Degradable substrate for electronic device, degradable substrate assembly for electronic device, and method for manufacturing degradable substrate for electronic device

Abstract

The present invention relates to a degradable substrate for electronic devices, a degradable substrate assembly for electronic devices, and a method for manufacturing the degradable substrate for electronic devices. The degradable substrate for electronic devices according to an embodiment of the present invention includes a substrate base material provided as a polymeric material, and a degradable gas bubble generating material provided in a particulate form and uniformly mixed with the substrate base material, and reacts with water to generate gas bubbles.

Description

[Technical Field]

[0001] The present invention relates to a degradable substrate for electronic devices, a degradable substrate assembly for electronic devices, and a method for manufacturing a degradable substrate for electronic devices, and more particularly to a degradable substrate for electronic devices, which reacts with water to be quickly decomposed and is harmless to humans and the environment, a degradable substrate assembly for electronic devices, and a method for manufacturing a degradable substrate for electronic devices. [Background technology]

[0002] In conventional semiconductors and electronics, one of the important indicators of a device is its reliability, i.e., stable operation without performance degradation even after long-term use. However, recent semiconductor technology has presented a technology called transient electronics or degradable electronics, which have a specifically controlled physical lifespan rather than a long period of time and can be used according to the user's purpose.

[0003] This technology is made up of substances whose elimination function is activated by water, heat, light, microorganisms, and other factors, and the performance of the manufactured elements maintains the same level as commercial elements, possessing functionality that can be used in industry or daily life, and can be completely decomposed physically and chemically to eliminate them when a situation arises where they are no longer needed or need to be removed.

[0004] There are two main methods for adjusting the properties of dissipation and decomposition. The first is to control the lifespan by adjusting the density, crystallinity, and thickness of the materials that make up the insulating layer (passivation) and protective layer (encapsulation). The second is to trigger decomposition with an external stimulus.

[0005] Existing technologies that enable active decomposition through external stimuli present technologies that can lead to ignition, corrosive compounds, or mechanical destruction through heat, light, or electrical stimuli. However, these technologies have the disadvantages of many substances being toxic to the human body or the environment, being highly chemically reactive and unstable, making them difficult to store, being difficult to synthesize reactive compounds that respond to external stimuli, and not being able to decompose quickly. Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a degradable substrate for an electronic device, a degradable substrate assembly for an electronic device, and a method for manufacturing a degradable substrate for an electronic device, which reacts with water and decomposes quickly.

[0007] Another object of the present invention is to provide a degradable substrate assembly for electronic devices and a method for manufacturing a degradable substrate for electronic devices, which has properties that are harmless to humans and the environment. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a degradable substrate for electronic devices, comprising: a substrate base material provided as a polymeric material; and a degradable gas bubble-generating material provided in particulate form and uniformly mixed with the substrate base material, which reacts with water to generate gas bubbles.

[0009] The substrate base material is any one of gelatin, polyvinylpyrrolidone (PVP), polyhydroxyalkanoate (PHA), polyhydroxybutyric acid (PHB), polyvinyl alcohol (PVA), collagen, cellulose, polylactic acid (PLA), poly(D,L-lactide-co-glycolic acid) (PLGA), polycaprolactone (PCL), or a mixture thereof.

[0010] The decomposable foam-generating substance comprises an organic acid and a bicarbonate.

[0011] The organic acid is any one of citric acid, malic acid, succinic acid, malonic acid, tartaric acid, and acetic acid, or a mixture thereof.

[0012] The bicarbonate is either sodium bicarbonate, potassium bicarbonate, or a mixture thereof.

[0013] The decomposable air bubble-generating substance has a molar ratio of the organic acid to the bicarbonate of 1:1 to 1:3.

[0014] The substrate base material and the degradable foam-generating material have a weight ratio of 4:1 to 1:2.

[0015] Further, a plasticizer is included, and the substrate base material is gelatin.

[0016] According to another aspect of the present invention, there is provided a degradable substrate assembly for an electronic device, comprising: a degradable substrate for an electronic device including a substrate base material provided as a polymer material; and a channel-forming module attached to a bottom surface of the degradable substrate for an electronic device and controlling a water supply state, the channel-forming module comprising: a channel-forming layer having an inlet-side channel and an operating-side channel formed therein; and a pneumatic valve control layer located below the channel-forming layer and interconnecting or separating the inlet-side channel and the operating-side channel.

[0017] The flow path forming layer has a storage area formed in the operating side flow path opposite to the area adjacent to the inlet side flow path, and the storage area is open upward and contacts the decomposable substrate for electronic elements.

[0018] The containment area is filled with a degradable foam-generating substance that reacts with water to generate foam.

[0019] The decomposable substrate for electronic devices further comprises a decomposable gas bubble-generating material in particulate form, uniformly mixed with the substrate base material, and reacting with water to generate gas bubbles.

[0020] The decomposable foam-generating substance comprises an organic acid and a bicarbonate.

[0021] According to another aspect of the present invention, there is provided a method for manufacturing a decomposable substrate for an electronic device, the method including the steps of: mixing a substrate base material with an organic solvent; mixing a decomposable gas bubble-generating material with the organic solvent; and drying the solution containing the mixed substrate base material and the decomposable gas bubble-generating material.

[0022] The substrate base material is a polymeric material.

[0023] The decomposable foam-generating substance comprises an organic acid and a bicarbonate.

[0024] The degradable gas bubble-generating substance is ground and then mixed with the organic solvent.

[0025] The degradable gas bubble-generating substance is pulverized in a ball mill. [Effects of the Invention]

[0026] According to the present invention, it is possible to provide a decomposable substrate for an electronic device, which reacts with water to generate bubbles and is quickly decomposed, a decomposable substrate assembly for an electronic device, and a method for manufacturing a decomposable substrate for an electronic device.

[0027] In addition, according to the present invention, a decomposable substrate assembly for electronic devices and a method for manufacturing a decomposable substrate for electronic devices can be provided, which are harmless to humans and the environment because the decomposition reaction is carried out using substances derived from nature. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a flowchart showing a method for producing a decomposable substrate for electronic devices according to one embodiment of the present invention. [Figure 2] FIG. 2 is a flow chart showing the process of preparing an organic solvent. [Figure 3] FIG. 3 is a diagram showing the process of pulverizing the degradable gas bubble-generating substance. [Figure 4] FIG. 4 is a diagram showing the change in particle size of the degradable gas bubble-generating substance as the grinding process progresses. [Figure 5] FIG. 5 is a diagram showing the average particle size and standard deviation of particle size of the degradable gas bubble-generating substance as the pulverization process progresses. [Figure 6] FIG. 6 is a diagram showing the pH of a solution produced during a decomposition reaction of a decomposable gas bubble-generating substance depending on the molar ratio of organic acid phosphorus to bicarbonate. [Figure 7] FIG. 7 is a diagram showing the process of decomposition of a decomposable substrate for electronic devices made of gelatin as a substrate base material, as an example. [Figure 8] FIG. 8 is a diagram showing the time required for decomposition depending on the temperature. [Figure 9] FIG. 9 is a diagram showing the mechanical properties of a decomposable substrate for an electronic device, which is produced after a plasticizer is further added to a solution in which a substrate base material and a decomposable gas bubble-generating material are mixed. [Figure 10] FIG. 10 is a diagram showing the glass transition temperature and melting point, which are thermal properties of decomposable substrates for electronic devices, depending on the content of glycerol, which is a plasticizer. [Figure 11] FIG. 11 is a diagram showing the transmittance characteristics of a substrate with and without a decomposable bubble-generating substance. [Figure 12] FIG. 12 is a diagram showing the contact angle of water molecules on the surface of a decomposable substrate for electronic devices over time depending on the type of plasticizer. [Figure 13] FIG. 13 shows the degradation reaction of a PLGA-based degradable substrate for electronic devices according to one embodiment. [Figure 14] FIG. 14 is a scanning electron microscope (SEM) photograph showing the surface and internal structure of a PLGA-based degradable substrate for electronic devices according to one embodiment. [Figure 15] FIG. 15 is a graph showing the mechanical properties of degradable substrates for electronic devices based on PLGA, depending on the mass ratio of the degradable gas bubble-generating substance to PLGA. [Figure 16]FIG. 16 is a graph showing the change in weight of a PLGA-based degradable substrate for electronic devices over time. [Figure 17] FIG. 17 is a diagram showing the decomposition process of an electronic device using a PLGA-based decomposable substrate for electronic devices according to one embodiment of the present invention. [Figure 18] FIG. 18 shows a remotely controllable electronic device made using a decomposable substrate for electronic devices according to one embodiment of the present invention. [Figure 19] FIG. 19 shows a comparative experiment showing the biocompatibility / biodegradability process of a degradable substrate for electronic devices according to one embodiment of the present invention and a comparative substrate inserted into mice for four weeks. [Figure 20] FIG. 20 shows a histological analysis of a portion of a biological tissue into which a degradable substrate for electronic devices according to one embodiment of the present invention and a comparative substrate were inserted, after being cut open according to FIG. 19. [Figure 21] FIG. 21 is an exploded perspective view of a disassembly substrate assembly for electronic devices according to another embodiment. [Figure 22] FIG. 22 shows a flow channel formed inside a decomposable substrate assembly for electronic devices. [Figure 23] FIG. 23 is a diagram showing a state in which the inlet-side flow channel and the operating-side flow channel are connected to each other. [Figure 24] FIG. 24 is a diagram showing a state in which a decomposition reaction is carried out after an element is formed on the upper surface of a decomposable substrate assembly for electronic elements. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical concept of the present invention is not limited to the embodiments described herein and may be embodied in other forms. The embodiments introduced herein are provided so that the disclosed content will be thorough and complete, and so that the concept of the present invention will be fully conveyed to those skilled in the art.

[0030] Furthermore, in various embodiments of this specification, terms such as "first," "second," and "third" are used to describe various components, but these components should not be limited by such terms. These terms are used merely to distinguish one component from another. Thus, what is referred to as a "first component" in one embodiment may also be referred to as a "second component" in another embodiment. Each embodiment described and exemplified herein also includes its complementary embodiment. Furthermore, in this specification, "and / or" is used to mean that at least one of the components listed before and after it is included.

[0031] In this specification, the singular expression includes the plural expression unless the context clearly dictates otherwise. Furthermore, the terms "comprise" or "have" are intended to specify the presence of a feature, number, step, component, or combination thereof described in the specification, and should not be understood to exclude the presence or possibility of addition of one or more other features, number, step, component, or combination thereof. Furthermore, in this specification, the term "coupled" is used to mean both indirectly and directly coupling multiple components.

[0032] Furthermore, when describing the present invention, if a detailed description of related publicly known functions or configurations is deemed to unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

[0033] FIG. 1 is a flowchart showing a method for producing a decomposable substrate for electronic devices according to one embodiment of the present invention.

[0034] Referring to Fig. 1, an organic solvent is prepared (S100), such as hexafluoroisopropanol (HFIP), acetone, butanone, ethyl acetate, methyl acetate, or chloroform.

[0035] FIG. 2 is a flow chart showing the process of preparing an organic solvent.

[0036] As shown in Figure 2, the organic solvent is provided in an anhydration state. This prevents mutual reaction when degradable bubbling agents (BA), which will be described later, are mixed. First, a dehydrating agent is added to the organic solvent (S110). The dehydrating agent is, for example, calcium chloride. The dehydrating agent is mixed with the organic solvent at a weight / volume ratio of 8% to 12% (w / v).

[0037] The dehydrating agent is then filtered to extract the dehydrated organic solvent (S120). After the organic solvent and the dehydrating agent are mixed, the dehydrating agent, which is the solute, sinks to the bottom. The dehydrating agent is then removed from the solution by filtering, and the dehydrated organic solvent is extracted. The filtering is performed by vacuum filtration.

[0038] Next, a substrate base material is mixed with the organic solvent (S200). The substrate base material is provided as a polymeric material. For example, the substrate base material may be any one of gelatin, polyvinylpyrrolidone (PVP), polyhydroxyalkanoate (PHA), polyhydroxybutyric acid (PHB), polyvinyl alcohol (PVA), collagen, cellulose, polylactic acid (PLA), poly(D,L-lactide-co-glycolic acid) (PLGA), polycaprolactone (PCL), or a mixture thereof. The substrate base material is mixed with the organic solvent at a volumetric ratio of 3 to 10% by weight.

[0039] Next, a decomposable gas bubble-generating substance is mixed (S300). The decomposable gas bubble-generating substance is mixed with the organic solvent and substrate base material using a mixer or the like to ensure a homogeneous mixture. When the decomposable substrate for electronic devices encounters water, the decomposable gas bubble-generating substance undergoes a gas bubble-generating reaction. The generated bubbles and the disappearance of the decomposable gas bubble-generating substance allow the decomposable substrate for electronic devices to decompose at a rapid rate. The decomposable gas bubble-generating substance is composed of an organic acid and a bicarbonate. When the decomposable gas bubble-generating substance encounters water and reacts, it generates carbon dioxide, which is then decomposed and disappeared at a rapid rate. The carbon dioxide is generated in the form of bubbles in the decomposable substrate for electronic devices, further accelerating the decomposition of the decomposable substrate for electronic devices. The organic acid is one of citric acid, malic acid, succinic acid, malonic acid, tartaric acid, and acetic acid, or a mixture thereof. The bicarbonate is one of sodium bicarbonate and potassium bicarbonate, or a mixture thereof. In the decomposable substrate for electronic devices, the substrate base material and the decomposable gas bubble-generating material have a weight ratio of 4:1 to 1:2.

[0040] FIG. 3 is a diagram showing the process of pulverizing the degradable gas bubble-generating substance.

[0041] As shown in FIG. 3, the decomposable gas bubble generating substance is mixed after being pulverized to a particle size within a predetermined range in order to adjust its reactivity and mechanical properties when it encounters water. The decomposable gas bubble generating substance is pulverized to an average particle size of 10 μm or less. As an example, the decomposable gas bubble generating substance is pulverized using a ball mill. Ball milling is performed by placing pulverizing balls 3 and the decomposable gas bubble generating substance 2 in a drum 1 and rotating the drum 1. Here, the decomposable gas bubble generating substance is mixed with one of the organic acids or bicarbonates. The pulverizing balls 3 are ceramic balls. As the drum 1 rotates, the pulverizing balls 3 and the decomposable gas bubble generating substance 2 collide with each other, pulverizing the decomposable gas bubble generating substance 2. Using ceramic balls as the pulverizing balls 3 allows the particle size of the decomposable gas bubble generating substance 2 to be reduced to 5 μm to 500 nm.

[0042] Figure 4 is a graph showing the change in particle size of the decomposable gas bubble-generating substance as the pulverization process progresses, and Figure 5 is a graph showing the average particle size and standard deviation of particle size of the decomposable gas bubble-generating substance as the pulverization process progresses.

[0043] Figure 4 shows microscopic images of the change in particle size over time when sodium bicarbonate (SB), a type of bicarbonate, and citric acid (CA), an organic acid, were milled using a ball mill. Initially, the particle size was around 500 μm on average, but as the milling process progressed, the particle size rapidly decreased. After 6 hours, the particle size was reduced to about 1 μm for sodium bicarbonate and about 2 μm for citric acid.

[0044] Figure 5 shows the changes in the average particle size and standard deviation for sodium bicarbonate and citric acid as they are milled. It can be seen that the average particle size and particle size deviation decrease as the milling process using a ball mill progresses. This means that the milling process reduces the particle size and increases the particle size uniformity.

[0045] The particle size of the degradable gas bubble-generating material is reduced and the particle size uniformity is improved when it is homogeneously mixed with the polymeric substrate base material, which is the substrate base material. This facilitates the fabrication of a degradable substrate for electronic devices, which is a composite mixture of the degradable gas bubble-generating material and the substrate base material, enables the degradable substrate for electronic devices to be used for various purposes, and improves the decomposition rate and uniformity of the decomposition region when it encounters water and undergoes a decomposition reaction. Therefore, the degradable gas bubble-generating material is preferably pulverized to an average particle size of at least 10 μm before mixing. More preferably, the degradable gas bubble-generating material is pulverized to an average particle size of at least 5 μm before mixing.

[0046] FIG. 6 is a diagram showing the pH of the solution produced during the decomposition reaction of the decomposable gas bubble-generating substance depending on the molar ratio of organic acid phosphorus and hydrogen carbonate.

[0047] FIG. 6 shows a case where the organic acid is citric acid (CA) and the bicarbonate is sodium bicarbonate (SB).

[0048] As shown in Figure 6, the pH of the decomposition solution can be adjusted by adjusting the ratio of organic acid to bicarbonate in the decomposition bubble-generating substance. Increasing the ratio of organic acid to bicarbonate creates a lower pH condition during the decomposition reaction, which can accelerate the decomposition rate of biodegradable metallic substances, such as magnesium (Mg), zinc (Zn), and iron (Fe), through a metal-acid reaction. Furthermore, maintaining an appropriate ratio between the organic acid and bicarbonate is essential for the interaction between them to occur at an appropriate rate. Therefore, a molar ratio of organic acid to bicarbonate of 1:1 to 1:3 is preferred.

[0049] The mixed solution of the substrate base material and the degradable gas bubble-generating material is then dried to produce a degradable substrate for electronic devices (S400). For example, the mixed solution of the substrate base material and the degradable gas bubble-generating material is poured into a mold having the shape of the degradable substrate for electronic devices and then completely dried for 1 to 2 days in a very low humidity environment (dried conditions) to produce the degradable substrate for electronic devices. Here, the degradable substrate for electronic devices is made to a thickness of 100 to 200 μm and can be used for electronic devices to be implanted in living bodies. As a result, the degradable substrate for electronic devices has a structure in which particles of the degradable gas bubble-generating material are evenly distributed in the substrate base material. When reacted with water, the degradable gas bubble-generating material disappears, and bubbles are generated by the interaction of the organic acid and bicarbonate, which are the gas bubble-generating materials, allowing the degradable substrate for electronic devices to quickly decompose.

[0050] Experimental example 1. Gelatin was used as the substrate base material. Gelatin-based degradable substrates for electronic devices were prepared by adding 0.6–1 g (3–5% w / v) of porcine gelatin and 0.3–1 g (1.5–5% w / v) of glycerol (a plasticizer) to 20 mL of HFIP in a glove box under a dry argon (Ar) atmosphere. Degradable bubble-generating materials were prepared by mixing and stirring 0.3–1.2 g (1.5–6% w / v) of ground organic acid (citric acid) and bicarbonate (sodium bicarbonate) (molecular ratio, organic acid:bicarbonate = 1:1–1:3). The solution was then poured into a PDMS (poly(dimethylsiloxane)) mold, dried for 24 hours, and then dried in a dryer for another 24 hours to prepare degradable substrates for electronic devices. The thickness was 50 to 200 μm depending on the ratio of the degradable gas bubble-generating material to the gelatin, where the degradable substrate for electronic devices had a weight ratio of gelatin to the degradable gas bubble-generating material of 10:3 to 1:2.

[0051] Experimental example 2. In another example, PLGA was used as the substrate base material. Degradable substrates for electronic devices based on PLGA were prepared under the same conditions as those for gelatin. 1-2 g (5-10% w / v) of PLGA (lactide:glycolide = 50:50, 65:35) was dissolved in 20 mL of acetone to form a polymer solution. The degradable gas bubble-generating agent was prepared by mixing 0.5-2 g (2.5-10% w / v) of ground organic acid and bicarbonate in a molecular ratio (1:1-1:3), pouring the mixture into a PDMS mold, and drying in the same manner as above to produce a degradable substrate for electronic devices. Here, the weight ratio of PLGA to the degradable gas bubble-generating agent was 4:1 to 1:2.

[0052] FIG. 7 is a diagram showing the decomposition process of a decomposable substrate for electronic devices made of gelatin as a substrate base material according to one embodiment, and FIG. 8 is a diagram showing the time required for decomposition depending on temperature.

[0053] As shown in Figures 7 and 8, it can be seen that the decomposition reaction occurs when the substrate reacts with water at room temperature (25°C), rapidly generating bubbles, and the decomposable substrate for electronic devices disappears within 60 seconds.

[0054] In addition, the decomposition reaction speed was accelerated at a temperature equivalent to body temperature (37°C), and destruction occurred within 30 seconds of starting the reaction with water. In other words, it was confirmed that the decomposition reaction speed is proportional to the ambient temperature.

[0055] 9 shows the mechanical properties of a degradable substrate for electronic devices prepared by adding a plasticizer to a solution containing a substrate base material and a degradable gas bubble-generating material. The plasticizer can be glycerol, sorbitol, or the like.

[0056] In this embodiment, gelatin is used as the polymeric material that is the substrate base material, and glycerol is used as the plasticizer.

[0057] As shown in Figure 9, the degradable substrate for electronic devices manufactured with the addition of a plasticizer exhibited over 90% recovery and durability after 1,000 repeated load / unload cycles in a mechanical durability test. In other words, the degradable substrate for electronic devices is manufactured by adding a plasticizer to a solution containing a substrate base material and a degradable bubble-generating material, followed by drying, which reduces fragility and provides softness and flexibility, making it suitable for use in wearable devices.

[0058] FIG. 10 is a diagram showing the glass transition temperature and melting point, which are thermal properties of decomposable substrates for electronic devices, depending on the content of glycerol, which is a plasticizer.

[0059] As shown in Figure 10, it can be seen that the glass transition temperature and melting point shift to lower values ​​as the amount of glycerol increases. Therefore, by adjusting the amount of plasticizer added, the glass transition temperature and melting point of the decomposable substrate for electronic devices can be adjusted according to the intended use.

[0060] FIG. 11 is a diagram showing the transmittance characteristics of a substrate with and without a decomposable bubble-generating substance.

[0061] Gelatin was used as the substrate base material, and glycerol was used as the plasticizer. It was confirmed that degradable substrates for electronic devices made with the addition of a degradable gas bubble-generating substance maintained a transmittance of 70% or more compared to substrates made without the degradable gas bubble-generating substance. In other words, even with the addition of a degradable gas bubble-generating substance, transmittance was maintained above a certain range, and degradable substrates for electronic devices can also be manufactured into shapes with transmittance above a certain range.

[0062] FIG. 12 is a diagram showing the contact angle of water molecules on the surface of a decomposable substrate for electronic devices over time depending on the type of plasticizer.

[0063] Gelatin was used as the polymeric material serving as the substrate base material. Referring to FIG. 12, it can be seen that the contact angle of water molecules on the surface of the decomposable substrate for electronic devices over time changes depending on the type of plasticizer. Here, the contact angle is inversely proportional to the hygroscopicity. This shows that the hygroscopicity of the decomposable substrate for electronic devices can be adjusted by selecting the type of plasticizer, and thus the decomposition rate can be controlled. Furthermore, to increase the decomposition rate of the decomposable substrate for electronic devices, it is preferable to use glycerol, which has a higher hygroscopicity than sorbitol, as the plasticizer.

[0064] FIG. 13 shows the degradation reaction of a PLGA-based degradable substrate for electronic devices according to one embodiment.

[0065] The substrate base material was PLGA, and the degradable gas bubble-generating materials were sodium bicarbonate and citric acid. The thickness of the degradable substrate for electronic devices was 50 μm to 300 μm.

[0066] It was confirmed that the PLGA-based degradable substrate for electronic devices disappeared within 60 seconds after reacting with water, indicating that even when based on PLGA, a polymer with a relatively slow decomposition rate compared to gelatin, the degradable substrate for electronic devices easily decomposes after reacting with water.

[0067] FIG. 14 is a scanning electron microscope (SEM) photograph showing the surface and internal structure of a PLGA-based degradable substrate for electronic devices according to one embodiment.

[0068] As shown in Figure 14, the degradable substrate for electronic devices, whose base material is PLGA, has a microporous structure, which allows water to penetrate inside quickly and react with water more quickly, explaining the fast disappearance phenomenon.

[0069] FIG. 15 is a graph showing the mechanical properties of degradable substrates for electronic devices based on PLGA, depending on the mass ratio of the degradable gas bubble-generating substance to PLGA.

[0070] 15, it can be seen that the flexibility of the degradable substrate for electronic devices decreases as the content of the degradable gas bubble-generating material relative to PLGA increases. Thus, the flexibility of the degradable substrate for electronic devices can be controlled by adjusting the mass ratio of the degradable gas bubble-generating material to PLGA.

[0071] FIG. 16 is a graph showing the change in weight of a PLGA-based degradable substrate for electronic devices over time.

[0072] It was confirmed that when the mass ratio of degradable gas bubble-generating material to PLGA was 50% and 100%, respectively, there was no significant change in mass over 30 days when exposed to an environment at a temperature of 22°C and a relative humidity of 40%, confirming that PLGA-based degradable substrates for electronic devices can be stored stably for long periods of time.

[0073] FIG. 17 is a diagram showing the decomposition process of an electronic device using a PLGA-based decomposable substrate for electronic devices according to one embodiment of the present invention.

[0074] The element region formed on the top surface of the substrate was fabricated using magnesium, selected from among degradable electrode materials (magnesium (Mg), iron (Fe), zinc (Zn), molybdenum (Mo), and tungsten (W)). To fabricate the element, poly(methyl methacrylate) (PMMA) and polyimide (PI) films were formed on a silicon wafer substrate with thicknesses of 50-500 nm and 1-10 μm, respectively. Then, magnesium films with thicknesses of 100-500 nm were deposited using sputtering, an electron beam evaporator, and a thermal evaporator. These films were then patterned using photolithography, a semiconductor process. A 50-300 nm thick insulating layer (passivation) of magnesium oxide (MgO) and silicon oxide (SiO2) was then deposited and patterned using sputtering and an electron beam evaporator to protect the metal layer. A thin PI layer was coated on top and then patterned and etched using photolithography and reactive ion etching (RIE). The entire silicon wafer substrate was then immersed in an acetone solution to remove the sacrificial PMMA layer. The PI / metal / insulation / PI layer on the PMMA was then separated from the silicon wafer substrate using a PDMS stamp, high-temperature release tape, or water-resistant release tape. The remaining PI film layer was then etched using RIE and transferred to a degradable substrate for electronic devices, completing the electronic device. It was confirmed that the electronic device using the degradable substrate for electronic devices was completely decomposed within 100 seconds when reacted with room-temperature water. Furthermore, the electronic device using the degradable substrate for electronic devices exhibited performance degradation to the point of almost complete non-functionality after approximately 60 seconds, a performance degradation rate 55 times faster than that of a substrate using a substrate-based material without a degradable bubble-generating material.

[0075] That is, it can be seen that the decomposition of an electronic device manufactured using a decomposable substrate for an electronic device is completed without any significant difference compared to the case where the decomposable substrate for an electronic device is decomposed alone.

[0076] FIG. 18 is a diagram showing a remotely controllable electronic device fabricated using a decomposable substrate for electronic devices according to one embodiment of the present invention.

[0077] As shown in Figure 18, a wearable chip was constructed by incorporating commercial electronic devices into a degradable substrate for electronic devices. These electronic devices receive power remotely using the NFC (Near Field Communication) frequency band (13.56 MHz) and operate. The degradable substrate for electronic devices uses gelatin as the substrate base material. The electronic devices are composed of a microcontroller, a linear regulator (LDO), diodes, capacitors, micro LEDs, a laser-cut patterned coil (Mg, thickness 5-50 μm), and connecting wires (Mg interconnect, thickness 1-10 μm), and are implemented for remote operation. The electronic devices thus fabricated were also confirmed to react with water and self-destruct within 300 seconds.

[0078] FIG. 19 shows a comparative experiment demonstrating the biocompatibility and biodegradability process in which a degradable substrate for electronic devices according to one embodiment of the present invention and a comparative substrate were inserted into mice for four weeks, and FIG. 20 shows histological analysis of the tissues in which the degradable substrate for electronic devices according to one embodiment of the present invention and a comparative substrate were inserted, after being cut open according to FIG. 19.

[0079] The degradable substrate for electronic devices used PLGA as the substrate base material, while the comparative substrate was made using only PLGA without a degradable gas bubble-generating substance. This demonstrates that the degradable substrate for electronic devices according to one embodiment of the present invention degrades stably in vivo, similar to the case where only PLGA is present. Furthermore, the biotissues in which the degradation reaction occurred showed no significant difference from the case where only PLGA was present, demonstrating that the addition of a degradable gas bubble-generating substance does not impair biocompatibility. In other words, because the degradable gas bubble-generating substance is a naturally occurring substance, the degradable substrate for electronic devices is harmless to the human body and the environment during its introduction into the body and its decomposition process.

[0080] Figure 21 is a diagram showing an exploded oblique view of a degradable substrate assembly for electronic elements according to another embodiment, Figure 22 is a diagram showing a flow path formed inside the degradable substrate assembly for electronic elements, and Figure 23 is a diagram showing the state in which the inlet side flow path and the operating side flow path are connected to each other.

[0081] As shown in FIGS. 21 to 23, the decomposable substrate assembly 20 for electronic elements includes a decomposable substrate 21 for electronic elements and flow path forming modules 22, 23, and 24.

[0082] The decomposable substrate for electronic devices 21 includes a substrate base material and a decomposable bubble-generating material, as in the above-described embodiment. Alternatively, the decomposable substrate for electronic devices may be provided as a substrate base material without the bubble-generating material.

[0083] The flow path forming modules 22, 23, 24 include a flow path forming layer 22 and an air pressure valve control layer 24. The flow path forming modules 22, 23, 24 are attached to the bottom surface of the decomposable substrate for electronic devices. The flow path forming modules 22, 23, 24 control the supply state of water supplied to the decomposable substrate for electronic devices 21. An inlet-side flow path 220 and an operating-side flow path 221 are formed inside the flow path forming layer 22. The inlet-side flow path 220 and the operating-side flow path 221 are provided in a disconnected state, separated by a predetermined distance. The area where the inlet-side flow path 220 and the operating-side flow path 221 are adjacent to each other but disconnected is provided in an open state downward.

[0084] In the operating channel 221, a receiving area 222 is formed opposite the area adjacent to the inlet channel 220. The receiving area 222 is open upward and provided to contact the decomposable substrate 21 for electronic devices. The receiving area 222 is provided in a state filled with a decomposable gas bubble-generating substance. As in the above-mentioned embodiment, the decomposable gas bubble-generating substance is made of an organic acid and a bicarbonate, and the mixture is filled in a paste state.

[0085] The pneumatic valve control layer 24 is located below the flow path forming layer 22. The pneumatic valve control layer 24 interconnects or separates the inlet-side flow path 220 and the operating-side flow path 221. Above the pneumatic valve control layer 24, a control space 240 that is open upward and is located below the area where the inlet-side flow path 220 and the operating-side flow path 221 are adjacent and disconnected from each other is formed. A control flow path 241 that is connected to the control space 240 is formed in the pneumatic valve control layer 24.

[0086] A membrane 23 is disposed between the flow path forming layer 22 and the pneumatic valve control layer 24 in a shape that covers the open upper part of the control space 240. The membrane 23 has a predetermined elasticity and is provided in a state in which it is in close contact with the bottom surface of the area where the inlet-side flow path 220 and the operation-side flow path 221 are adjacent to each other. As a result, even when water is supplied to the inlet-side flow path 220, the inlet-side flow path 220 and the operation-side flow path 221 maintain a disconnected state through the membrane 23. When the control space 240 is evacuated and decomposed through the control flow path 241, the membrane 23 moves toward the control space 240, and the inlet-side flow path 220 and the operation-side flow path 221 are connected through the space formed above the membrane 23. As a result, water supplied through the inlet-side flow path 220 is supplied to the decomposable substrate for electronic devices through the containing area 222, causing the decomposable substrate for electronic devices to decompose. Also, even when the decomposable substrate for electronic elements is provided without the decomposable bubble-generating substance, the decomposable bubble-generating substance is filled into the storage area 222 instead, and the bubbles generated in the storage area 222 promote the decomposition of the decomposable substrate for electronic elements.

[0087] FIG. 24 is a diagram showing a state in which a decomposition reaction is carried out after an element is formed on the upper surface of a decomposable substrate assembly for electronic elements.

[0088] As an embodiment for this purpose, first, molds for the flow path forming modules 22, 23, and 24 were produced using 3D printing. After this, Sylgard A and B were mixed in a ratio of 10:1, and then the mold was filled with PDMS (Polydimethylsiloxane), which was then cured to produce the flow path forming layer 22 and the air pressure valve control layer 24.

[0089] The elements on the top surface of the degradable substrate for electronic elements were fabricated using a remotely operated electronic layer (RF electronic layer) made of micro LEDs, diodes, capacitors, Mg coils (10-50 μm thick), and Mg connecting wires (1-5 μm thick). The containment area 222 was filled with a paste containing a mixture of bicarbonate and organic acid, a degradable bubble-generating substance. The LED was positioned above the containment area 222 as the main part of the element to be destroyed. It was confirmed that this allowed the elements positioned above the containment area to be quickly destroyed and stopped from operating.

[0090] Although the present invention has been described in detail using preferred embodiments, the scope of the present invention should not be limited to the specific embodiments, but should be interpreted by the appended claims. Furthermore, those skilled in the art will understand that many modifications and variations are possible without departing from the scope of the present invention.

Claims

1. a step of mixing calcium chloride with the organic solvent at a concentration of 8% to 12% w / v to dehydrate the organic solvent; mixing a substrate base material and a plasticizer in the dehydrated organic solvent at 5% w / v and 5-6% w / v, respectively; mixing a degradable gas bubble-generating material into the solution in which the substrate base material and the plasticizer are mixed; and drying the solution containing the substrate base material and the degradable gas bubble-generating material. The method for manufacturing a degradable substrate for an electronic device, wherein the substrate base material is gelatin.

2. 2. The method for manufacturing a decomposable substrate for electronic devices according to claim 1, wherein the decomposable bubble-generating substance comprises an organic acid and a bicarbonate.

3. 3. The method for producing a decomposable substrate for electronic devices according to claim 2, wherein the organic acid is any one of citric acid, malic acid, succinic acid, malonic acid, tartaric acid, and acetic acid, or a mixture thereof.

4. 3. The method for producing a decomposable substrate for electronic devices according to claim 2, wherein the hydrogen carbonate is either one of sodium hydrogen carbonate and potassium hydrogen carbonate, or a mixture thereof.

5. 3. The method for manufacturing a decomposable substrate for electronic devices according to claim 2, wherein the decomposable bubble-generating substance has a molar ratio of the organic acid to the bicarbonate of 1:1 to 1:

3.

6. 2. The method of claim 1, wherein the substrate base material and the decomposable bubble-generating material are mixed in a weight ratio of 4:1 to 1:2.

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