Patent Description:
Natural silk produced by silkworms has been used to make fabrics for thousands of years. More recently, silkworm silk has been used to fabricate biodegradable medical implants, protective fabrics, and biodegradable wearable electronics. However, existing techniques for manufacturing electrical circuit components from silkworm silk require post processing to incorporate functional properties into the silkworm silk and can be non-scalable and/or cost prohibitive.

Accordingly, there exists a need for electrical circuit components made from silkworm silk and methods for manufacturing such components that avoid at least some of the difficulties associated with conventional fabrication of electrical circuit components from silkworm silk.

In <NPL>, a method is disclosed to improve the mechanical properties of silk fibers obtained by feeding silkworms with amounts of carbon nanotube/lignosulfonate composite. The method comprises a purification process in order to reduce the proportion of lignosulfonate, thereby increasing the proportion of carbon nanotubes in the silk fibers. References to other prior art are listed in the References Section below.

An electrical circuit component includes at least one fiber of silkworm silk, the at least one fiber having an outer surface and an interior region bounded by the outer surface. The electrical circuit component includes a plurality of portions of silkworm-digested, structured material located in the interior region or on the outer surface of the at least one fiber, wherein the at least one fiber and the silkworm-digested, structured material have a desired electrical property. The electrical circuit component includes at least one conductor for connecting the at least one fiber to an electrical circuit, wherein the at least one silkworm silk fiber forms a first electrode, and further includes a second electrode and an electrolyte, which is located between the first and second electrodes. The first and second electrodes and the electrolyte form a supercapacitor.

A method for manufacturing an electrical circuit component includes preparing a mixture of a structured material and silkworm food. The method further includes feeding the mixture to at least one silkworm. The method further includes harvesting silk produced by the at least one silkworm, wherein the harvested silk includes at least one silkworm silk fiber including silkworm-digested portions of the structured material embedded in or on the at least one fiber. The method further includes incorporating the at least one fiber into an electrical circuit component, wherein the at least one silkworm silk fiber forms a first electrode and together with a second electrode and an electrolyte located between the first and second electrodes form a supercapacitor.

Feeding Bombyx mori larvae with chemically-modified diets affects the structure and properties of the resulted silk. Herein, we provide a road map for the use of silkworms as a factory to produce semiconducting/metallic natural silk that can be used in many technological applications such as supercapacitor electrodes. The silkworms were fed with four different types of chemicals; carbon material (graphite), sulfide (MoS<NUM>), oxide (TiO<NUM> nanotubes), and a mixture of reactive chemicals (KMnO<NUM>/MnCl<NUM>). All the fed materials were successfully integrated into the resulted silk. The capacitive performance of the resulted silk was evaluated as self-standing fabric electrodes as well as on glassy carbon substrates. The self-standing silk and the silk@glassy carbon substrate showed a great enhancement in the capacitive performance over that of the unmodified counterparts. The specific capacitance of the self-standing blank silk negative and positive electrodes was enhanced <NUM> and <NUM> folds at <NUM> mV/s, respectively upon the modification with KMnO<NUM>/MnCl<NUM> compared to that of the plain silk electrodes.

Metals and semiconductors are the backbone of our modern industry. Therefore, there is a continuous need to develop new methods and technologies to produce such essential materials with the desired characteristics at low cost. Of special interest, enormous efforts have been devoted to develop flexible wearable devices. Those wearable devices are usually made of synthetic nanofibers. However, one of the cheapest and commonly used fibers is the natural silk (NS)<NUM>,<NUM>, which has been used, through many decades, as fabric for many applications such as biodegradable medical implants, durable protective fabrics, and eco-friendly wearable electronics. <NUM>-<NUM> NS consists mainly of a polymerized protein known as fibroin covered with a glue-like material named sericin. <NUM> It is fabricated through the organisms of silkworms from a liquid combination of polymers at room temperature, resulting in a silk that is insoluble in water. <NUM>,<NUM> The fibroin of the Bombyx mori larvae is a semi-crystalline biopolymer consisting of glycine, alanine and serine. <NUM> However, the as-produced spun silks are usually treated with additives to make them functional, which adds to the cost and requires tedious optimization. A promising approach to overcome such obstacles can occur through additives to the food of the silkworms (usually mulberry leaves). <NUM>,<NUM> Feeding the worms with special chemical materials, which can be incorporated in the glands of the worms and mix with the fibroin liquid, is expected to result in a modified-silk composite that comprises the properties of both NS and the incorporated materials. <NUM>-<NUM> The fact that NS radiates heat more than it absorbs and self-cool, makes it a good candidate for electronic applications.

Feeding Bombyx mori larvae with nanostructured materials such as CNTs,<NUM>,<NUM> graphene,<NUM> TiO<NUM><NUM>,<NUM> and other metal oxides<NUM> have been investigated in recent reports. Details of the feeding process are provided in Appendix A. The feeding process proved that Bombyx mori larvae can intake nanostructured materials, which affect the crystallinity of the resulting silk. Feeding the worms with TiO<NUM> was also proved to be nontoxic<NUM> and even used with bacteria to enhance energy harvesting devices. <NUM> However, most of the previous reports were limited to the investigation of the mechanical and photonic properties of such modified silk. <NUM>,<NUM> Tailoring the properties of the NS to be used in electronic devices, energy generation, and energy storage devices is yet to be reported. Of special interest, flexible supercapacitors are emerging as promising platforms for energy storage. <NUM>-<NUM>.

Herein, we demonstrate the ability to modify the structure and supercapacitive behavior of NS by feeding the Bombyx mori larvae with four different types of materials (graphite, TiO<NUM> nanotubes, MoS<NUM>, and KMnO<NUM>/MnCl<NUM>) for use as supercapacitor electrodes. The study shows that modification of the NS enhanced its capacitive behavior, paving the way for their use in flexible supercapacitor applications.

All of the studied silkworms started the feeding on their <NUM>th instar and they did not reject the food. It was observed that the larvae fed with MoS<NUM> were eating more than usual while the ones fed with KMnO<NUM>/MnCl<NUM> were eating in a lower rate than usual. The larvae fed with graphite and TiO<NUM> did not show any unusual behavior in the feeding process. While the cocoons of the blank fed larvae were of homogeneous size and white in color, the chemically-modified ones showed a non-homogenous size and off-white in color. After degumming, all the fabricated fibers were of a clear white color. The resulted silk was given the names S/B, S/G, S/TiO<NUM>, S/MoS<NUM> and S/Mn for the blank silk, the graphite modified silk, the TiO<NUM> modified silk, the MoS<NUM> modified silk and the KMnO<NUM>/MnCl<NUM>, respectively.

The morphology of the silk fibers was investigated using FESEM imaging as shown in <FIG>. Note that the thickness of the fabricated fibers is independent of the type of the chemical additive, having diameters ranging from <NUM> to <NUM>, in agreement with previous reports. <NUM>,<NUM> The fed materials appeared as debris on the surface of the fibers and/or within their internal fibroins. While the S/B fibers showed a trigonal shaped cross-section as presented in the inset of <FIG>, the S/G and S/TiO<NUM> showed an oval-shaped cross-section with the additives clearly appearing on the surface of the fibers. However, the S/MoS<NUM> and S/Mn showed a flattened oval cross-section and the fibers were more flat than usual, which may suggest that the additives (MoS<NUM>, Mn) were interfered with the fiber materials and reconstructed its protein structure. <NUM> The elemental composition of the fibers was studied using the EDS technique and the results are presented in Table <NUM> below. The resulting composition showed that the added material did not exceed <NUM> at% of the total atoms in the fiber, which is an accepted ratio due to the low concentration (<NUM> wt% solution) used in the diet. The S/B and S/G did not vary greatly due to the fact that graphite is only made of carbon atoms. However, the S/MoS<NUM> analysis showed <NUM> at% of Mo and <NUM> atom% of S. the S/TiO<NUM> showed a Ti composition of <NUM> at% and the S/Mn showed <NUM> at% of Mn and <NUM> at% of K "from the added KMnO<NUM>", with no signal for Cl atoms at different positions of the S/Mn fibers indicating that Cl<NUM> gas may have evaporated from the reaction medium during the formation of MnO<NUM>. <NUM> Although the EDS analysis showed a minor ratio of the added materials, the SEM images showed a major effect on the morphology of the resulted fiber. The investigation of the crystal structure of the silk was performed using XRD as presented in <FIG>. The XRD patterns show that all the resulted silk has a mesophase behavior with a broad peak around <NUM>°, which can be attributed to the β-sheet of silk II structure. <NUM>-<NUM> Note that the presence of the β-sheet structure is more pronounced in the blank silk and in the S/Mn than in the S/G, S/MoS<NUM> and S/TiO<NUM>. The mesophase structure of the silk is believed to facilitate the diffusion of ions to the internal parts of the silk fibers.

<FIG> illustrate results of the morphological and structural analysis of the silk. <FIG> are FESEM images of the fabricated fibers (inset: cross section in the fiber) "pseudo-color is used for clarity" <FIG>, S/B; <FIG>, S/G; <FIG>, S/MoS<NUM>; <FIG>, S/TiO<NUM>; <FIG>, S/Mn; and <FIG>, the corresponding XRD patterns.

As the Raman spectroscopy has been used as a good tool to investigate the deformation of polymers backbone structure <NUM>, the Raman spectra of the fabricated silk were recorded as shown in <FIG>. All fibers showed the same peak position with different intensities, indicating more or less a similar internal structure. The Raman active peaks of the studied fibers are in the range between <NUM> to <NUM>-<NUM>, in a good agreement with literature. <NUM>,<NUM> The observed Raman peaks of the B. Mori silk appeared at <NUM>, <NUM> and <NUM>-<NUM> as indicated by arrows in <FIG>. The FTIR spectra in <FIG> showed the typical peaks at <NUM>, <NUM> and <NUM>-<NUM> characteristic of the silk fibers but with different intensities for different samples. <NUM>,<NUM>,<NUM> The peak at <NUM>-<NUM> indicated the presence of amide I structure and the peak is due to the vibration of the C=O bond. The peak at <NUM>-<NUM> indicated the presence of amide II structure and the peak is due to the deformation of the N-H bond in the β sheet structure. The Peak at <NUM>-<NUM> indicated the presence of amide III structure and the peak is due to the vibration of the O-C-O bonds and the N-H bond. Thermogravimetric analysis was performed to indicate the thermal stability of the resulted silk fibers. <FIG> shows that all the silk fibers were stable up to <NUM>° C then the blank silk started to decompose at ~ <NUM>° C. The modified silk showed enhanced thermal stability. At <NUM>° C, the remaining weight of the silk was <NUM>, <NUM>, <NUM>, <NUM> and <NUM>% for S/TiO<NUM>, S/G, S/MoS<NUM>, S/Mn, and S/B, respectively.

To test the capacitive performance of the natural silk, the self-standing silk was tested once as a positive electrode and once as a negative electrode in a <NUM>-electrode system with <NUM> KOH as the electrolyte. Although <NUM> KOH is a high concentration electrolyte, it is commonly used with the carbon-based materials in supercapacitor applications. <NUM>-<NUM> Examples of the electrodes produced from the silkworm silk and used in the experiment are shown in <FIG>.

<FIG> illustrate results of the capacitive performance testing. More particularly, <FIG> illustrates CVs of the studied self-standing silk fiber at <NUM> mV/s in positive potential window (inset: legend of <FIG>, <FIG> illustrates CVs of the studied self-standing silk fiber at <NUM> mV/s in negative potential window, <FIG> illustrates CVs of the studied silk @ GC at <NUM> mV/s in positive potential window, <FIG> illustrates GCDs of the studied self-standing fibers at <NUM> A/g in positive potential window (inset: enlarged figure), <FIG> illustrates GCDs of the studied self-standing fibers at <NUM> A/g in negative potential window (inset: enlarged figure), <FIG> illustrates GCDs of the studied silk @ GC at <NUM> A/g in negative potential window.

Usually, the carbon materials show a typical rectangular cyclic voltammogram (CV) reflecting the electrical double layer behaviour (EDL). <NUM> However, the CVs of the positive and negative silk electrodes in <FIG> did not show an EDL behavior indicating diffusion processes for the ions in the polymeric structure of the silk. <NUM> It is expected that the OH- ion from the KOH reacted with the organic polymer of the silk fibers resulting in a diffusion and pseudocapacitive behavior to the silk electrodes. The ions from the KOH can react with MoS<NUM>, TiO<NUM>, and MnO<NUM> to give MoSSOH,<NUM> TiOOK<NUM> and MnOOK<NUM>, respectively. The CVs of the positive silk electrodes at a scan rate of <NUM> mV/s (<FIG>) show that the redox peaks are more visible in the S/TiO<NUM> while the other additives did not affect the shape of the CV of the S/B. This can be ascribed to the accumulation of TiO<NUM> on the surface of the silk fibers while other additives affected the morphological shape of the silk fibers and did not accumulate with high amount on the surface of the fibers. At a scan rate of <NUM> mV/s and at a positive potential window, the specific capacitance of the S/Mn showed the highest specific capacitance of <NUM> mF/g while the S/TiO<NUM>, S/MoS<NUM>, S/G and S/B showed <NUM>, <NUM>, <NUM>, and <NUM> mF/g, respectively. This shows that all the additives dramatically increased the specific capacitance values of silk electrodes. The CVs of the negative silk electrodes at a scan rate of <NUM> mV/s (<FIG>) show clearer redox peaks than the positive electrodes. The specific capacitance of the negative electrodes calculated at a scan rate of <NUM> mV/s was <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> mF/g for S/Mn, S/B, S/MoS<NUM>, S/G and S/TiO<NUM>, respectively. To make a deeper study with accurate weight of the active material, the strands of the silk fibers were coiled over a glassy carbon (GC) electrode (see <FIG>) and measured as a positive electrode. The calculated specific capacitance of silk fibers @ GC at <NUM> mV/s (<FIG>) showed a capacitance of <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> mF/g for S/MoS<NUM>, S/TiO<NUM>, S/Mn, S/G and S/B, respectively. The contribution of the GC current collector affected the shape of the CVs and shifted them to the EDL rectangular shape. Also, the GC affected the values of the specific capacitance and the order of the materials in their capacitance values. Therefore, the current collector affects greatly the overall performance of the material and we will focus herein on the self-standing fibers as they are more reliable for the study. As one of the most important metrics of supercapacitors is their ability to store and release charges, the time of the charge and discharge was also studied for the silk fibers. <FIG> and <FIG> show the galvanic charge/discharge (GCD) curves of the self-standing silk fibers at a current density of <NUM> A/g. The GCD curves show a pseudocapacitive behavior. <NUM> For the positive electrodes, the specific capacitance calculated from the GCD at <NUM> A/g showed the same trend as that calculated from the CVs at <NUM> mV/s. The specific capacitance values of the positive electrodes calculated at <NUM> A/g were <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> mF/g for S/Mn, S/TiO<NUM>, S/MoS<NUM>, S/G and S/B, respectively. However, for the negative electrodes, the specific capacitance values calculated at <NUM> A/g were <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> mF/g for S/Mn, S/TiO<NUM>, S/B, S/MoS<NUM> and S/G, respectively. The GCD curves of the silk @ GC positive electrodes at <NUM> A/g are presented in <FIG>. The specific capacitance of the positive silk @ GC calculated at <NUM> A/g were <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> mF/g for S/TiO<NUM>, S/MoS<NUM>, S/Mn, S/G and S/B, respectively. As for the CV results of the silk @ GC, the trend is different, and the effect of the current collector is shifting the shape of the GCD curves to the ideal shape of the EDL capacitor materials. However, the specific capacitance values of the silk with additives are still much higher than this of the blank silk. The CV and GCD results showed that the blank silk (S/B) behaved better as a negative electrode than as a positive electrode and so did the addition of Mn ions (S/Mn) and usually MnO<NUM> acts as a better capacitive material when used as a negative electrode. <NUM> However, the S/G, S/MoS<NUM> and S/TiO<NUM> enhanced the performance of the silk as a positive electrode than as a negative electrode. Although the amounts of the additives were relatively low, their effect can be attributed to both the nature of the materials and their effect on the morphology of the silk fiber, which controls the diffusion of ions into the silk fibers.

<FIG> illustrate results of ectrochemical stability testing of the silk fibers. More particularly, <FIG> illustrates Nyquist plots of the studied silk @ GC in the range <NUM> to <NUM> (inset: fitting circuit and fitting curve). <FIG> illustrates the change in specific capacitance with scan rate (<NUM>, <NUM>, <NUM>, and <NUM> mV/s) for the self-standing fiber in positive potential window (inset: legend for <FIG>). <FIG> illustrates the change in specific capacitance with current density (<NUM>, <NUM>, <NUM>1nd <NUM> A/g) for the self-standing fiber in positive potential window. <FIG> illustrates the change in specific capacitance with scan rate (<NUM>, <NUM>, <NUM>, and <NUM> mV/s) for the self-standing fiber in negative potential window. <FIG> illustrates the change in specific capacitance with current density (<NUM>, <NUM>, <NUM>1nd <NUM> A/g) for the self-standing fiber in negative potential window. <FIG> illustrates retention of the studied self-standing fiber in both positive and negative potential window.

The conductivity is one of the main factors that affects the overall performance of a supercapacitor electrode. <FIG> shows the Nyquist plots of <NUM> of silk fibers coiled over the same area of a glassy carbon electrode. The resulted curves were fitted to the inset circuit in <FIG>, with R<NUM> representing the electrolyte resistance and R<NUM> representing the charge transfer resistance of the material. This circuit showed a perfect match with all the Nyquist plots as presented in the inset of <FIG>. The R<NUM> values of the silk fibers were <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>Ω for S/B, S/G, S/TiO<NUM>, S/MoS<NUM> and S/Mn, respectively. Those R<NUM> values show that the additives greatly enhanced the conductivity of the silk fibers and hence enhanced their specific capacitance. The supercapacitors should be able to work under different conditions of scan rates and current densities. The value of the specific capacitance of self-standing silk positive electrodes versus the scan rate is presented in <FIG>. Note that the specific capacitance values have the same trend except at <NUM> mV/s. At <NUM> mV/s, the specific capacitance values are <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> mF/g for S/Mn, S/MoS<NUM>, S/TiO<NUM>, S/G, S/B, respectively. On the other hand, from the GCD calculations of the positive self-standing silk electrodes (<FIG>), the trends differed over the high current density. It showed the values of <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> mF/g at <NUM> A/g for S/Mn, S/MoS<NUM>, S/G, S/TiO<NUM>, and S/B, respectively. For the negative self-standing silk electrodes, the change of specific capacitance with scan rate is presented in <FIG>. The values of the S/Mn and S/B were always much higher than those of the S/G, Si/MoS<NUM>, and Si/TiO<NUM>. At a scan rate of <NUM> mV/s, the specific capacitance values of the negative self-standing electrodes were <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> mF/g for S/Mn, S/B, S/G, S/TiO<NUM>, and S/MoS<NUM>, respectively. The trend of the specific capacitance at different current densities is presented in <FIG>. At a current density of <NUM> A/g, the specific capacitance values of the negative self-standing electrodes were <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> mF/g for S/Mn, S/MoS<NUM>, S/G, S/TiO<NUM>, and S/B, respectively. Although the S/TiO<NUM>, S/MoS<NUM>' and S/G specific capacitance values as negative electrode (from GCD) are higher than that of the S/B but it is lower than their positive electrode values (from GCD). Thus, it is believed that S/TiO<NUM>, S/MoS<NUM>' and S/G act better as positive electrodes than as negative electrodes. Despite the different trends over the different scan rates and current densities, the performance of all silk with additives was better as positive electrodes than the blank silk and the S/Mn was always better as a negative electrode. One of the performance metrics of the supercapacitor materials is their stability upon cycling. <FIG> shows the retention percentage of the self-standing silk as positive and negative electrodes over <NUM> cycles. The retention fluctuates at the first <NUM> cycles and reaches a relative stability after <NUM> cycles. The positive electrodes showed retention of <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>% for S/TiO<NUM>, S/MoS<NUM>, S/G, S/Mn, and S/B, respectively after <NUM> cycles. The negative electrodes showed retention of <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>% for S/MoS<NUM>, S/TiO<NUM>, S/Mn, S/B, and S/G, respectively. From the retention results we conclude that the silk fiber has a better retention as a positive electrode in general and that the additives enhanced the retention and cyclability of the electrodes. the above <NUM>% retention values are attributed to the further diffusion of ions into the material and enhancement of reaction over time. <NUM>,<NUM> Noteworthy to mention that the specific capacitance values in mF are acceptable for self-standing carbon-based materials with no high conductive current collectors. <NUM>-<NUM>.

We demonstrate the ability to fabricate functionalized natural silk fibers by feeding the silkworms with the material of interest. Specifically, this work highlights the possibility of using natural silk fibers as supercapacitor electrodes upon feeding the worms with high capacitive materials such as graphite, MoS<NUM>, TiO<NUM>, and KMnO<NUM>/MnCl<NUM>. The study showed that the fed materi6al did not greatly affect the crystallinity of the silk fibroin and all the added materials enhanced the capacitance performance and the thermal stability of the silk fibers. It was observed that both S/B and S/Mn contained more β-sheet silk, have close thermal stability, and both acted better as negative electrodes. The study proved that natural silk can be tuned for use in energy storage devices.

<FIG> is an exemplary process for fabricating an electrical circuit component using modified silkworm silk. Referring to <FIG>, in step <NUM>, a mixture of a structured material and natural silkworm food is prepared. In the examples described above, the structured material may be one or more of graphite, molybdenum disulphide, titanium dioxide, potassium manganate and/or manganese dichloride. One of these materials may be mixed with natural silkworm food, such as mulberry leaves. In some formulations, the structured material may be nanoparticles or nanotubes of the material.

In step <NUM>, the mixture is fed to at least one silkworm. The feeding process is described in detail in Appendix A.

In step <NUM>, silk produced by the silkworm or silkworms is harvested. Details of the harvesting and the processing of the modified silkworm silk after harvesting are provided in Appendix A.

In step <NUM>, the harvested silk is incorporated into an electrical circuit component. In one example, the electrical circuit component may be a positive or negative electrode of a capacitor.

<FIG> is a diagram of a glucose biosensor and a process of manufacturing the biosensor. In the upper-left quadrant, metal formed on a layer of chemically modified silk is selectively etched away to leave a source and a drain electrode positioned on a silk and enzyme film, as shown in the upper-right figure. The lower left figure shows the deposition of the gate electrode and the etching of remaining metal surrounding the source and drain electrodes. The lower right figure shows the resulting enzymatic biosensor with gate, drain, and source electrodes present on a silk and enzyme film. The silk and enzyme file may be formed of natural silk produced by silkworms fed with materials to embed glucose enzymes in the silk and produce a current flowing from the drain when the silk and enzyme film comes in contact with glucose. The drain current increases with increasing Vds. The drain current can be measured to determine the concentration of glucose in a sample, such as a blood sample.

<FIG> are images of electrodes formed using silkworm silk modified with one of the above-described materials. In the experiment described above, the silk electrodes were incorporated into a capacitor, and the capacitance was measured. In an alternate example, due to its flexibility and durability, the modified silkworm silk can be incorporated into a garment as part of a wearable sensor.

In one example, the wearable sensor may be a glucose biosensor capable of measuring a wearer's blood glucose level. Glucose biosensors are gaining great interest in medicinal applications due to their benefit in exploring diabetes patients' biological changes. However, enzymatic glucose biosensors are the ones that opened the gate for researchers, since enzymes are highly selective to different substrates. Since wearable flexible and biocompatible materials are the main targets when modifying a biosensor, Natural Silk (NS) will be the most promising material for such applications. NS is not very conducive in nature; our target is to feed the silkworms with a chemically modified diet that will impact in the produced silk fibroin and transform it into conductive silk. The resulted flexible fibers can then be used as a substrate for the enzymatic silk that will bind to the glucose and detect its presence in blood working as a biosensor.

The Bombyx mori larvae were brought from a local market in their <NUM>rd instar while the study started at the <NUM>th instar. The mulberry leaves were also brought from a local market. The graphite with particle size of <NUM> mesh was purchased from NICE. The TiO<NUM> was prepared as reported<NUM> through anodization of Ti sheet at <NUM> V in <NUM> HClO<NUM> electrolyte. The MoS<NUM> were prepared as reported in our previous work.

A mixture of <NUM> KMnO<NUM>: <NUM> MnCl<NUM> was used as a possible source for MnO<NUM>. <NUM>,<NUM> The KOH used in electrochemical measurements was purchased from AppliChem with purity <NUM>%.

mori larvae were divided into <NUM> groups and each group has <NUM> larvae and were kept in a transparent dry box with good ventilation. The first group was only feeding on diet of blank mulberry leaves (S/B). While the rest <NUM> groups were feeding on diet of mulberry leaves previously wetted with solutions of <NUM> wt% graphite (S/G), <NUM> wt% TiO<NUM> (S/TiO<NUM>), <NUM> wt% MoS<NUM> (S/MoS<NUM>) and <NUM> wt% KMnO<NUM>/MnCl<NUM> (S/Mn), respectively. The modified diet started at the worms' <NUM>th instar and ended by starting the spinning process. More notes about the feeding process can be found in the Supporting Information. The produced cocoons were degummed before the characterization and the electrochemical measurements. The degumming process included drying the cocoons at <NUM>° C for <NUM> hours then the cocoons were immersed in a solution of <NUM> wt% of Na<NUM>CO<NUM> at <NUM>° C for <NUM> minutes and this process were repeated <NUM> times then the cocoons were washed with distilled water for <NUM> minutes and repeated <NUM> times.

The produced silk was characterized using scanning electron microscope (SEM) (FEDEM, Zeiss SEM Ultra <NUM>, <NUM> kV) the fibers were sputtered with gold at <NUM> A for <NUM> minutes before the SEM imaging. The composition of the fibroin was detected using the energy dispersive X-ray analysis (EDX) (JED <NUM>). The protein signals of the silk fibroin were investigated using a dispersive Raman microscope (Pro Raman-L Analyzer) with an excitation wavelength of <NUM> and Fourier transform infrared spectroscopy (FT-IR) via Perkin Elmer Spectrum One spectrophotometer using KBr pellets. The crystal structure and the change in crystal parameters were investigated using the X-ray powder diffraction (XRD) (Panalytical X'pert PRO MPD X-Diffractometer) with Cu Kα radiation (λ = <NUM>, <NUM> kV, <NUM> mA). Thermogravimetric analysis (TGA) was conducted on the natural silk using the device (TGA NETZSCH STA <NUM> C/CD) at a heating rate of <NUM>° C/min and a nitrogen flaw rate of <NUM>/min.

The capacitive performance of the resulted silk was tested using three-electrode system in which <NUM> KOH was used as the electrolyte, coiled Pt as the counter electrode, calomel electrode as the reference electrode and the silk as the working electrode. The silk working electrode was fabricated in two separate methods. To be able to test the performance of the fiber itself, the degummed inner layer of the cocoons was cut into a square of <NUM>*<NUM><NUM> area as presented in <FIG> and a drop of Ag paste was used as a current collector on the point of attachment to the alligator clip of the potentiostat. Half the piece of fiber was immersed in the electrolyte and half the weight of the fiber was taken as the weight of the active material in the electrode. Since the electrolyte upwards in the fiber besides the fiber piece was not homogeneous so another method was used to assure the results. The strands of fiber were weighted and coiled over a length of <NUM> of a glassy carbon (GC) rod as presented in <FIG>. The part covered with the fiber was immersed completely in the electrolyte and used as the working electrode.

The electrochemical measurements were performed using BioLogic SP-<NUM> potentiostat and included measuring cyclic voltammetry (CV) in potential windows (<NUM> to <NUM>) and (-<NUM> to <NUM>) in order to identify the performance of the active materials as positive and negative electrodes respectively. The cyclic voltammetry was measured at different scan rates (<NUM>, <NUM>, <NUM> and <NUM> mV/s). The capacitance was measured form the cyclic voltammogram using Equation <NUM>. The capacitive performance can also be calculated using Equation <NUM> from the charge/discharge measurement. The galvanostatic charge/discharge measurement (GCD) was performed at different applied currents (<NUM> to <NUM> A/g). The stability of the silk fibers was measured up to <NUM> cycle at applied current of <NUM> A/g. The electrochemical impedance spectroscopy (EIS) of the system was measured at frequency range between <NUM> to <NUM>. The measurements were repeated twice on two different samples from each type of fibroin.

Cs is the specific capacitance, I is the response current density, v is the potential scan rate, ΔV is the potential window, and m is the mass of electrode material. <MAT> dt is the discharging time (s), I is the discharging current (A), m is the mass of the active material (g) within the electrode, and dV is the discharging potential range (V).

The disclosure of each of the following references is hereby incorporated herein by reference in its entirety.

Claim 1:
An electrical circuit component comprising:
at least one fiber of silkworm silk, the at least one fiber having an outer surface and an interior region bounded by the outer surface;
a plurality of portions of silkworm-digested, structured material located in the interior region or on the outer surface of the at least one fiber, wherein the at least one fiber and the silkworm-digested, structured material have a desired electrical property;
at least one conductor for connecting the at least one fiber to an electrical circuit, wherein the at least one silkworm silk fiber forms a first electrode,
a second electrode, and
an electrolyte located between the first and second electrodes,
wherein the first and second electrodes and the electrolyte form a supercapacitor.