Film Patch Research Articles

Biomimicry and topology optimization for adhesive toughness design in bonded heterogeneous films

Heterogeneous films have recently been extensively studied due to their superior material properties compared to homogeneous films. However, studies focusing on the design of heterogeneous films, especially with multi-material phases and structures, have been relatively scarce. This paper presents a bioinspired design methodology aimed at optimizing the mechanical properties of heterogeneous films through the strategic arrangement of stiff and soft material blocks. The heterogeneous film is represented as a composite beam and the interfacial failure process is simulated by a cohesive zone model. Then an optimization algorithm is employed to adjust the distribution of stiff materials within the soft film patch in the heterogeneous film. The results show that a nearly twofold increase in adhesive toughness for the optimized film compared to the original. Further discussions shed light on the energy distribution and variations in the fracture process zone size, providing insights into the observed enhancements. In terms of efficiency, the proposed optimization method distinctly outperforms the greedy method, demonstrating the potential for a more effective and efficient design of heterogeneous films with improved mechanical properties.

Treatment characteristics of chronic low back pain patients treated with buprenorphine buccal film or transdermal patch.

Aims: Retrospective insurance claims analysis exploring treatment characteristics in chronic low back pain patients prescribed buprenorphine buccal film (Belbuca®) or transdermal patches. Patients and methods: The first buprenorphine prescription (buccal film or transdermal patch) was an index event. Patients were observed over 6month pre- and post-index periods. Propensity score matching minimized the selection bias. Results: Buccal film patients had a higher buprenorphine daily dose (501.7 vs 270.9 µg; p <0.001). The patch-to-film switching rate was higher than vice versa (11.5 vs 3.8%; p <0.001). The buccal film showed a greater reduction in opioid prescriptions (-1.1 vs -0.7; p =0.012), daily morphine milligram equivalents (-12.6 vs -7.3; p <0.001) and opioid treatment duration (-13.4 vs -7.6days; p =0.022). Conclusion: Buccal film was associated with higher buprenorphine doses and a greater reduction of opioid burden.

Economic burden and dosing trends of buprenorphine buccal film and transdermal patch in chronic low back pain.

Aim: Exploring prescribing trends and economic burden of chronic low back pain (cLBP) patients prescribed buprenorphine buccal film (Belbuca®) or transdermal patches. Methods: In the MarketScan® commercial insurance claims (employees and their spouses/dependents, 2018-2021), the first film or patch prescription date was an index event. The observation covered 6-month pre-index and 12-month post-index periods. Results: Patients were propensity-score matched (708 per cohort). Buprenorphine initiation had stable cost trends in buccal film and increasing trends in transdermal patch cohort. Between-cohort comparisons of healthcare expenditures, cost trends and resource utilization showed significant differences, mostly in favor of buccal film. Buccal film also had higher daily doses and wider dosing range. Conclusion: Buprenorphine film is more cost-effective cLBP treatment with more flexible dosing.

Dual delivery systems combining nanocrystals and dissolving microneedles for improved local vaginal delivery of fluconazole.

Fluconazole (FLZ) has been widely used in the treatment of infection caused by Candida albicans, including the treatment of vulvovaginal candidiasis (VVC). However, when delivered orally, FLZ faces numerous limitations due to its poor solubility and undergoes the symptoms of first-pass metabolism. In this study, we developed the combinatorial approach of nanocrystals (NCs) and dissolving microneedles (DMNs) for effective local vaginal delivery of FLZ. The formulation containing 1.0% w/v PVA as stabilizer with 12h of milling time process was found to be an optimal combination to fabricate FLZ as NCs (FLZ-NCs) with optimum size particle and PDI value (less than 0.25). Furthermore, the in vitro release study also showed a superior percentage of FLZ release up to 89.51 ± 7.52%. In combination with the DMNs, the FLZ recovery was 96.45 ± 2.38% with the insertion percentage in average of 76.14 ± 2.28% and height decreased percentage was only 7.53 ± 0.56%. Moreover, the ex vivo investigation and anti-candidiasis activity of DMNs-FLZ-NCs in vaginal model showed better results compared to other conventional preparations, such as film patch and hydrogel containing FLZ.

Behavioral responses of free-flying Drosophila melanogaster to shiny, reflecting surfaces

Active locomotion plays an important role in the life of many animals, permitting them to explore the environment, find vital resources, and escape predators. Most insect species rely on a combination of visual cues such as celestial bodies, landmarks, or linearly polarized light to navigate or orient themselves in their surroundings. In nature, linearly polarized light can arise either from atmospheric scattering or from reflections off shiny non-metallic surfaces like water. Multiple reports have described different behavioral responses of various insects to such shiny surfaces. Our goal was to test whether free-flying Drosophila melanogaster, a molecular genetic model organism and behavioral generalist, also manifests specific behavioral responses when confronted with such polarized reflections. Fruit flies were placed in a custom-built arena with controlled environmental parameters (temperature, humidity, and light intensity). Flight detections and landings were quantified for three different stimuli: a diffusely reflecting matt plate, a small patch of shiny acetate film, and real water. We compared hydrated and dehydrated fly populations, since the state of hydration may change the motivation of flies to seek or avoid water. Our analysis reveals for the first time that flying fruit flies indeed use vision to avoid flying over shiny surfaces.

Analysis of Structural Boundary Effects of Copper-Coated Films and Their Application to Space Antennas

Copper-coated films are a solution for flexible electronic devices. One of the applications is a flexible-tension film-deployable antenna, which is a large deployable space antenna with broad application prospects. To analyze the possibility of applying coated films to the antenna, surface accuracy evaluation is required. The finite element method (FEM) was used to analyze the surface accuracy of the copper-coated thin-film structures. Both wrinkling and stretching–bending coupling deformation were considered. Simplified models were applied to study factors influencing the surface accuracy under boundary effects. Different sizes of coated area and different boundary conditions were simulated. The results showed the characteristic boundary effects of copper-coated thin-film structures and the influence curve of film thickness and patch size on boundary effects. These findings will inform the design and analysis of variable-stiffness thin-film antennas. On this basis, the application of a flexible-tension film-deployable antenna is discussed, along with a measure to improve the surface accuracy.

Low-cost thin film patch antennas and antenna arrays with various background wall materials for indoor wireless communications

The present study introduces an inkjet-printed flexible coplanar waveguide patch antenna array concept. Single antenna and four-element antenna arrays were characterized, which were attached to a subminiature version A connector via an innovative solderless, 3D-printed ‘plug-and-play-type’ tightener. Furthermore, indoor wireless communication and Internet of Things scenarios with commonly used wall materials including gypsum and plywood boards, on which patch antennas and antenna arrays can be attached, were also presented. In order to validate the concept, design and fabrication iterations in parallel with numerical and experimental investigations were executed. To elaborate, single antenna and antenna array configurations without and with wall materials were characterized to see their functionality at 2.4 GHz resonance frequency and beyond 300 MHz bandwidth, respectively. The results demonstrate that the investigated configurations fulfill short-range radio transmission and can be utilized, e.g., for indoor backscattering-type communications and wireless sensing applications, as an affordable and versatile alternative to their conventional counterparts. Being attached to their corresponding background materials, single-antenna specimens were measured to have return losses beyond 18 dB and peak gains around 1 dBi, while higher peak gains above 6 dBi were detected for antenna arrays. Moreover, the antenna arrays can enable multiple-input and multiple-output communication. The proposed arrays had diversity performance in terms of return losses higher than 15 dB, isolation of more than 20 dB, envelope correlation coefficient , diversity gain dB, mean effective gain dB, power ratio factor dB, and channel capacity loss bits/s/Hz.

Flexible reversible polymer nano-composite thin film patch for wearable temperature sensor

A flexible polymer nano-composite thin film patch for wearable temperature sensors was fabricated, which presents excellent energy storage and temperature indication properties. In this composite patch, conductive silver (Ag) nanoparticles (NPs) were used as functional fillers while polyvinyl alcohol (PVA) used as polymer material. The effects of Ag NPs concentration on morphology and temperature indication were experimentally investigated using a field-emission scanning electron microscope (FE-SEM), thermogravimetric analyser (TGA) and differential thermal analysis (DTA). The findings showed that Ag was uniformly distributed across matrix membranes. Also, the prepared PVA-Ag nanocomposite thin film patch showed improved mechanical properties and conductivity. The consequence of X-Ray Diffraction (XRD) displayed a semi-crystalline nature. The results show the potential for incorporating subordinate AgNP concentrations as a substitute to enhance performance in terms of mechanical, thermal, and antibacterial qualities without treatment. The electrical properties were studied through the current-voltage(I–V) characteristics showing the linear I–V ohmic contact and low contact resistance. With heat storage and temperature regulation capabilities, a flexible polymer nano-composite patch for a wearable temperature sensor was created and has significant promise for use in the future in energy storage, thermal management, and wearable temperature sensors.

Design and characteristic analysis of flexible CNT film patch for potential application in ultrasonic therapy

Ultrasonic therapy has drawn increasing attention due to its noninvasiveness, great sensitivity and strong penetration capabilities. However, most of traditional rigid ultrasonic probes cannot achieve a solid interfacial contact with irregular nonplanar surfaces, which leads to unstable therapeutic effects and limitations of widespread use in practical applications. In this paper, a new flexible ultrasonic patch based on carbon nanotube (CNT) films is designed and fabricated to achieve a potential application in ultrasonic therapy. This patch is composed of a CNT film, a thermal protective layer and a heat sinking layer, and has the advantages of simple structure, soft, ultrathin and completely conforming to the treatment area. Theoretical and experimental studies are performed to investigate the acoustic and temperature fields before and after deformation. Effects of key design parameters of the patch on acoustic performances and temperature distributions are revealed. Numerical results indicate that the CNT film patch can produce ultrasounds over a wide frequency range and temperatures under the threshold of burn injury whether it is bent or not. Furthermore, it is also noted that the sound waves emitted from the bending patch are focused at the center of the bending patch, which demonstrates that the target treatment area can be controlled.

3D metamaterial ultra-wideband absorber for curved surface

This paper proposes a three-dimensional metamaterial absorber based on a resistive film patch array to develop a low-cost, lightweight absorber for curved surfaces. An excellent absorption over a large frequency band is achieved through two different yet controllable mechanisms; in the first mechanism, a considerable attenuation in the wave power is achieved via graphite resistive films. The absorption is then intensified through magnetic dipoles created by the surface currents, leading to absorption peaks. The simulation results of the absorber show that a broadband absorption greater than 85% is achieved over 35–400 GHz for both TE and TM polarization waves at normal incidence. The structure has more than 167% and 80% absorption bandwidth above 85% and 90%, respectively. It is shown that the proposed metamaterial absorber is independent of incident wave polarization. In addition, the structure is insensitive to incident angles up to 60° for TE mode and full range angle 90° for TM mode. To describe the physical mechanism of the absorber, E-field, power loss density and surface current distributions on the structure are calculated and shown. Moreover, the oblique incidence absorption efficiency is also explained. This absorber paves the way for practical applications, such as sensing, imaging and stealth technology. In addition, the proposed structure can be extended to terahertz, infrared and optical regions.

Transparent broadband absorber based on a multilayer ITO conductive film.

Present study reports a novel visible-light transparent, microwave broadband absorbing metamaterial. The designed structure is implemented using three different sizes of indium tin oxide (ITO) conductive film patch arrays, which is capable of achieving a reflection coefficient ≤ -10 dB from 2.2 to 18 GHz in simulations. Moreover, a fractional bandwidth of about 156.4% and the absorber thickness of only 0.088 times the cutoff wavelength (the lowest absorption frequency) was achieved. Changing the angle of incidence ensures a good absorption effect with large angle stability, and the absorber has good transmission in the visible range. In accordance with the simulation, a sample with a size of 299 × 299 mm was fabricated, and its wave absorption performance was assessed. The experimental results and the various incidence angles in the simulation of the TE and TM modes correspond well, allowing for the realization of large angle broadband absorption at frequencies ranging from 2.2 to 18 GHz. Thus, it has been found that the structure has good optical transparency and broadband radar absorption capability, both of which will have a wide range of applications in the fields of multi-spectrum stealth and electromagnetic compatibility.

Influence of mechanical properties of coating and substrate on wear performance of HDLC and TiN-coated AISI 5140 alloy steel

This paper investigates the mechanical and wears resistance properties of AISI 5140 alloy steel coated with thin films of hydrogenated diamond-like carbon (HDLC) and titanium nitride (TiN). HDLC and TiN films were sputtered onto AISI 5140 alloy steel samples using the magnetron sputtering technique. In addition to coatings, the metallic substrates were also evaluated for hardness and wear resistance. The findings on wear losses, patterns, and wear trace widths were determined after the wear tests. In tribological tests, a variety of wear patterns were observed on both thin film coatings. The primary wear mechanisms of TiN coatings were found to be tribochemical wear, substrate material loss, and wear debris. However, the HDLC coating experienced wear due to ploughing action, with minor patches of the thin film being removed from the underlying material, but scanning electron microscopy observations showed no detectable wear. Using Raman spectroscopy, the structural properties of HDLC were analyzed, and the findings were compared to those of wear patterns. The results showed that the coating significantly improved the wear resistance of the AISI 5140 alloy steel and that the TiN-coated AISI 5140 alloy steel sample was more comparable to wear than the HDLC-coated AISI 5140 alloy steel sample. It is also shown that, as compared to an uncoated metallic substrate, the resilience of thin film coated components is a key factor impacting component life.

A metal hybrid resistive film ultra-wideband metamaterial absorber for infrared region

An ultra-wideband metamaterial absorber (MA) based on the resistive film is proposed. Unlike conventional MAs based on the resistive film, the proposed absorber features a hybrid resonant layer of resistive film and metal patch at the same top layer. The absorption of the proposed absorber exceeds 90% over the ultra-wideband frequency range of 20 –220 THz, covering most of the infrared region, while the relative absorption bandwidth is up to 167%. The coupling of resistive film and metal pattern at the same layer plays the significant role in enhancing the absorption performance, which is interpreted by the investigation of the surface current distribution. Moreover, the absorber is insensitive to polarization and incident angle. The proposed absorber with high absorption capability as well as simple and compact structure is a proper candidate for the applications in the infrared frequency regime.

Multifunctional fish gelatin hydrogel inverse opal films for wound healing

BackgroundWound healing has become a worldwide healthcare issue. Attempts in the area focus on developing patches with the capabilities of avoiding wound infection, promoting tissue remolding, and reporting treatment status that are of great value for wound treatment.ResultsIn this paper, we present a novel inverse opal film (IOF) patch based on a photo-crosslinking fish gelatin hydrogel with the desired features for wound healing and dynamic monitoring. The film with vibrant structure colors was constructed by using the mixture of fish gelatin methacryloyl, chitosan, and polyacrylic acid (PAA) to replicate colloidal crystal templates. As the structures of these natural biomolecules are well-retained during the fabrication, the resultant IOF was with brilliant biocompatibility, low immunogenicity, antibacterial property, as well as with the functions of promoting tissue growth and wound healing. In addition, the IOF presented interconnected nanopores and high specific surface areas for vascular endothelial growth factor loading, which could further improve its angiogenesis capability. More attractively, as the pH-responsive PAA was incorporated, the IOF patch could report the wound healing status through its real-time structural colors or reflectance spectra.ConclusionsThese features implied the practical value of the multifunctional fish gelatin hydrogel IOFs in clinical wound management.Graphical

Superconducting hot-electron bolometer mixers and their applications

Superconducting hot electron bolometer (HEB) mixers are the most sensitive heterodyne detectors at frequencies beyond 1 THz, and are used for many astronomical observations. HEB, consisting of a narrow and short superconducting thin film patch connected to an antenna via contact pads, is brought into a highly sensitive operating regime by applying a DC current and a certain amount of local-oscillator power. Potentially, superconducting HEB mixers are capable of exhibiting high sensitivity for frequencies up to several tens of THz, as their output noise and conversion gain are nearly frequency independent according to the mixing mechanism. Moreover, the understanding of mixing mechanism has evolved over time from lumped-element model to distributed hot-spot model. In this review, we provide an overview of theoretical and experimental studies on HEBs and their applications, especially in astronomical observations on ground, airborne and space telescopes.

Evaluation of a Multifunctional Polyvinylpyrrolidone/Hyaluronic Acid-Based Bilayer Film Patch with Anti-Inflammatory Properties as an Enhancer of the Wound Healing Process.

The management of acute and chronic wounds is still a socioeconomic burden for society due to the lack of suitable tools capable of supporting all the healing phases. The exponential spread of diabetes worldwide and the consequent increase of complicated diabetic ulcers require further efforts to develop scalable, low-cost, and easy-to-use treatments for tackling this emergency. Recently, we explored the fabrication of a polyvinylpyrrolidone/hyaluronic acid-based bilayer wound dressing, characterizing its physicochemical features and detailing its excellent antimicrobial activity. Here, we further demonstrate its biocompatibility on fibroblasts, keratinocytes, and red blood cells. The bilayer shows anti-inflammatory properties, statistically reducing the level of IL-6, IL-1β, and TNF-α, and a capacity to accelerate wound healing in vitro and in healthy and diabetic mice models compared to untreated mice. The outcomes suggest that this bilayer material can be an effective tool for managing different skin injuries.

Herbal transdermal patches made from optimized polyvinyl alcohol blended film: Herbal extraction process, film properties, and in vitro study

Herbal transdermal patches were prepared by incorporating Lysiphyllum strychnifolium stem extract into optimized polyvinyl alcohol (PVA) blended film as a matrix layer for controlled drug release. A microwave-assisted technique was used for extracting L. strychnifolium stems. The optimum extraction conditions predicted by the Design-Expert® program were 80% of ethanol solvent, 800 W power, 20 s extraction time, and one extraction cycle. The prediction was accurate with a low percentage error. The total phenolics and total flavonoids of the herbal extract were 515.48 ± 43.08 and 59.78 ± 2.11 mg CE/g extract, respectively. Antioxidant activity of the herbal extract was 1.85 ± 0.12 and 0.533 ± 0.056 μg/ml from DPPH and FRAP assay, respectively. Nitric oxide scavenging assay of the herbal extract gave an IC50 of 114.42 ± 22.39 μg/mL. The blank optimized PVA blended film and herbal transdermal patches had desirable properties and compatible, homogeneous, smooth, and compact blended ingredients. The herbal transdermal patches could control the release and skin permeation behavior of astilbin from the matrix layer. The kinetics of the release and permeation behavior of astilbin were fitted to the Korsmeyer–Peppas and zero-order model, respectively. Thus, the transdermal patches containing L. strychnifolium extract are suitable for use in herbal medicine applications.

Single-Use System Integrity III: Gas Flow Rate through Laser-Drilled Microchannels in Polymeric Film Material.

This study investigated the gas flow mechanism through microchannels in a flexible single-use packaging system composed of multilayer plastic film. The relationship was studied between the gas flow rate and several parameters, which included the differential pressure as an external parameter and channel geometries as internal parameters. Based on the results of this study, empirical formulas were derived that show the different dependency of the parameters for each gas flow regime. It was found that these formulas are suitable for calculating the size of a leak in a defective product directly from the corresponding flow rate. The test samples used were 50 mm patches of an ethylene vinyl acetate multilayer film (300 μm and 360 µm thick) and a polyethylene multilayer film (400 μm thick). Artificial leaks in a range of sizes from 2 μm to 100 μm were laser drilled into the center of each patch. The patches were assembled in a filter holder to form a leak-tight seal and were mounted on the test setup. The test setup included the flow measurement device and the pressure controller that used compressed air to produce a certain differential pressure. Various differential pressures were applied to each test unit to cover the whole range of desired use-case conditions. To understand and interpret the effect of the physics and geometry of the microchannels on flow rate measurement, the microscopic investigations performed in our previous study were used. All measurements were carried out under laboratory temperature conditions of 20°C.

Focusing effects of ballistic transverse-quantized excitons in metal nanofilms

New type of behavior of transverse-quantized excitons was discovered in metal nanofilms. These excitons demonstrated ballistic properties, propagating along nanofilms in straight lines along centimeter distances, reflecting at the film patch boundaries, and refracting at the boundary separating films of different materials but with the same exciton energy. Exciton reflection and focusing was explored in elliptically shaped metal film patches, along with exciton refraction on the boundary line separating two different film patches with compatible transverse-confinement-generated electronic structures. These transverse-quantized excitons interact with phonons very weakly, prohibited by symmetry selection rules. The latter statement was confirmed in time-resolved experiments. Weak interactions explain rectilinear trajectories and long lifetimes of excitons in thin metal films.

Single-Use System Integrity II: Characterization of Liquid Leakage Mechanisms.

This study investigated the liquid leakage mechanism through microchannels in a flexible single-use packaging system composed of multilayer plastic film. Based on this study, a relationship between the maximum allowable leakage limit (MALL) and the loss of package integrity can be established under different use-case conditions. The MALL is defined as the greatest leak size that does not pose any risk to the product. A specifically designed liquid leak test was used to determine the leakage time, i.e., the time it takes for a package to show leakage. As a result, this method was able to determine the leak size for which no liquid leakage is observed after 30 days. This leak size varied between 2 µm and 10 µm and can be considered the MALL for liquid egress under different use-case conditions. This article also compared the MALL results of this liquid leak test with those of the microbial ingress test, showing a direct correlation between both tests. As test samples, an ethylene vinyl acetate multilayer film (300 µm thick) and a polyethylene multilayer film (400 µm thick) were cut into 50 mm patches. Before the patches were assembled in a filter holder to form a leak-tight seal, artificial leaks in sizes of 2 -25 µm were laser drilled into the center of each patch. The test units were filled aseptically with culture media and mounted vertically on the test setup. Various pressures were applied to each test unit to simulate the constraints that single-use systems may be subject to under real-world conditions. To detect the exact leakage time, electric circuits with timers were attached below each film patch. Microscopic investigations, including light microscopy and computed tomography, were used to interpret and understand the physics and geometries of the microchannels to explain any deviation from the expected results.