-switchmg device of FIG. 6A, after activation by transferring the RC material into the gap. DETAILED DESCRIPTION

[0024] Although certain embodiments and examples are described below, those of skill in the art will appreciate that the invention extends beyond the specifically disclosed embodiments and/or uses and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the invention herein disclosed should not be limited by any particular embodiments described below.

[0025] In various embodiments disclosed herein, devices and apparatuses comprise a self-switching device. The self-switching device includes a thin film conductive line having a gap. A resistance change (RC) material is disposed in the gap. Upon application of a current across the gap, the RC material transitions from a low resistance state (LRS) to a high resistance state (HRS). After attaining the HRS, the RC material self-transitions from the HRS to the LRS. The self-switching device can serve many functions, including providing interval timing, overstress protection and periodic or pulsed power to a variety of core devices connected thereto.

[0026] One or more components of various devices and apparatuses described advantageously may comprise of thin film features. One or more of the thin film features are printed features. As described herein, suitable printing processes for forming the thin features include screen printing, roll-to-roll printing, ink-jet printing, among other suitable printing processes. Printed devices or components thereof can provide various advantages, including reduced thickness, compact dimensions. Printed devices can also enable increased functionalities for a given footprint of the device by enabling, among other things, stacking of the printed devices or components thereof. Unlike devices manufactured using other processes, some printed devices can also be flexible, which can be suitable for wearable devices including wearable medical devices, displays, sensors, smartcards, smart packaging, smart clothing, signage, advertisements, among other devices.

Example Thin Film Self-Switching Devices Having a Resistance Change Material

[0027] FIGS. 1 A and IB schematically illustrate a plan view and a side or cross- sectional view of an example self-switching device 100, according to embodiments. The device 100 comprises a substrate 102 (FIG. IB) having formed thereon a thin film conductive line 124 configured to be electrically biased thereacross by a power or energy source, e.g., a primar battery (e.g., one-time use battery), a secondary battery (e.g., rechargeable battery), a fuel cell, a capacitor, and/or a supercapacitor (e.g., a symmetric or asymmetric supercapacitor including an electric double-layer capacitor (EDLC) and/or a pseudo capacitor). The conductive line 124 has a gap 1 2, having disposed therein a resistance change (RC) material 116. The RC material 116 is adapted such that, once the self-switching device 100 is activated, e.g., by application of a bias across the gap using a power or energy source, current flows through the thin film conductive line 124 and across the gap 112, whereby the RC material 116 transitions from a low resistance state (LRS) to a high resistance state (HRS). After the RC material 116 attains the HRS, the RC material 116 transitions from the HRS to the LRS by self-switching. In various embodiments, the cycle of transitions of the RC material 116 from the LRS to HRS, and from the HRS to the LRS occurs at least once, such that the current flowing across the conductive line 124 cycles at least once from a relatively high current to a relatively low current, such that a core device that may be connected to a power supply through the self-switching device 00 is activated and deactivated by self-switching at least once. In various embodiments, the cycle including the LRS to HRS and HRS to LRS transitions occurs only once. In various embodiments, a change from LRS to HRS may lack or not include a subsequent change from HRS to LRS. In various embodiments, the cycle including the LRS to HRS and HRS to LRS transitions occurs a plurality of times (e.g., 2 times, 3 times, 5 times, 10 times, 15 times, 25 times, 50 times, 100 times, 1 ,000 times, 10,000 times, 100,000 times, and ranges between such values). More times is also possible. That is, after transitioning from the LRS to the HRS and from the HRS to the LRS by self-switching as described above, the RC material 116 repeats the transitions from the LRS to the HRS and from the HRS to the LRS by self-switching. In some embodiments, the transition from the HRS to the LRS and the transition from the LRS to the HRS repeats cyclically until, e.g., the self-switching device 100 is interrupted or deactivated, e.g., by removal or upon disappearance of the bias across the gap 1 12.

[0028] The self-switching device 100 may be formed on a substrate 102, which may be formed of a suitable material, which may have attributes such as being flexible or rigid, electrically conductive or insulating, thermally conductive or insulating, optically transparent or opaque, organic or inorganic, among other attributes. Suitable classes of materials for the substrate 102 include, but not limited to, a polymeric material, a textile-based material, a device, a metallic material, a semiconductor material or a celiulose-based material. Specific examples of the substrate 102 include, e.g., a plastic (e.g., polyester, polyimide, polycarbonate), a polyester film (e.g., Mylar), a polycarbonate film, an aluminum foil, a copper foil, a stainless steel foil, a carbon foam, or a paper, such as a graphite paper, a graphene paper, a cardboard, a coated paper, such as a plastic-coated paper, and/or a fiber paper, or combinations thereof, and/or the like. A self-switching device 100 that is printed on a flexible substrate may be integrated with flexible printed energy storage devices and/or core devices that can be used in a wide array of devices and implementations.

[0029] As described herein, self-switching refers to a process by which an increase or a decrease in the amount of current flowing through a switching device, such as the self- switching device 100, e.g., an HRS to LRS transition or a LRS to HRS transition, occurs intrinsically by an internal change in the electrical resistance across the switching device, e.g., by a change in resistance of the RC material 1 16, instead of externally controlling the current or voltage applied to the self-switching device.

[0030] In some embodiments, the LRS to HRS and HRS to LRS transitions of the RC material 116 are accompanied by a first order transition accompanied by a change in the arrangement of atoms or molecules of the RC material 116. The change in the arrangement of atoms or molecules can include, e.g., a phase change. In some embodiments, the LRS to HRS transition corresponds to a first phase change of the RC material 1 16, and the HRS to LRS transition corresponds to a second phase change of the RC material 1 16. For example, the LRS to HRS transition can include a solid- to-liquid transition of the RC material 1 16, and the HRS to LRS transition can include a liquid-to-solid transition of the RC material 1 16. However, in other examples, the HRS to LRS transition can include a solid-to-liquid transition of the RC material 116, and the LRS to HRS transition can include a liquid-to-solid transition of the RC material 116.

[0031] Other implementations are possible, for example where the LRS to HRS and HRS to LRS transitions of the RC material 116 are accompanied by a different first order transition, a second order transition a transition involving a glass transition, or other transitions in which the electrical resistance of the RC material 116 reversibly changes under application of current, electric or magnetic field, voltage or heat. Without loss of generality, first-order transitions include transitions that can exhibit a discontinuitv' in the first derivative of the free energy with respect to a thermodynamic variable. First-order transitions can be associated with the presence of a latent heat. For example, first order transitions include solid-to-liquid and liquid-to-solid transitions. Second-order transitions include transitions that can be continuous in the first derivative while exhibiting a discontinuity in a second derivative of the free energy. Second order transitions, can be associated with a relatively continuous phase transition. For example, second order transitions include ferromagnetic phase transition and superconducting transitions. In other embodiments, the LRS to HRS and HRS to LRS transitions of the RC material 116 can be associated with a glass transition, which can occur in addition to or instead of first or second order transitions. In these embodiments, the LRS to HRS and HRS to LRS transitions of the RC material 116 can occur between a glass or amorphous state and a solid or a liquid state. For example, the LRS to HRS and HRS to LRS transitions of the RC material 1 16 can involve crystalline-to-glass and glass-to-crystalline transitions of the RC material 1 16, or liquid-to-glass and glass-to-liquid transitions, or both. Embodiments in which the RC material 116 undergoes other transitions are possible, such as dendritic or filament growth/dissolution transitions or a Mott transition, to name a few examples.

[0032] The LRS to HRS and HRS to LRS transitions according to various embodiments advantageously can occur under a constant bias or voltage, e.g., a constant DC bias, across the RC material 116 or across the gap 1 12 in the thin film conductive lines 124. For example, when a constant voltage source such as a thin film battery is connected across the self-switching device 100, the LRS to HRS and HRS to LRS transitions can occur while the self-switching device 100 is connected to the storage device. However, embodiments are not so limited, and the LRS to HRS and FIRS to LRS transitions can occur under different biases or voltages across the RC material 116. For example, when the LRS to HRS and HRS to LRS transitions are accompanied by thermally- induced phase changes, the high-to-low temperature transition such as the HRS to LRS transition can occur at less or no bias compared to the low-to-high temperature transition such as the LRS to HRS transition.

[0033] The LRS to HRS and HRS to LRS transitions according to various embodiments advantageously may be apolar or nonpolar. That is, the LRS to HRS and HRS to LRS transitions can occur regardless of whether one side of the thin film conductive line 124 or the gap 112 of the self-switching device 100 is biased positively or negatively relative to the other side. [0034] According to various embodiments, the RC material 116 is adapted to undergo the LRS to HRS or the HRS to LRS transitions, e.g., solid-to-liquid or liquid-to-solid transitions, at a relatively low temperature. The transition temperature can be, e.g., 30 °C to 35 °C, 35 °C to 40 °C, 40 °C to 45 °C, 45 °C to 50 °C, 50 °C to 55 °C, 55 °C to 60 °C, 60 °C to 70 °C, 70 °C to 80 °C, 90 °C to 100 °C, 100 °C to 110 °C, 110 °C to 120 °C, 120 °C to 130 °C, 130 °C to 140 °C, 140 °C to 150 °C, 150 °C to 160 °C, 160 °C to 170 °C, 170 °C to 180 °C, 180 °C to 190 °C, 190 °C to 200 °C, or any temperature in a range defined by any of these values, for instance 40 °C to 80 °C. It will be appreciated that the relatively low temperature transition can be advantageous for, among other advantages, certain switching characteristics, e.g., relatively low power/voltage operation, relatively fast switching times. The relatively low temperature can also enhance material compatibility with other parts of the device. For example, low temperature operation may be desirable to suppress degradation that may result from reacting or interdiffusion with other parts of the self-switching device 100 that contact the RC material 116, such as the thin film conductive line 124, the resistive heating element 132 (e.g., as shown in and described with respect to FIGS. 3A-3C), the heat conductive element 140 (e.g., as shown in and described with respect to FIGS. 5A-5B) or the encapsulation 136 (e.g., as shown in and described with respect to FIG. 4).

[0035] According to various embodiments, the self-switching device 100 is configured such that the RC material 116 is adapted to undergo the LRS to HRS transition, the HRS to LRS transition, or a combined cycle thereof, within a time duration that is suitable for the application at hand. The duration of each or the combination of the LRS to HRS and HRS to LRS transitions can be, e.g., 0.01 sec. to 0.02 sec, 0.02 sec. to 0.05 sec, 0.05 sec. to 0.1 sec, 0.1 sec. to 0.2 sec, 0.2 sec. to 0.5 sec, 0.5 sec. to 1 sec, 1 sec. to 2 se , 2 sec to 5 sec, 5 sec. to 10 se , 10 sec. to 20 sec, 20 sec. to 50 se , 50 sec, to 100 sec, 100 sec. to 200 sec, 200 sec. to 500 sec, 500 sec. to 1000 sec, or any time duration in a range defined by any of these values, for instance 0.5 sec. to 5 sec. It will be appreciated that the transition times can be adjusted by adjusting the switching characteristics, e.g., transition temperature of the RC material 116 and electrical/thermal characteristics as well as physical dimensions of various components of the self-switching device 100, for different applications.

[0036] According to various embodiments, the RC material 1 6 is such that the ratio of electrical resistances between the HRS and LRS is suitably high for various applications of the self-switching device 100. The ratio of the resistances between the HRS and LRS can be, e.g., 1 to 2, 2 to 5, 5 to 10, 10 to 20, 20 to 50, 50 to 100, 100 to 200, 200 to 500, 500 to 1000, 1000 to 2000, 2000 to 5000, 5000 to 10,000, 10,000 to 20,000, 20,000 to 50,000, 50,000 to 100,000, or any ratio in a range defined by any of these values. It will be appreciated that the relatively high ratio of resistances can be advantageous for, among other advantages, low power and/or low voltage operation.

[0037] In some embodiments, the RC material 116 comprises an organic material. The RC material 116 may include a material selected from an ionic liquid, a polymeric material, an alcohol, an aldehyde, an amine, a carboxylic acid, an ester, a ketone, a phenol, or a combination thereof, which have physical characteristics that are suited to provide various switching properties described herein. Non-limiting examples of suitable compounds that can be included as part of the RC material 116 are provided in TABLE 1 below.

TABLE 1. EXAMPLE RESISTANCE CHANGE MATERIALS

Compound Compound Name Melting Class Temp,

(°Q ionic liquids l-(4-methoxyphenyl)-3-methylimidazolium 45 trifluoromethanesulfonate

ionic liquids 1 -octyl-3-methylimidazolium l-carbonicohedral 70 ionic liquids 1 -(1 -propoxymethyl)-3-(l -butoxymethyl)imidazolium 48 hexafluorophosphate

ionic liquids l-nonyl-3-methylimidazolium hexafluorophosphate 48 ionic liquids 1 -octyl-3-ethylimidazolium tosylate 70 ionic liquids l -hydrocinnamyl-3-methylimidazolium 48 bis((trifluoromethy)sulfonyl)imide

ionic liquids l-hydrocinnamyl-3-methylimidazolium hexafluorophosphate 52 ionic liquids l,3-di(l -bitoxymethyl)imidazolium hexafluorophosphate 57 ionic liquids l-(l-decyloxymethyl)-3-methylimidazolium tetrafluoroborate 56 ionic liquids 1 -(1 -decyloxymethyl)-3-methylimi<dazolium 46 hexafluorophosphate

ionic liquids 1 -(1 -hexyloxymethyl)-3-(l -butoxymethyl)imidazolium 50 hexafluorophosphate

ionic liquids 1 -dodecyl-3-methylimidazolium chloride 44 ionic liquids l -dodecyl-3-methylimidazolium hexafluorophosphate 60 ionic liquids l-(l-undecyloxymethyl)3-methylimidazolium tetrafluoroborate 61 ionic liquids 1 -(l.-undecyloxymethyl)3-methylimidazolium 52 hexaf! uorophosphate

ionic liquids 1 -(1 -heptyloxymethyl)-3-(l - 57 butoxymethyl)imidazoliumhyl)imidazolium

hexafluorophosphate

ionic liquids 1 -tridecyl-3-methylimidazolium tetrafluoroborate 49 ionic liquids 1 -tetradecyl-3-methylimidazolium chloride 49 ionic liquids 1 -tetradecyl-3-methylimidazolium bromide 46 Compound Compound Name Melting Class Temp,

(°Q ionic liquids 1 -tetradecyl-3-methylimidazolium tetrafluoroborate 42 ionic liquids l -tetradecyl-3-methylimidazolium trifluoromethanesulfonate 50 ionic liquids 1 -tetradecyl- 3 -methylimidazolium hexafluorophosphate 74 ionic liquids l-(l -nonyloxymethyl)-3-(l-butoxymethyl)imidazolium 50 hexafluorophosphate

ionic liquids 1 -pentadecyl-3 -methylimidazolium tetrafluoroborate 55 ionic liquids 1 -(1 -decyloxymethyl)-3-(l -butoxymethyl)imidazolium 54 hexafluorophosphate

ionic liquids l-hexadecyl-3-methylimidazolium chloride 42 ionic liquids 1 -hexadecy 1-3 -methylimidazolium bromide 40 ionic liquids l-hexadecyl-3-methylimidazolium tetrafluoroborate 49 ionic liquids 1 -hexadecyl-3 -methylimidazolium 42 bis((trifluoromethy)sulfonyl)imide

ionic liquids l-hexadecyl-3-methylimidazolium trifluoromethanesulfonate 58 ionic liquids 1 -hexadecyl-3 -methylimidazolium hexafluorophosphate 75 ionic liquids 1 -( 1 -undecyloxymethyl)-3 ~(1 -butoxymethyl)imidazolium 60 hexafluorophosphate

ionic liquids 1 -octadecyl-3-methylimidazolium chloride 53 ionic liquids l -octadecyl-3-methylimidazolium tetrafluoroborate 66 ionic liquids l-octadecyl-3 -methylimidazolium 44 bis((trifluoromethy)sulfonyl)imide

ionic liquids l -octadecyl-3-methylimidazolium trifluoromethanesulfonate 66 ionic liquids 1 -octadecy 1-3 -methylimidazolium hexafluorophosphate 80 ionic liquids 1 -cosyl-3 -methylimidazolium bromide 60 ionic liquids 1 ,3-dibenzylimidazolium bromide 62 ionic liquids 1.2-dimethyl-3-ethylimidazolium trifluoroacetate 59 ionic liquids 1.2-dimethyl-3-propylimidazolium hexafluorophosphate 78 Compound Compound Name Melting Class Temp,

(°Q ionic liquids 1 -butyl-3-methylbenzotriazolium mesylate 57 ionic liquids 1 -benzyl-3 -methy Ibenzotriazoliurn 69 bis((trifluoromethy)sulfonyl)imide

ionic liquids N-methyl-N-ethyl-pyrrolidinium mesylate 40 ionic liquids N-methyl-N-pr opy 1 -pyrrol idini um m esy late 80 ionic liquids N-methyl-N-propyl-pyrrolidinium tosylate 80 ionic liquids N-m ethy 1 -N-butyl -pyrrol idi ni um mesylate 63 ionic liquids 1 -ethyl-2-methylpyrrolimnimum 45 bis((trifluoromethy)sulfonyl)imide

ionic liquids 1 -dodecyl-3-methylpyridinium hexafluorophosphate 55 ionic liquids l -dodecyl-4-methylpyridinium hexafluorophosphate 56 ionic liquids l -tetradecyl-3-methylpyridinium hexafluorophosphate 68 ionic liquids l -tetradecyl-4-methylpyridinium hexafluorophosphate 71 ionic liquids l-hexadecyl-3-methylpyridinium hexafluorophosphate 74 ionic liquids l-hexadecyl-4-methylpyridinium hexafluorophosphate 75 ionic liquids 4-ethyl-2-isopropyl-3-dodecyl-4,5-dihydro-thiazolium 42 hexafluorophosphate

ionic liquids Tri-methylsulfonium bis((trifluoromethy)suifonyl)imide 44 ionic liquids Terammoniumethylammonium 2,2,2- 64

(trifluoromethylsulfonyl)acetamide

ionic liquids Tri methyl -meth oxym ethy 1 amrn oni um tetrafl uor oborate 46 ionic liquids Trimethyl-allylammonium bis((trifluoromethy)sulfonyl)imide 41 ionic liquids Trim ethyl- propargyl ammonium 45 bis((trif1uoromethy)sulfonyl)imide

ionic liquids Metoxymethylenedimethylethylammonium bis(oxalate)borate 51 ionic liquids Ethoxymethylene-dimethyl-ethyl ammonium bis(oxalate)borate 46 Compound Compound Name Melting Class Temp,

(°Q ionic liquids Methoxyethyl-dimethyl-ethylammonium ammonium 48 bis(oxalate)borate

ionic liquids Tetraethylammomum tetrafluoroborate 72 ionic liquids Tetraethylammonium hexafluorophosphate 70 ionic liquids Triethyl-hexylammonium mesylate 62 ionic liquids Tetrabutylammonium tri(trifluoromethylsuifonyl)methyl 59 ionic liquids Tributyl-hexylammonium tosylate 50 ionic liquids Trioctyl-propyl ammonium bromide 74 ionic liquids Triyl-tetradecyl ammonium bromide 63 ionic liquids Tridodecyl-methyl ammonium bromide 75 ionic liquids Tridecylmethylphosphonium nitrate 59 polymers Polyisoprene, trans 60 polymers Poly(vinyl butyraf) 49 polymers Poly (propyl vinyl ether) 3.8K 76 polymers Polypropelene glycol 66 polymers Polyfbutyl vinyl ether) 64 polymers Polyethylene oxide 400K 66 polymers Poly(ethylene adipate) 10K 54 polymers Polyethylene glycol 1.5K 47 alcohols Menthol 43 alcohols Diphenyl methanol 69 aldehydes 3,4-Dimethoxy-benzaldehyde 44 aldehydes 4-Clorobenzaldehyde 47 aldehydes 4-Bromobenzaldehyde 56 aldehydes 3 -Ni tr obenzal dehy de 8 aldehydes 4-Hydroxy-3-methoxybenzaldehyde 80 amines 2-Amino-6-methylpyridine 41 Compound Compound Name Melting Class Temp,

(°Q amines 2-Benzoylpyridine 42 amines 4-Methylaniline 45 amines 2-Aminobiphenyl 49 amines 6- Ami no- 1 -hexanol 57 amines Methoxy aniline 58 amines 4-Bromoaniline 66 amines 4-Iodoaniline 67 amines 2-Nitroaniline 71 amines 4-Cloroaniline 72 carboxyiic Chloroacetic acid 61 acids

carboxyiic Bromoacetic acid 50 acids

carboxyiic 3-Cloropropanoic acid 41 acids

carboxyiic Dodecanese acid 43 acids

carboxyiic 3-Phenylpropanoic acid 48 acids

carboxyiic Trichloroacetic acid 57 acids

carboxyiic 2-Butenoic acid 72 acids

carboxyiic Phenylacetic acid 76 acids

esters 1-Naphtyl acetate 48 esters Methyl 2-hydroxy-2-phenylacetate 52 Compound Compound Name Melting Class Temp,

(°Q esters Phenyl benzoate 70 esters Diphenyl phtalate 75 esters Methyl 3 -pyridinecarboxylate 42 esters Phenyl 2-hydroxybenzoate 42 ketones 2-Benzoylpyridine 42 ketones Benzoin methyl ether 48 ketones Benzophenone 48 ketones 4-Bromoacetophenone 51 ketones 2-Acetylnaphtalene 53 ketones 1 ,3 -Dipheny 1-2-propen- -one 58 ketones Benzoin ethyl ether 60 ketones 4-Methoxy benzophenone 62 ketones 4-Nitroacetophenone 80 phenols Phenyl 2-hydroxybenzoate 42 phenols 5-Methyl-2-isopropyl-phenol 50 phenols 4-Hydroxy-3-methoxybenzaldehide 80

[0038] Still referring to FIGS. 1 A and IB, according to embodiments, application of a voltage or a current across the gap 1 12 generates heat, and the generated heat can in turn cause the transition of the RC material 1 1 6 from the LRS to the HRS. For example, in embodiments where the LRS to HRS and HRS to LRS transitions correspond to or are accompanied by temperature- induced solid-to-liquid and liquid-to-solid phase transitions, respectively, the heat for causing the solid-to-liquid phase transition can be generated by resistive heating, otherwise referred to as Joule heating, while the liquid-to-solid phase transition can be caused by heat transfer to the environment. Generally, power (P) dissipated by a resistor, e.g., the RC material 1 16 or the thin film conductive line 124, that is converted to thermal energy can be expressed as:

P = (Va - Vh)I [1] where I is the current, and (Va-Vb) is the voltage drop across the resistor. Where Ohm's law is applicable, i.e., where voltage (V) substantially linearly vanes with resistance (R) across the resistive element, the power (P) can be further expressed as:

[0039] For example, in operation, in embodiments where the LRS to HRS transition occurs by a solid-to-liquid phase transition, the RC material 116 can initially be in in a solid phase, which may be more electrically conductive relative to the RC material 116 in a liquid phase. When a bias or current is applied across the gap 112, current flows therethrough, thereby generating heat according to the resistive heating equation(s) above. When the amount and/or the rate of heat that is generated in the resistive element is sufficiently high relative to the amount and/or the rate of heat that is conducted away to the environment from the resistive element such that the temperature of RC material 1 16 substantially reaches or exceeds the melting temperature of the RC material 116, the RC material 116 starts to melt, accompanied by an increase in the electrical resistance. The increase in the electrical resistance results in a reduction in the amount of power that is dissipated by the resistive region, and when the amount and/or the rate of heat that is generated in the resistive element is sufficiently low relative to the amount and/or the rate of heat that is conducted away to the environment from the resistive element such that the temperature of RC material 1 6 falls substantially below the melting temperature of the RC material 116, the RC material 116 starts to solidify back to the solid phase, thus completing a cycle of switching. As described above, the cycle of melting by resistive heating followed by solidifying by ambient cooling can repeat for any number of cycles.

[0040] Still referring to FIGS. 1 A and IB, in the illustrated embodiment, the self- switching device 100 can be configured such that the RC material 116 is substantially more resistive relative to the conductive line 124, such that the RC material 116 dissipates a substantial amount of the power dissipated by the self-switching device 100. In embodiments where the resistance changes are accompanied by temperature-induced transitions, the RC material 1 6 can undergo a low-to-high temperature phase transition, e.g., a solid-to-liquid transition, at least in part by self-heating. The phase transition of the RC material 116 can occur substantially at least in part by self-heating, e.g., when the ratio of resistances or the ratio of resistivities between the RC material 116 in the LRS and the conductive line 124 is 1 to 10, 10 to 100, 100 to 1000, 1000 to 10,000, 10,000 to 100,000, 100,000 to 1,000,000, or a ratio in a range defined by any of these values. For example, the RC material 116 in the LRS can have a sheet resistance of 1 Ohm/sq./mil to 10 Ohm/sq./mil, 10 Ohm'sq./mil to 100 Ohm/sq./mil, 100 Ohm/sq./mil to 1000 Ohm/sq./mil, 1000 Ohm/sq./mil to 10,000 Ohm/sq./mil, or a sheet resistance in a range defined by any of these values. On the other hand, the thin film conductive line 124 can have a sheet resistance of 0.001 Ohm/sq./mil to 0.01 Ohm/sq./mil, 0.01 Ohm/sq. mil to 0.1 Ohm/sq./mil, 0.1 Ohm/sq./mil to 1 Ohm/sq./mil, 1 Ohm/sq./mil to 10 Ohm/sq./mil, 10 Ohm/sq./mil to 100 Ohm/sq./mil, or a sheet resistance in a range defined by any of these values. A suitable ratio of resistances or resistivities between the RC material 116 in the LRS and the thm film conductive line 124 can be achieved, e.g., by forming the thin film conductive line 124 comprising a low resistivity or sheet resistance material For example, the low resistivity material may include gold (Au), silver ( Ag), copper (Cu), bismuth (Bi), carbon (C) (e.g., conductive carbon, carbon nanotubes, graphene, and/or graphite), aluminum (Al), nickel (Ni), combinations thereof, and/or the like. In some embodiments, the thin film conductive line 124 may be printed using a conductive ink that comprises the low resistivity material. Other implementations are possible, for example in which the self-switching device 100 comprises a separate heating element such that the LRS to HRS transition, or the low-to- high temperature phase transition, e.g., a solid-to-liquid transition, is induced at least in part by heating of the RC material 116 through the heating element (e.g., as shown in and described with respect to FIGS. 3A-3C).

[0041] In various embodiments described herein, the RC material 1 16 can comprise a homogenous material having a suitable ratio of resistances between the HRS and the LRS. However, embodiments are not so limited and, in some implementations, the RC material 1 16 can comprise a composite material having an additive therein to enhance the ratio of resistances between the IKS and the LRS. The additive can have a suitable shape and composition and be present in the RC material 1 16 at a suitable concentration such that the ratio of resistances or the ratio of resistivities between the RC material 1 16 in the HRS and the LRS, e.g., the between the liquid state and the solid state, is 1 to 2, 2 to 5, 5 to 10, 10 to 20, 20 to 50, 50 to 100, 100 to 200, 200 to 500, 500 to 1000, 1000 to 2000, 2000 to 5000, 5000 to 10,000, 10,000 to 20,000, 20,000 to 50,000, 50, 000 to 100,000, or a ratio in a range defined by any of these values. When present, a suitable ratio of resistances or resistivities can be achieved by incorporating additives that can have the effect of one or both of increasing the relative resistivity of the RC 1 16 in the HRS or decrease the relative resistivity of the RC 1 16 in the LRS.

[ 0042] The presence of conductive additives can decrease the resistivity of the RC material 116 in the LRS, e.g., the solid state. Without being bound to any theory, when the RC material 116 is in the solid state, and when the volume concentration of conductive additives in the form of particles is above a critical threshold, e.g., above a percolation threshold, the conductive additives may be immobilized within the RC material 116 and form a percolating conductive path by contacting ones of the conductive particles. Without loss of generality, under some circumstances, as the RC material 116 is solidified, the conductive additives may be concentrated at localized regions, e.g., surface or interface regions of the RC material 116 to form a network of percolating conductive path due to, for example, surface forces. Under some other circumstances, when the RC material 116 comprises poly crystalline domains or grains, the conductive additives may be pushed out of the crystalline domains or grains and may be preferentially disposed in grain boundaries between the crystalline domains or grains and pushed towards each other to make a network of percolating conductive path. When the RC material 116 melts, the percolating path may substantially be interrupted because of, e.g., movement of the additives, thereby significantly reducing the conductivity of the RC material 1 16.

[0043] Example conductive additives include particles comprising carbon, graphite, pyrolytic graphite, graphene, reduced graphene oxide, carbon nanotubes (multiwall and single wall), carbon nanoonions, and metals: silver, nickel, copper, copped coated with nickel, copper coated with silver, plastic or glass coated with silver, or other suitable conductive particles. The conductive particles can comprise micro- and/or nanoparticles. The particles can have the shape of flakes, nanorods, nanowires, spherical or any other suitable shape that can be effective in forming a percolation network.

[0044] In some embodiments, the conductive additives advantageously can increase the thermal conductivity of the RC material 116, thereby enhancing the thermal uniformity of the RC material 116 during heating or cooling, which can lead to a sharper transition rate of the RC material 116 between the LRS and HRS or solid and liquid states. [0045] The inventors have found that, depending on the shape, size and the material composition, the conductive additives can he present at a concentration by volume of 0.01% to 0.02%, 0.02% to 0.05%, 0.05% to 0.1%, 0.1% to 0.2%, 0.2% to 0.5%, 0.5 % to 1%, 1% to 2%, 2% to 5%, 5% to 10%, or a concentration in a range defined by any of these values. The concentration can be critical in defining a percolation threshold, under some circumstances.

[0046] Other additives are possible, which can be formed of a conductor, semiconductor or insulator, which can increase or decrease the thermal conductivity or increase or decrease the electrical resistivity of the RC material 116 in one or both of the HRS or LRS.

[0047] In some embodiments, the gap 112 has a gap width and the RC material 116 in the HRS or in a liquid state has a viscosity such that, when the RC material is in the liquid state, the RC material 116 is held in the gap 112 by surface tension or capillar}' force. For example, the gap 112 has a width of about 1-10 μτη, 10-100 μιη, 00-1000 μηι, 1000-2000 μηι, 2000-10,000 μιη, or a width in a range defined by any of these values, for instance a width of about 2-2000 μηι.

[0048] It will be appreciated that one or more features of the self-switching device 100, including the thin film conductive line 124 and/or the RC material 116, may be thin film features. When one or more features is a thin film feature, at least part of the self-switching device 100 advantageously can have a thickness in a range of 1-2000 microns, at which thickness the printed features or the entire device can be substantially flexible. Thus, the self- switching device 100 can be suitable for integration as part of flexible or wearable devices including wearable medical devices, displays, sensors, smartcards, smart packaging, smart clothing, signage, advertisements, etc.

[0049] When printed, the overall thickness of the self-switching device 100, as well as other printed devices such as a power supply and/or a core device electrically connected thereto, advantageously can be made relatively thin. The entire self-switching device 100, including the substrate 102, can have a thickness of 10-50 microns, 50-100 microns, 100-200 microns, 200-300 microns, 300-400 microns, 400-500 microns, 500-600 microns, 600-700 microns, 700-800 microns 800-900 microns, 900-1000 microns, 1000-1200 microns, 1200- 1400 microns, 1400-1600 microns, 1600-1800 microns, 1800-2000 microns, or a thickness in a range defined by any of these values. In various embodiments, other devices that are integrated with the self-switching device 100, including energy storage devices and core devices described below, can also have any of these thicknesses.

Example Self-Switching Apparatuses Including a Thin Film Self-Switching Device Having a Resistance Change Material

[0050] By electrically connecting the self-switching device 100 described above with a core device or a powered component and an energy or a power source, various devices and apparatuses may be fabricated, including medical devices, displays, sensors, smartcards, smart packaging, smart clothing, signage, advertisements, etc.

[0051] FIG. 2 schematically illustrates a self-switching apparatus 200 including a substrate 102 having formed thereon a core device 104 and a power source 108 configured to deliver power sufficient to activate the core device 104. The self-switching apparatus 200 additionally includes a self-switching device 100 electrically connected between the power source 108 and the core device 04. The core device 104 and the power source 108 are configured to, upon activation of the apparatus 200, e.g., using an activation switch 128, deliver power to activate the core device 104. The self-switching device 100 can be configured substantially as described above, and include a resistance change (RC) material 116 disposed in a gap 1 12 formed in a conductive line 24. The self-switching device 100 is configured such that, after the core device 104 is activated by the power source 108, the RC material 1 16 transitions from a low resistance state (LRS) to a high resistance state (HRS) by self-switching, thereby deactivating the core device 104. The transition from the LRS to the HRS by self- switching can be followed by a transition of the RC material 1 16 from the HRS to the LRS by self-switchmg, thereby reactivating the core device. As described above, the self-switching device 100 can be configured such that the RC material 1 6 undergoes one or more cycles of the transitions between the LRS and HRS in a self-switchmg manner as described above, thereby cyclically self-deactivating and self-reactivating the core device 104 by the corresponding number of cy cles.

[0052] The core device 104 may include any device that can be cyclically activated and deactivated at least once, including a light emitting device (e.g., flashing light emitting diode (LED) or organic light emitting diode (OLED)), a sound-generating device, a sensor device, a power supply device, a display device, a signage device, an energy storage device and a memory device, a wearable device, a medical diagnostic device, a medical skin patch device, an advertisement device, combinations thereof, and the like, among many other possible device, whose functionalities can be enabled or enhanced by cyclic switching. For example, the core device 104 may be included as part of greeting cards, business cards, flashing stickers, jewelry, point of purchase advertisement and other decorative and advertisement applications.

[0053] One example implementation of various self-switching devices described herein is a thin film interval timing (TFIT) device, where the core device is cyclically activated and deactivated at substantially regular time intervals. In operation, after being activated via the activation switch 128, which can be, e.g., an electrical switch, a push button or a photodiode, the core device 104 is initially powered by the power source 108. Thereafter, the core device 104 is cyclically activated and deactivated at regular cycle durations or time intervals, as described above. The TFIT device may particularly be suitable for controlling the core device 104 comprising a thin film device such as a printed LED, a printed OLED, a luminescent lamp, a sound-generating device, a sensor device, etc. The core device 04 can be connected to the power source 08, which may be a printed energy storage device, by the conductive line 124, which can be printed conductive lines. The TFIT device can be positioned on any part of the conductive lines 124 that is part of the circuit that includes the core device 104, the power source 108 and the self-switching device 100.

[0054] For example, when the core device 104 includes an LED, the LED flashes on and off at a suitable interval of, e.g., 0.5 to 5 sec. While IC-based timing circuits, which can be based on silicon BIT or CMOS technologies, can have relatively limited degree of freedom in terms of voltage and/or current, TFIT devices based on the self-switching devices described herein can be designed with wider degree of freedom, because the operational voltage or current can be controlled by controlling the volume, geometry and composition of the RC material 1 16. For example, by controlling the length and the cross-sectional area of the RC material 116, the switching voltage and current can be tuned. It will be appreciated that, for the same amount of material, the RC material 1 16 in a thin film form with a relatively large surface area can have a relatively lower melting temperature and/or a relatively faster melting rate. Thus, in some embodiments, the RC material 1 16 is substantially configured as a two-dimensional sheet layer, where the thickness is substantially smaller compared to the length and the width of the RC material 1 16, e.g., by a ratio of 1 : 10, 1 :5, 1 :3: 1 :2, or a ratio in a range defined by any of these values. In embodiments where the transitions between LRS and FIRS are controlled in part by resistive heating, the switching voltages may be designed to be relatively low because the heating may be controlled by the current rather than voltage.

[0055] Another example implementation of various self-switching devices described herein is a protection device for protecting a core device from an electrical overstress (EOS) condition, such as an electrical overcurrent condition. For example, when a core device 104, which normally operates within a temperature range in which the RC material 116 is in an LRS, e.g., a solid state, passes an abnormal level of current and generates heat such that the temperature of the RC material 116 in thermal communication with the core device 104 increases to a temperature within a range in which the RC material 116 is in an HRS, e.g., a liquid state, the current flow may be substantially be shut-off by the high resistance of the RC material 116. Thus, the self-switching device 00 can serve as current controlling devices that can be connected to a core device 104 such as, e.g. , an LED, that is configured to automatically preventing a battery run-off discharge and protecting the core device 104 from being damaged by an EOS condition.

[0056] Yet another implementation of various self-switching devices described herein is a temperature sensor. For example, when a core device 104, which normally operates within a temperature range in which the RC material 1 16 is in an LRS, e.g., a solid state, is at a temperature within a range in which the RC material 116 is in an FIRS, e.g., a liquid state, the current flow through the core device 104 may be prevented or shut-off by the high resistance of the RC material 1 16. Thus, the self-switching device 100 can serve as a temperature sensor based on the amount of current flow through the self-switching device 100.

[0057] Still referring to FIG. 2, the power source 108 can include any suitable power or energy source for providing power or energy to the core device 104 at a level sufficient to induce the switching of the self-switching device 100. In various embodiments, the power source 108 may be a printed energy storage device such as a primary battery (e.g., one-time use battery), a secondary battery (e.g., rechargeable battery), a fuel cell, a capacitor, and/or a supercapacitor (e.g., a symmetric or asymmetric supercapacitor including electric double-layer capacitor (EDLC) and/or pseudo capacitor). [0058] Still referring to FIG. 2, in the illustrated embodiment, a single self- switching device 100 is disposed between the core device 04 and the power source 108. However, embodiments are not so limited, and in other implementations, a plurality of self- switching devices 100 can be electrically connected in series, in parallel or a combination of both in series and in parallel. By connecting in series, the voltage of operation may be correspondingly adjusted. By connecting in parallel, the current of operation may be correspondingly adjusted. In implementations including a plurality of self-switching devices 100, the self-switching devices 100 may have the same or different properties, including current and switching times. For example, by printing self-switching devices 100 configured for the same or different switching cycle times, a TFIT having a random or uniform switching cycle times with customized voltage and/or current specifications can be fabricated.

[0059] In some embodiments described above, where the resistance changes are accompanied by temperature-induced transitions, the RC material 116 can undergo a low-to- high temperature transition, e.g., a solid-to-liquid transition, at least in part by self-heating. The inventors have discovered that, under some circumstances, the low-to-high temperature transition can be enhanced, e.g., increased in speed and/or efficiency, when the RC material 1 16 is heated by a resistive heating element.

[0060] FIG. 3 A schematically illustrates a plan view of a self-switching device 300A having a resistive heating element 132 configured to heat a resistance change (RC) material 1 16 disposed in a gap 1 12 formed therein, according to embodiments. FIG. 3B schematically illustrate a side view of a self-switching device 300B, which can be a side view or a cross-sectional view of the self-switching device 300A illustrated in FIG. 3A. FIG. 3C schematically illustrates a side view of a self-switching device 300C that is similar to the switching device 300A/300B illustrated in FIGS. 3A/3B, in which the resistance change (RC) material 116 partially fills the gap 112 formed in a resistive heating element. The self- switching devices 300B and 300C are similar to each other except, in the illustrated self- switching device 300B in FIG. 3B, the RC material 116 substantially entirely fills or overfills the gap 112 formed in the resistive heating element 132, while in the illustrated embodiment in FIG. 3C, the RC material 116 underfills the gap 1 12 formed in the resistive heating element 132. Among other things, advantageously, the volume of the RC material to be transitioned between the LRS and HRS can be controlled, to tune the switching speed and switching current and/or voltage to various values described herein. For example, a smaller volume of the RC 116 may enable easier encapsulation and allow for the transitions between the LRS and HRS to occur at a faster rate and/or with a reduced current. For higher voltage and/or slower transition rate, however, a larger volume of RC material 116 may be used.

[0061] The self-switching devices 300A, 300B, 300C may be similar to the self- switching device 100 described above with respect to FIGS. 1 A and IB in various aspects, and the descriptions of the possible similarities are not repeated herein in reference to FIGS. 3A- 3C for brevity.

[0062] In each of the illustrated self-switching devices 300A-300C, similar to the self-switching device 100 (FIGS. I A, IB), the thin film conductive line 124 has a gap 112. However, instead of having directly disposed in the gap 112 a resistance change (RC) material 116, the illustrated self-switching devices 300A-300C have resistive heating elements 132 electrically connected to the ends of the thin film conductive lines. The resistive heating elements 132 in turn form the gap 112, in which the RC material 116 is disposed. As configured, application of the current across the resistive heating element 132 produces heat, and the produced heat in turn at least partly causes the transition of the RC material 116 from the low temperature state to the high temperature state, or the LRS to the FIRS.

[0063] For the heating of the RC material 116 to be substantially caused indirectly by conduction from the heated resistive heating element 132, the resistance and/or resistivity of the resistive heating element 132 can be configured to be substantially higher than those of the thin film conductive line 124 and the RC material 116. The phase transition of the RC material 116 can occur substantially at least in part through heating by the resistive heating element 132 when the ratio of resistances or the ratio of resistivities between the resistive heating element 132 and those of the RC material 116 in the LRS and/or the thin film conductive line 124, are 1 to 10, 10 to 100, 100 to 1000, 1000 to 10,000, 10,000 to 100,000, 100,000 to 1,000,000, or a ratio in a range defined by any of these values.

[0064] To adjust the relative amounts of power dissipated by the RC material 116 and the resistive heating element 132, and/or to tune various device attributes for different application needs (e.g., to adjust the flashing time, accommodate different loads of the core device, etc.), electrical connections and resistances between the features may be adjusted accordingly. For example, while the illustrated embodiment shows the RC material 1 16 and the resistive heating element 132 connected in electrical series, embodiments are not so limited, and in other embodiments, the RC material 116 and the resistive heating element 132 may be electrically connected in parallel, or in a combination of series and parallel. In addition, in the illustrated embodiment, the resistive heating element 132 has a larger footprint in plan view and a larger cross-sectional area in the direction of the current flow compared to the thin film conductive line 124. Such configuration can be advantageous, e.g., for effective transfer the heat from the resistive heating element 132 to the RC material 116 through the high contact surface area. However, embodiments are not so limited. In other embodiments, the resistive heating element 132 can have smaller lateral footprint and/or smaller-cross sectional area in the direction of the current flow compared to the conductive line 124, depending on the relative resistivities and/or resistances therebetween. In addition, the width of the gap, and the length, width and the thickness of the RC material 116 can vary. Furthermore, the resistivity of RC material 116 can be changed by varying the composition and concentration of conductive additives, as discussed herein.

[0065] Some RC materials have sufficiently low volatility such that they can be exposed to air in operation. For example, many ionic liquids have suitably low volatility such that an enclosure of the RC material 1 16 may not be needed. However, in embodiments where the RC material 1 16 is substantially volatile, an encapsulation may be provided to suppress evaporation of the RC material 116. For example, the encapsulation 136 may be provided when the RC material 1 16 has a boiling point, below about 150 °C. FIG. 4 schematically illustrates a cross-sectional view of an example self-switching device 400 having an encapsulated resistance change (RC) material disposed in a gap 112 formed in a resistive heating element 132. The self-switching device 400 may be similar to the self-switching device 300C described above with respect to FIG. 3C in various aspects, and the descriptions of the possible similarities are not repeated herein in reference to FIG. 4 for brevity. In some implementations, the resistive heating element 132 may be omitted.

[0066] In addition, as described above, in some embodiments, the gap 112 formed in the thin film conductive line 124 or in the resistive heating element 132 when present has a width, and the RC material 1 16 in the liquid state has a viscosity such that, when the RC material is in the liquid state, the RC material 1 16 is held in the gap 112 by surface tension or capillary force. However, embodiments are not so limited and in the illustrated embodiment of FIG. 4, the RC material 116 may be inhibited or prevented from escaping using the encapsulation 136. The encapsulation 136 may suppress contamination of the RC material 116. The encapsulation may be formed by a printed dielectric ink or a laminate, for example.

[0067] Some RC materials have sufficiently high heat conductivity such that heat generated by the resistive heating element can sufficiently provide uniform heating of RC material 116. However, some RC materials have a sufficiently low heat conductivity such that the switching speed and/or efficiency can be enhanced by the presence of a heat conductive element 140, as illustrated in FIGS. 5 A and 5B. The heat conductive element 140 may be electrically insulating. FIGS. 5 A and 5B schematically illustrate a plan view (FIG. 5 A) and a cross-sectional view (FIG. 5B), respectively, of an example self-switching device 500 having a resistive heating element 32 configured to heat a resistance change (RC) material 116 disposed in a gap 12 formed therein, where the RC material is in thermal communication with a heat conductive element 140. The self-switching device 500 may be similar to the self- switching device 300A/300B described above with respect to FIGS. 3A/3B in various aspects, and the descriptions of the possible similarities are not repeated herein in reference to FIG. 5 A and 5B for brevity. In the illustrated embodiment, the self-switching device 500 comprises the heat conductive element 140 in addition to the resistive heating element 132 contacting the heat conductive element 140. In some implementations, the resistive heating element 132 may be omitted. In some implementations, an encapsulation 136 may be added. In some implementations, the resistive heating element 132 may be omitted and an encapsulation 136 may be added.

[0068] Still referring to FIGS. 5A and 5B, in the illustrated embodiment, the heat conductive element 140 can have a higher thermal conductance relative to the RC material 116. As configured, the heat generated by the resistive heating elements 132 can deliver the heat more effectively to additional surfaces of the RC material 116, thereby increasing the rate of heating of the RC material 116 and/or the uniformity of the temperature of RC material 116 during heating. The heat conductive element 140 is formed of a suitable material such that, while being more thermally conductive, the current path from the resistive heating element 132 through the heat conductive element 140 can be more electrically resistive relative to the current path from the resistive heating element 132 through directly through the RC material 1 16, thereby suppressing resistive heating of the heat conductive element 140. The heat conductive element 140 can be formed using an ink containing non-electricaily conductive but highly thermally conductive materials, e.g., graphene oxide and boron nitride.

[0069] In various embodiments described above, the RC material 116 is present as a permanent part of the self-switching device. However, embodiments are not so limited. In the following, embodiments in which the RC material 116 can be removably present, and configured to be delivered to the gap 112 when the self-switching device is ready to be used. Referring to FIGS. 6A and 6B, a self-switching device 600 includes a thin film conductive line 124 configured to be electrically biased thereacross and a gap 112 in the resistive heating element 132. The gap 112, while being configured hold a resistance change (RC) material 116, initially does not contain the RC material 116. The self-switching device 600 additionally includes a reservoir 144 containing the RC material 116, wherein the reservoir 1 16 is in fluidic communication with the gap 1 12 and configured to transfer the RC material in a liquid state to the gap 1 12.

[0070] The self-switching device 600A may be similar to the self-switching device 300C described above with respect to FIG. 3C in various aspects, and the descriptions of the possible similarities are not repeated herein in reference to FIG. 6A and 6B for brevity. For example, features such as the resistive heating element 132, encapsulation 136, and/or heat conductive element 140 may be added and/or omitted. FIG. 6 A schematically illustrates a plan view of the self-switching device 600 in a first state, prior to transferring the RC material 116 in a liquid state to the gap 112. FIG. 6B schematically illustrates the self-switching device 600 in a second state, after activation by fluidic transfer of the RC material to the gap 112.

[0071] In operation, referring to FIG. 6A, the RC material 116 is initially not present in the gap 112. Instead, the RC material 1 16 is present in the reservoir 144. In embodiments where the RC material 1 16 is in a solid phase without being heated, the reservoir 144 is configured to liquefy the RC material 116 prior to transferring the RC material to the gap 112. For example, the reservoir 144 may include a heating element configured to liquefy the RC material 144 by heating prior to being transferred to the gap 112. [0072] In some embodiments, once the RC material 16 is liquefied, the RC material 1 16 may expand, and the liquefied RC material 116 may be drawn into the gap 112 by capillary force. Once RC material 116 is drawn into the gap 1 12, the self-switching device 600 can operates in a similar manner as described above.

[0073] In some other embodiments, where the capillary force may not be sufficient to draw the RC material 116 into the gap 112, the reservoir 144 may be configured to apply or receive mechanical pressure on the RC 116, thereby squeezing the liquefied RC material 116 into the gap 112 formed in the conductive line 124.

[0074] One or more features of the self-switching device 100 advantageously can be printed from an ink containing the component materials. The one or more layers or the entire self-switching device 100 can be printed using a suitable printing technique. Example printing processes that can be used to print the one or more layers include coating, roiling, spraying, layering, spin coating, lamination and/or affixing processes, for example, screen printing, Inkjet printing, electro-optical printing, electroink printing, photoresist and other resist printing, thermal printing, laser jet printing, magnetic printing, pad printing, flexographic printing, hybrid offset lithography, gravure and other intaglio printing, die slot deposition, among other suitable printing techniques.

[0075] The inks for printing one or more layers of the self-switching device 100 can be prepared by mixing various ink components, including various materials described above with a suitable solvent and/or a binder, and mixed using a techniques such as mixing using a stir bar, mixing with a magnetic stirrer, vortexing (using a vortex machine), shaking (using a shaker), planetary centrifugal mixing, by rotation, three roll milling, ball milling, soni cation and mixing using mortar and pestle, to name a few.

[0076] After printing the one or more layers using an ink, the one or more layers can be treated using one or more post-printing processes, including drying/curing processes including short wave infrared (IR) radiation, medium wave IR-radiation, hot air conventional ovens, electron beam curing and near infrared radiation, among other techniques.

[0077] Without limitation, examples of various energy storage devices that can be printed and integrated with the self-switching devices as described herein, e.g., with respect to FIG. 2, are disclosed in U.S. Patent Application No. 15/926,896, entitled "DIATOMACEOUS ENERGY STORAGE DEVICES," filed March 20, 2018, U.S. Patent Application No. 14/249,316, entitled "PRINTED ENERGY STORAGE DEVICE," filed April 9, 2014, and U.S. Patent Application No. 14/332,802, entitled "PRINTED SILVER OXIDE BATTERIES," filed July 16, 2016. The content of each of these applications is incorporated herein by reference in its entirety.

[0078] Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise," "comprising," "include," "including" and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to." The word "coupled", as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Likewise, the word "connected", as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Additionally, the words "herein," "above," "below," and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this appli cation. Where the context permits, words in the above Detailed Description using the singular or plural number may also include the plural or singular number, respectively. The word "or" in reference to a list of two or more items, that word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.

[0079] Moreover, conditional language used herein, such as, among others, "can," "could," "might," "may," "e.g.," "for example," "such as" and the like, unless specificall - stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or states. Thus, such conditional language is not generally intended to imply that features, elements and/or states are in any way required for one or more embodiments or whether these features, elements and/or states are included or are to be performed in any particular embodiment.

[0080] While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosure. Indeed, the novel apparatus, methods, and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the disclosure. For example, while blocks are presented in a given arrangement, alternative embodiments may perform similar functionalities with different components and/or circuit topologies, and some blocks may be deleted, moved, added, subdivided, combined, and/or modified. Each of these blocks may be implemented in a variety of different ways. Any suitable combination of the elements and acts of the various embodiments described above can be combined to provide further embodiments. The various features and processes described above may be implemented independently of one another, or may be combined in various ways. All possible combinations and subcombinations of features of this disclosure are intended to fall within the scope of this disclosure.

[0081] In addition, unless otherwise specified, none of the steps of the methods of the present disclosure are confined to any particular order of performance. Modifications of the disclosed examples incorporating the spirit and substance of the disclosure may occur to persons skilled in the art and such modifications are within the scope of the present disclosure. Furthermore, all references cited herein are incorporated by reference in their entirety.

[0082] While the methods and devices described herein may be susceptible to various modifications and alternative forms, specific examples thereof have been shown in the drawings and are herein described in detail it should be understood, however, that the invention is not to be limited to the particular forms or methods disclosed, but, to the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the various examples described and the appended claims. Further, the disclosure herein of any particular feature, aspect, method, property, characteristic, quality, attribute, element, or the like in connection with an example can be used in all other examples set forth herein. Any methods disclosed herein need not be performed in the order recited. Depending on the example, one or more acts, events, or functions of any of the algorithms, methods, or processes described herein can be performed in a different sequence, can be added, merged, or left out altogether (e.g., not all described acts or events are necessary for the practice of the method). In some examples, acts or events can be performed concurrently. Further, no element, feature, block, or step, or group of elements, features, blocks, or steps, are necessary or indispensable to each example. Additionally, all possible combinations, subcombinations, and rearrangements of systems, methods, features, elements, modules, blocks, and so forth are withm the scope of this disclosure. The use of sequential, or time-ordered language, such as "then," "next," "after," "subsequently," and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to facilitate the flow of the text and is not intended to limit the sequence of operations performed. Thus, some examples may be performed using the sequence of operations described herein, while other examples may be performed following a different sequence of operations.

[0083] The ranges disclosed herein also encompass any and all overlap, sub-ranges, and combinations thereof. Language such as "up to," "at least," "greater than," "less than," "between," and the like includes the number recited. Numbers preceded by a term such as "about" or "approximately" include the recited numbers and should be interpreted based on the circumstances (e.g., as accurate as reasonably possible under the circumstances, for example ±5%, ±10%, ±15%, etc.). For example, "about 1 V" includes "1 V." Numbers not preceded by a term such as "about" or "approximately" may be understood to based on the circumstances to be as accurate as reasonably possible under the circumstances, for example ±5%, ±10%, ±15%, etc. For example, "1 V" includes "0.9-1.1 V." Phrases preceded by a term such as "substantially" include the recited phrase and should be interpreted based on the circumstances (e.g., as much as reasonably possible under the circumstances). For example, "substantially perpendicular" includes "perpendicular." Unless stated otherwise, all measurements are at standard conditions including temperature and pressure. The phrase "at least one of is intended to require at least one item from the subsequent listing, not one type of each item from each item in the subsequent listing. For example, "at least one of A, B, and C" can include A, B, C, A and B, A and C, B and C, or A, B, and C.

Claims

WHAT IS CLAIMED IS:

1. A self-switching device, comprising:

a thin film conductive line; and

a gap in the thin film conductive line having disposed therein a resistance change (RC) material,

wherein upon application of a current across the gap, the RC material transitions from a low resistance state (LRS) to a high resistance state (HRS), and wherein upon attaining the HRS, the RC material transitions from the HRS to the LRS by self- switching.

2. The device of Claim 1 , wherem the RC material transitions from the LRS to the HRS and from the HRS to the LRS without changing a voltage applied to the self-switching device.

3. The device of Claim 1 , wherein the RC material transitions from the LRS to the HRS and from the HRS to the LRS under a positive voltage or a negative voltage applied to the self-switching device.

4. The device of Claim 1 , wherein after transitioning from the HRS to the LRS by self-switching, the RC material transitions from the LRS to the HRS by self-switching.

5. The device of Claim 4, wherein the transition from the HRS to the LRS by self- switching and the transition from the LRS to the HRS by self-switching repeats cyclically.

6. The device of Claim 1 , wherein application of the current across the gap generates heat, and wherein the generated heat causes the transition from the LRS to the HRS.

7. The device of Claim 1 , wherein the transition from the LRS to the HRS corresponds to a first phase change of the RC material, and the transition from the HRS to the LRS corresponds to a second phase change of the RC material.

8. The device of Claim 7, wherein the transition from the LRS to the HRS corresponds to a solid-to-liquid transition of the RC material, and the transition from the HRS to the LRS corresponds to a liquid-to-solid transition of the RC material.

9. The device of Claim 1, wherein the RC material has a melting temperature of about 40 °C to 80 °C.

10. The device of Claim 1 , wherein the transition from the LRS to the HRS and the transition from the HRS to the LRS occur withm an interval of about 0.1 second to about 10 minutes.

11. The device of Claim 1 , wherein the HRS has a higher resistance value compared to the LRS by a factor between about 2 and about 1000.

12. The device of Claim 1, wherein the RC material in the LRS has an electrical resistance that is substantially higher than an electrical resistance of the thin film conductive line, such that the transition from the LRS to the HRS is caused at least in part by self-heating of the RC material in the gap.

13. The device of Claim 1, further comprising a resistive heating element electrically connected to the RC material and the thin film conductive line, wherein application of the current across the resistive heating element produces heat, and wherein the produced heat causes the transition of the RC material from the LRS to the HRS.

14. The device of Claim 1 , wherein the transition from the HRS to the LRS comprises conduction of heat away from the RC material to a surrounding environment.

15. The device of Claim 1 , further comprising a heat conductive element and a resistive heating element contacting the heat conductive element, wherein application of the current across the resistive heating element produces heat, and wherein the produced heat that is conducted through the heat conductive element causes the transition of the from the LRS to the HRS,

16. The device of Claim 1 , wherein the device has a thickness in a range of 1 micron to 2000 microns.

17. The device of Claim 1 , further comprising;

an electrically powered component; and

an energy source electrically coupled to the electrically powered component by the thin film conductive line.

18. The device of Claim 17, further comprising a switch for activating the electrically powered component.

19. The device of Claim 18, wherein the RC material is between the switch and the electrically powered device.

20. The device of Claim 17, wherein the thin film conductive line is formed from a printed conductive ink.

21. The device of Claim 17, wherein at least one of the electrically powered component and the energy source is formed from a printed ink.

22. The device of Claim 1 , wherein the RC material is exposed to air.

23. The device of Claim 1, wherein the RC material is enclosed to inhibit evaporation of the RC material.

24. The device of Claim 1, wherein the gap has a width and the RC material in the HRS is in a liquid state having a viscosity such that, when the RC material is in the liquid state, the RC material is held in the gap by a capillary force.

25. The device of Claim 24, wherein the gap has a width between about 10 μιη and about 2000 μηι.

26. The device of any one of Claims 1 -25, wherein the RC material comprises an organic material.

27. The device of any one of Claims 1-25, wherein the RC material comprises a material selected from the group consisting of an ionic liquid, a polymeric material, an alcohol, an aldehyde, an amine, a carboxylic acid, an ester, a ketone, a phenol, or a combination thereof.

28. The device of any one of Claims 1-25, wherein the RC material comprises a composite material comprising an organic material and a conductive additive.

29. The device of any one of Claims 1-25, wherein the RC material comprises a composite material comprising an organic material and a carbon-based conductive additive selected from the group consisting of carbon, graphite, pyrolytic graphite, graphene, reduced graphene oxide, carbon nanotubes, carbon nanoonions, or a combination thereof.

30. The device of any one of Claims 1-25, wherein the RC material comprises a composite material comprising an organic material and a metal-containing additive selected from the group consisting of silver, nickel, copper, copped coated with nickel, copper coated with silver, a plastic coated with a metal, a glass coated with a metal, or a combination thereof.

31. A self-switching apparatus, comprising:

a core device and a power source configured to deliver power sufficient to activate the core device; and a self-switching device electrically connected between the power source and the core device, the self-switching device comprising a resistance change (RC) material,

wherein, after the core device is activated by the power source, the RC material transitions from a low resistance state (LRS) to a high resistance state (HRS) by self- switching, thereby deactivating the core device.

32. The apparatus of Claim 31 , wherein the transition from the LRS to the HRS by self-switching is followed by a transition of the RC material from the HRS to the LRS by self- switching, thereby reactivating the core device.

33. The apparatus of Claim 32, wherein the deactivation and the self-reactivation repeats cyclically.

34. The apparatus of Claim 31, wherein the core device is a device selected from the group consisting of a light emitting device, a sound-generating device, or a sensor device.

35. The apparatus of Claim 31 , wherein one or more of the core device, the self- switching device and the power source are printed devices having a thickness in a range of 1 μηι to 2000 μτη.

36. The apparatus of Claim 31, wherein the self-switching device of the apparatus comprises:

a thin film conductive line; and

a gap in the thin film conductive line having disposed therein the RC material, wherein the RC material transitions from the LRS to the HRS by self-switching by a current applied across the gap, and

wherein upon deactivation of the core device, the RC material transitions from the HRS to the LRS by self-switching, thereby reactivating the core device.

37. The apparatus of Claim 36, wherein the self-switching device of the apparatus is according to the device of any one of Claims 2-25.

38. The apparatus of Claim 36, wherein the RC material comprises an organic material.

39. The apparatus of Claim 36, wherein the RC material comprises a material selected from the group consisting of an ionic liquid, a polymeric material, an alcohol, an aldehyde, an amine, a carboxyhc acid, an ester, a ketone, a phenol, or a combination thereof.

40. The apparatus of Claim 36, wherein the RC material comprises a composite material comprising an organic material and a conductive additive.

41. The apparatus of Claim 36, wherein the RC material comprises a composite material comprising an organic material and a carbon-based conductive additive selected from the group consisting of carbon, graphite, pyrolytic graphite, graphene, reduced graphene oxide, carbon nanotubes, carbon nanoonions, or a combination thereof.

42. The apparatus of Claim 36, wherein the RC material comprises a composite material comprising an organic material and a metal-containing additive selected from the group consisting of silver, nickel, copper, copped coated with nickel, copper coated with silver, a plastic coated with a metal, a glass coated with a metal, or a combination thereof.

43. A self-switching device, comprising:

a thin film conductive line configured to be electrically biased thereacross; a gap in the thin film conductive line configured hold a resistance change (RC) material; and

a reservoir containing the RC material,

wherein the reservoir is in fluidic communication with the gap and configured to transfer the RC material in a liquid state to the gap.

44. The device of Claim 43, wherein the reservoir is configured to liquefy the RC material prior to transferring the RC material to the gap.

45. The device of Claim 44, wherein the reservoir is configured to liquefy the RC material by heating.

46. The device of Claim 43, wherein the gap has a spacing and the RC material in the liquid state has a viscosity such that upon being transferred to the gap, the RC material is held in the gap at least in part by capillary action.

47. The device of Claim 43, wherein the reservoir is configured to apply pressure to the RC in the liquid state to transfer the RC material into the gap.

48. The device of Claim 43 configured such that, after the RC material is tra sferred to the gap, the RC material cools to a solid state.

49. The device of Claim 48, wherein the RC material in the solid state corresponds to a low resistance state (LRS) and the RC material in the liquid state corresponds to a high resistance state (HRS), and wherein, after the RC material cools to the solid state, upon application of a current across the gap having the RC material disposed therein, the RC material transitions from the LRS to the HRS, and wherein upon attaining the HRS, the RC material transitions from the HRS to the LRS by self-switching.

50. The device of Claim 49, wherein the device is according to the device of any one of Claims 2-25.

51. The apparatus of Claim 43, wherein the RC material comprises an organic material.

52. The device of Claim 43, wherein the RC material comprises a material selected from the group consisting of an ionic liquid, a polymeric material, an alcohol, an aldehyde, an amine, a carboxylic acid, an ester, a ketone, a phenol, or a combination thereof.

53. The device of Claim 43, wherein the RC material comprises a composite material comprising an organic material and a conductive additive.

54. The device of Claim 43, wherein the RC material comprises a composite material comprising an organic material and a carbon-based conductive additive selected from the group consisting of carbon, graphite, pyrolytic graphite, graphene, reduced graphene oxide, carbon nanotubes, carbon nanoonions, or a combination thereof.

55. The device of Claim 43, wherein the RC material comprises a composite material comprising an organic material and a metal-containing additive selected from the group consisting of silver, nickel, copper, copped coated with nickel, copper coated with silver, a plastic coated with a metal, a glass coated with a metal, or a combination thereof.