COMSOL Multiphysics Simulation Research Articles

Output Enhancement of a 3D‐Printed Triboelectric Nanogenerator Using Laser Surface 3D Patterning

This study investigates the performance of contact separation and sliding modes of triboelectric Nanogenerators (TENGs) using COMSOL Multiphysics simulation environment. The output performance of a plain surface TENG is compared with square, rectangular, and pyramid‐patterned TENGs. The pyramid pattern emerges as the most efficient geometry, demonstrating a solid output of 95.8 V (Voc) and 0.99 μA (Isc). Advanced 3D printing techniques (3DP) including powder‐based multijet fusion and resin‐based polyjet fusion are utilized to print polyamide 12 (PA12) and VeroClear, respectively. The laser surface patterning technique is used to make precise micropatterns on the surfaces of the VeroClear and PA12 layers, resulting in a consistent and effective surface morphology that enhances the surface area of triboelectric layers, and outperforms traditional approaches of patterning in consistency and efficacy. The validation of simulation results is made where the pyramid pattern is emerged as the most efficient geometry experimentally. Performance is maintained with minimal degradation after 102 cycles, and a 22 μF–63 V capacitor is successfully used to store the generated charge. This study not only sets the path for pre‐experimental analysis using simulation environment but also provides a clear demonstration of advanced manufacturing techniques for printing and patterning 3D‐printed triboelectric materials.

Optimization of the Laser Drilling Processing Parameters for Carbon Steel Based on Multi-Physics Simulation

The laser drilling of carbon steel is always suffered from the formation of slag, the presence of cutting burrs, the generation of a significant quantity of spatter, and the incomplete penetration of the substrate. In order to avoid these defects formed during the laser drilling of carbon steel, the COMSOL multi-physics simulation method was used to model and optimize the laser drilling process. Considering the splash evolution of the material during the complex drilling process, the transient evolution of the temperature field, the flow of the molten fluid, the geometrical changes, and the absorption of the laser energy during the laser drilling process were investigated. The simulated borehole dimensions are consistent with the experimental results. The process parameters have a great influence on the fluid flow pattern and material slag splashing. The laser power has a significant effect on the laser processing compared with the process parameters. With the increase in laser power and the decrease in laser heat source radius, the time required for perforation is reduced, the flow of melt is accelerated, the perforation efficiency is increased, and the hole wall is smoother, but the degree of spattering is greater. The optimized process parameters were obtained: laser heat source radius of 0.3 mm, laser power of 3000 W. These findings can help reduce the machining defects in carbon steel with excellent mechanical properties by optimizing the laser drilling processing parameters.

Magnetic and Thermal Behavior of a Planar Toroidal Transformer

This paper presents a study on the magnetic and thermal behaviors of a planar toroidal transformer, comprising two planar toroidal coils. In our configuration, the primary coil consists of twenty turns, while the secondary coil consists of ten turns. This design combines the advantages of both toroidal and planar transformers: it employs flat coils, akin to those utilized in planar transformers, while retaining a toroidal shape for its magnetic core. This combination enables leveraging the distinctive characteristics of both transformer types. This study delves into electromagnetic and thermal behaviors. Electromagnetic behavior is elucidated through Maxwell’s equations, offering insights into the distribution of magnetic fields, potentials, and electric current densities. Fluid flow is modeled via the Navier–Stokes equations. By coupling these equation sets, a more comprehensive and accurate portrayal of the thermal phenomena surrounding electrical equipment is attained. Such research is invaluable in the design and optimization of electrical systems, empowering engineers to forecast and manage thermal effects more efficiently. Consequently, this aids in enhancing the reliability, durability, and performance optimization of electrical equipment. The mathematical model was solved using the finite element method integrated into the COMSOL Multiphysics software v. 6.0. The COMSOL Multiphysics simulation showed correct behavior of potential, electric field, current density, and uniformly distributed temperature. In addition, this planar toroidal coil transformer model offers many advantages, such as small dimensions, high resonance frequency, and high operating reliability. This study made it possible to identify the range of its optimal functioning.

Simulation-guided development of advanced PID control algorithm for skin cooling in radiofrequency lipolysis.

The clinical outcomes of bipolar radiofrequency (RF) lipolysis, a prevalent non-invasive fat reduction procedure, hinge on the delicate balance between effective lipolysis and patient safety, with skin overheating and subsequent tissue damage as primary concerns. This study aimed to investigate a novel bipolar radiofrequency lipolysis technique, safeguarding the skin through an innovative PID temperature control algorithm. Utilizing COMSOL Multiphysics simulation software, a two-dimensional fat and skin tissue model was established, simulating various PID temperature control schemes. The crux of the simulation involved a comparative analysis of different PID temperatures at 45 °C, 50 °C, and 55 °C and constant power strategies, assessing their implications on skin temperature. Concurrently, a custom bipolar radiofrequency lipolysis device was developed, with ex vivo experiments conducted using porcine tissue for empirical validation. The findings indicated that with PID settings of Kp =7, Ki =2, and Kd =0, and skin temperature control at 45 °C or 50 °C, the innovative PID-based epidermal temperature control strategy successfully maintained the epidermal temperature within a safe range. This maintenance was achieved without compromising the effectiveness of RF lipolysis, significantly reducing the risk of thermal damage to the skin layers. Our research confirms the substantial practical utility of this advanced PID-based bipolar RF lipolysis technique in clinical aesthetic procedures, enhancing patient safety during adipose tissue ablation therapies.

Hollow Stair-Stepping Spherical High-Entropy Prussian Blue Analogue for High-Rate Sodium Ion Batteries.

Prussian blue analogues (PBAs) are considered to be one of the most suitable sodium storage materials, especially with the introduction of the high-entropy (HE) concept into their structure to further improve their various abilities. However, severe agglomeration of the HEPBA particles still limits the fast charging capabilities. Here, an HEPBA (Nax(FeMnCoNiCu)[Fe(CN)6]y□1-y·nH2O) with a hollow stair-stepping spherical structure has been prepared through the chemical etching process of the traditional cubic structure of HEPBA. Electrochemical characterization (sodium ion battery), kinetic analysis, and COMSOL Multiphysics simulations reveal that the nature of the high-entropy and the hollow stair-stepping spherical structure can greatly improve the diffusion behavior of Na+ ions. Moreover, the hollow structure effectively mitigates the volume change of HEPBA during SIBs operation, ultimately extending the lifespan. Consequently, the as-prepared HEPBA cathode exhibits excellent rate performance (126.5 and 76.4 mAh g-1 at 0.1 and 4.0 A g-1, respectively) and stable long-term capability (maintaining its 75.6% capacity after 1000 cycles) due to its unique structure. Furthermore, the waste of the etching process can easily be recycled to prepare more HEPBA product. This processing method holds great promise for designing nanostructures of advanced high-entropy Prussian blue analogues for sodium ion batteries.

Enhancing ionic conductivity and controlling lithium dendrite growth via ferroelectric ceramic Bi4Ti3O12

BackgroundSolid polymer electrolytes (SPEs) have gained numerous research interest in the field of lithium metal batteries. Solid polymer electrolytes have improved safety compared to liquid electrolytes. Despite this, their low ionic conductivity remains a major barrier to practical applications. To overcome the challenge of low ionic conductivity in SPEs, our study introduces a novel approach that integrates ferroelectric ceramics with polymer solid electrolytes. MethodsWe used a one-step molten salt method to synthesize Bi4Ti3O12 (BIT), combined with a poly (vinylidene difluoride) matrix to form the composite solid-state electrolyte. Through various electrochemical characterizations and COMSOL Multiphysics simulations, we discovered that the ferroelectric properties of BIT significantly increase the dissociation of lithium salts, leading to a greater concentration of mobile lithium ions and more efficient ion transport. Significant findingsThis electrolyte showed a remarkable improvement in lithium-ion conductivity, reaching a value of 8.5 × 10−4 S cm−1 at room temperature. Batteries made with these composite electrolytes demonstrate superior cycling stability, the capacity retention rates for LFP/SPEs/Li cells remain high, reaching 95 % even after 1,000 cycles at room temperature (25 °C). These findings highlight the promising applications of ferroelectric ceramics in solid-state batteries.

Optically controlled variable damping system based on PLZT ceramic/ERF in rectangular microchannel

Variable damping control technology based on intelligent materials of electromagnetic excitation has been widely used in the field of (semi-) active vibration control and fluid control. Unfortunately, a major drawback is the electromagnetic noise interference and low response speed. In this paper, a new optically controlled variable damping system based on PLZT ceramic/electrorheological fluid (ERF) is proposed. The mathematical models of the photovoltage generated by PLZT ceramics and the pressure difference between the two ends of the microchannel are established and verified by numerical simulation in COMSOL Multiphysics. Meanwhile, with the increase of light intensity, liquid flow rate and decrease of microchannel height and width, the pressure difference shows an uptrend. Optically controlled variable damping system based on PLZT ceramic/ERF is a control method with the advantages of a clean excitation source, remote control, no electromagnetic interference, and fast response speed, and has a good application prospect in the field of vibration control and fluid control.

Design of a highly sensitive and precise long-range surface plasmon resonance sensor for early detection of malaria

This manuscript presents an innovative Kretschmann configured for Long Range Surface Plasmon Resonance (LRSPR) sensor for malaria detection. It utilizes tungsten diselenide (WSe2) as a bio+molecular recognition element (BRE) layer to attach target analyte. The optimized sensor design demonstrates exceptional performance in detecting different malaria stages (Schizont with refractive index (RI) = 1.371, Trophozoite with RI = 1.381, and Ring with RI = 1.396) at a 633 nm wavelength. In comparison to conventional surface plasmon resonance (CSPR), the LRSPR biosensor exhibits a substantial improvement, a 6.67 to 10 times increase in detection accuracy (DA), an impressive 40 to 86.55 times enhancement in imaging figure of merit (IFOM), and a 6.0 to 8.66 times boost in imaging sensitivity (Simg.) for the sequential detection of different stages of malaria. COMSOL Multiphysics simulations highlight a deeper penetration depth (PD) of 258.71 nm, 276.85 nm, and 373.04 nm for the detection of Schizont, Trophozoite, and Ring stages, respectively.

A Novel Mechano-Synthesized Zeolitic Tetrazolate Framework for a High-Performance Triboelectric Nanogenerator and Self-Powered Selective Neurochemical Detection.

Designing a high-performing triboelectric novel material with eco-friendly, rapid, and cost-effective synthesis is the future of material research in triboelectric nanogenerators (TENG). We report a mechanochemical ball mill synthesis of a zeolitic tetrazolate framework (ZTF-8) that is isostructural with the well-known zeolitic imidazolate framework ZIF-8. ZTF-8 is extremely stable in water, 0.1 M aqueous acid/base solutions for 75 days at 25 °C, and boiling water (100 °C) for 7 days. Kelvin probe force microscopy and molecular electrostatic surface potential computational analysis exhibited that ZTF-8 has a very high positive surface potential. Atomic force microscopy and three-dimensional digital microscopy studies reveal the high roughness profile in the ZTF-8 film. The unique structure, exceptional acid/base stability, good dielectric property, and high roughness profile combined with the extremely electropositive nature of ZTF-8 make it a suitable candidate as a polymer-free triboelectric positive material in TENG with outstanding performance (power density of 720 mW/m2). High triboelectric output was further validated using the COMSOL Multiphysics simulation tool. Simple mechanical hand tapping of the ZTF-based TENG (ZTF-TENG) device generates high electric output, which was practically used to power numerous low-powered devices like tally counter, clinical thermometer, and digital clock and also illuminates 125 light-emitting diodes. In addition, the efficiency of ZTF-TENG was utilized as a self-powered device for a selective dopamine (DA) sensor with good sensitivity (377.76 mV/μM/cm2), wide range linearity (5-120 μM), and excellent limit of detection (0.42 μM).

Rapid construction of nickel phyllosilicate with ultrathin layers and high performance for CO2 methanation

The traditional techniques for the synthesis of nickel phyllosilicates usually time-consuming and energy-intensive, which often lead to the formation of layers with excessive thickness due to uncontrolled crystal growth. In order to overcome these challenges, this work introduces a microwave-assisted synthesis strategy to facilitate the synthesis of Ni-phyllosilicate-based catalysts within an exceptionally short duration of only five minutes, attaining a peak temperature of merely 102 °C. To enhance the specific surface area and to increase the exposure of active sites, an investigation was conducted involving three surfactants. The employment of hexadecyl trimethyl ammonium bromide (CTAB) has yielded remarkable results, with an ultrahigh specific surface area reaching 535 m2 g−1 and an ultrathin lamellar thickness of 1.43 nm. The catalyst exhibited an impressive CO2 conversion of 81.7 % at 400 °C, 60 L g−1 h−1, 0.1 MPa. It also demonstrated a substantial turnover frequency for CO2 (TOFCO2) of 5.4 ± 0.1 × 10−2 s−1, alongside a relatively low activation energy (Ea) of 80.74 kJ·mol−1. Moreover, the catalyst maintained its high stability over a period of 100 h and displayed high resistance to sintering. To further elucidate growth temperature gradient of the catalyst and concentration gradient of the materials involved, COMSOL Multiphysics (COMSOL) simulations were effectively utilized. In conclusion, this work breaks the limitation associated with traditional, laborious synthesis methods for Ni-phyllosilicates, which can produce materials with high surface area and thin-layer characteristics.

Computational Studies Using COMSOL Multiphysics on Dielectrophoretic Characterization and Separation of Mesenchymal Stem Cells Undergoing Tenogenic Differentiation

Stem cells have unique self-renewal and differentiation capacities, which are advantageous for regenerative medicine and tissue engineering applications. Stem cells can recreate cells needed to repair injured tissues and organs in the body, for example, by regenerating connective tissues, which provide support, protection, and a structural framework for various organs and other tissues. However, a significant limitation is the susceptibility of tendons to injury with long-term loss of function. Mesenchymal Stem Cell (MSC) therapies are promising for healing tendon injuries and tears but controlling stem cell differentiation and generating homogeneous tenogenic stem cell populations remains challenging. Therefore, separating differentiating and non-differentiating MSCs to collect homogenous cells is critical for further tissue repair after transplantation. To substantiate our hypothesis that differentiating and non-differentiating stem cells have unique dielectric properties, we focused on characterizing-obtaining dielectric signatures for differentiating tenogenic and non-tenogenic MSCs on the third day of differentiation using dielectrophoresis (DEP) focused on crossover frequencies [1, 2]. The estimated values for membrane capacitance, conductivity, and permittivity after 3-day treatment of undifferentiated cells differentiating into tenogenic MSCs are 2.46±0.1 pF, 0.82±0.01 S/m, and 1.97±0.05, respectively, and cytoplasm conductivity 0.82±0.02 S/m. The treated stem cells undergo differentiation, but the untreated cells don’t. The results showed a significant difference between the 3-day treatment and no-treatment group. The estimated properties from the dielectrophoretic characterization studies are crucial in designing a DEP-based enrichment microdevice to collect homogeneous differentiated stem cell populations for tendon repair. Using particle tracing, creeping flow (transport of diluted species model), and electric current physics in COMSOL Multiphysics simulation software, we designed a microdevice that achieves 100% separation of untreated and treated mesenchymal stem cells undergoing differentiation towards tendon. Applying dielectrophoresis to the microdevice architecture demonstrated high selectivity and yield, processing one million treated and untreated stem cells in 6.4 and 27.8 hours, respectively.

Optimization of Bilayer Resistive Random Access Memory Based on Ti/HfO2/ZrO2/Pt.

In this paper, the electrothermal coupling model of metal oxide resistive random access memory (RRAM) is analyzed by using a 2D axisymmetrical structure in COMSOL Multiphysics simulation software. The RRAM structure is a Ti/HfO2/ZrO2/Pt bilayer structure, and the SET and RESET processes of Ti/HfO2/ZrO2/Pt are verified and analyzed. It is found that the width and thickness of CF1 (the conductive filament of the HfO2 layer), CF2 (the conductive filament of the ZrO2 layer), and resistive dielectric layers affect the electrical performance of the device. Under the condition of the width ratio of conductive filament to transition layer (6:14) and the thickness ratio of HfO2 to ZrO2 (7.5:7.5), Ti/HfO2/ZrO2/Pt has stable high and low resistance states. On this basis, the comparison of three commonly used RRAM metal top electrode materials (Ti, Pt, and Al) shows that the resistance switching ratio of the Ti electrode is the highest at about 11.67. Finally, combining the optimal conductive filament size and the optimal top electrode material, the I-V hysteresis loop was obtained, and the switching ratio Roff/Ron = 10.46 was calculated. Therefore, in this paper, a perfect RRAM model is established, the resistance mechanism is explained and analyzed, and the optimal geometrical size and electrode material for the hysteresis characteristics of the Ti/HfO2/ZrO2/Pt structure are found.

Experimental and computational thermoelectric generator for waste heat recovery for aeronautic application

This study is a comprehensive exploration of a polymer nanocomposite-based Thermoelectric Generator (TEG) developed within the European project InComEss, specifically designed for aeronautical applications. The focus lies on evaluating the TEG's performance under thermal conditions representative of various aircraft flight stages. The TEG module, consisting of four sections with 17 p-n strips each, is constructed from aerospace-grade polycarbonate, exhibiting dimensions of 50 * 1 * 0.3 mm. In the laboratory phase, the TEG's performance is systematically assessed through a series of experiments. Temperature gradients, ranging from −15 °C to 55 °C, emulate conditions experienced during ascending and descending flight stages. The results indicate promising outcomes, showcasing the potential viability of polymer-based TEGs for aeronautical applications. Specifically, temperature gradients of 40–70 °C, representative of atmospheric conditions and wing leading edge skin conditions, are applied across four test trials. The model validation demonstrates creditable agreement between computational outcomes and experimental data. Insights gained from COMSOL Multiphysics simulations includes temperature distribution, electric potential, and flow dynamics. Simulations conducted under varied temperature ranges provide valuable insights into the TEG's performance variability. Key findings include temperature distribution profiles, electric potential outputs under open and closed-circuit conditions, and a detailed flow analysis within a controlled thermal environment. The validated computational model not only enhances understanding of the TEG's behaviour, but also establishes a foundation for optimizing design parameters to enhance thermoelectric efficiency. The error analysis underscores the model's reliability, exhibiting an average error of 5.68 % between computational and experimental results, reinforcing its suitability for scientific investigations of this nature.

Growth mechanism of intermetallic compound in SnAg/Cu interface of micro-bumps under extremely low-temperature by phase field method

Scientific investigation will increasingly focus on deep space exploration. Spacecraft will be subjected to extremely low-temperature, changing internal microstructure and micro-bumps mechanics, reducing reliability. Thus, micro-bumps must be tested in extremely low temperatures. This research examines the impact of low-temperature storage on IMC (Intermetallic Compound) growth and micro-bumps crystallography at −196 °C. Secondly, a diffusion-weak coupled phase field theory is summarized, and the COMSOL multi-physics simulation platform simulates the growth of IMC layer in micro-bumps developing during extremely low-temperature storage. Finally, microhardness and elastic modulus of various phases were studied. Experimental data indicate that holding Sn at −196 °C for 1000 h produces recrystallization, resulting in tiny grains with diverse orientations. Micro-bumps with Sn/IMC interfaces have highest von Mises equivalent stress. Strain gradient thickens IMC layer at low temperatures with storage time, and edge IMC layer is thinner than axis IMC layer. The diffusion-force weak coupling phase field model's driving force curve indicates that stress gradient, not phase separation, drives IMC growth at extremely low temperatures. Low-temperature storage enhances Sn microhardness and elastic modulus through compressive stress and grain refining. IMC microhardness and elasticity decrease with tensile stress.

Strong electric field at the sharp tips of Cu(OH)2 nanochrysanthemums for selective electrochemical CO2 conversion into ethylene

Electrochemical CO2 reduction reaction (CO2RR) is an attractive approach for the mitigation of CO2 emissions and the production of value-added chemicals. However, it remains a challenge to achieve high selectivity of desirable C2 products like ethylene (C2H4) with high economic value and large market. Herein, we report the fabrication of unprecedented Cu(OH)2 nanochrysanthemums catalyst layer (CL). Interestingly, Cu(OH)2 nanochrysanthemums CL exhibits a C2H4 Faradaic efficiency (FE) of 51.2 ± 0.5% and a FE(C2H4+C2H5OH) of 70.0 ± 0.5% in pH nearly neutral electrolytes. It is worth mentioning that Cu(OH)2 nanochrysanthemums CL achieves the highest FEC2 among documented Cu(OH)2 electrocatalysts. The high FEC2H4 and FEC2 can be attributed to the high electrochemical surface area (ECSA, 21.9 mF/cm2) of Cu(OH)2 nanochrysanthemums. In addition, the wellbalanced hydrophilicity-hydrophobicity of the Cu(OH)2 nanochrysanthemums CL also contributes to the high FEC2H4 and FEC2 by simultaneously satisfying efficient transfer of hydrophobic CO2 and C2H4 as well as hydrophilic H2O and C2H5OH. COMSOL multiphysics simulations and density functional theory (DFT) calculations further suggest that the negatively charged sharp tips of Cu(OH)2 nanochrysanthemums would trigger the accumulation of K+ and offer strong local electric field of 9.8 V/μm, promoting C–C coupling and suppressing hydrogen evolution reaction (HER).

A 3D Hierarchical Host with Gradient-Distributed Dielectric Properties toward Dendrite-free Lithium Metal Anode.

The conventional conductive three-dimensional (3D) host fails to effectively stabilize lithium metal anodes (LMAs) due to the internal incongruity arising from nonuniform lithium-ion gradient and uniform electric fields. This results in undesirable Li "top-growth" behavior and dendritic Li growth, significantly impeding the practical application of LMAs. Herein, we construct a 3D hierarchical host with gradient-distributed dielectric properties (GDD-CH) that effectively regulate Li-ion diffusion and deposition behavior. It comprises a 3D carbon fiber host modified by layer-by-layer bottom-up attenuating Sb particles, which could promote Li-ion homogeneously distribution and reduce ion concentration gradient via unique gradient dielectric polarization. Sb transforms into superionic conductive Li3Sb alloy during cycling, facilitating Li-ion dredging and pumps towards the bottom, dominating a bottom-up deposition regime confirmed by COMSOL Multiphysics simulations and physicochemical characterizations. Consequently, a stable cycling performance of symmetrical cells over 2000 h under a high current density of 10 mA cm-2 is achieved. The GDD-CH-based lithium metal battery shows remarkable cycling stability and ultra-high energy density of 378 Wh kg-1 with a low N/P ratio (1.51). This strategy of dielectric gradient design broadens the perspective for regulating the Li deposition mechanism and paves the way for developing high-energy-density lithium metal anodes with long durability.

A 3D Hierarchical Host with Gradient‐Distributed Dielectric Properties toward Dendrite‐free Lithium Metal Anode

AbstractThe conventional conductive three‐dimensional (3D) host fails to effectively stabilize lithium metal anodes (LMAs) due to the internal incongruity arising from nonuniform lithium‐ion gradient and uniform electric fields. This results in undesirable Li “top‐growth” behavior and dendritic Li growth, significantly impeding the practical application of LMAs. Herein, we construct a 3D hierarchical host with gradient‐distributed dielectric properties (GDD‐CH) that effectively regulate Li‐ion diffusion and deposition behavior. It comprises a 3D carbon fiber host modified by layer‐by‐layer bottom‐up attenuating Sb particles, which could promote Li‐ion homogeneously distribution and reduce ion concentration gradient via unique gradient dielectric polarization. Sb transforms into superionic conductive Li3Sb alloy during cycling, facilitating Li‐ion dredging and pumps towards the bottom, dominating a bottom‐up deposition regime confirmed by COMSOL Multiphysics simulations and physicochemical characterizations. Consequently, a stable cycling performance of symmetrical cells over 2000 h under a high current density of 10 mA cm−2 is achieved. The GDD‐CH‐based lithium metal battery shows remarkable cycling stability and ultra‐high energy density of 378 Wh kg−1 with a low N/P ratio (1.51). This strategy of dielectric gradient design broadens the perspective for regulating the Li deposition mechanism and paves the way for developing high‐energy‐density lithium metal anodes with long durability.

Unraveling Drug Delivery from Cyclodextrin Polymer-Coated Breast Implants: Integrating a Unidirectional Diffusion Mathematical Model with COMSOL Simulations.

Breast cancer ranks among the most commonly diagnosed cancers worldwide and bears the highest mortality rate. As an integral component of cancer treatment, mastectomy entails the complete removal of the affected breast. Typically, breast reconstruction, involving the use of silicone implants (augmentation mammaplasty), is employed to address the aftermath of mastectomy. To mitigate postoperative risks associated with mammaplasty, such as capsular contracture or bacterial infections, the functionalization of breast implants with coatings of cyclodextrin polymers as drug delivery systems represents an excellent alternative. In this context, our work focuses on the application of a mathematical model for simulating drug release from breast implants coated with cyclodextrin polymers. The proposed model considers a unidirectional diffusion process following Fick's second law, which was solved using the orthogonal collocation method, a numerical technique employed to approximate solutions for ordinary and partial differential equations. We conducted simulations to obtain release profiles for three therapeutic molecules: pirfenidone, used for preventing capsular contracture; rose Bengal, an anticancer agent; and the antimicrobial peptide KR-12. Furthermore, we calculated the diffusion profiles of these drugs through the cyclodextrin polymers, determining parameters related to diffusivity, solute solid-liquid partition coefficients, and the Sherwood number. Finally, integrating these parameters in COMSOL multiphysics simulations, the unidirectional diffusion mathematical model was validated.

Simulated and measured piezoelectric energy harvesting of dynamic load in tires

From 2007 in US and from 2022 in EU it is mandatory to use TPMS monitoring in new cars. Sensors mounted in tires require a continuous power supply, which currently only is from batteries. Piezoelectric energy harvesting is a promising technology to harvest energy from tire movement and deformation to prolong usage of batteries and even avoid them inside tires.This study presents a simpler method to simultaneous model the tire deformation and piezoelectric harvester performance by using a new simulation approach - dynamic bending zone. For this, angular and initial velocities were used for rolling motion, while angled polarization was introduced in the model for the piezoelectric material to generate correct voltage from tire deformation. We combined this numerical simulation in COMSOL Multiphysics with real-life measurements of electrical output of a piezoelectric energy harvester that was mounted onto a tire. This modelling approach allowed for 10 times decrease in simulation time as well as simpler investigation of systems parameters influencing the output power. By using experimental data, the simulation could be fine-tuned for material properties and for easier extrapolation of tire deformation with output harvested energy from simulations done at low velocity to the high velocity experimental data.

Influence of surface roughness on the fluid flow in microchannel

Surface roughness is a crucial factor of fluid flow in microfluidic channels. Most of the existing studies focus on the effect of regular microstructured surfaces on fluid flow, while researchs about the impact of random rough surfaces on fluid flow remains limited. Therefore, in this study, a random rough surface model and two microstructured surface models were established, and the effects surface roughness on the fluid flow at Wenzel state and Cassie-Baxter state were studied using COMSOL multi-physics simulation software. Our findings reveal that both the flow velocity and the fluid flow rate at the microchannel outlet decreases with the surface roughness increases. Notably, the flow rate and velocity of the fluid flow at Cassie-Baxter state is higher than that of fluid flow at Wenzel state.