Fractal Electrodes Research Articles

Improving the gas sensing performance of halide perovskite MAPbI3 film via fractal geometry electrode structure

The first successful fabrication of metal halide Perovskite MAPbI3 Film for NH3 gas sensing using fractal electrode structure is reported. High performance NH3 gas sensor was fabricated on ITO glass substrate by laser-patterning method. Gas sensors were fabricated using Hilbert, Peano, and Gosper curve structure electrodes, and their performance is compared to conventional interdigitated electrode. Gas sensing performance on Hilbert electrode design showed the highest response of 2.82 at 10 ppm NH3 gas, which is 145 % times higher compared to conventional interdigitated structures. Simulation study demonstrates that the electric field intensity and number of nodes of the fractal electrode are higher than those of the traditional interdigitated electrode. This study demonstrates that fractal electrode is a feasible strategy for optimizing the potential performance of MAPbI3-based Perovskite gas sensor with low-cost fabrication with no extra processing.

Laser layered scanning strategy for fractal Ag mesh transparent conductive electrodes using selective laser ablation and its application to transparent heaters

In this study, 800 nm-thick silver (Ag) films were deposited on glass substrates via radio frequency (RF) magnetron sputtering. Based on a laser layered scanning strategy during selective laser ablation (SLA), periodic (1–4) and pattern-combined (4–9) fractal Ag mesh transparent conductive electrodes (TCEs) with two layered mesh thicknesses were prepared to investigate the influences of mesh thickness matching on their optical and electrical properties. The results revealed that constructing the layered mesh thickness by selectively removing the thick Ag layer could enhance the TCE optical transmittance without greatly sacrificing its electrical conductivity. The two kinds of fractal layered Ag mesh TCEs with mesh thickness matching of 800 nm: 500 nm were confirmed to have high performance uniformity, and respectively exhibited the highest figure of merit value of 16.03 × 10–2 Ω−1 and 15.23 × 10–2 Ω−1. Moreover, the best periodic (1–4) fractal layered Ag mesh TCE was adopted to fabricate a transparent heater (TH), which exhibited excellent heating performance (a maximum temperature of 143.1 ℃ with a response time of ∼ 80 s under a lower voltage of 1.3 V), switching cycle stability and deicing ability. The sheet resistance stability of the TH under different test conditions was also demonstrated. This work has a certain reference value for the preparation of high-performance TCEs and THs.

ФРАКТАЛЬНА РАДІОФІЗИКА Частина 4. ПРАКТИЧНЕ ЗАСТОСУВАННЯ

Subject and Purpose. At the beginning of the 21st century, a fundamentally new scientific direction was formed in radiophysics — fractal radiophysics. The subject of this review is the main practical ideas of "fractalization" in radio physics. The purpose of the work is a systematic presentation of the main results of the practical application of fractal theory in radiophysics, as well as a detailed analysis of the originality, novelty, and practical value of the obtained results. Methods and Methodology. The results of using the fractal approach in various fields of modern radiophysics are presented. The results of the application of fractal and multifractal analysis methods for various radiophysical objects, phenomena and processes are considered. The main features, advantages and disadvantages of this approach, as well as existing problems, are highlighted. Results. The main practical results of applying the fractal approach in radio physics are considered. The main features of solving the problem of radio wave propagation in fractal media are also discussed. The usage of fractals in applied electrodynamics is demonstrated by the example of fractal antennas, resonators, filters, capacitors, transistors, diplexers, frequency-selective surfaces and metamaterials, etc. Fractals in semiconductor and vacuum electronics are described by the example of the fractal structures of the cathode spot and the cathodes themselves, fractal electrodes and diffusers, as well as the avalanche breakdown of the p-n junction. The features of the application of fractal ideas in statistical and nonlinear radiophysics are considered. To illustrate the "fractalization" of physics and radiophysics of the geospace, the fractal processes that occur during earthquakes, in the atmosphere, ionosphere and magnetosphere, etc., are used. Conclusions. The main directions of practical application of the theory of fractals in modern radiophysics are analyzed, as well as the features of the new results obtained, which reflect one of the main properties of the surrounding world — its fractality, are discussed.

Simulation Studies on the Design and Analysis of Interdigital and Fractal-Based Micro-Supercapacitors

Micro supercapacitors (MSC) are recently replacing traditional batteries in flexible and portable electronic devices owing to their outstanding features such as high power density and long cycle life. In-plane supercapacitors are usually built in an interdigital electrode (IDE) structure because of its fabrication simplicity and flexibility. This helps to reduce ion diffusion length and enables easy on-chip integration of the device. Recent researches show that by replacing the interdigital electrode structure with the new architecture technique of Fractal electrode design, the effective area of the electrode-electrolyte interface and capacitance can be increased. This work investigates the effect of the device architecture on the energy storage capacity of in-plane MSCs. IDE and Fractal-based electrodes are simulated using COMSOL Multiphysics and analyzed for performance using cyclic voltammetry, galvanic charge-discharge technique and electric field distribution. The results indicate that the device with fractal design has more areal capacitance than the traditional interdigital structure. The highest capacitance was achieved by the proposed Sierpinski Fractal electrode design which exhibited 85.59% more areal capacitance than the conventional IDE. This can be attributed to the significant increase in effective electrode area and the edging effect of the electric field in the sharp edges of fractal electrodes.

Directional Activated Exciton Highway via Fractal Electric Field Modulation for Ultrasensitive Carbon Nanotube-Based Sensors.

The electrical vapor sensor based on carbon nanotubes (CNTs) has attracted wide attention due to its excellent conductivity, stable interfacial structure, and low dimensional quantum effects. However, the conductivity and contact interface activity were still limited by the random distribution of coated CNTs, which led to limited performance. We developed a new strategy to unify the CNT directions with image fractal designing of the electrode system. In such a system, directional aligned CNTs were gained under a well-modulated electric field, leading to microscale CNT exciton highways and molecule-scale host-guest site activation. The carrier mobility of the aligned CNT device is 20-fold higher than that of the random network CNT device. With excellent electrical properties, such modulated CNT devices based on fractal electrodes behave as an ultrasensitive vapor sensor for methylphenethylamine, a mimic of illicit drug methamphetamine. The detection limit reached as low as 0.998 ppq, 6 orders of magnitude sensitive than the reported 5 ppb record based on interdigital electrodes with random distributed CNTs. Since the device is easily fabricated in wafer-level and compatible with the CMOS process, such a fractal design strategy for aligned CNT preparation will be widely applied in a variety of wafer-level electrical functional devices.

Inspired by nature: Self-fractal cobalt sulfate composite electrode for sodium ion storage

Generally, the metal sulfide itself has poor conductivity, and the volume expansion occurs when it is converted with sodium, which will destroy the integrity of the electrode structure, resulting in poor cycle performance and rate performance. To solve the problems of low initial coulombic efficiency (ICE) and volume expansion of metal compounds used as anodes in sodium-ion batteries (SIBs). Inspired by nature, the CoSO4/hard carbon/graphene (CHG) fractal structure electrode was designed. Self-fractal structures with electron/ion transport channels and high strain tolerance proved to be an effective strategy to overcome these challenges. The fractal dimension (D) is measured by synchronous Small Angle X-ray scattering, and the D remains stable during charging and discharging. The fractal CHG also showed excellent electrochemical performance, especially 97.4% ICE. Theoretical calculation shows that self-fractal CHG can promote the formation of a thin solid electrolyte interface (SEI). Synchrotron radiation absorption spectrum proved the reaction mechanism of CHG. This study not only proves that cobalt sulfate is a feasible strategy for developing high-performance SIBs anodes but also provides an advanced method for measuring the fractal dimension of energy storage electrode materials.

An Intelligent Model for Supercapacitors with a Graphene-Based Fractal Electrode to Investigate the Cyclic Voltammetry

The aim of this study was to investigate the performance measurement of supercapacitors using the electrochemical properties of cyclic voltammetry (CV). The use of CV is crucial in evaluating the electrochemical performance of supercapacitors and determining the surface area of the catalyst with regard to the fractal properties of the electrode. The study specifically focused on the CV behavior of a supercapacitor formed by a cobalt-doped ceria/reduced graphene oxide (Co-CeO2/rGO) fractal nanocomposite, and its assessment was conducted using a machine learning (ML) model with the enhanced XGBoost. The model was trained using an experimental open-source dataset. The results showed that the proposed XGBoost model had a superior ability to predict the CV behavior of the supercapacitor, with nearly perfect results for the MAE, RMSE, and R-squared metrics, which are effective at evaluating the performance of regression models. With the successful design of the proposed intelligent prediction model, the study is expected to provide valuable insights into forming novel nanocomposite forms with high accuracy and minimal need for experiments.

Role of Ir Decoration in Activating a Multiscale Fractal Surface in Porous Ni for the Oxygen Evolution Reaction

Interfacial engineering of electrocatalysts is a pivotal approach for promoting the energy conversion efficiency of water electrolysis systems. Anchoring clusters or even single atoms of a foreign element on the surface of a support, usually 3D structured, can alter its local electronic structure leading to superior electrocatalytic activity. Herein, we report a method to decorate a 3D fractal Ni electrode with Ir atoms via a galvanic displacement reaction. The resulting electrode has a very low Ir loading of 1.6 μmole cmgeo–2, with iridium atoms present as 4–5 nm diameter nanoclusters on the electrode surface. The activity for the electrochemical oxygen evolution reaction (OER) of the 3D fractal Ni electrode was improved by decoration with Ir, resulting in an overpotential of 195 mV at 10 mA cm–2 and a Tafel slope of 44 mV dec–1. Apart from increasing the electrocatalytic activity for the OER due to the very presence of more active iridium atoms, the galvanic displacement reaction resulted in a factor 8–10 increase of the electrochemically active surface area due to the creation/activation of a secondary pore structure that contributes also to the better electrocatalytic performance of the resulting electrode. Using operando acoustic emission, it is demonstrated that the galvanic displacement reaction and the presence of Ir nanoclusters have the additional effect of reducing the average O2 bubble size formed during the OER. As a result, the blocking effect of O2 bubbles at high current density is less drastic than on the 3D fractal Ni electrode, resulting in a less severe decrease of the electrochemically active area at large current density. All three effects contribute toward improving the OER performance of the Ir-decorated 3D fractal Ni electrode.

Comparison of fractal and grid electrodes for studying the effects of spatial confinement on dissociated retinal neuronal and glial behavior

Understanding the impact of the geometry and material composition of electrodes on the survival and behavior of retinal cells is of importance for both fundamental cell studies and neuromodulation applications. We investigate how dissociated retinal cells from C57BL/6J mice interact with electrodes made of vertically-aligned carbon nanotubes grown on silicon dioxide substrates. We compare electrodes with different degrees of spatial confinement, specifically fractal and grid electrodes featuring connected and disconnected gaps between the electrodes, respectively. For both electrodes, we find that neuron processes predominantly accumulate on the electrode rather than the gap surfaces and that this behavior is strongest for the grid electrodes. However, the ‘closed’ character of the grid electrode gaps inhibits glia from covering the gap surfaces. This lack of glial coverage for the grids is expected to have long-term detrimental effects on neuronal survival and electrical activity. In contrast, the interconnected gaps within the fractal electrodes promote glial coverage. We describe the differing cell responses to the two electrodes and hypothesize that there is an optimal geometry that maximizes the positive response of both neurons and glia when interacting with electrodes.

Controlled assembly of retinal cells on fractal and Euclidean electrodes

Controlled assembly of retinal cells on artificial surfaces is important for fundamental cell research and medical applications. We investigate fractal electrodes with branches of vertically-aligned carbon nanotubes and silicon dioxide gaps between the branches that form repeating patterns spanning from micro- to milli-meters, along with single-scaled Euclidean electrodes. Fluorescence and electron microscopy show neurons adhere in large numbers to branches while glial cells cover the gaps. This ensures neurons will be close to the electrodes' stimulating electric fields in applications. Furthermore, glia won't hinder neuron-branch interactions but will be sufficiently close for neurons to benefit from the glia's life-supporting functions. This cell 'herding' is adjusted using the fractal electrode's dimension and number of repeating levels. We explain how this tuning facilitates substantial glial coverage in the gaps which fuels neural networks with small-world structural characteristics. The large branch-gap interface then allows these networks to connect to the neuron-rich branches.

Optimizing electrode structure of carbon nanotube gas sensors for sensitivity improvement based on electric field enhancement effect of fractal geometry

With the rapid development of carbon nanotubes gas sensor, the sensitivity of the sensing response is becoming more and more demanding. Different from the traditional studies on gas-sensitive materials, this paper combines the microscopic dimensional effects and physical properties of fractal geometry theory from the structure and morphology of sensor devices. The electrode structures of carbon nanotubes gas sensor is designed and optimized by Hilbert–Piano curve. Simulation experiments demonstrate that the electric field intensity and hot spot distribution of the fractal electrode are superior to those of the traditional interdigital electrode. Moreover, a novel chemiresistive gas sensor is fabricated combining the characteristics of carbon nanotubes and fractal geometry, and a test with exposure to nitric oxide showed that the sensors with fractal electrode structures improved the gas sensing sensitivity over sensors with traditional geometrical structures. It provides a new idea for the exploration of gas sensing technology.

Graphene foam pressure sensor based on fractal electrode with high sensitivity and wide linear range

Piezoresistive sensors based on three-dimensional graphene foams (GFs) can be used in health monitoring, electronic skin and wearable smart devices. It is still challenging to obtain sensors with high sensitivity and a wide linear range through a simple and an efficient method. In this paper, a graphene foam pressure sensor based on a fractal electrode (GFPSFE) is proposed. The GFPSFE contains a wave-structured GF (WSGF), a fractal electrode (FE), and a normal electrode. The FE regulates the contact resistance of the WSGF, improving the sensitivity and the linear range of the GFPSFE. We compared three GFPSFEs with different FEs, and investigated the influence of FEs on the sensitivity and the linear range of GFPSFEs. The GFPSFE with zigzag FE (Z-GFPSFE) has high sensitivity (134.75 kPa−1), wide linear range (0–35 kPa), fast response/recovery (83 ms and 166 ms), and excellent stability (2000 cycles). In addition, the sensor was attached to the human body to measure motions and pulse, demonstrating the potential application in the fields of health monitoring and human-machine interfaces.

Screen-printable and flexible in-plane micro-supercapacitors with fractal electrode design

New microscale energy devices need to be developed to accommodate the evolution of integrated flexible electronic systems. Supercapacitors have the advantages of high power density and long cycle life, and can be used independently or combined with batteries to provide electric energy for future electronics. Screen printing is a simple, cost-effective method for fast and scalable fabrication of micro-supercapacitors (MSCs) on various types of substrates that does not involve complicated process or expensive equipment. Currently, most researches of MSCs have been focused on materials and ink development with conventional interdigital architecture, few studies have been aimed at electrode pattern design. Herein, we demonstrate an in-plane MSCs via screen printing with designable electrode patterns on flexible substrate. The thickness of the device is less than 1 mm, ensuring good flexibility. By replacing the carbon ink with the silver ink as current collectors, the performance is improved due to lower device resistance. Owing to the geometric controllability of the screen printing method, we are able to study the effects of electrode design on the output performance by simply changing the screen mesh patterns. In particular, we demonstrate that by adapting the mathematical fractal concept such as Hilbert curve as electrode patterns, the areal capacitance of MSCs can reach up to 28.7 mF cm−2, which is 46.8% higher than that of the traditional interdigital structure. The results suggest that the fractal-based design represents a universal protocol for producing MSCs. Without changing electrode materials or fabrication facilities, the design strategy is highly compatible with industrial scale screen printing for roll-to-toll processing. This high-capacitance, cost-effective and flexible MSCs open a promising pathway for providing electric energy for the Internet of Things and future wearable systems.

In Vivo Evaluation of Fractal Microelectrodes Towards a More Targeted and Energy‐Efficient Vagus Nerve Stimulation

Vagus nerve stimulation (VNS) is a moderately effective treatment option for intractable epilepsy, depression, and pain, with promising applications in the treatment of gastrointestinal motility disorders like gastroparesis. The wide-ranging potential indications of VNS suggest an opportunity for a better understanding of underlying neural circuits that can be targeted using microscale electrodes. However, microscale Platinum (Pt) electrodes often have limited charge injection capacity due to their high impedance. Recently, we experimentally demonstrated that microscale Pt electrodes with Vicsek fractal geometry can facilitate electrochemical charge transfer more efficiently with 57% higher cathodic charge storage capacity than conventional circular microelectrodes. Here we are investigating whether the fractal electrode may be more effective in eliciting small fibers in the vagus nerve with less energy consumption due to its enhanced charge injection capability. To evaluate the in vivo performance of these novel microelectrode designs and to determine whether these electrodes are capable of stimulating small, unmyelinated C fibers that supply the stomach, we designed a cuff electrode with an array with four pairs of fractal and circular microelectrode to explore the possibility of radial selective stimulation of vagus nerve. We determined the dimension of the cuff to be 760 μm in diameter to wrap around a rat's vagus nerve so that it can withstand the swelling of the nerve from chronic implantation. We patterned fractal microelectrode to have a geometrical surface area equivalent to that of a circle with 100 μm of diameter. Using a rat model, we have stimulated the right cervical vagus nerve with fractal/circular electrode and recorded the compound action potential (CAP) distal from the stimulation site with 5-7 mm of conduction distance or the dorsal trunk of the abdominal vagus (conduction distance: 70 mm). We used an autonomous neural control (ANC) system, which can stimulate and record from the nerve with randomized stimulus parameter combinations (pulse amplitude: 0-0.4 mA, pulse width: 0.02-1 ms). We adapted a cathode-first, alternating monophasic stimulation for the reliable suppression of stimulus artifact (pulse repetition frequency: 5 Hz). Results from right cervical VNS experiments in anesthetized rats showed that both the fractal and the circular electrodes can recruit small, myelinated Ad and B fibers to a similar degree (pulse amplitude: 0-0.4 mA, pulse width: 0.1 ms) (Figure 1.), but fractal electrodes produce a more uniform and consistent fiber recruitment profile (Figure 2.). We observed volleys within the slow conduction velocity range (< 3 m/s), which we suspect to be signals from the C-fibers. Our next plan is to obtain more experimental data to statistically identify the efficiency of various electrode designs in stimulating small fibers and to investigate the electrical potential profile of these electrodes in a biophysical model.

Numerical study of a three‐dimensional electroosmotic micromixer with Koch fractal curve structure

AbstractBACKGROUNDA new type of three‐dimensional electroosmotic micromixer is designed based on the Koch fractal curve principle. According to the fractal principle, the influences of fractal structure, voltage size, electrode spacing and electrode configuration on the mixing performance were proposed and studied.RESULTSThe simulation results show that under the combined action of fractal and electric field, irregular alternating vortices are generated in the microchannel, which can disturb the flow of fluid and greatly improve the mixing of fluids in the electroosmotic micromixer. In particular, when the direct current voltage is 10 V, the electrode spacing is 0.15 mm and the electroosmotic micromixer has three groups of alternately placed electrode pairs, the mixing efficiency can reach 98%.CONCLUSIONSThis new type of electroosmotic micromixer is suitable for many occasions, including the mixing of biochemical reagents, and has high application value. © 2021 Society of Chemical Industry (SCI).

Influence of electrode roughness on DC biased admittance of quasi-reversible charge transfer with uncompensated solution resistance

Abstract The theory is developed for the DC potential biased electrochemical impedance spectroscopy (EIS) of quasi-reversible charge transfer with uncompensated solution resistance developed for rough and fractal electrodes. Theory shows that the influence of the real and apparent kinetics is contained in DC bias dependent characteristic length called the diffusion-kinetics-ohmic coupling length (LQΩ). Theory characterizes fractal irregularities of an electrode through its power spectrum which is experimentally obtained from SEM or AFM recordings. EIS response of DC biased quasi-reversible systems is an interplay of phenomenological lengths, i.e., LQΩ, diffusion length (LD) and morphological characteristics (fractal dimension and lengths in roughness), manifesting themselves at different frequencies. High frequency regime, LD > LQΩ, electrode kinetics follows the Warburg response with the macroscopic area of the electrode. There is an emergence of anomalous intermediate region, LD ~ LQΩ, which is influenced by various fractal morphological characteristics. This regime has maximum in phase angle (ϕ > 450) as well as signature of the fractal roughness.

Effects of Fractal Electrode Geometry in Charge Injection Capacity of TiN Microelectrodes.

Microelectrodes are basic tools for investigating small-scale brain dynamics. Noble metals such as gold (Au), platinum (Pt), and iridium oxide (IrOx) have been used as an electrode material because of their biocompatibility and good charge transfer capability. Their main charge transfer mechanism is the Faradaic process with redox reactions. Unfortunately, the decrease in electrode size accelerates the irreversible electrochemical dissolution during electrical stimulation due to increased current density. The dissolution can be prevented by alternating the electrode material to capacitive charge injection materials such as titanium nitride (TiN). However, electrical conductivity of TiN is relatively lower than the noble metals, which results in a lower charge injection capability. Therefore, there is a need to increase the charge injection limit of TiN electrodes for a high-performing neurostimulation. Our previous work suggested that the Vicseck fractal design can increase the charge injection limit of the microelectrodes. In this work, the effects of the fractal design in capacitive charge injection material were experimentally investigated by using TiN microelectrodes with circular and fractal designs. We measured the cyclic voltammetry, electrochemical impedance spectroscopy, and voltage transients. In addition, the charge injection limits of theses microelectrodes were estimated to quantify the effects of planar geometry on TiN microelectrodes. Despite our previous results showing superior charge injection capability of fractal Pt microelectrodes, the TiN showed no significant improvements due to the fractal geometry. This may be because the increase in charge injection capability of fractal microelectrodes is due to increased Faradaic charge injection process, which is minimized for TiN materials. Thus, our data suggests that the material as well as the geometry of the microelectrodes play key roles in optimizing stimulation microelectrode performance.Clinical relevance-As with the Faradaic charge injection-dominant materials, the capacitive charge injection materials could also benefit from additional investigation to fully characterize effects of electrode geometry for improved neurostimulation performance.

Ir Decorated Fractal Ni Catalysts for the Oxygen Evolution Reaction

Porous and fractal Ni electrode synthesized by the Dynamic Hydrogen Bubbling Template (DHBT) method (Ni DHBT electrode) have shown very promising performances for the oxygen evolution reaction (OER) in alkaline electrolyte. This was thought to arise as a result of the extended electrochemical active surface area and its superaerophilic properties that facilitates the release of oxygen bubbles[1]. Herein, we report on a method to decorate the Ni DHBT electrode with Ir atoms via a galvanic replacement (GR) reaction. The resulting electrode has very low loadings of Ir (0.26 atom % as determined by EDX). As shown in Figure 1, micrometer-sized pores are observed at the surface of deposits, with pore walls exhibiting a highly porous cauliflower-like secondary structure, with much smaller pore diameter (typically less than 500 nm). The structure seen in Figure 1 was observed over the entire 0.32 cm2 geometric surface area of the deposits. The morphology of the Ir-modified electrode is not changed with respect to Ni DHBT electrode, indicating that the GR reaction is occurring only at the surface of the deposit. Voltammetry cyclic tests in 1M KOH solution showed hydrogen adsorption/desorption (Hupd) peaks of Ir as well as the redox peaks of Ni(OH)2 which suggested the coexistence of Ir and Ni content at electrode/electrolyte interface. The activity for the OER of Ni DHBT electrode was further improved by decoration with Ir, resulting in an overpotential of 195mV at 10 mA/cm2 and a Tafel slope of 46 mV/dec. To the best of our acknowledgment, this is one of the best performing Ni based OER catalysts reported so far. The interaction of oxygen bubbles with the electrode surface will also be assessed using both optical imaging and acoustic emission characterization.[1] M. Hao et al., “Hydrogen Bubble Templating of Fractal Ni Catalysts for Water Oxidation in Alkaline Media,” ACS Appl. Energy Mater., vol. 2, no. 8, pp. 5734–5743, Aug. 2019. Figure 1

Stamp-assisted flexible graphene-based micro-supercapacitors

The rapid growth of portable and wearable electronics have greatly stimulated simplified fabrication of energy storage devices, from which micro-supercapacitors (MSCs) are an ideal power source, due to high power density and long lifetime. However, the development of a simple and cost-effective procedure towards the fabrication of high-performance MSCs is still a challenge. To this end, here we report a self-patterned stamping process through pre-designed patterns (Fractal & Interdigital) on parafilm® coated polyethylene terephthalate (PET) substrate for the fabrication of a flexible and planar MSC. The imprinted patterns on parafilm® are filled by graphene oxide (GO)/carbon aerogel/MnO2 hybrid paste as a binder and additive-free active material, followed by GO reduction through a safe, low cost, and effective procedure using nascent hydrogen. In contrast to the hydrazine based reduction method, nascent hydrogen affords the integrity and stability to the active material without any peeling off from the substrate, with low ohmic resistance. The prepared MSCs display large capacitance and energy density of 8.7 mF cm−2 (43.66 F cm−3) and 6 mWh cm−3 for Interdigital electrode and 14.2 mF cm−2 (71.34 F cm−3) and 9.9 mWh cm−3 for Fractal electrode, respectively. Furthermore, the MSC displays capacitance retention of 85% after 25,000 cycles. The presented procedure is a simple and cost-effective strategy towards the fabrication of flexible MSCs with state-of-the-art performance.

Fractal solar panels: Optimizing aesthetic and electrical performances.

Solar energy technologies have been plagued by their limited visual appeal. Because the electrical power generated by solar panels increases with their surface area and therefore their occupancy of the observer’s visual field, aesthetics will play an increasingly critical role in their future success in urban environments. Inspired by previous psychology research highlighting the aesthetic qualities of fractal patterns, we investigated panel designs featuring fractal electrodes. We conducted behavioral studies which compared observers’ preferences for fractal and conventional bus-bar electrode patterns, along with computer simulations which compared their electrical performances. This led us to develop a hybrid electrode pattern which best combines the fractal and bus-bar designs. Here we show that the new hybrid electrode matches the electrical performance of bus-bars in terms of light transmission and minimizing electrical power losses, while benefiting from the superior aesthetics of fractal patterns. This innovative integration of psychology and engineering studies provides a framework for developing novel electrode patterns with increased implementation and acceptance.