Optical Transparency Research Articles

Digital light processing 3D bioprinting of biomimetic corneal stroma equivalent using gelatin methacryloyl and oxidized carboxymethylcellulose interpenetrating network hydrogel.

Corneal blindness, a leading cause of visual impairment globally, has created a pressing need for alternatives to corneal transplantation due to the severe shortage of donor tissues. In this study, we present a novel interpenetrating network hydrogel composed of gelatin methacryloyl (GelMA) and oxidized carboxymethyl cellulose (OxiCMC) for bioprinting a biomimetic corneal stroma equivalent. We tested different combinations of GelMA and OxiCMC to optimize printability and subsequently evaluated these combinations using rheological studies for gelation and other physical, chemical, and biological properties. Using digital light processing (DLP) bioprinting, with tartrazine as a photoabsorber, we successfully biofabricated three-dimensional constructs with improved shape fidelity, high resolution, and excellent reproducibility. The bioprinted constructs mimic the native corneal stroma's curvature, with central and peripheral thicknesses of 478.9 ± 56.5 µm and 864.0 ± 79.3 µm, respectively. The dual crosslinking strategy, which combines Schiff base reaction and photocrosslinking, showed an improved compressive modulus (106.3 ± 7.7 kPa) that closely matched that of native tissues (115.3 ± 13.6 kPa), without relying on synthetic polymers, toxic crosslinkers, or nanoparticles. Importantly, the optical transparency of tartrazine-containing corneal constructs was comparable to the native cornea following phosphate-buffered saline washing. Morphological analyses using scanning electron microscopy confirmed the improved porosity, interconnected network, and structural integrity of the GelMA-OxiCMC hydrogel, facilitating better nutrient diffusion and cell viability. In vitro biological assays demonstrated high cell viability (>93%) and desirable proliferation of human corneal keratocytes within the biofabricated constructs. Our findings indicate that the GelMA-OxiCMC hydrogel system for DLP bioprinting presents a promising alternative for corneal tissue engineering, offering a potential solution to the donor cornea shortage and advancing regenerative medicine for corneal repair.&#xD.

Research on the Application of Flexible Pressure Sensors in Wearable Devices

The potential applications of transparent, adaptable electronic devices in the human body are driving up demand for them. For flexible and wearable electronics, such as medical surveillance devices and artificial skin, pressure sensing is mandatory. The flexibility and sensitivity of pressure sensors have advanced recently owing to developments in material and device structure. Moreover, their low manufacturing costs enable widespread implementation, leading to promising application prospects. The sensors utilize different materials and structures, including capacitive pressure sensors with ionically charged CFMs, magnetic particle-infused carbon sponges, CNT-PDMS composites, and MoSe2/MWNT combinations. These sensors offer advantages such as high sensitivity, wide pressure-detecting ranges, optical transparency, and energy efficiency. They can detect both large and subtle human movements, from walking and finger bending to breathing and eye blinking. The fabrication methods range from simple and cost-effective processes to more complex techniques like photolithography. Many of the sensors incorporate carbon nanotubes (CNTs) in various forms, exploiting their excellent electrical properties. The review highlights the potential of these sensors for healthcare monitoring, clinical diagnosis, and integration into wearable electronics, emphasizing their flexibility, biocompatibility, and ability to provide real-time, non-invasive measurements of physiological signals. Moreover, their low manufacturing costs enable widespread implementation, leading to promising application prospects.

The Dissemination of Rift Valley Fever Virus to the Eye and Sensory Neurons of Zebrafish Larvae Is Stat1-Dependent

The Rift Valley fever virus (RVFV) causes haemorrhagic fever, encephalitis, and permanent blindness and has been listed by the WHO as a priority pathogen. To study RVFV pathogenesis and identify small-molecule antivirals, we established a novel In Vivo model using zebrafish larvae. Pericardial injection of RVFV resulted in ~4 log10 viral RNA copies/larva, which was inhibited by the antiviral 2′-fluoro-2′-deoxycytidine. The optical transparency of the larvae allowed detection of RVFVeGFP in the liver and sensory nervous system, including the optic tectum and retina, but not the brain or spinal cord. Thus, RVFV-induced blindness likely occurs due to direct damage to the eye and peripheral neurons, rather than the brain. Treatment with the JAK-inhibitor ruxolitinib, as well as knockout of stat1a but not stat1b, enhanced RVFV replication to ~6 log10 viral RNA copies/larva and ultra-bright livers, although without dissemination to sensory neurons or the eye, thereby confirming the critical role of stat1 in RVFV pathogenesis.

Ferroelectric Optical Memristors Enabled by Non-Volatile Electro-Optic Effect.

Memristors enable non-volatile memory and neuromorphic computing. Optical memristors are the fundamental element for programmable photonic integrated circuits due to their high-bandwidth computing, low crosstalk, and minimal power consumption. Here, an optical memristor enabled by a non-volatile electro-optic (EO) effect, where refractive index modulation under zero field is realized by deliberate control of domain alignment in the ferroelectric material Pb(Mg1/3Nb2/3)O3-PbTiO3(PMN-PT) is proposed. The non-volatile EO memristor is designed exclusively for the modulation of the optical phase without degrading the optical transparency, and it allows the support for deterministic and repeated non-volatile multilevel EO states. A non-volatile tunable waveplate composed of the optical memrisor for free-space optics, which allows for deterministic multilevel, and non-volatile phase shifts from 0 to π/2 is presented. The state switching rate of the memristor is less than 100ms, with a switching energy consumption of 234nJ, and the states can be retained for up to 12h without requiring static power consumption. These results demonstrate a novel approach to fully realizing non-volatile optical memristors, where only optical phase modulation is involved, providing unprecedented opportunities for the development of new ferroelectric memristors.

High-Mobility All-Transparent TFTs with Dual-Functional Amorphous IZTO for Channel and Transparent Conductive Electrodes

The increasing demand for advanced transparent and flexible display technologies has led to significant research in thin-film transistors (TFTs) with high mobility, transparency, and mechanical robustness. In this study, we fabricated all-transparent TFTs (AT-TFTs) utilizing amorphous indium-zinc-tin-oxide (a-IZTO) as a dual-functional material for both the channel layer and transparent conductive electrodes (TCEs). The a-IZTO was deposited using radio-frequency magnetron sputtering, with its composition adjusted for both channel and electrode functionality. XRD analysis confirmed the amorphous nature of the a-IZTO layers, ensuring structural stability post-thermal annealing. The a-IZTO TCEs demonstrated high optical transparency (89.57% in the visible range) and excellent flexibility, maintaining a low sheet resistance with minimal degradation even after 100,000 bending cycles. The fabricated AT-TFTs exhibit superior field-effect mobility (30.12 cm2/V·s), an on/off current ratio exceeding 108, and a subthreshold swing of 0.36 V/dec. The AT-TFT device demonstrated a minimum transmittance of 75.46% in the visible light range, confirming its suitability for next-generation flexible and transparent displays.

Smart windows with high optical transparency and structural color

Smart windows with high optical transparency and structural color

Transparent dual‐band wide‐angle polarization‐insensitive single‐layer frequency selective surface for mm‐wave 5G communication systems

AbstractA highly transparent single‐layer frequency selective surface (FSS) with an optical transmittance of 92.7% at 550 nm, designed for 5G communication systems operating in dual frequency bands of 26 and 38 GHz is proposed. The dual‐band FSS not only achieves high optical transparency but also maintains good electrical performance. The transmission performance of the FSS is stable to the polarization and angles of incidence for electromagnetic waves. As a proof of concept, the FSS with periodic square loops patterned on a 188‐µm‐thick substrate is fabricated. Each loop is constructed with metallic mesh electrodes having a pitch of 10 µm. Measurements are conducted using two different systems: a free‐space measurement system and a vector network analyser‐based material characterization kit. After calibrating the measurement systems, the scattering parameters of the fabricated surface are measured. The results obtained from both measurement systems show good agreement and also agree with the simulated results. The designed surface has an insertion loss of less than 3 dB in the dual passband region. The proposed dual‐band FSS has the merits of polarization independence, angular insensitivity, and high transparency.

Design of High Performance Graphene Thin Films Perovskite Solar Cells by Numerical Modeling Based on Coupled Differential Equations

In this study, graphene a two dimensional nanomaterial was prepared by modified Hummer’s method and the optical properties were explored using UV-visible spectroscopy to determine absorption coefficients at different wavelengths based on Beer-Lambert’s law. Graphene based lead-free methyl ammonium germanium halide solar cell was designed in the second stage using graphene oxide (GO) as carrier absorbers and transporters. Numerical modelling of the device in solar capacitance stimulating (SCAPS 1D) program based on second order differential equation was done. A photovoltaic parameters of 0.6227 V, 38.58 mAcm-2, 83.07 %, 19.95 % were recorded as the open-circuit voltage, current density, fill factor and power conversion efficiency (PCE) for FTO/GO/Perovskite/Cu2O/Au. Using the same settings for the second design, the Au/spiro-ometad/FASnI3/TiO2/FTO, the current density increases sharply from 0.50 V and with valence and conduction band at -0.35 eV and 1.78 eV respectively. The light transmittance and heat distribution across the device determine by origin pro-version 9.8.0200 indicated uniform transmission and absorption. The study showed that the presence of graphene, improved the optical transparency and enhanced carrier generation and interaction between other layers which optimized the electrical conductivity and efficiency of the solar cells when compared to previous studies in the literature. The results emphasized a viable approach in the design of efficient and stable solar cells at a reduced cost and optical losses. If mass produced can be deployed commercially due to enhanced solar energy absorption potential ahead of the Si based PVCs.

Ultrawideband Microwave Metamaterial Absorber with Excellent Absorption Performance and High Optical Transparency Based on Double-Layer Mesh Structures

Ultrawideband Microwave Metamaterial Absorber with Excellent Absorption Performance and High Optical Transparency Based on Double-Layer Mesh Structures

Engineered Polystyrene‐Zirconium Dioxide Nanocomposite With Enhanced Optical Properties

ABSTRACTThe demand for transparent polymers with high‐refractive indices (RIs) is increasing due to their versatility; however, low RIs also hold significance. Engineering the RI of polymer nanocomposites is crucial which benefits industry and research. The study investigates the influence of ZrO2 nanoparticles on the optical and surface properties of the polystyrene matrix. UV–Vis spectroscopy confirms that transparency is maintained with a light transmittance of 90 even with a ZrO2 loading of 16 wt%, while ellipsometry shows a steady increase in the RI due to the incorporation of nanoparticles. The RI of composites exceeds that of pure polystyrene (RI: 1.3–1.7) and utilizes the RI of ZrO2 (> 2.00) without altering the sample thickness. The microscopic image shows uniform distribution of particles up to 8 wt%, with slight agglomeration at higher contents. Scanning electron microscopy examination shows that the ZrO2 nanoparticles (20–150 nm) form loose agglomerated structures, while atomic force microscopy examination shows aggregate formation at 16 wt%. The addition of ZrO2 increases the surface roughness and water contact angle up to 4 wt%, which is related to the concentration of the nanofiller and the minimal interaction between ZrO2 and water. The results demonstrate the potential of ZrO2‐loaded nanocomposites for applications requiring high RIs and optical transparency.

Oxytocin-mediated social preference and socially reinforced reward learning in the miniature fish Danionella cerebrum.

Integrative studies of diverse neuronal networks that govern social behavior are hindered by a lack of methods to record neural activity comprehensively across the entire brain. The recent development of the miniature fish Danionella cerebrum as a model organism offers one potential solution, as the small size and optical transparency of these animals make it possible to visualize circuit activity throughout the nervous system.1,2,3,4 Here, we establish the feasibility of using Danionella as a model for social behavior and socially reinforced learning by showing that adult fish exhibit strong affiliative tendencies and that social interactions can serve as the reinforcer in an appetitive conditioning paradigm. Fish exhibited an acute ability to identify conspecifics and distinguish them from closely related species, which was mediated by both visual and particularly olfactory cues. These behaviors were abolished by pharmacological and genetic interference with oxytocin signaling, demonstrating the conservation of key neural mechanisms observed in other vertebrates.5,6,7,8,9,10,11 Our work validates Danionella as a tool for understanding the social brain in general and its modulation by neuropeptide signaling in particular.

Sustainable Soft Electronics with Biodegradable Regenerated Cellulose Films and Printed Recyclable Silver Nanowires

AbstractThis study describes the production of biodegradable and recyclable flexible electronic devices created by screen‐printing silver nanowires (AgNWs) onto regenerated cellulose films (RCFs). RCFs, derived from microcrystalline cellulose (MCC), are developed and further enhanced for flexibility with additives such as glycerol and poly(ethylene glycol) diglycidyl ether (PEGDE). The resulting cellulose films display relatively high tensile strength (up to 120 MPa), low Young's Modulus (down to 1500 MPa), and 90% optical transparency. Ink with AgNWs and poly(ethylene oxide) (PEO) as a binder is screen‐printed on regenerated cellulose films. The printed AgNWs patterns exhibit high electrical conductivity, excellent electromechanical performance, and strong interfacial adhesion with RCFs. To demonstrate the application of printed AgNWs on RCFs for soft electronics, transparent conductive electrodes (TCEs) are fabricated. Grid and honeycomb structures are printed separately and evaluated in terms of sheet resistance and optical transparency. TCEs with ≈80% transparency and very low sheet resistance (0.045 Ω sq−1) are obtained. Furthermore, enzymatic hydrolysis of the cellulose substrate and the recovery for reuse of the AgNWs are demonstrated, showing the potential of integrating natural polymers and recyclable nanomaterials for eco‐friendly and sustainable soft flexible electronics.

Zebrafish navigating the metabolic maze: insights into human disease - assets, challenges and future implications.

Zebrafish (Danio rerio) have become indispensable models for advancing our understanding of multiple metabolic disorders such as obesity, diabetes mellitus, dyslipidemia, and metabolic syndrome. This review provides a comprehensive analysis of zebrafish as a powerful tool for dissecting the genetic and molecular mechanisms of these diseases, focusing on key genes, like pparγ, lepr, ins, and srebp. Zebrafish offer distinct advantages, including genetic tractability, optical transparency in early development, and the conservation of key metabolic pathways with humans. Studies have successfully used zebrafish to uncover conserved metabolic mechanisms, identify novel disease pathways, and facilitate high-throughput screening of potential therapeutic compounds. The review also highlights the novelty of using zebrafish to model multifactorial metabolic disorders, addressing challenges such as interspecies differences in metabolism and the complexity of human metabolic disease etiology. Moving forward, future research will benefit from integrating advanced omics technologies to map disease-specific molecular signatures, applying personalized medicine approaches to optimize treatments, and utilizing computational models to predict therapeutic outcomes. By embracing these innovative strategies, zebrafish research has the potential to revolutionize the diagnosis, treatment, and prevention of metabolic disorders, offering new avenues for translational applications. Continued interdisciplinary collaboration and investment in zebrafish-based studies will be crucial to fully harnessing their potential for advancing therapeutic development.

THE FIRST EXPERIENCE OF USING 3-D PRINTED MODELS OF INTRACRANIAL ARTERIES IN TRAINING AND TEACHING ENDOVASCULAR NEUROINTERVENTIONS

Rationale: Endovascular intervention is often the first-line treatment for patients with intracranial artery pathology. Specialists performing therapeutic interventions on cerebral vessels must have practical training, since the cost of error is extremely high. For this reason, these interventions are performed by residents and interns less often than other endovascular surgeries. Printing of 3D models is a unique educational tool that can improve the effectiveness of training in endovascular techniques. However, to date, the role of this new technology in training specialists, as well as the features of its application, have not been sufficiently covered.Objective: to analyze the effect of 3D printing of an individually recreated digital model of vascular structures of the brain on the results of training and education in the technical aspects of endovascular neurointerventions. Materials and methods: At the first stage of the study, an analysis of the fundamental possibility of 3D printing was carried out, based on an individually recreated digital threedimensional model of vessels (using the carotid artery bifurcation as an example). Silicone was selected as the raw material for 3D printing. It was found that when printing with one-component silicone, there is significant ribbing of the model. Two-component silicone compounds were tested; their compliance with the required characteristics of the vascular model in terms of optical transparency and strength was demonstrated. 20 variants of carotid artery bifurcation models were manufactured. The task of the second stage was to create 3D models of vascular structures of a more complex shape and a smaller internal diameter than at the first stage. As a result, 3D models were designed and samples of cerebral arteries (2-5 mm) were created on their basis. At the third stage, the arterial vascular models were used for training in endovascular neurointerventions.Results: Five endovascular surgeons (with conditional numbers 1-5) took part in the simulation training. None of them managed to successfully complete all 10 attempts, while at least one success was recorded for all of them. Number of successful attempts: 8, 7, 7, 1, 3 respectively. Number of attempts to the first success: 1, 2, 1, 7, 6. Time spent on a successful attempt (M±σ): 25±8, 30±12, 45±15, 45, 65/60 min. Overall assessment of the effectiveness and feasibility of the simulation training by the surgeon on a 5-point scale: 3, 4, 5, 5, 3. Most of the training participants noted the low realism of the modelsand the discrepancy between the characteristics of the inner wall of the model and the real endothelium of the vessel: the silicone was too rigid, which limits its use as a training prototype.Conclusion: 3D printing of vascular structures for the purpose of practicing in neurovascular intervention seems to be a promising technique. The first experience demonstrated that its implementation is accompanied by significant difficulties associated with both the initial experience the new method and with the existing limitations of the technology itself.

MXenes in Perovskite Solar Cells: Emerging Applications and Performance Enhancements

Perovskite solar cells (PSCs) have emerged as promising candidates for next-generation photovoltaic technology due to their remarkable power-conversion efficiencies (PCEs). Since their introduction, the PCE of PSCs has advanced from 3.8% to over 26%. Nonetheless, challenges pertaining to stability and reliability continue to impede their commercial viability. Recent progress in interface engineering and materials science has underscored the potential of two-dimensional (2D) materials, particularly MXenes, in mitigating these challenges. MXenes represent a class of two-dimensional materials with significant potential for application in PSCs, attributed to their exceptional electrical conductivity, high carrier mobility, remarkable optical transparency, chemical stability, and tunable surface chemical properties. When employed as electron transport layers, MXenes enhance charge transfer and extraction efficiency, leading to substantial improvements in PCEs. Furthermore, their integration into hole transport layers and use as interfacial modifiers contribute to the mitigation of degradation pathways, thereby enhancing device longevity. The unique structural and electronic characteristics of MXenes facilitate their application as transparent electrodes, presenting opportunities for cost reduction and improved optical properties. This review provides a comprehensive overview of the current advancements in MXene-based PSCs, emphasizing significant accomplishments and exploring future research directions aimed at enhancing the efficiency and stability of these devices.

Direct Ink Writing Additive Manufacturing of Silica Aerogels.

Silica aerogels (SAs) have garnered significant attention due to their high porosity, low density, hydrophobic properties, low thermal conductivity, and optical transparency. The traditional method for producing SAs, known as "sol-gel" technology, involves precursor preparation, aging, and drying processes. However, aerogels produced through this method often exhibit drawbacks such as poor processability and low precision, which prevent them from fully leveraging their potential properties, including catalysis, adsorption, insulation, and sensing. In contrast, direct ink writing (DIW) technology offers a promising avenue for creating functional structures from SAs. This technique enables the production of inks with shear-thinning behavior, facilitating the high-precision printing of complex SA structures. This review summarizes the advancements in DIW additive manufacturing (AM) of SAs and the challenges currently faced in this field. Briefly, we first introduce the ink preparation, 3D printing process, drying and heat treatment suitable for DIW 3D printing silica aerogels, followed by the discussion of the current state of research and key challenges of DIW 3D printing SAs.

Fabrication of Biomimetic Cell Culture Membranes Using Robust and Reusable Nickel Micropillar Molds

AbstractIn the practical application of organ-on-a-chip, mass production technology for flexible porous membranes is an essential element for mimicking the basement membrane of the body. Porous PDMS membrane is a promising material due to its high optical transparency, flexibility, and biocompatibility. However, the fabrication process is complex and costly. Even with soft lithography, a relatively straightforward method, there is a risk that the negative resist pillars used as molds peeling off from the substrate in mass production. In this study, we propose a novel mass production method for fabricating porous PDMS membranes using high-strength nickel (Ni) micropillars as molds by combining photolithography and electroforming technologies. The unibody structure of Ni micropillars ensures high reliability and provides a semi-permanent mold without degradation or detachment. We successfully fabricated two types of Ni micropillars and subsequently formed their corresponding porous PDMS membranes (D (diameter) = 8 μm, P (pitch) = 30 μm, and D = 10 μm, P = 20 μm). The porous PDMS membrane showed non-inferiority to the control group in terms of viability when cultured with human vascular endothelial cells. Furthermore, we showed that the porous PDMS membrane can be used to evaluate the vascular permeability of nanoparticles.

Ultrathin transparent indium tin oxide-based electrodes for enhanced performance of perovskite solar cells

Abstract Perovskite solar cells (PSCs) have been given much attention in photovoltaics-based power generation, particularly in building integrated photovoltaics (BIPV) applications due to their lightweight and promising technical performance. PSCs exhibit remarkable transparency to visible light, which makes them an ideal candidate for BIPV applications such as glass-based solar facades and clear solar windows. As the PSC is yet an immature technology, much research is still required to validate its visibility and cost-effectiveness for different applications including electrical vehicles. This paper takes one step forward in achieving this goal by presenting a new ultrathin transparent electrodes (UTE) design that comprises a square patch layout to improve the performance of transparent conductive materials. The proposed electrode design is aimed to improve the absorption of the material in the ultra-violet (UV) region with high optical transparency. To assess the angular dependence on the absorption characteristics, both transverse magnetic and transverse electric modes are studied at various oblique angles of incident light. Furthermore, interference theory is applied numerically to validate the proposed UTE design. The impact of various geometric parameters including period, ground height, spacer height, and top square resonator length on the performance of the proposed UTE layout is investigated through detailed simulation analysis. Moreover, surface electric field patterns are analyzed to understand the absorption mechanism of the proposed UTE. Results reveal the effectiveness of the proposed structure for various BIPV applications including electric vehicles, wearable electronics, and tandem devices.

Optical transparency in live animals: a leap toward deep-tissue applications

Optical transparency in live animals: a leap toward deep-tissue applications

Tunable Transparent Conductors Based on SnO2: Theoretical and Experimental Studies of Codoping.

Transparent conducting oxides (TCOs) are widely used in modern electronics because they have both high transmittance and good conductivity, which is beneficial for many applications such as light-emitting diodes. Tailoring electronic states and hence the conductive types by design is important for developing new materials with optimal properties for TCOs. SnO2, with a wide band gap, low cost, no toxins, and high stability, is a promising host material for TCOs. Here, we performed a set of hybrid-exchange density functional theory calculations on the two-element and three-element codoped SnO2 by using Sr, Ta, Al, Ga, V, and Nb, which were then validated by the relevant experimental works on SnO2. As predicted by the first-principles calculations, the controllability of the electronic states to be n- or p-type can be demonstrated experimentally by varying the relative doping concentration between donors (Ta/Nb) and acceptors (Al/Ga). One of the main advantages for these codoping methods is that the charge neutrality problem caused by the dopant can be circumvented. The thin films fabricated showed a low sheet resistance (down to ∼450 Ω/□) and a high optical transparency (above 80%). The combination of our calculations and experimental material fabrication and characterizations has shown a great potential for codoping SnO2 for (i) the efficient processing of the integrated circuit composed of both p-type and n-type transistors (using the same target precursors during the deposition) and (ii) a good lattice matching for p-n junctions. Most importantly, our calculations, supported by the experimental works, point to a promising route to accelerate the discovery process for the alternative cost-effective and high-performance indium-free TCOs using computational material design.