Use of silk as an oxide substitute in semiconductor devices and sensors and method for producing it.

Abstract

Nanoscale silk layers on semiconductors enable the construction of transistors that can switch between ionic or dielectric behavior, and enable a new class of hybrid functional devices in which semiconductor and biopolymer technologies coexist, leveraging their respective strengths. The device may include a first layer, which is conductive or semiconducting. The device may include a regenerated amphiphilic protein layer on the first layer, the regenerated amphiphilic protein layer being structured such that, in a first hydration state of the regenerated amphiphilic protein layer, a first electric double layer (EDL) is formed at the interface between the first layer and the regenerated amphiphilic protein layer.

Description

[Background technology]

[0001] (Cross-reference of related applications) This application incorporates, by reference to, U.S. Application No. 63 / 499,130, filed on 28 April 2023, and claims its priority for all purposes.

[0002] (Statement regarding research funded by the federal government) This invention was made with government support under authorization number N00014-19-2399, granted by the U.S. Office of Naval Research. The government has certain rights in this invention.

[0003] Semiconductor materials, devices, and processes have traditionally involved materials and processes that are not sustainable or renewable. There is a need for materials and processes to produce sustainable and renewable semiconductor devices. [Overview of the Initiative] [Means for solving the problem]

[0004] Nanoscale silk layers on semiconductors enable the construction of transistors that can switch between ionic and dielectric behavior, allowing for a new class of hybrid functional devices where semiconductor and biopolymer technologies coexist, leveraging their respective strengths.

[0005] In some respects, the techniques described herein relate to a device comprising a first layer, which is conductive or semiconducting, and a regenerating amphiphilic protein layer on the first layer, wherein the regenerating amphiphilic protein layer is structured such that, in a first hydrated state of the regenerating amphiphilic protein layer, a first electric double layer (EDL) is formed at the interface between the first layer and the regenerating amphiphilic protein layer.

[0006] In some respects, the techniques described herein relate to a device comprising a second layer, the second layer being conductive or semiconducting, a regenerating amphiphilic protein layer located on the second layer, and in a first hydration state of the regenerating amphiphilic protein layer, a second EDL is formed at the interface between the second layer and the regenerating amphiphilic protein layer.

[0007] In some respects, the techniques described herein relate to a device in which a regenerating amphiphilic protein layer is accessible to ambient moisture.

[0008] In some respects, the techniques described herein relate to a device in which a first hydration state is initiated by the capture of environmental moisture by a regenerating amphiphilic protein layer.

[0009] In some respects, the techniques described herein relate to a device in which a regenerated amphiphilic protein layer is formed by depositing silk fibroin films, each less than 5 nm in size, by spin-coating a silk solution of 0.01–0.1% by weight or 0.05% by weight to form a deposited silk film, rinsing the deposited silk film in a tank of deionized water, and patterning the deposited silk film.

[0010] In some respects, the techniques described herein relate to a device wherein patterning a deposited silk film involves O2 plasma etching of the deposited silk film through a photoresist mask using poly(methyl methacrylate) (PMMA) as a passivation layer.

[0011] In some respects, the techniques described herein relate to a device in which the first and second EDLs formed in the first hydration state enhance the current flow by more than six orders of magnitude.

[0012] In some respects, the techniques described herein relate to a device wherein a first EDL comprises an electronic surface charge and reversed charged ions matched at the interface between a first layer and a regenerating amphiphilic protein layer, and a second EDL comprises an electronic surface charge and reversed charged ions matched at the interface between a second layer and a regenerating amphiphilic protein layer.

[0013] In some respects, the techniques described herein relate to a device in which a first layer is a lateral gate electrode of a transistor and a second layer is a semiconductor layer of the transistor.

[0014] In some respects, the techniques described herein relate to a device in which the lateral gate electrode and semiconductor layer do not overlap in the cross-sectional view.

[0015] In some respects, the techniques described herein relate to devices in which the semiconductor layer is formed from a semiconducting material.

[0016] In some respects, the techniques described herein relate to devices in which the semiconducting material comprises indium gallium zinc oxide (IGZO).

[0017] In some respects, the techniques described herein relate to a device in which, in the second hydration state of the regenerated amphiphilic protein layer, the first EDL and the second EDL are not formed.

[0018] In some respects, the techniques described herein relate to a device in which the second hydration state corresponds to the absence of captured H2O molecules within the regenerating amphiphilic protein layer.

[0019] In some aspects, the techniques described herein relate to a device that includes 14 devices, and in a second hydration state, the capacitive coupling between the lateral gate electrode and the semiconductor layer is determined by the dielectric constant of the regenerated amphiphilic protein layer.

[0020] In some aspects, the techniques described herein relate to a device in which the capacitive coupling is insufficient to modulate the charge carrier density in the semiconductor layer.

[0021] In some aspects, the techniques described herein relate to a device in which when the regenerated amphiphilic protein layer transitions from the second hydration state to the first hydration state, the transistor transitions from the field-effect mode of operation to the electrolyte-gated mode of operation.

[0022] In some aspects, the techniques described herein relate to a device that further includes a substrate, and the first layer and the second layer are each on the substrate.

[0023] In some aspects, the techniques described herein relate to a device that further includes a bottom gate electrode between the substrate and the semiconductor layer.

[0024] In some aspects, the techniques described herein relate to a device in which the substrate is Si / SiO2.

[0025] In some aspects, the techniques described herein relate to a device in which the regenerated amphiphilic protein layer is a regenerated silk fibroin layer.

[0026] In some aspects, the techniques described herein relate to a device having a regenerative amphiphilic protein layer with a thickness of 1 nm to 20 nm, 2 nm to 15 nm, or 3 nm to 10 nm, including but not limited to a thickness of at least 1 nm, at least 2 nm, at least 3 nm, at least 4 nm, or at least 5 nm, and a maximum thickness of 20 nm, 15 nm, 10 nm, or 5 nm.

[0027] In some aspects, the techniques described herein relate to a semiconductor device comprising a substrate, a source electrode, a drain electrode, a lateral gate electrode, and a semiconductor layer each on the substrate, and a regenerative amphiphilic protein layer on the semiconductor layer and the gate electrode, the regenerative amphiphilic protein layer being structured to transition from a field effect mode to an electrolyte gating mode upon exposure to humidity to capture H2O molecules.

[0028] In some aspects, the techniques described herein relate to a semiconductor device where the humidity is from exhaled breath.

[0029] In some aspects, the techniques described herein relate to a semiconductor device where the regenerative amphiphilic protein layer is structured to be in an electrolyte gating mode during exhalation.

[0030] In some aspects, the techniques described herein relate to a semiconductor device where in the electrolyte gating mode, a first electrical double layer (EDL) is formed at the interface between the lateral gate electrode and the regenerative amphiphilic protein layer, and a second electrical double layer (EDL) is formed at the interface between the regenerative amphiphilic protein layer and the semiconductor layer.

[0031] In some respects, the techniques described herein relate to semiconductor devices in which a regenerating amphiphilic protein layer is further structured to transition from an electrolyte-gated mode to a field-effect mode by the extraction of captured H2O molecules during inhalation.

[0032] In some respects, the techniques described herein relate to semiconductor devices in which a regenerating amphiphilic protein layer is structured to be in an electrolyte-gated mode during exhalation and in a field-effect mode during inhalation.

[0033] In some respects, the techniques described herein relate to a semiconductor device wherein exhalation causes a regenerating amphiphilic protein layer to transition from an electrolyte-gated mode to an electrolyte-gated mode within about 30 milliseconds, and inhalation causes a regenerating amphiphilic protein layer to transition from an electrolyte-gated mode to an electrolyte-gated mode within about 300 milliseconds.

[0034] In some respects, the techniques described herein relate to semiconductor devices in which the transition between electrolyte-gated modes and field-effect modes enables tracking of multiple respiratory cycles.

[0035] In some respects, the techniques described herein relate to semiconductor devices, which further include a bottom gate electrode between a substrate and a semiconductor layer.

[0036] In some respects, the techniques described herein relate to semiconductor devices in which the regenerated amphiphilic protein layer is a regenerated silk fibroin layer.

[0037] In some respects, the techniques described herein relate to devices having regenerated amphipathic protein layers having thicknesses of 1 nm to 20 nm, 2 nm to 15 nm, or 3 nm to 10 nm, including, but not limited to, thicknesses of at least 1 nm, at least 2 nm, at least 3 nm, at least 4 nm, or at least 5 nm, and up to 20 nm, up to 15 nm, up to 10 nm, or up to 5 nm.

[0038] In some respects, the techniques described herein are methods for forming a regenerated amphiphilic protein layer, the methods comprising: depositing silk fibroin films, each less than 5 nm in size, by spin-coating a silk solution of 0.01–0.1% by weight or 0.05% by weight to form a deposited silk film; rinsing the deposited silk film in a tank of deionized water; and patterning the deposited silk film.

[0039] In some respects, the techniques described herein are methods for patterning a deposited silk film, which include O2 plasma etching of the deposited silk film through a photoresist mask using poly(methyl methacrylate) (PMMA) as a passivation layer.

[0040] In some respects, the techniques described herein are methods relating to a method in which a regenerated amphiphilic protein layer is formed on a first layer and a second layer, wherein the first layer is conductive or semiconducting and the second layer is conductive or semiconducting.

[0041] In some respects, the techniques described herein are methods relating to a method in which a regenerated amphiphilic protein layer is structured such that, in a hydrated state, a first electrical double layer (EDL) is formed at the interface between the first layer and the regenerated amphiphilic protein layer, and a second EDL is formed at the interface between the second layer and the regenerated amphiphilic protein layer. [Brief explanation of the drawing]

[0042] A further detailed description of this disclosure and certain aspects thereof can be understood by referring to the following diagram.

[0043] [Figure 1] Figure 1 depicts a device comprising a regenerating amphiphilic protein layer according to an exemplary embodiment of the present disclosure.

[0044] [Figure 2] Figure 2 illustrates a flowchart illustrating a method for forming a regenerated amphiphilic protein layer according to an exemplary embodiment of the present disclosure.

[0045] [Figure 3] Figure 3. Architecture and fabrication of silk / FET. a, b) Graphic representation of IGZO silk / FET with a lateral gate electrode (a) interfacially contacted with an ultrathin silk layer, accompanied by a microscopic image of the device (b). c) Schematic diagram of the fabrication. d, e) Microscopic images (scale bar: 50 μm) of ultrathin silk film patterned in square (d) and striped (e) patterns on a Si / SiO2 substrate. f, g) Atomic force micrographs of striped patterned silk film (f. scale bar: 10 μm) and profile (g. inset).

[0046] [Figure 4] Figure 4. Silk / FET operating mechanism. a) Representation of a planar capacitor with electrodes in direct contact with an ultrathin silk layer under either dry or high humidity conditions (left and right, respectively), showing the expected lateral profiles of potential (black) and electric field (red) across the insulating layer in both cases. b) Transfer characteristic curves of the silk / FET under either dry or high humidity conditions. c) Specific gate capacitance measurements performed under high humidity conditions.

[0047] [Figure 5]Figure 5. Respiratory sensing. a) Transfer characteristics of silk / FET measured close to the mouth (with Au electrode), showing the reversible transition between field-effect mode and electrolyte-gated mode. b) Time-series measurements of respiratory sensing dynamics, characterized by a rapid response time of approximately 30 milliseconds and a recovery time of 300 milliseconds. c) Continuous monitoring of multiple respiratory cycles over a period of approximately 20 seconds. d) Photograph of an array of respiratory sensors on a surgical mask (scale bar: 0.5 mm).

[0048] [Figure 6] Figure 6. Atomic force microscope images and thickness profiles of ultrathin silk films on Si / SiO2 substrates at different processing stages. a) Untreated silk (film edge obtained by scratching the film with a sharp tip), b) Silk film after rinsing with water, c) Silk film after PMMA deposition, patterning, and acetone bath treatment.

[0049] [Figure 7] Figure 7. Silk film thickness as a function of spin coating rate and initial concentration of silk solution. The shaded areas correspond to the thickness range used in this study.

[0050] [Figure 8] Figure 8. Electrical characteristics evaluation of a conventional bottom-gated IGZO device on a Si / SiO2 wafer (SiO2 thickness approximately 300 nm, 10.8 nF / cm2) with an Au electrode (channel width and length are 1,000 μm and 50 μm, respectively). a, b) The transfer curve (a) and output curve (b) exhibit well-behaved n-type FET characteristics that are linear and saturate scale at an electron mobility of 5.63 cm2 / Vs, threshold voltage VT = 10.8 V, and subthreshold swing of 2.13 V / decade. c) Transfer curves obtained with either silk or PMMA as a capping layer, showing only slight differences.

[0051] [Figure 9]Figure 9. Contact resistance values ​​for silk / FETs processed with Au and Al contact electrodes, measured in either a bottom gate or side gate configuration. The Au electrode exhibits greater contact resistance than the Al contact, which is particularly evident in side gate operation.

[0052] [Figure 10] Figure 10. Cyclic stress test of humidity-sensing silk / FET, where the device is transitioned between high humidity and low humidity settings over 20 cycles. [Modes for carrying out the invention]

[0053] Detailed explanation Before this disclosure is described in further detail, please understand that this disclosure is not limited to the specific embodiments described herein. Also, please understand that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to be restrictive. The scope of this disclosure will be limited solely by the claims. As used herein, the singular forms "a," "an," and "the" include multiple embodiments unless the context explicitly indicates otherwise.

[0054] It should be apparent to those skilled in the art that, in addition to those already described, many additional modifications are possible without departing from the concept of the present invention. In interpreting this disclosure, all terms should be interpreted in the broadest possible form that is consistent with the context. Variations of the term “comprising” should be interpreted in a non-inclusive form as referring to an element, component, or step, and so the elements, components, or steps referred to may be combined with other elements, components, or steps not explicitly mentioned. Embodiments that refer to “comprising” an element are also assumed to “consisting essentially of” and “consisting of” those elements. When two or more ranges are enumerated with respect to a particular value, this disclosure assumes all combinations of upper and lower bounds of those ranges that are not explicitly enumerated. For example, the enumeration of values ​​from 1 to 10 or 2 to 9 also assumes values ​​from 1 to 9 or 2 to 10.

[0055] As used herein, “silk fibroin” refers to silk fibroin protein, whether produced by silkworms, spiders, or other insects, or otherwise (Adv. Protein Chem., 13: 107-242 (1958) by Lucas et al.). Any type of silk fibroin can be used in the different embodiments described herein. Silk fibroin produced by silkworms, such as the “silkworm moth,” is the most common and represents a renewable resource that does not harm the earth. For example, silk fibroin used in silk films can be obtained by extracting sericin from the cocoons of the “silkworm moth.” Organic silkworm cocoons are also commercially available. However, many different types of silk can be used, and include spider silk (e.g., obtained from the “orb-weaver spider”), genetically modified silk such as silk from bacteria, yeast, mammalian cells, genetically modified animals, or genetically modified plants, and their variants. See, for example, WO 97 / 08315 and U.S. Patent No. 5,245,012 (each of which is incorporated herein by reference as a whole).

[0056] Silk is emerging as a uniquely versatile biomaterial platform capable of targeting diverse applications across several fields in life and materials science. In fact, beyond its well-known use in high-end fabrics, current research efforts are leveraging the exclusive and multifaceted nature of silk fibroin, i.e., the structural proteins of silk fibers, and its highly versatile processability, to achieve multifunctional, multi-scale platforms with arbitrary shapes and shape factors. Some examples of such platforms include biochemical implants and cell scaffolds, biochemical sensing interfaces, bioresponsive coatings, sustainable design products, as well as transient optics, photonics, and electronics. In particular, the latter set of technological applications greatly benefit from the potential for precisely patterning silk through various techniques, including casting, nanoimprinting, and inkjet printing, and involving both conventional and advanced photolithography methods such as UV, multiphoton, electron beam, and hard mask lithography. These remarkable developments have achieved excellent lateral resolution at the wafer scale. In recent years, increased control over naturally derived structural protein formulations and their self-assembly has enabled the application of high-resolution manufacturing techniques for silk-based materials, leading to bioactive interfaces with unprecedented miniaturized formats and functionality.

[0057] Disclosed herein are functionalities arising from the preparation of biomaterial thickness at the nanoscale in the context of solid-state electronics. In particular, at the length scale disclosed herein, the absorption and transport of water molecules into biomaterials, which can be introduced either by direct vapor flow or by changes in ambient humidity, leads to the dynamic and reversible formation of electric double layers (EDLs) at semiconductor / silk and metal / silk interfaces, which are effectively utilized in inorganic thin-film field-effect transistors (silk / FETs) that can be easily switched from conventional field-effect modes to electrolyte-gated operation. This humidity-controlled reconfigurability is demonstrated in small, highly sensitive respiratory sensors.

[0058] Disclosed herein are hybrid biopolymer / semiconductor devices obtained by integrating a nanoscale silk layer into a well-established class of inorganic field-effect transistors (silk / FETs). The devices offer two distinct operating modes, namely, a conventional field-effect mode or an electrolyte-gated mode, enabled by the precisely controlled thickness, morphology, and biochemistry of the integrated silk layer. The different operating modes are selectively accessed by dynamically modulating the free water content within the nanoscale protein layer from the vapor phase. The utility of these hybrid devices is exemplified in highly sensitive and ultrafast respiratory sensors, highlighting the opportunities offered by the integration of nanoscale biomaterial interfaces with conventional semiconductor devices, enabling functional achievements at the intersection of the microelectronics and biological worlds.

[0059] Referring to Figure 1, the device 100 according to an exemplary embodiment may include a first layer 116. This first layer 116 may be conductive or semiconducting. In the embodiment of Figure 1, the first layer 116 is semiconducting and is formed from a semiconducting material. In the exemplary embodiment, the semiconducting first layer 116 may be part of a transistor and may be described herein as a semiconductor layer 116.

[0060] In addition, device 100 may include a second layer 120 / 122 which may be conductive or semiconducting. In the embodiment shown in Figure 1, the second layer 120 / 122 is conductive. Furthermore, the second layer 120 / 122 may be a side gate electrode of the transistor and may be referred to herein as a side gate electrode 120 / 122. In the exemplary embodiment shown in Figure 1, the side gate electrode and the semiconductor layer may not overlap in the cross-sectional view. Furthermore, in the exemplary embodiment, the transistor may include a source electrode 112 and a gate electrode 114 which may both be conductive.

[0061] The regenerated amphiphilic protein layer 130 may be on the first layer and / or the second layer. In exemplary embodiments, "on" may mean a state of contact rather than indicating a specific sequence or order. In exemplary embodiments, the regenerated amphiphilic protein layer 130 may be formed from a biomaterial such as silk fibroin. For example, the regenerated amphiphilic protein layer 130 may be a regenerated silk fibroin layer.

[0062] In exemplary embodiments, each of the first layer 116, the second layer 120 / 122, and the regenerating amphipathic protein layer 130 may be formed on the substrate 110. The substrate 110 may be planar and may be formed from any suitable material, including, but not limited to, plastic, Si / SiO2, or biomimetic materials. In one embodiment, the substrate 110 is Si / SiO2.

[0063] The regenerated amphipathic protein layer can be structured such that, in the first hydration state of the regenerated amphipathic protein layer, a first electrical double layer (EDL) may be formed at the interface between the first layer 116 and the regenerated amphipathic protein layer 130, and a second EDL may be formed at the interface between the second layer 120 / 122 and the regenerated amphipathic protein layer 130.

[0064] In exemplary embodiments, the first and second EDLs that may be formed in the first hydration state can increase the current flow by more than six orders of magnitude.

[0065] In exemplary embodiments, the first EDL may include electronic surface charges and reverse-charged ions matched at the interface between the first layer and the regenerating amphiphilic protein layer, and the second EDL may include electronic surface charges and reverse-charged ions matched at the interface between the second layer and the regenerating amphiphilic protein layer.

[0066] Exemplary embodiments are described with reference to Figure 1, which illustrates an exemplary ordering of the elements of device 100, including a first layer 116, a second layer 120 / 122, and a regenerating amphipathic protein layer 130. However, such ordering is for illustrative purposes only, and embodiments are not limited thereto. Furthermore, the materials forming the elements described herein may be deposited in a sequence, for example, as shown, the first layer 116 and the second layer 120 / 122 may be formed on a substrate 110, and the regenerating amphipathic protein layer 130 may be formed on the first layer 116 and the second layer 120 / 122, but embodiments are not limited thereto.

[0067] In exemplary embodiments, the regenerated amphiphilic protein layer 130 may be accessible to ambient moisture. The regenerated amphiphilic protein layer 130 may initiate a first hydration state by capturing ambient moisture, as further described herein, and may initiate a second hydration state by releasing the captured ambient moisture. In exemplary embodiments, the first hydration state may correspond to the regenerated amphiphilic protein layer 130 having captured H2O molecules, and the second hydration state may correspond to the absence (e.g., complete or partial absence) of captured H2O molecules within the regenerated amphiphilic protein layer 130. In other words, the second hydration state may correspond to dehydration. However, embodiments are not limited thereto, and the first and second hydration states of the regenerated amphiphilic protein layer 130 may be initiated in the presence or absence of other electrolytes.

[0068] In the second hydration state of the regenerated amphiphilic protein layer, the first and second EDLs may not be formed. Instead, for example, the capacitive coupling between the lateral gate electrode 120 / 122 and the semiconductor layer 116 may be determined by the dielectric constant of the regenerated amphiphilic protein layer 130. In exemplary embodiments, in the second hydration state, there may be a capacitive coupling between the lateral gate electrode and the semiconductor layer that is insufficient to modulate the charge carrier density within the semiconductor layer.

[0069] In an exemplary embodiment, when the regenerated amphiphilic protein layer transitions from a second hydration state to a first hydration state, the transistor transitions from a field-effect operating mode to an electrolyte-gated operating mode. For example, the transistor transitions from field-effect operation of a metal-insulator semiconductor structure to field-effect operation of an electrolyte-gated device.

[0070] In exemplary embodiments, the regenerated amphiphilic protein layer 130 may be formed by depositing silk fibroin films, each less than 5 nm in size, by spin-coating a silk solution of 0.01 to 0.1% by weight or 0.05% by weight to form a deposited silk film, rinsing the deposited silk film in a tank of deionized water, and patterning the deposited silk film.

[0071] It has been unexpectedly discovered that the regenerated amphiphilic protein layer 130 can be adjusted at the nanoscale using this exemplary method (e.g., at the time of manufacture). Furthermore, it has been unexpectedly discovered that functionality may arise from adjusting the thickness of the regenerated amphiphilic protein layer 130 at the nanoscale. In exemplary embodiments, the regenerated amphiphilic protein layer may have thicknesses of 1 nm to 20 nm, 2 nm to 15 nm, or 3 nm to 10 nm, including, but not limited to, thicknesses of at least 1 nm, at least 2 nm, at least 3 nm, at least 4 nm, or at least 5 nm, and up to 20 nm, up to 15 nm, up to 10 nm, or up to 5 nm. Adjusting the thickness to these ranges may, unexpectedly and advantageously, provide controlled / controllable absorption and release of water or other chemical species in the gaseous or liquid phase.

[0072] In exemplary embodiments, patterning a deposited silk film involves O2 plasma etching the deposited silk film through a photoresist mask using poly(methyl methacrylate) (PMMA) as a passivation layer.

[0073] In exemplary embodiments, the semiconducting material of the semiconductor layer 116 may include, but is not limited to, any semiconducting material such as polymers, small molecules, or carbon-based (e.g., graphene or nanotube) semiconductors. In one embodiment, the semiconducting material is indium gallium zinc oxide (IGZO).

[0074] In an exemplary embodiment, the device 100 may include a bottom gate electrode (not shown in Figure 1) between the substrate 110 and the semiconductor layer 116 in order to operate the transistor in field-effect mode.

[0075] Referring to Figure 1, an exemplary embodiment may include a semiconductor device 100 comprising a substrate 110 and a source electrode 112, a drain electrode 114, a side gate electrode 120 / 122, and a semiconductor layer 116, each located on the substrate 110. The semiconductor device 100 may further include a regenerating amphiphilic protein layer 130 on the semiconductor layer and the gate electrode. The regenerating amphiphilic protein layer 130 may also be located on the source electrode 112 and the drain electrode 114. The regenerating amphiphilic protein layer 130 may be structured to transition from a field-effect mode to an electrolyte-gated mode by being exposed to humidity to capture H2O molecules.

[0076] In exemplary embodiments, humidity may be from exhaled breath, and the regenerated amphiphilic protein layer 130 may be structured to be in electrolyte-gated mode during exhalation.

[0077] In the electrolyte-gate mode, a first electric double layer (EDL) may be formed at the interface between the lateral gate electrode 120 / 122 and the regenerating amphiphilic protein layer, and a second electric double layer (EDL) may be formed at the interface between the regenerating amphiphilic protein layer 130 and the semiconductor layer 116.

[0078] In exemplary embodiments, the regenerated amphiphilic protein layer 130 may be further structured to transition from an electrolyte-gated mode to a field-effect mode by the extraction of captured H2O molecules during inhalation.

[0079] In exemplary embodiments, the regenerated amphiphilic protein layer 130 may be structured to be in an electrolyte-gated mode during exhalation and in an electric field-effect mode during inhalation.

[0080] In one embodiment, exhalation can cause the regenerated amphiphilic protein layer 130 to transition from the field-effect mode to the electrolyte-gated mode within approximately 30 milliseconds, and inhalation can cause the regenerated amphiphilic protein layer 130 to transition from the electrolyte-gated mode to the field-effect mode within approximately 300 milliseconds.

[0081] In exemplary embodiments, the transition between the electrolyte-gated mode and the field-effect mode allows for the tracking of multiple respiratory cycles.

[0082] In an exemplary embodiment, the semiconductor device 100 may include a bottom gate electrode (not shown) between the substrate 110 and the semiconductor layer 116.

[0083] In exemplary embodiments, the regenerated amphiphilic protein layer may be a regenerated silk fibroin layer. The regenerated amphiphilic protein layer may have thicknesses of 1 nm to 20 nm, 2 nm to 15 nm, or 3 nm to 10 nm, including, but not limited to, thicknesses of at least 1 nm, at least 2 nm, at least 3 nm, at least 4 nm, or at least 5 nm, and up to 20 nm, up to 15 nm, up to 10 nm, or up to 5 nm.

[0084] Referring to Figure 2, a method for forming a regenerated amphiphilic protein layer according to an exemplary embodiment may include: depositing silk fibroin films, each less than 5 nm in size, by spin-coating a silk solution of 0.01 to 0.1% by weight or 0.05% by weight to form a deposited silk film (210); rinsing the deposited silk film in a tank of deionized water (220); and patterning the deposited silk film (230).

[0085] In exemplary embodiments, patterning a deposited silk film may involve O2 plasma etching of the deposited silk film through a photoresist mask using poly(methyl methacrylate) (PMMA) as a passivation layer.

[0086] In exemplary embodiments, the regenerated amphipathic protein layer may be formed on a first layer and a second layer. The first layer may be conductive or semiconducting, and the second layer may be conductive or semiconducting.

[0087] In exemplary embodiments, the regenerated amphipathic protein layer may be structured such that, in a hydrated state, a first electrical double layer (EDL) is formed at the interface between the first layer and the regenerated amphipathic protein layer, and a second EDL is formed at the interface between the second layer and the regenerated amphipathic protein layer.

[0088] Unless otherwise specified or indicated by the context, the terms “a,” “an,” and “the” mean “one or more.” For example, “a molecule” should be interpreted as meaning “one or more molecules.”

[0089] As used herein, “about,” “approximately,” “substantially,” and “significantly” will be understood by those skilled in the art and will vary to some extent depending on the context in which they are used. Where there are uses of terms that are not clear to those skilled in the art given the context in which they are used, “about” and “approximately” will mean ≤±10% of a particular term, and “substantially” and “significantly” will mean >±10% of a particular term.

[0090] As used herein, the terms “include” and “including” have the same meaning as the terms “comprise” and “comprising.” The terms “comprise” and “comprising” should further be interpreted as “open” transitional terms that allow for the inclusion of additional components to those components enumerated in the claims. The terms “consist” and “consisting of” should be interpreted as “closed” transitional terms that do not allow for the inclusion of additional components other than those enumerated in the claims. The term “consisting essentially of” is partially restrictive and should be interpreted as allowing for the inclusion of only additional components that do not fundamentally alter the essence of the claimed subject matter.

[0091] All methods described herein can be carried out in any preferred order unless otherwise indicated herein or clearly contradicted by the context. The use of all examples or exemplary language provided herein (e.g., "such as") is intended solely to better illustrate the invention and does not impose any limitation on the scope of the invention unless otherwise claimed. Nothing in this specification should be construed as indicating that any non-claim element is essential to the practice of the invention.

[0092] All references cited herein, including publications, patent applications, and patents, are individually and specifically indicated so as to be incorporated by reference, and are incorporated herein by reference to the same extent as they are incorporated herein by reference.

[0093] Preferred aspects of the Invention, including best modes known to the inventors for carrying out the Invention, are described herein. Variations of these preferred aspects may become apparent to those skilled in the art by careful reading of the foregoing description. The inventors anticipate that those skilled in the art will adopt such variations appropriately, and they intend that the Invention may be practiced in ways other than those specifically described herein. Thus, the Invention includes all modifications and equivalents of the subject matter enumerated in the claims appended herein, as made possible by applicable law. Furthermore, any combination of the elements described above in all possible variations is also encompassed by the Invention, unless otherwise shown herein or clearly contradicted by context.

[0094] Although the present invention is illustrated and described in detail in the preceding drawings and description, it should be considered, by their nature, illustrative and non-restrictive, that only the illustrative embodiments are shown and described, and that it is desirable that all variations and modifications within the spirit of the invention be protected. For example, any feature or function of any of the embodiments disclosed herein may be incorporated into any of the other embodiments disclosed herein.

[0095] This disclosure is made in connection with a particular embodiment described and explained in detail, but various modifications and improvements thereto will be readily apparent to those skilled in the art. Accordingly, the spirit and scope of this disclosure should not be limited by the embodiments described above, but should be understood in the broadest sense permitted by law. [Examples]

[0096] Nanometric biomaterial interface on thin-film transistors

[0097] Over the past 20 years, indium gallium zinc oxide (IGZO) has attracted considerable attention as a highly mobile, easily processable transparent oxide semiconductor, finding applications in backplane microelectronics for large-area and flexible display technologies. The hybrid biodevice structure disclosed in this study, shown in Figure 3a, is based on this semiconductor technology in which IGZO transistors are fabricated on a Si / SiO2 substrate, in addition to coplanar side gate electrodes used to operate silk / FETs in electrolyte-gated mode. The deposition of an ultrathin fibroin film (<5 nm) was carried out by spin-coating a low-concentration silk solution (0.05 wt%) directly onto the device, followed by rinsing in deionized water. The film was then patterned by O2 plasma etching of undesirable areas through a photoresist mask, and poly(methyl methacrylate) (PMMA) was used as a passivation layer to protect the fibroin from the harsh chemicals used in conventional photolithography processes, and subsequently removed via acetone bath treatment. The strong adhesive properties of silk fibroin, while not necessarily constrained by any particular theory, may be due to its amphiphilic molecular structure of hydrogen bonds and its high-density network. As a result of these adhesive properties, these processing steps yield a stable, highly transparent biomaterial layer with a controlled thickness ranging from 3 to 300 nm (see Figures 3f, 3g, 6, and 7), exhibiting a lateral resolution of several micrometers.

[0098] Under normal humidity and temperature conditions, referred to herein as "dry conditions," the presence of silk on the upper interface of the IGZO does not affect the characteristic behavior of the device. Figure 8 reports the transfer and output characteristics of an IGZO transistor measured within a bottom gate configuration when exposed to either PMMA or silk. Despite the different material properties at these interfaces, the latter set of measurements shows that the threshold voltage (V) in the silk / FET remains constant as long as the device is kept within dry conditions. T), exhibiting only slight variations in subthreshold swing, hysteresis, off-drain source current, or charge mobility. Consistent with the aforementioned examples of field-effect transistors based on silk dielectrics, these results confirm that the polar portions of fibroin in the absence of water do not introduce significant trapping sites or energy disturbances within the IGZO that could lead to a degradation of transistor performance.

[0099] Dual-mode operation in silk / FET

[0100] Figure 4a shows the proposed operating modes of the silk / FET when controlled through a lateral gate electrode under either dry or high humidity environmental conditions. In conventional FETs, the application of a gate potential modulates the take-up of charge carriers in the transistor channel through a capacitive effect, which is determined by the dielectric polarizability of the gate insulator and the overall geometry of the device (i.e., by the overlapping area between the gate electrode and the semiconductor channel and their relative distance). In conventional FET structures, the gate electrode is typically placed across (or beneath) the transistor channel area, and the specific capacitance established through this mechanism is generally 0.01–1 μFcm. -2 It is within the range. Despite the good dielectric properties of silk, when the device operates under dry conditions, the absence of geometric overlap between the lateral gate electrode and the silk / FET channel results in very little capacitive coupling, which is insufficient to modulate the charge carrier density within the IGZO. Conversely, under high humidity conditions, the gate mechanism of the silk / FET changes drastically due to the formation of two EDLs at the semiconductor / silk interface and the gate metal / silk interface, respectively. As a first approximation, the EDL can be recalled as a conventional parallel-plate capacitor where electronic surface charges and inversely charged ions are matched at the (semi)conductor / electrolyte interface in a dense and closely localized distribution. In electrolyte-gated FETs, generally, 10 μFcm -2These strong capacitive couplings, far exceeding the limit, lead to large-scale charge modulation within the transistor channel with subvolt polarization, with only minor dependence on dielectric film thickness or electrode geometry. In the disclosed devices, EDL formation relates to the silk material's ability to capture H2O molecules from ambient moisture, which may be due to a unique thin-film microstructure emerging from the device's processing steps, including acetone bath treatment (see Experimental section), although we do not wish to be constrained by any particular theory. In practice, water absorption and transport within silk are the focus of several studies, consistently highlighting the primary influence of the secondary structure of fibroin on both of these properties. The relative ratio of amorphous to crystalline regions within the film can affect their hydration dynamics, among other properties. For example, while it is known that increased crystalline content induces a water vapor barrier effect, silk films immersed in polar organic solvents such as methanol, ethanol, or acetone exhibit a secondary structural arrangement characterized by a superior capacity for water absorption. Furthermore, the acceptance of a greater degree of free water within the film, which has been shown to reach up to 12% by weight in high humidity settings, may be associated with improved plasticization of the silk chain, which can play a role in favorable to high-speed water transport.

[0101] The significant difference in device behavior between dry and high humidity conditions can be seen in Figure 4b, which clearly demonstrates the transition of the side-gate silk / FET from the conventional field-effect mechanism (based on dielectric polarization, thus exhibiting extremely low off-current and virtually no modulation) to the electrolyte-gated mode of operation. Under high humidity conditions, the device actually exhibits well-behaved n-type device characteristics, with a response time of approximately 10 4 It has an on / off current ratio, a threshold voltage of -0.27V, and a subthreshold swing of 0.18V / decade.

[0102] The dramatic current increase achieved through EDL formation at the ultrathin silk interface is evident from gate impedance measurements performed on the silk / FET, exceeding the current by six orders of magnitude (from tens of pA to a maximum of tens of μA), and from there, several μFcm under high humidity conditions. -2 The specific capacitance C' was extracted (in Figure 4c, the capacitance value under dry conditions was too low to be measured).

[0103] High-speed and highly sensitive respiratory sensor

[0104] The ability to modify the device's operating mechanism in response to exposure to humidity opens up new opportunities for bioelectronic sensing, particularly in the context of respiratory system monitoring and respiratory analysis. In recent years, several pathological conditions and respiratory syndromes, including cardiovascular and pulmonary diseases as well as sleep apnea, have correlated with abnormalities in respiratory frequency and depth. For this reason, further efforts have focused on developing small and cost-effective monitoring devices for respiratory diagnosis, with particular emphasis on achieving high sensitivity and sub-second responses to closely track respiratory cycle dynamics. Among respiratory system monitoring technologies, a common sensing strategy relies on the absorption and desorption of moisture by water-responsive electronic materials, which is particularly technologically relevant when it can be directly integrated into conventional electronic devices.

[0105] Due to their nanometric thickness and good transport properties, the humidity-driven reconfigurability of the disclosed silk / FETs from the field-effect mode of operation to the electrolyte-gated mode is characterized by remarkable reversibility and fast dynamics. These devices can, in practice, be effectively utilized toward respiratory sensing applications, achieving sensitivity and response times comparable to or exceeding those of previous embodiments.

[0106] Figure 5a shows three consecutively measured transfer curves of silk / FET obtained at different moments during one respiratory cycle consisting of the expiratory phase and subsequent exhalation. In light of the mechanism described herein, first, the dry silk / FET is biased and then exposed to respiratory humidity during exhalation, thus transitioning from an unmodulated field-effect mode to electrolyte-gated mode. Subsequently, in response to inspiration, water molecules are extracted from the nanoscale silk layer, almost completely restoring the initial dry conditions. With a response time of approximately 30 milliseconds and a recovery of 300 milliseconds, the fast transition kinetics allow for precise tracking of multiple respiratory cycles and I in response to exhalation. DS Signal 10 4 High sensitivity is maintained with a doubling of the original sensitivity (see Figures 3b and 3c).

[0107] conclusion

[0108] In conclusion, this disclosure provides a new perspective on the potential of silk-based biohybrid electronic nanointerfaces. The seamless integration of inorganic semiconductor technology with nanoscale biopolymer thin films generates innovative device concepts and configurations that fuse the exceptional performance of conventional microelectronic components with the unique functionality conferred by biopolymers. In fact, by carefully controlling processing conditions from the solution phase, nanoscale manipulation of silk film thickness enables optimization of the water transport properties and surface interactions of this multifaceted biomaterial, thus allowing for unprecedented reconfigurability in microelectronic platforms. In the context of bioelectronics and respiratory sensing, the already excellent sensitivity and fast dynamics of silk / FETs can be complemented by biochemical sensing functionality, which can be implemented, for example, by introducing bioreactive elements into the silk matrix, toward multi-sample and environmentally stable microelectronic sensing platforms.

[0109] Experimental Section

[0110] chemicals

[0111] Indium nitrate hydrate (In(NO3)3·xH2O, 99.999%, Aldrich), gallium nitrate hydrate (Ga(NO3)3·xH2O, 99.999%, Aldrich), zinc nitrate hexahydrate (Zn·6H2O, 99.999%, Aldrich), and deionized water were obtained from the milliQ Nanopure System and exhibited a resistivity of approximately 18 MΩ·cm.

[0112] Preparation and treatment of metal hydrate precursor solutions

[0113] The solution for IGZO was prepared by the following procedure: Metal precursors consisting of indium nitrate hydrate, gallium nitrate hydrate, and zinc nitrate hexahydrate powders were dissolved in distilled water. The resulting solution was then thoroughly stirred for more than 12 hours and filtered through a 0.22 μm membrane filter before use.

[0114] Preparation of silk

[0115] Silk fibroin was extracted from silkworm cocoons using an established protocol (see Nat. Protoc. 2011, 6, 1612. by DN Rockwood, RC Preda, T. Yucel, X. Wang, ML Lovett, and DL Kaplan). In summary, the cocoons were cut into small pieces and boiled in a 0.02 m Na2CO3 aqueous solution for 10 minutes to remove hydrophilic sericin proteins. The extracted silk fibers were rinsed with distilled water and then dried in ambient air for 2 days. The dried silk fibers were dissolved in a 9.3 m LiBr solution at 60°C for 4 hours, and stirred after 1–2 hours. The dissolved silk fibroin was dialyzed against distilled water in a dialysis cassette (Slide-a-Lyzer, Pierce, MWCO 3.5K) for 36 hours to obtain a 5-8 wt% silk fibroin solution in water, which was then centrifuged twice at 8,000 rpm. The clear suspended solid was collected and then further diluted to 0.05 wt% in deionized water and stored at 4°C for further processing unless otherwise noted.

[0116] FET processing

[0117] Si wafers with a 300 nm thick SiO2 dielectric (highly n-doped, ρ < 0.005 Ω·cm, manufactured by universitywafer) were used as the bottom gate and substrate for FET processing. 1 cm × 1 cm substrates were immersed in Piranha (concentrated H2SO4 and 30% aqueous H2O2, volume ratio 3:1) until oxygen stopped foaming. Once the substrates cooled, they were rinsed multiple times with water. Aqueous precursor solutions of inorganic materials were deposited onto the newly cleaned substrates via spin coating. The dried films were then annealed at 350°C for 30 minutes to decompose the ligands. The thickness of the active layer was approximately 5–6 nm. The IGZO films were then patterned via conventional photolithography and wet etching with HCl:H2O (1:100) for 1 minute. 50nm thick AI or Au source, drain, and gate electrodes were deposited by thermal evaporation onto a mask patterned by photolithography.

[0118] Lamination and patterning of ultrathin silk

[0119] A diluted silk solution was spin-cast onto an IGZO FET at 3,000 rpm, followed by rinsing in a deionized water bath to yield a nanoscale thin film. Prior to photolithography, a protective PMMA (polymethyl methacrylate) C4 coating was spin-coated onto the substrate (fired at 180°C for 1 minute at 3,000 rpm). Photoresist S1805 was spin-coated (fired at 115°C for 1 minute at 3,000 rpm), exposed through a photomask for 3 seconds, and deployed within MF-CD26 for 1 minute. O2 etching was performed at 100 W for 2 minutes to remove PMMA and silk in the unexposed areas, followed by acetone bath treatment to remove any remaining photoresist and PMMA. Electrode passivation was performed through the deposition of an SU8 layer and photolithographic patterning.

[0120] measurement

[0121] Electrical measurements were performed using a parameter analyzer (Keithley 4200A-SCS) equipped with a capacitance / voltage unit. The source electrode was grounded, and the source gate voltage V GS and the source drain voltage V DS were controlled. Experiments under dry conditions and high humidity conditions were carried out using a custom chamber. The thin film morphology was obtained by atomic force microscopy (Bruker, Innova SPM).

Claims

1. A device, wherein the device is A first layer, wherein the first layer is conductive or semiconducting, The regenerated amphipathic protein layer on the first layer, wherein the regenerated amphipathic protein layer is In the first hydration state of the regenerated amphiphilic protein layer, the first electric double layer (EDL) is structured to be formed at the interface between the first layer and the regenerated amphiphilic protein layer. A device equipped with the following features.

2. The aforementioned device further, The second layer, The second layer is conductive or semiconducting, The aforementioned regenerating amphipathic protein layer is located on the second layer, In the first hydration state of the regenerated amphiphilic protein layer, the second EDL is formed at the interface between the second layer and the regenerated amphiphilic protein layer. The device according to claim 1, further comprising a second layer.

3. The device according to claim 1, wherein the regenerating amphiphilic protein layer is capable of accessing environmental moisture.

4. The device according to claim 3, wherein the first hydration state is initiated by the capture of environmental moisture by the regenerating amphiphilic protein layer.

5. The aforementioned regenerated amphiphilic protein layer is A silk fibroin film, each less than 5 nm in size, is deposited by spin-coating a silk solution of 0.01 to 0.1% by weight or 0.05% by weight, thereby forming a deposited silk film. The deposited silk film is rinsed in a tank of deionized water, Patterning the aforementioned deposited silk film and The device according to claim 3, formed by...

6. Patterning the aforementioned deposited silk film involves using poly(methyl methacrylate) (PMMA) as a passivation layer and passing the deposited silk film through a photoresist mask. ２ The device according to claim 5, comprising plasma etching.

7. The device according to claim 2, wherein the first and second EDLs formed in the first hydration state enhance the current flow by more than six orders of magnitude.

8. The first EDL includes an electronic surface charge and inversely charged ions that are matched at the interface between the first layer and the regenerating amphiphilic protein layer. The second EDL includes an electronic surface charge and inversely charged ions that are matched at the interface between the second layer and the regenerating amphiphilic protein layer. The device according to claim 2.

9. The device according to claim 2, wherein the first layer is a lateral gate electrode of a transistor, and the second layer is a semiconductor layer of the transistor.

10. The device according to claim 9, wherein the lateral gate electrode and the semiconductor layer do not overlap in the cross-sectional view.

11. The device according to claim 9, wherein the semiconductor layer is formed from a semiconducting material.

12. The device according to claim 11, wherein the semiconducting material comprises indium gallium zinc oxide (IGZO).

13. The device according to claim 9, wherein in the second hydration state of the regenerated amphiphilic protein layer, the first EDL and the second EDL are not formed.

14. The second hydration state is the captured H in the regenerated amphiphilic protein layer. ２ The device according to claim 13, which addresses the absence of O molecules.

15. The device according to claim 14, wherein in the second hydration state, the capacitive coupling between the lateral gate electrode and the semiconductor layer is determined by the dielectric constant of the regenerated amphiphilic protein layer.

16. The device according to claim 15, wherein capacitive coupling is insufficient to modulate the charge carrier density within the semiconductor layer.

17. The device according to claim 13, wherein when the regenerated amphiphilic protein layer transitions from the second hydrated state to the first hydrated state, the transistor transitions from a field-effect operating mode to an electrolyte-gated operating mode.

18. The device further comprises a substrate, The device according to claim 9, wherein the first layer and the second layer are each located on the substrate.

19. The device according to claim 18, further comprising a bottom gate electrode between the substrate and the semiconductor layer.

20. The substrate is Si / SiO ２ The device according to claim 18.

21. The device according to claim 1, wherein the regenerated amphiphilic protein layer is a regenerated silk fibroin layer.

22. The device according to claim 1, wherein the regenerated amphipathic protein layer has a thickness of 1 nm to 20 nm, 2 nm to 15 nm, or 3 nm to 10 nm, including, but not limited to, a thickness of at least 1 nm, at least 2 nm, at least 3 nm, at least 4 nm, or at least 5 nm, and a thickness of up to 20 nm, up to 15 nm, up to 10 nm, or up to 5 nm.

23. A semiconductor device, wherein the semiconductor device is circuit board and Each of the following components is located on the substrate: a source electrode, a drain electrode, a side gate electrode, and a semiconductor layer. The semiconductor layer and the regenerated amphiphilic protein layer on the gate electrode Equipped with, The aforementioned regenerated amphiphilic protein layer is H ２ A semiconductor device structured to transition from a field-effect mode to an electrolyte-gated mode by being exposed to humidity to capture oxygen molecules.

24. The semiconductor device according to claim 23, wherein the humidity is from exhaled breath.

25. The semiconductor device according to claim 24, wherein the regenerating amphiphilic protein layer is structured to be in the electrolyte-gated mode during exhalation.

26. In the aforementioned electrolyte gate mode, The first electric double layer (EDL) is formed at the interface between the lateral gate electrode and the regenerating amphiphilic protein layer. The second electric double layer (EDL) is formed at the interface between the regenerating amphiphilic protein layer and the semiconductor layer. The semiconductor device according to claim 24.

27. The regenerated amphiphilic protein layer further contains the captured H ２ The semiconductor device according to claim 24, wherein the O molecule is extracted during inhalation, thereby structuring to transition from the electrolyte gated mode to the field-effect mode.

28. The semiconductor device according to claim 27, wherein the regenerating amphiphilic protein layer is structured to be in the electrolyte-gated mode during exhalation and in the field-effect mode during inhalation.

29. The exhaled air causes the regenerated amphiphilic protein layer to transition from the field-effect mode to the electrolyte-gated mode within approximately 30 milliseconds. The aforementioned inhalation causes the regenerating amphiphilic protein layer to transition from the electrolyte-gated mode to the field-effect mode within approximately 300 milliseconds. The semiconductor device according to claim 27.

30. The semiconductor device according to claim 27, wherein the transition between the electrolyte-gated mode and the field-effect mode enables tracking of multiple respiratory cycles.

31. The semiconductor device according to claim 27, further comprising a bottom gate electrode between the substrate and the semiconductor layer.

32. The semiconductor device according to claim 23, wherein the regenerated amphiphilic protein layer is a regenerated silk fibroin layer.

33. The device according to claim 23, wherein the regenerated amphipathic protein layer has a thickness of 1 nm to 20 nm, 2 nm to 15 nm, or 3 nm to 10 nm, including, but not limited to, a thickness of at least 1 nm, at least 2 nm, at least 3 nm, at least 4 nm, or at least 5 nm, and a thickness of up to 20 nm, up to 15 nm, up to 10 nm, or up to 5 nm.

34. A method for forming a regenerated amphiphilic protein layer, wherein the method is A silk fibroin film, each less than 5 nm in size, is deposited by spin-coating a silk solution of 0.01 to 0.1% by weight or 0.05% by weight, thereby forming a deposited silk film. The deposited silk film is rinsed in a tank of deionized water, Patterning the aforementioned deposited silk film and Methods that include...

35. Patterning the aforementioned deposited silk film involves using poly(methyl methacrylate) (PMMA) as a passivation layer and passing the deposited silk film through a photoresist mask. ２ The method according to claim 34, comprising plasma etching.

36. The method according to claim 34, wherein the regenerated amphipathic protein layer is formed on a first layer and a second layer, the first layer being conductive or semiconducting, and the second layer being conductive or semiconducting.

37. The method according to claim 36, wherein the regenerated amphiphilic protein layer is structured such that, in a hydrated state, a first electric double layer (EDL) is formed at the interface between the first layer and the regenerated amphiphilic protein layer, and a second EDL is formed at the interface between the second layer and the regenerated amphiphilic protein layer.

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