UV Resin Research Articles

Hydrogen Sensor with a Thick Catalyst Layer Anchored on Polyimide Film

AbstractHydrogen sensors are important in a hydrogen‐driven society to prevent explosions caused by hydrogen leaks into the atmosphere. In previous studies, resistive hydrogen sensors on polymer films have metal oxide nanostructures decorated with novel metals that enable good responses at room temperature. However, the in situ growth process of sensing nanostructures has the disadvantage of ineffective fabrication, particularly when preparing a thick catalyst layer to produce reliable readouts from the catalytic hydrogen combustion. This work presents a catalytic combustion hydrogen sensor with a thick catalyst layer anchored in a UV resin layer on polyimide film. Catalyst anchoring channels are made by UV imprinting with a glass mold. The sensor consists of a sensing electrode and a microheater, both made of Au within an area of 1.2 mm diameter. UV imprinting produces a UV resin layer of 27 µm thick and catalyst anchoring channels of 14 µm deep and 20–30 µm wide, which are filled with Pt/TiO2 as a catalyst. The sensing response is 7.9% for 1% H2 under ambient conditions, and the detection range is 0.1–3% H2. The UV‐resin microstructures can effectively retain a thick catalyst layer to enhance sensitivity, and their low thermal conductivity reduces heat loss.

Development of a 3D printer for long fiber-reinforced plastic and evaluation of the mechanical properties of printed parts

The field of three-dimensional (3D) printing, a technology that allows low-cost printing of complex 3D shapes with a high degree of modeling freedom, has exhibited significant growth over the last few years. This paper proposes a new 3D printing mechanism for long fiber-reinforced plastic as part of an effort to realize 3D-printed shapes with favorable mechanical properties and describes how prototype parts were printed using the new method. We also devise a method for modifying the fiber surface and other techniques for improving adhesion of fibers and UV resin. Mechanical testing of prototype parts printed using the proposed method indicates that the parts exhibit excellent mechanical properties as a result of filling with long fibers, indicating that the method yields a material with few voids and a high fiber volume fraction.

Novel Resin-Based Antibacterial Root Surface Coating Material to Combat Dental Caries.

Root caries caused by cariogenic bacteria are a burden on a large number of individuals worldwide, especially the elderly. Applying a protective coating to exposed root surfaces has the potential to inhibit the development of caries, thus preserving natural teeth. This study aimed to develop a novel antibacterial coating to combat root caries and evaluate its effectiveness using the antibacterial monomer dimethylaminohexadecyl methacrylate (DMAHDM). DMAHDM was synthesized and incorporated into a resin consisting of 55.8% urethane dimethacrylate (UDMA) and 44.2% TEG-DVBE (UV) at a 10% mass fraction of glass filler. Multiple concentrations of DMAHDM were tested for their impact on the resin's mechanical and physical properties. S. mutans biofilms grown on resin disks were analyzed for antibacterial efficacy. Cytotoxicity was assessed against human gingival fibroblasts (HGFs). The results showed an 8-log reduction in colony-forming units (CFUs) against S. mutans biofilm (mean ± sd; n = 6) (p < 0.05) when 5% DMAHDM was incorporated into the UV resin. There was a 90% reduction in metabolic activity and lactic acid production. A low level of cytotoxicity against HGF was observed without compromising the physical and mechanical properties of the resin. This coating material demonstrated promising physical properties, potent antibacterial effects, and low toxicity, suggesting its potential to protect exposed roots from caries in various dental procedures and among elderly individuals with gingival recession.

A study of mechanical properties of photosensitive resins used in vat photopolymerization process

In recent years, the rapid advancement of Additive Manufacturing (AM) technology has led to resource-efficient processes and reduced gaps between design and product/prototypes. Particularly, sectors like medicine and dentistry stand to gain from these advancements if materials with suitable mechanical characteristics for clinical use are available. One such evolving AM process is VAT photopolymerization through LCD 3D Printer technology, characterized by the curing of photosensitive polymeric resins. This study aims to assess the impact of the angle of layer photopolymerization of UV resin in three positions (horizontal, vertical, and inclined at 45°) using a cost-effective LCD 3D Printer. Additionally, specimens, distributed across five positions on the printing platform, underwent testing with three types of UV light-curing resin. Mechanical properties, including tensile stress, elasticity modulus, and hardness, were evaluated and analyzed statistically. Results indicate that both the chosen manufacturing platform position and the inclined layer angle significantly influence the final characteristics of the workpiece.

Toward Sustainable Electroluminescent Devices for Lighting and Sensing

AbstractIn today's rapidly evolving technological landscape, electroluminescent devices have emerged as pivotal components, illuminating a path toward energy‐efficient lighting solutions, advanced displays, and integrated sensing technologies, profoundly impacting sectors ranging from consumer electronics to sustainable urban development. Based in such socio‐scientific‐economic scenario, and in the pursuit of sustainable and environmentally conscious technologies, this work presents a novel approach to the development of a multifunctional electroluminescent (EL) device capable of both efficient lighting and electric field frequency sensing applications. The proposed device integrates a composite based on zinc sulfide co‐doped with copper (ZnS:Cu) phosphor particles and plant‐based UV resin, to achieve enhanced functional properties and reduced environmental impact. The developed anycubic plant‐based UV resin clear (ECOr)/ZnS:Cu inks display viscosity values between 0.5 and 100 Pa.s (ensuring good quality of screen‐prints), and after printing composites exhibit thermal stability up to ≈200 °C; morphological homogeneity, dielectric properties dependent on the ZnS:Cu content (dielectric constant of 12.8 for the sample with 80 wt.% of filler); 30 cd.m2 luminance for the sample with 80 wt.% of ZnS:Cu; and colorimetric electric field frequency sensing capability in the 0–3 kHz range. Thus, this research contributes to the advancement of sustainable technologies that prioritize both multifunctionality and environmental responsibility in the fabrication of electroluminescent devices for lighting and sensing.

Use of high-performance polymeric materials in customized low-cost robotic grippers for biomechatronic applications: experimental and analytical research

Advancements in materials science and 3D printing technologies have opened up new avenues for developing low-cost robotic grippers with high-performance capabilities, making them suitable for various biomechatronic applications. In this research, it has been explored the utilization of high-performance polymer materials, such as Polyetherketoneketone (PEKK), Polyethylene Terephthalate Glycol (PET-G) and MED 857 (DraftWhite), in the designing and developing of customized robotic grippers. The primary focus of made analyses was oriented on materials characterization, both experimentally and analytically. Computer-Aided Engineering (CAE) methods were employed to simulate bending experiments, allowing for a comprehensive analysis of the mechanical behavior of the selected materials. These simulations were validated through physical bending experiments using samples fabricated via 3D printing technologies, including Fused Filament Fabrication (FFF) for PET-G and PEKK, as well as Jetted Photopolymer (PolyJet) technology employing UV Resin for MED 857. The findings of this research provided advantages of utilizing advanced materials like PEKK in low-cost robotic grippers for biomechatronic applications. The experimental and analytical approaches offer valuable insights into material selection, design optimization, and the development of cost-effective high-performing robotic systems with a wide range of applications in the field of biomechatronics.

Surface Roughness Analysis of Microchannels Featuring Microfluidic Devices Fabricated by Three Different Materials and Methods

In recent years, the utilization of microfluidic devices for precise manipulation of small flows has significantly increased. The effective management of microfluidics is closely associated with microchannel fabrication. The fabrication method employed for microfluidic devices directly impacts the roughness of the microchannels, consequently influencing the flows within them. In this study, the surface roughness of microchannels was investigated through three different fabrication processes: PDMS lithography, PLA printing, and UV resin printing. This research compared and analyzed the surface roughness of the microchannels fabricated using these methods. Furthermore, supported by a dynamic fluid simulator, the impact of surface roughness on flow behavior was shown. Results reveal varying degrees of roughness prominence in curved regions. Comparing microfluidic device fabrication techniques is crucial to optimize the process, control roughness, analyze flow rates, and select a proper material to be used in the development of microfluidic devices.

Experimental investigations into nonlinear dynamic behaviours of triply periodical minimal surface structures

Natural frequency, damping ratio and dynamic stiffness are fundamental to the performance of structures subjected to dynamic loads. Triply Periodic Minimal Surface (TPMS) composite structures, celebrated for their superior energy absorption capacity and specific strength, represent some of the most promising meta-structures. However, their dynamic properties are yet to be fully understood, thereby hindering their practical applications within civil engineering domains. Damping properties, crucial to vibration reduction, remain particularly elusive; previous studies have not successfully established a connection between these properties and the force excitation amplitude in TPMS structures. This study aims to compare the damping properties of different TPMS structures and to investigate their potential for adoption within civil engineering fields. Three types of TPMSs, including Schoen I-graph-wrapped package surface (IWP), Schwarz primitive (Primitive) and Schoen Gyroid (Gyroid), have been adopted to design solid and sheetal TPMS composite structures with identical relative density (50%) to compare their damping properties under varying excitation amplitudes. These TPMS structures are manufactured from photosensitive resin (UV resin) using stereolithography 3D printing technology. Owing to the lack of previous research into the damping properties and dynamic stiffness of TPMS structures as support structures, we have conducted single-freedom modal tests to determine the modal parameters, including natural frequency and damping ratios. Our novel results indicate that the natural frequency and damping ratio of the TPMS structures vary with the excitation amplitude. Additionally, the dynamic stiffness of TPMS structures reveals a similar decreasing trend to frequency when load amplitude escalates. As the excitation amplitude increases, the TPMS structures demonstrate softening and are capable of offering a higher vibration damping coefficient. Notably, the SS-Gyroid structure exhibits higher stiffness and damping ratio compared to other TPMS structures. These fresh insights pave the way for the integration of 3D printed smart TPMS structures within civil engineering, particularly for vibration reduction and efficient material usage. A judicious TPMS structure design can provide relatively high stiffness and damping ratio without excessive material use.

3D Resin-coated pressure sensor response for bite force assessment: A pilot study.

Occlusal splints with sensors help in the bruxism diagnosis and monitoring, by recording the patient's bite force. The aim of this study was to evaluate the accuracy of a pressure sensor when it is covered with different thicknesses of a 3D printing resin (Anycubic 405nm Translucent Green UV Resin, Anycubic, UK). In this preliminary study, the evaluated sensor (FlexiForce A201 Sensor, Tekscan) was firstly calibrated without any type of cover material, and later tested with 3D printing resin with different thicknesses (1 mm, 1.15 mm, 1.4 mm and 1.6 mm). The load tests were performed by a force tester (MultiTest 2.5 dV, Mecmesin). When the pressure sensor was covered with resin of 1mm and 1.6 mm thick specimens, a higher difference was found between the applied load and the corresponding sensor reading. It was concluded that it is possible to use this type of pressure sensor and that it showed better accuracy with the 1.15 mm and 1.4 mm 3D printing resin covering.

Solid-State White Light-Emitting Diodes Based on 3D-Printed CsPbX3-Resin Color Conversion Layers

Inorganic metal halide-based perovskites have tremendous potential for use in solid-state lighting due to their earth-abundant elements, solution processability, high photoluminescence quantum yield (PLQY), and tunable band gap energy and emission. However, the stability issue remains a challenge. Here, we report the use of a 3D printing technique to fabricate resin-perovskite color conversion layers to bridge the gap between material development and device applications. This not only simplified the fabrication process but also significantly improved the performance of the device. By using an economic 3D printer, color-emitting perovskite nanocrystals (green, yellow, and red) were mixed with highly transparent UV resin to obtain a thin color conversion layer. These 3D-printed color conversion layers retained above 80% of their original PLQY after 180 days of storage in ambient conditions, confirming their exceptional stability. Furthermore, we stacked the printed color conversion layers on top of the UV light-emitting diode chip, resulting in white lights with tunable correlated color temperatures, high color rendering indexes up to 94, color coordinates of (0.32, 0.33) close to the standard neutral white light, and high luminous efficacy of radiation up to 299 lm/W. As a result of this work, the adoption of solid-state lighting on a broader scale will be one step closer to reality.

Fatigue and Wear Performance of Autoclave-Processed and Vacuum-Infused Carbon Fibre Reinforced Polymer Gears

This study focuses on investigating the fatigue and wear behaviour of carbon fibre reinforced polymer (CFRP) gears, which have shown promising potential as lightweight and high-performance alternatives to conventional gears. The gears were fabricated via an autoclave process using an 8-layer composite made of T300 plain weave carbon fabric and ET445 resin and were tested in pair with a 42CrMo4 steel pinion and under nominal tooth bending stress ranging from 60 to 150 MPa. In-situ temperature monitoring was performed, using an infrared camera, and wear rates were regularly assessed. The result of the wear test indicates adhesive wear and three-body abrasion wear mechanisms between the CFRP gears and the steel counterpart. A finite element analysis was performed to examine the in-mesh contact and root stress behaviour of both new and worn gears at various loads and a specified running time. The results point to a substantial divergence from ideal meshing and stress conditions as the wear level is increased. The fatigue results indicated that the CFRP gears exhibited superior performance compared to conventional plastic and composite short-fibrous polymer gears. The described composite gear material was additionally compared with two other composite configurations, including an autoclave-cured T700S plain weave prepreg with DT120 toughened resin and a vacuum-impregnated T300 spread plain weave carbon fabric with LG 900 UV resin. The study found that the use of the T700S-DT120 resulted in additional improvements.

Programmable UV-Curable Resin by Dielectric Force.

In this study, UV-curable resin was formed into different patterns through the programmable control of dielectric force. The dielectric force is mainly generated by the dielectric chip formed by the interdigitated electrodes. This study observed that of the control factors affecting the size of the UV resin driving area, current played an important role. We maintained the same voltage-controlled condition, changing the current from 0.1 A to 0.5 A as 0.1 A intervals. The area of droplets was significantly different at each current condition. On the other hand, we maintained the same current condition, and changed the voltage from 100 V to 300 V at 50 V intervals. The area of droplets for each voltage condition was not obviously different. The applied frequency of the AC (Alternating Current) electric field increased from 10 kHz to 50 kHz. After driving the UV resin, the pattern line width of the UV resin could be finely controlled from 224 um to 137 um. In order to form a specific pattern, controlling the current and frequency could achieved a more accurate shape. In this article, UV resin with different patterns was formed through the action of this dielectric force, and after UV curing, tiny structural parts could be successfully demonstrated.

Green, Sustainable Architectural Bamboo with High Light Transmission and Excellent Electromagnetic Shielding as a Candidate for Energy-Saving Buildings.

Currently, light-transmitting, energy-saving, and electromagnetic shielding materials are essential for reducing indoor energy consumption and improving the electromagnetic environment. Here, we developed a cellulose composite with excellent optical transmittance that retained the natural shape and fiber structure of bamboo. The modified whole bamboo possessed an impressive optical transmittance of approximately 60% at 6.23mm, illuminance of 1000 luminance (lux), water absorption stability (mass change rate less than 4%), longitudinal tensile strength (46.40MPa), and surface properties (80.2 HD). These were attributed to not only the retention of the natural circular hollow structure of the bamboo rod on the macro, but also the complete bamboo fiber skeleton template impregnated with UV resin on the micro. Moreover, a multilayered device consisting of translucent whole bamboo, transparent bamboo sheets, and electromagnetic shielding film exhibited remarkable heat insulation and heat preservation performance as well as an electromagnetic shielding performance of 46.3dB. The impressive optical transmittance, mechanical properties, thermal performance, and electromagnetic shielding abilities combined with the renewable and sustainable nature, as well as the fast and efficient manufacturing process, make this bamboo composite material suitable for effective application in transparent, energy-saving, and electromagnetic shielding buildings.

Hybrid direct ink write 3D printing of high-performance composite structures

PurposeDirect ink writing (DIW) is a robust additive manufacturing technology for the fabrication of fiber-reinforced thermoset composites. However, this technique is currently limited to low design complexity and minimal heights. This study aims to investigate the feasibility of UV-assisted DIW of composites to enhance the green-part strength of the printed inks and resolve the complexity and the height limitations of DIW technology.Design/methodology/approachThe experimental approach involved the preparation of the thermoset inks that are composed of nanoclay, epoxy, photopolymer and glass fiber reinforcement. Composite specimens were fabricated in complex geometries from these ink feedstocks using UV-assisted, hybrid 3D-printing technology. Fabricated specimens were characterized using optical microscopy, three-point bending mechanical tests and numerical simulations.FindingsThe introduced hybrid, UV-assisted 3D-printing technology allowed the fabrication of tall and overhanging thermoset composite structures up to 30% glass fiber reinforcement without sagging during or after printing. Glass fiber reinforcement tremendously enhanced the mechanical performance of the composites. UV-curable resin addition led to a reduction in strength (approximately 15%) compared to composites fabricated without UV resin. However, this reduction can be eliminated by increasing the glass fiber content within the hybrid thermoset composite. Numerical simulations indicate that the fiber orientation significantly affects the mechanical performance of the printed composites.Originality/valueThis study showed that the fabrication of high-performing thermoset composites in complex geometries was possible via hybrid DIW technology. This new technology will tremendously expand the application envelope of the additively manufactured thermoset composites and the fabrication of large composite structures with high mechanical performance and dimensional freedom will benefit various engineering fields including the fields of aerospace, automotive and marine engineering.

The jetting process and spreading characteristics of the power-law fluids for material jetting process

Materials jetting, known as one of the 3D printing technologies, is widely applied in microelectronics packaging, biology and ceramic 3D printing due to its ability to print multi-materials by drop-on-demand. However, most of the materials are power-law fluids in 3D printing applications, the generation of satellites during the jetting process and droplet spreading characteristics are unclear and they have a great effect on the quality of the printout. In this paper, a common electromechanical and fluid-solid coupling model of the jet dispenser and observation platform of the jetting process are established. This modeling method is also suitable for other needle-driven jet dispensers. A commercial UV resin is adopted to study the jetting process of power-law fluid. To reveal the mechanism of satellite generation, the effects of input signals (rising time and falling time) on the dynamic characteristics of the needle and the jetting process are analyzed. On the basis thereof, the effectiveness of the optimal control parameters is demonstrated to eliminate satellites. In addition, the simulation and experimental results show that the falling time and fluid pressure can be controlled to adjust the spreading diameter and height of the droplet. Subsequently, the minimum line width of 0.276 mm is successfully printed with a nozzle of 0.07 mm.

Vertically-aligned boron nitride composite as a highly thermally conductive material using magnetic field-assisted three-dimensional printing

With the development of electronic devices, the efficient thermal management of electronic devices has attracted increasing attention. In this study, we fabricated a composite that exhibited effective thermal conductivity by vertically aligning fillers using a generated vertical magnetic field in a three-dimensional (3D) printer. To this end, magnets were placed in the printer such that the same poles faced each other. Consequently, the magnets repelled each other and formed a vertical magnetic field, which enabled the vertical placement of Fe3O4-decorated BN in UV resin. UV resin is a mixture of 1,6-hexanediol diacrylate, diurethane dimethacrylate, and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide in a mass ratio of 69 : 30: 1. Owing to the effective transfer of heat in the vertical direction, the printed composite achieved a thermal conductivity value of 1.36 W m−1 K−1 at a filler content of 17.5 vol%. This result demonstrate the effectiveness of this method for aligning fillers on a slurry within a 3D printer, and we believe that it will provide a new paradigm for composite printing.

Facile Fabrication of Flexible Polymeric Membranes with Micro and Nano Apertures over Large Areas.

Freestanding, flexible and open through-hole polymeric micro- and nanostructured membranes were successfully fabricated over large areas (>16 cm2) via solvent removal of sacrificial scaffolds filled with polymer resin by spontaneous capillary flow. Most of the polymeric membranes were obtained through a rapid UV curing processes via cationic or free radical UV polymerisation. Free standing microstructured membranes were fabricated across a range of curable polymer materials, including: EBECRYL3708 (radical UV polymerisation), CUVR1534 (cationic UV polymerisation) UV lacquer, fluorinated perfluoropolyether urethane methacrylate UV resin (MD700), optical adhesive UV resin with high refractive index (NOA84) and medical adhesive UV resin (1161-M). The present method was also extended to make a thermal set polydimethylsiloxane (PDMS) membranes. The pore sizes for the as-fabricated membranes ranged from 100 µm down to 200 nm and membrane thickness could be varied from 100 µm down to 10 µm. Aspect ratios as high as 16.7 were achieved for the 100 µm thick membranes for pore diameters of approximately 6 µm. Wide-area and uniform, open through-hole 30 µm thick membranes with 15 µm pore size were fabricated over 44 × 44 mm2 areas. As an application example, arrays of Au nanodots and Pd nanodots, as small as 130 nm, were deposited on Si substrates using a nanoaperture polymer through-hole membrane as a stencil.

Preliminary Technological and Environmental Considerations for Generating Mechanical Components using Plant-based UV Resin

The scope of this paper is to determine the evolution of the dimensional value of the part and to study if there is gas and particle emission produced by the plant-based resin in the 3D printing process with mask stereolithography. For dimensional measurement, a solution with digital calliper is used. For the measurement of emission, two devices are used for indoor air quality. In the vertical direction of part body printed, it is possible to observe a descending linear type of direction with a minimum value at the highest element 3D printed. The data taken into account in this study are mathematically studied using the EXCEL regression equation for dimension. The gases emitted are measured with the booth devices in parallel for formaldehyde and volatile organic compound gases. For CO2 and particles, one of these devices is used. The air quality index was determined in relation to CO2 and, respectively, particle emitted. In the printing process, an increase in CO2 emission of 500 ppm can be observed in the initial phase of the process and a lower value in the body area. It is possible to consider that the quality air in 3D printing with plant-based clear resin is in the good to medium level from all types of emission. These data were put in ac-cordance with the level value offered by the manufacturer of the measuring devices. In this study the dimensional aspects are evaluated in parallel for two types of part bodies and the dimensional equations are the same after three mount times.

Novel antibacterial low-shrinkage-stress resin-based cement

ObjectiveA low-shrinkage-stress resin-based cement with antibacterial properties could be beneficial to create a cement with lower stress at the tooth-restoration interface, which could help to enhance the longevity of the fixed dental restoration by reducing microleakage and recurrent caries. To date, there has been no report on the development of a low-shrinkage-stress and bio-interactive cement. Therefore, the objectives of this study were to develop a novel low-shrinkage-stress resin-based cement containing dimethylaminohexadecyl methacrylate (DMAHDM) and investigate the mechanical and antibacterial properties for the first time. MethodsThe monomers urethane dimethacrylate (UDMA) and triethylene glycol divinylbenzyl ether (TEG-DVBE) were combined and denoted as UV resin. Three cements were fabricated: (1) UV+ 0%DMAHDM (experimental control); (2) UV+ 3%DMAHDM, (3) UV+ %5DMAHDM. RelyX Ultimate cement was used as commercial control. Mechanical properties and Streptococcus mutans (S. mutans) biofilms growth on cement were evaluated. ResultsThe novel bio-interactive cement demonstrated excellent antibacterial and mechanical properties. Compared to commercial and experimental controls, adding DMAHDM into the UV cement significantly reduced colony forming unit (CFU) counts by approximately 7 orders of magnitude, metabolic activities from 0.29 ± 0.03 A540/cm2 to 0.01 ± 0.01 A540/cm2, and lactic acid production from 22.3 ± 0.74 mmol/L to 1.2 ± 0.27 mmol/L (n = 6) (p < 0.05). The low-shrinkage-stress cement demonstrated a high degree of conversion of around 70 %, while reducing the shrinkage stress by approximately 60%, compared to a commercial control (p < 0.05). ConclusionsThe new antibacterial low-shrinkage-stress resin-based cement provides strong antibacterial action and maintains excellent mechanical properties with reduced polymerization shrinkage stress. Clinical significanceA low-shrinkage-stress resin-based cement containing DMAHDM was developed with potent antibacterial effects and promising mechanical properties. This cement may potentially enhance the longevity of fixed dental restoration such as a dental crown, inlay, onlay, and veneers through its excellent mechanical properties, low shrinkage stress, and strong antibacterial properties.

Highly thermally conductive and EMI shielding composite reinforced with aligned carbon fibers and MXene

Measures to ensure the thermal management of electronic devices have attracted increasing interest. In this study, a composite material with high thermal conductivity and electromagnetic wave shielding performance was fabricated by vertically aligning carbon fibers (CFs) using a perpendicular magnetic field. MXene was added as a double filler with aligned CFs to increase the thermal conductivity and electromagnetic wave shielding performance. Magnets were placed outside the mold with the same poles faced each other, and the magnets repelled each other to form a perpendicular magnetic field. In this manner, the Fe3O4 decorated CFs aligned perpendicularly to the UV resin. MXene was dispersed between the aligned CFs to form a heat conduction path, and an interface was generated to reflect and absorb electromagnetic waves. Owing to the effective heat transfer in the vertical direction, the printed composite exhibited a thermal conductivity of 1.96 W/mK and electromagnetic shielding effect of 14.06 dB.