Microsphere-Structured Protein Hydrogel Dielectrics for Capacitive Wearable Sensors.

The desire for healthy living has created a crucial need for portable flexible health-monitoring devices based on biomaterials. Toward this end, we report a microsphere-structured hydrogel that uses bovine serum albumin (BSA) as a dielectric layer for capacitive pressure sensors. We developed a theoretical model that describes how stacking dielectric layers of spheres affects the performance of capacitive sensors. We also prepared a prototype sensor featuring the unique microsphere structure to create capacitive sensors with high sensitivity (360.91 strain sensitivity), excellent cyclical stability, and a long service life (over 5000 stretching-compression cycles). Furthermore, the design of the hydrogel sensor allows for easy integration into fabrics to create devices such as smart wristbands, which can collect a diverse range of health data. Thus, BSA-hydrogel-based sensors not only provide safe wearable devices but also advance the performance of high-sensitivity capacitive sensors.

Understanding the Electric Double-Layer Structure, Capacitance, and Charging Dynamics.

Significant progress has been made in recent years in theoretical modeling of the electric double layer (EDL), a key concept in electrochemistry important for energy storage, electrocatalysis, and multitudes of other technological applications. However, major challenges remain in understanding the microscopic details of the electrochemical interface and charging mechanisms under realistic conditions. This review delves into theoretical methods to describe the equilibrium and dynamic responses of the EDL structure and capacitance for electrochemical systems commonly deployed for capacitive energy storage. Special emphasis is given to recent advances that intend to capture the nonclassical EDL behavior such as oscillatory ion distributions, polarization of nonmetallic electrodes, charge transfer, and various forms of phase transitions in the micropores of electrodes interfacing with an organic electrolyte or ionic liquid. This comprehensive analysis highlights theoretical insights into predictable relationships between materials characteristics and electrochemical performance and offers a perspective on opportunities for further development toward rational design and optimization of electrochemical systems.

Unlocking Bimetallic Active Centers via Heterostructure Engineering for Exceptional Phosphate Electrosorption: Internal Electric Field-Induced Electronic Structure Reconstruction.

Development of electrode materials exhibiting exceptional phosphate removal performance represents a promising strategy to mitigate eutrophication and meet ever-stricter stringent emission standards. Herein, we precisely designed a novel LaCeOx heterostructure-decorated hierarchical carbon composite (L8C2PC) for high-efficiency phosphate electrosorption. This approach establishes an internal electric field within the LaCeOx heterostructure, where the electrons transfer from Ce atoms to neighboring La atoms through superexchange interactions in La-O-Ce coordination units. The modulatory heterostructure endows a positive shift of the d band of La sites and the increase of electron density at Fermi level, promoting stronger orbital overlap and binding interactions. The introduction of oxygen vacancies during the in situ nucleation process reduces the kinetic barrier for phosphate-ion migration and supplies additional active centers. Moreover, the hierarchical carbon framework ensures electrical double-layer capacitance for phosphate storage and interconnected ion migration channels. Such synergistically multiple active centers grant the L8C2PC electrode with high-efficiency record in phosphate electrosorption. As expected, the L8C2PC electrode demonstrates the highest removal capability among the reported electrode materials with a saturation capacity of 401.31 mg P g-1 and a dynamic capacity of 91.83 mg P g-1 at 1.2 V. This electrochemical system also performs well in the dephosphorization in natural water samples with low concentration that enable effluent concentration to meet the first-class discharge standard for China (0.5 mg P L-1). This study advances efficient dephosphorization techniques to a new level and offers a deep understanding of the internal electric field that regulates metal orbitals and electron densities in heterostructure engineering.

3D Printing of Capacitive Pressure Sensors with Tuned Wide Detection Range and High Sensitivity Inspired by Bio-Inspired Kapok Structures.

Flexible pressure sensors have drawn considerable attention for their potential applications as electronic skins with both sensitivity and pressure response range. Although the introduction of surface microstructures effectively enhances sensitivity, the confined volume of their compressible structures results in a limited pressure response range. To address this issue, a biomimetic kapok structure is proposed and implemented for constructing the dielectric layer of flexible capacitive pressure sensors employing 3D printing technology. The structure is designed with easily deformable concave and rotational structures, enabling continuous deformation under pressure. This design results in a significant expansion of the pressure response range and improvement in sensitivity. Further, the study purposively analyses crucial parameters of the devised structure that affect its compressibility and stability. These include the concave angle θ, height ratio d1/d2, rotation angle α, and width k. As a result, the ultimate pressure sensors demonstrate remarkable features such as high sensitivity (≈2.38 kPa-1 in the range of 0-10 kPa), broad detection range (734 kPa), fast response time (23 ms), and outstanding pressure resolution (0.4% at 500 kPa). This study confirms the viability of bionic structures for flexible sensors, and their potential to expand the scope of wearable electronic devices.

Nanostructured NiS2-based flexible smart sensors for human respiration monitoring.

The growing demand for wearable healthcare devices has led to an urgent need for cost-effective, wireless and portable breath monitoring systems. However, it is essential to explore novel nanomaterials that combine state-of-the-art flexible sensors with high performance and sensing capabilities along with scalability and industrially acceptable processing. In this study, we demonstrate a highly efficient NiS2-based flexible capacitive sensor fabricated via a solution-processible route using a novel single-source precursor [Ni{S2P(OPr)2}2]. The developed sensor could precisely detect the human respiration rate and exhibit rapid responsiveness, exceptional sensitivity and selectivity at ambient temperatures, with an ultra-fast response and recovery. The device effectively differentiates the exhaled breath patterns including slow, fast, oral and nasal breath, as well as post-exercise breath rates. Moreover, the sensor shows outstanding bending stability, repeatability, reliable and robust sensing performance and is capable of contactless sensing. The sensor was further employed with a user-friendly wireless interface to facilitate smartphone-enabled real-time breath monitoring systems. This work opens up numerous avenues for cost-effective, sustainable and versatile sensors with potential applications for Internet of Things-based flexible and wearable electronics.This article is part of the theme issue 'Celebrating the 15th anniversary of the Royal Society Newton International Fellowship'.

Self-powered sensing platform for monitoring uric acid in sweat using cobalt nanocrystal-graphene quantum dot-Ti3C2TX monolithic film electrode with excellent supercapacitor and sensing behavior.

The synthesis of cobalt nanocrystal-graphene quantum dot-Ti3C2TX monolithic film electrode (Co-GQD-Ti3C2TX) is reported via self-assembly of Ti3C2TX nanosheets induced by protonated arginine-functionalized graphene quantum dot and subsequent reduction of cobalt (III). The resulting Co-GQD-Ti3C2TX shows good monolithic architecture, mechanical property, dispersibility and conductivity. The structure achieves excellent supercapacitor and sensing behavior. The self-charging supercapacitor produced by printing viscous Co-GQD-Ti3C2TX hydrogel on the back of flexible solar cell surface provides high specific capacitance (296 F g-1 at 1 A g-1), high-rate capacity (153 F g-1 at 20 A g-1), capacity retention (98.1% over 10,000-cycle) and energy density (29.6 W h kg-1 at 299.9 W kg-1). The electrochemical chip produced by printing Co-GQD-Ti3C2TX hydrogel on paper exhibits sensitive electrochemical response towards uric acid. The increase of uric acid between 0.01 and 800 µM causes a linear increase in differential pulse voltammetry signal with a detection limit of 0.0032 µM. The self-powered sensing platform integrating self-charging supercapacitor, electrochemical chip and micro electrochemical workstation was contentedly applied to monitoring uric acid in sweats and shows one broad application prospect in wearable electronic health monitoring device.

Pinpointing Moisture: The Capacitive Detection for Standing Tree Health.

BACKGROUND: the feasibility of the capacitance method for detecting the water content in standing tree trunks was investigated using capacitance-based equipment that was designed for measuring the water content of standing tree trunks. METHODS: In laboratory experiments, the best insertion depth of the probe for standing wood was determined by measurement experiments conducted at various depths. The bark was to be peeled when specimens and standing wood were being measured. The actual water content of the test object was obtained by specimens being weighed and the standing wood being weighed after the wood core was extracted. RESULTS: A forecast of the moisture content of standing wood within a range of 0 to 180% was achieved by the measuring instrument. The feasibility of the device for basswood and fir trees is preliminarily studied. When compared to the drying method, the average error of the test results was found to be less than 8%, with basswood at 7.75%, and fir at 7.35%. CONCLUSIONS: It was concluded that the measuring instrument has a wide measuring range and is suitable for measuring wood with low moisture content, as well as standing timber with high moisture content. The measuring instrument, being small in size, easy to carry, and capable of switching modes, is considered to have a good application prospect in the field of forest precision monitoring and quality improvement.

Monoolein-Based Wireless Capacitive Sensor for Probing Skin Hydration.

Capacitive humidity sensors typically consist of interdigitated electrodes coated with a dielectric layer sensitive to varying relative humidity levels. Previous studies have investigated different polymeric materials that exhibit changes in conductivity in response to water vapor to design capacitive humidity sensors. However, lipid films like monoolein have not yet been integrated with humidity sensors, nor has the potential use of capacitive sensors for skin hydration measurements been fully explored. This study explores the application of monoolein-coated wireless capacitive sensors for assessing relative humidity and skin hydration, utilizing the sensitive dielectric properties of the monoolein-water system. This sensitivity hinges on the water absorption and release from the surrounding environment. Tested across various humidity levels and temperatures, these novel double functional sensors feature interdigitated electrodes covered with monoolein and show promising potential for wireless detection of skin hydration. The water uptake and rheological behavior of monoolein in response to humidity were evaluated using a quartz crystal microbalance with dissipation monitoring. The findings from these experiments suggest that the capacitance of the system is primarily influenced by the amount of water in the monoolein system, with the lyotropic or physical state of monoolein playing a secondary role. A proof-of-principle demonstration compared the sensor's performance under varying conditions to that of other commercially available skin hydration meters, affirming its effectiveness, reliability, and commercial viability.

Dirac Electrons with Molecular Relaxation Time at Electrochemical Interface between Graphene and Water.

The time dynamics of charge accumulation at the electrochemical interface between graphene and water is important for supercapacitors, batteries, and chemical and biological sensors. By using impedance spectroscopy, we have found that measured capacitance (Cm) at this interface with the gate voltage Vgate ≈ 0.1 V follows approximate laws Cm~T1.2 and Cm~T0.11 (T is Vgate period) in frequency ranges (1000-50,000) Hz and (0.02-300) Hz, respectively. In the first range, this dependence demonstrates that the interfacial capacitance (Cint) is only partially charged during the charging period. The observed weaker frequency dependence of the measured capacitance (Cm) at frequencies below 300 Hz is primarily determined by the molecular relaxation of the double-layer capacitance (Cdl) and by the graphene quantum capacitance (Cq), and it also implies that Cint is mostly charged. We have also found a voltage dependence of Cm below 10 Hz, which is likely related to the voltage dependence of Cq. The observation of this effect only at low frequencies indicates that Cq relaxation time is much longer than is typical for electron processes, probably due to Dirac cone reconstruction from graphene electrons with increased effective mass as a result of their quasichemical bonding with interfacial molecular charges.

Synergy of Oxygen Vacancy and Surface Modulation Endows Hollow Hydrangea-like MnCo2O4.5 with Enhanced Capacitive Performance.

Surface chemistry and bulk structure jointly play crucial roles in achieving high-performance supercapacitors. Here, the synergistic effect of surface chemistry properties (vacancy and phosphorization) and structure-derived properties (hollow hydrangea-like structure) on energy storage is explored by the surface treatment and architecture design of the nanostructures. The theoretical calculations and experiments prove that surface chemistry modulation is capable of improving electronic conductivity and electrolyte wettability. The structural engineering of both hollow and nanosheets produces a high specific surface area and an abundant pore structure, which is favorable in exposing more active sites and shortens the ion diffusion distance. Benefiting from its admirable physicochemical properties, the surface phosphorylated MnCo2O4.5 hollow hydrangea-like structure (P-MnCoO) delivers a high capacitance of 425 F g-1 at 1 A g-1, a superior capability rate of 63.9%, capacitance retention at 10 A g-1, and extremely long cyclic stability (91.1% after 10,000 cycles). The fabricated P-MnCoO/AC asymmetric supercapacitor achieved superior energy and power density. This work opens a new avenue to further improve the electrochemical performance of metal oxides for supercapacitors.

Nitrogen-Doped Porous Carbons Derived from Peanut Shells as Efficient Electrodes for High-Performance Supercapacitors.

The doping of porous carbon materials with nitrogen is an effective approach to enhance the electrochemical performance of electrode materials. In this study, nitrogen-doped porous carbon derived from peanut shells was prepared as an electrode for supercapacitors. Melamine, urea, urea phosphate, and ammonium dihydrogen phosphate were employed as different nitrogen dopants. The optimized electrode material PA-1-1 prepared by peanut shells, with ammonium dihydrogen phosphate as a nitrogen dopant, exhibited a N content of 3.11% and a specific surface area of 602.7 m2/g. In 6 M KOH, the PA-1-1 electrode delivered a high specific capacitance of 208.3 F/g at a current density of 1 A/g. Furthermore, the PA-1-1 electrode demonstrated an excellent rate performance with a specific capacitance of 170.0 F/g (retention rate of 81.6%) maintained at 20 A/g. It delivered a capacitance of PA-1-1 with a specific capacitance retention of 98.8% at 20 A/g after 5000 cycles, indicating excellent cycling stability. The PA-1-1//PA-1-1 symmetric supercapacitor exhibited an energy density of 17.7 Wh/kg at a power density of 2467.0 W/kg. This work not only presents attractive N-doped porous carbon materials for supercapacitors but also offers a novel insight into the rational design of biochar carbon derived from waste peelings.

Nanostructured Transition Metal Oxides on Carbon Fibers for Supercapacitor and Li-Ion Battery Electrodes: An Overview.

Nowadays, owing to the new technological and industrial requirements for equipment, such as flexibility or multifunctionally, the development of all-solid-state supercapacitors and Li-ion batteries has become a goal for researchers. For these purposes, the composite material approach has been widely proposed due to the promising features of woven carbon fiber as a substrate material for this type of material. Carbon fiber displays excellent mechanical properties, flexibility, and high electrical conductivity, allowing it to act as a substrate and a collector at the same time. However, carbon fiber's energy-storage capability is limited. Several coatings have been proposed for this, with nanostructured transition metal oxides being one of the most popular due to their high theoretical capacity and surface area. In this overview, the main techniques used to achieve these coatings-such as solvothermal synthesis, MOF-derived obtention, and electrochemical deposition-are summarized, as well as the main strategies for alleviating the low electrical conductivity of transition metal oxides, which is the main drawback of these materials.

Hydrogel Capacitors Based on MoS2 Nanosheets and Applications in Glucose Monitoring.

Non-invasive/minimally invasive continuous monitoring of blood glucose and blood glucose administration have a high impact on chronic disease management in diabetic patients, but the existing technology is yet to achieve the above two purposes at the same time. Therefore, this study proposes a microfluidic microneedle patch based on 3D printing technology and an integrated control system design for blood glucose measurement, and a drug delivery control circuit based on a 555 chip. The proposed method provides an improved preparation of a PVA-PEG-MoS2 nanosheet hydrogel, making use of its dielectric properties to fabricate a microcapacitor and then embedding it in a microfluidic chip. When MoS2 nanosheets react with interstitial liquid glucose (and during the calibration process), the permittivity of the hydrogel is changed, resulting in changes in the capacitance of the capacitor. By converting the capacitance change into the square-wave period change in the output of the 555 chip with the control circuit design accordingly, the minimally invasive continuous measurement of blood glucose and the controlled release of hypoglycemic drugs are realized. In this study, the cross-linking structure of MoS2 nanosheets in hydrogel was examined using infrared spectroscopy and scanning electron microscopy (SEM) methods. Moreover, the critical doping mass fraction of MoS2 nanosheets was determined to be 2% via the measurement of the dielectric constant. Meanwhile, the circuit design and the relationship between the pulse cycle and glucose concentration is validated. The results show that, compared with capacitors in series, the microcapacitors embedded in microfluidic channels can be connected in parallel to obtain better linearized blood glucose measurement results.

Effects of Side-Chain Length and Functionality on Polar Poly(dioxythiophene)s for Saline-Based Organic Electrochemical Transistors.

Understanding the impact of side chains on the aqueous redox properties of conjugated polymers is crucial to unlocking their potential in bioelectrochemical devices, such as organic electrochemical transistors (OECTs). Here, we report a series of polar propylenedioxythiophene-based copolymers functionalized with glyme side chains of varying lengths as well as an analogue with short hydroxyl side chains. We show that long polar side chains are not required for achieving high volumetric capacitance (C*), as short hydroxy substituents can afford facile doping and high C* in saline-based electrolytes. Furthermore, we demonstrate that varying the length of the polar glyme chains leads to subtle changes in material properties. Increasing the length of glyme side chain is generally associated with an enhancement in OECT performance, doping kinetics, and stability, with the polymer bearing the longest side chains exhibiting the highest performance ([µC*]OECT = 200 ± 8 F cm-1 V-1 s-1). The origin of this performance enhancement is investigated in different device configurations using in situ techniques (e.g., time-resolved spectroelectrochemistry and chronoamperometry). These studies suggest that the performance improvement is not due to significant changes in C* but rather due to variations in the inferred mobility. Through a thorough comparison of two different architectures, we demonstrate that device geometry can obfuscate the benchmarking of OECT active channel materials, likely due to contact resistance effects. By complementing all electrochemical and spectroscopic experiments with in situ measurements performed within a planar OECT device configuration, this work seeks to unambiguously assign material design principles to fine-tune the properties of poly(dioxythiophene)s relevant for application in OECTs.

Designing Quantum Capacitive Peptide Interfaces for Electroanalytical Applications.

Redox-active moieties assembled on metallic interfaces have been shown to follow quantum mechanical rules, where the quantum capacitance of the interface (directly associated with the electronic structure of the redox-active moieties) plays a key role in the electron transfer dynamics of the interface. Modifying these interfaces with biological receptors has significant advantages (simplifying molecular diagnostics methods, reducing size, time, and cost while maintaining high sensitivity), enabling the fabrication of miniaturized electroanalytical devices that can compete with traditional ELISA and RT-PCR benchtop assay methods. Owing to their intrinsic characteristics, the use of peptide-based redox-active moieties is a promising chemical route for modifying metallic surfaces, resulting in a high quantum capacitive signal sensitivity. In the present work, different ferrocene-tagged peptides with a structure of Fc-Glu-XX-XX-Cys-NH2 (XX = serine, phenylalanine, glycine) were used to form self-assembled monolayers on gold. The feasibility of using these interfaces in an electroanalytical assay was verified by detecting the NS1 DENV (Dengue Virus) biomarker to compare the efficiency of peptide structures for biosensing purposes. Parameters such as the formal potential of the interface, normalized electronic density of states (DOS), quantum capacitance, and electron transfer rate constants were obtained for Ser-, Phe-, and Gly-peptides. The Gly-peptide structure presented the highest analytical performance for sensing NS1 with a sensitivity of 5.6% per decade and the lowest LOD (1.4 ng mL-1) and LOQ (2.6 ng mL-1), followed by Phe-peptide, whereas Ser-peptide had the lowest performance. This work demonstrates that the use of peptides to fabricate a self-assembled monolayer as a biosensor component has advantages for low-cost point-of-care diagnostics. It also shows that the performance of the sensing interface depends strongly on how the chemistry of the surface is designed as a whole, not only on the redox-active group.

Impact of Faradaic Interlayer Confinement and Carbon-Centered Macrostructure Designs for Ion Capture and the Recovery of Elements.

Environmental protection associated with renewable energy is among the most critical challenges for translational ion-capture based on capacitive storage of ions in electrical double layers at the interface of electrode and electrolyte. Electric double-layer capacitance with charge induction and faradaic pseudo-capacitance with charge transfer classifies the capacitance of the electrochemical interface. The electrochemical interface in most energy technologies involves porous and pseudocapacitive redox materials that offer varying degrees of electrolyte confinement. In this review, we discuss the factors affecting water desalination, such as the effect of nanopores for ion capture, the ion sieving effect, the effect of hydration energy, and hydration radius in the carbon sub-nanometer pore. Moreover, the surface phenomena of electrodes, including carbon corrosion, and the potential of zero charge to control the oxidation of carbon electrodes are explained along with protection mechanisms. The various capacitive deionization (CDI) operations and the corresponding electrochemical cell technologies are briefly introduced, including the significance of double-layer charging materials with faradaic intercalation, which suffer less from co-ion expulsion. Finally, we revisit the effects of various nanoarchitectures and the construction of capacitive deionization electrodes for clean water technology.

Unlocking the Full Potential of Heteroatom-Doped Graphene-Based Supercapacitors through Stacking Models and SHAP-Guided Optimization.

Graphene-based supercapacitors have emerged as a promising candidate for energy storage due to their superior capacitive properties. Heteroatom-doping is a method of improving the capacitive properties of graphene-based electrodes, but the optimal doping conditions and electrochemical properties are not yet fully understood due to the synergistic effects that occur. Many parameters, such as doping content, defects, specific surface area (SA), electrolyte, and more, could affect the capacitance (CAP). In this study, we use machine learning to solve these critical issues. We applied many models, such as Light Gradient Boost Machine, Extreme Gradient Boost, Polynomial Regression, Neural Network, Elastic Net, Lasso Regression, Ridge Regression, Random Forest, Support Vector Machine, K-Nearest Neighbors, Gradient Boost, AdaBoost, and Decision Tree, to find a suitable model for CAP prediction. Moreover, we enhance the prediction result by taking advantage of the top candidate model and creating a stacking concept (called "stacking models"). The SHAP value was used to identify the range of properties that affect CAP, and it was discussed in detail. Our results suggest that high-CAP graphene supercapacitors should have a large SA, with 4-5% nitrogen, 10-15% oxygen, high percentages of sulfur, a defect ratio close to 1, with acid electrolyte, and a low current density. These findings, along with the developed model and code, are expected to serve as a valuable computational tool for future electrochemical research from fundamental to applications.

High reproducibility of a novel supported anterior drawer test for diagnosing ankle instability.

BACKGROUND: The manual traditional anterior drawer test (ADT) is essential for deciding the treatment for chronic ankle instability, but it has been shown to have a comparatively low reproducibility and accuracy, especially in less experienced hands. To clarify the inter-examiner reproducibility, we compared the actual distance of anterior translation between junior and senior examiners in ADT. We also evaluated the diagnostic abilities of traditional ADT, and a novel modified ADT (supported ADT). METHODS: Thirty ankles were included in this study, and ankle instability was defined using stress radiography. All subjects underwent two methods of manual ADT by junior and senior examiners, and ankle instability was judged in a blinded fashion. The anterior drawer distance was calculated from the lengthening measured using a capacitance-type sensor device. RESULTS: The degree of anterior translation determined by the junior examiner was significantly lower than that determined by the senior examiner when traditional ADT was performed (3.3 vs. 4.5 mm, P = 0.016), but there was no significant difference in anterior translation between the two examiners when supported ADT was performed (4.6 vs. 4.1 mm, P = 0.168). The inter-examiner reliability of supported ADT was higher than that of traditional ADT. For the junior examiner, the diagnostic accuracy of supported ADT was higher than that of traditional ADT (sensitivity, 0.40 vs. 0.80; specificity, 0.75 vs. 0.80). CONCLUSION: Supported ADT may have the advantage of being a simple manual test of ankle instability with less error between examiners.

The cochlear outer hair cell speed paradox.

Cochlear outer hair cells (OHCs) are among the fastest known biological motors and are essential for high-frequency hearing in mammals. It is commonly hypothesized that OHCs amplify vibrations in the cochlea through cycle-by-cycle changes in length, but recent data suggest OHCs are low-pass filtered and unable to follow high-frequency signals. The fact that OHCs are required for high-frequency hearing but appear to be throttled by slow electromotility is the "OHC speed paradox." The present report resolves this paradox and reveals origins of ultrafast OHC function and power output in the context of the cochlear load. Results demonstrate that the speed of electromotility reflects how fast the cell can extend against the load, and does not reflect the intrinsic speed of the motor element itself or the nearly instantaneous speed at which the coulomb force is transmitted. OHC power output at auditory frequencies is revealed by emergence of an imaginary nonlinear capacitance reflecting the phase of electrical charge displacement required for the motor to overcome the viscous cochlear load.

Implementation of Parameter Observer for Capacitors.

This paper describes the implementation of a parameter observer (PO) intended to estimate the capacitance and equivalent serial resistance of a capacitor (ESR). The implemented observer consists of a dynamic second-order discrete-time system. The input signal of the observer is the voltage at the terminals of the capacitor measured during its discharge across a variable resistance in two steps. The implemented observer can be used in quasi-online or offline mode. The theoretical and experimental supporting materials provide a comprehensive picture of the implementation and conditions of use of the PO. The experimental verification was carried out with a microcontroller with Cortex®-M7 core architecture. The sampling time of the PO was 20 µs, and the estimation of the parameters was obtained before the end of the discharge of the capacitor. In the cases described in the paper, this means approximately 25 ms. Due to the PO's capabilities (estimation speed, reduced computational complexity and precision)-proved by the experiments carried out on three electrolytic capacitors of 100 µF, 220 µF and 440 µF-the implementation is of interest for several applications, primarily in the field of power electronic applications.