Programmable optical switching integrated chip for 4-bit binary true/inverse/complement code conversions based on fluorinated photopolymers.

In this work, programmable optical switching integrated chips for 4-bit binary true/inverse/complement optical code conversions (OCCs) are proposed based on fluorinated photopolymers. Fluorinated bis-phenol-A novolac resin (FAR) with low absorption loss and fluorinated polyacrylate (FPA) with high thermal stability are self-synthesized as core and cladding layer, respectively. The basic architecture of operating unit for the photonic chip designed is composed of directional coupler Mach-Zehnder interferometer (DC-MZI) thermo-optic (TO) switching, X-junction, and Y-bunching waveguide structures. The waveguide module by cascading 16 operating units could realize OCCs function through optical transmission matrix. The response time of the 4-bit binary OCCs is measured as about 300 µs. The insertion loss and extinction ratio of the actual chip are obtained as about 10.5 dB and 15.2 dB, respectively. The electric driving power consumption for OCCs is less than 6 mW. The true/inverse/complement OCCs are achieved by the programmable modulation circuit. The proposed technique is suitable for achieving optical digital computing system with high-speed signal processing and low power consumption.

Triple-layered optical interconnecting integrated waveguide chip based on epoxy cross-linking fluorinated polymer photonic platform.

In this study, a triple-layered optical interconnecting integrated waveguide chip was designed and fabricated using an epoxy cross-linking polymer photonic platform. Fluorinated photopolymers FSU-8 and AF-Z-PC EP were self-synthesized as waveguide cores and cladding materials, respectively. The triple-layered optical interconnecting waveguide device comprised 4 × 4 arrayed waveguide grating (AWG) -based wavelength-selective switching (WSS) arrays, 4 × 4 multi-mode interference (MMI) -cascaded channel-selective switching (CSS) arrays, and 3 × 3 direct-coupling (DC) interlayered switching arrays. The overall optical polymer waveguide module was fabricated by direct UV writing. For the multilayered WSS arrays, the wavelength-shifting sensitivity was ∼0.48 nm/°C. For the multilayered CSS arrays, the average switching time was ∼280 µs, and the maximum power consumption was <30 mW. For interlayered switching arrays, the extinction ratio approximated 15.2 dB. The transmission loss for the triple-layered optical waveguide chip was measured as 10.0-12.1 dB. The flexible multilayered photonic integrated circuits (PIC) can be used in high-density integrated optical interconnecting systems with a large-volume optical information transmission capacity.

Investigation of aging resistance for dental resin composites with and without glass flakes.

OBJECTIVES: Outstanding physical-mechanical properties and aging resistance are key requirements for dental resin composite since it will be placed in the oral environment for a long time. In this work, a new dental resin composite mainly modified by glass flakes was fabricated, and the aging resistance was evaluated by comparing with commercial composites without glass flakes. MATERIALS AND METHODS: The new dental resin composite was produced through hand blending of inorganic glass flakes/Si-Al-borosilicate glass (58wt%:7wt% of dental resin composite), POSS-MA (5wt% of resin matrix), Bis-GMA/TEGDMA(64.4wt%:27.6wt% of resin matrix), and CQ/EDMAB (0.9wt%:2.1wt% of resin matrix) together. The flexural strength, elasticity modulus, and hardness, as well as wear were tested for evaluating the aging resistance of different dental resin composite. RESULTS: Among 6 kinds of commercial composites in this study, after 6-month water storage, the maximum percentage of performance degradation is that the flexural strength decreased 39.96%, elasticity modulus decreased 51.53% and hardness decreased 12.52%. In contrast, the new synthesized material decreased 14.53%, 20.88%, and 0.61%, respectively, and performed lesser wear depth compared to some other groups (P < 0.05). CONCLUSIONS: It was observed that the new dental resin composite performed better performance stability and wear resistance when compared with commercial dimethacrylate-based or low shrinkage dental resin composite tested in this study. CLINICAL RELEVANCE: This possibly paves a path for designing tailored dental composite for practical application. Since the aging resistance of dental resin composite modified by glass flakes is superior, it has the potential to be used for promoting the durability of dental resin composite.

Interlayer directional coupling thermo-optic waveguide switches based on functionalized epoxy-crosslinking polymers.

In this study, interlayer directional coupling (DC) thermo-optic (TO) waveguide switches were designed and fabricated using functionalized epoxy-crosslinking polymers. Fluorinated SU-8 (FSU-8) with a photo-initiating epoxy-crosslinking network was self-synthesized as a waveguide core material. A copolymer of methyl methacrylate and glycidyl methacrylate P(MMA-co-GMA) with a thermo-initiating epoxy crosslinking structure was self-synthesized as a waveguide cladding material. Compared with commercial pure SU-8 and PMMA, FSU-8 exhibited a lower absorption loss and P(MMA-co-GMA) exhibited a higher thermal stability. Using epoxy-crosslinking functionalized polymers, the structure of the waveguides and electrode heaters were optimized, and the performance parameters of the interlayer DC TO switches were simulated. At a signal wavelength of 1550 nm, the insertion loss, extinction ratio, and power consumption of the actual interlayer devices were measured as 6.7 dB, 15.6 dB, and 9 mW, respectively. The rising and falling response times of the TO switches were obtained as 631.6 µs and 362 µs, respectively. The self-leveling ability and solvent resistance characteristic of the epoxy-crosslinking network for FSU-8 and P(MMA-co-GMA) may guarantee the realization of interlayer DC TO waveguide switches. The proposed technique will be suitable for photonic integrated waveguide chips with multilayer stacking dynamic optical information interactions.

Metal-printing tunable interlayer waveguide coupler using low-loss fluorinated polycarbonate.

Tunable three-dimensional (3D) integrated optical waveguide chips with optical interconnection function are beneficial to expand the application of optical devices in a 3D integrated photonic module. Here, we propose a thermo-optic (TO) tunable interlayer waveguide coupler based on the metal-printing technique. Low-loss fluorinated polycarbonate (AF-Ali-PC MA) and poly (methyl methacrylate-glycidyl methacrylate) [P(MMA-co-GMA)] are synthesized as waveguide core and cladding layer, respectively. The thermal stability and optical adsorption characteristics of AF-Ali-PC MA are analyzed. Optical signal transmission features of the interlayer coupling waveguides are simulated. The optical response properties and fabrication process flows of a dynamic multilayer waveguide chip can be greatly improved by the metal-printing technique. The on-off time of the TO interlayer coupling chip is obtained as 250 µs, and the electrical power consumption is measured as 7.6 mW. To the best of our knowledge, this is the first time that a TO tunable interlayer waveguide coupler is achieved by an efficient metal-printing method, which is suitable for large-scale photonic integrated circuit (PIC) systems and multilayer optical interconnection (OXC) networks.

Dual Cross-Linked Hydrogels with Injectable, Self-Healing, and Antibacterial Properties Based on the Chemical and Physical Cross-Linking.

Injectable hydrogels have become a promising material for biomedical engineering applications, but microbial infection remains a common challenge in their application. In this study, we presented an injectable antibacterial hydrogel with self-healing property based on a dual cross-linking network structure of dynamic benzoxaborole-sugar and quadruple hydrogen bonds of the 2-ureido-4-pyrimidone (UPy) moieties at physiological pH. Dynamic rheological experiments demonstrated the gelatinous behavior of the double cross-linking network (storage modulus G' > loss modulus G″), and the modulus showed frequency-dependent behavior. The noncovalent interactions of UPy units in the polymer segment endowed the injectable hydrogels with good mechanical strength. By varying the solid contents, UPy units, as well as the pH, the mechanical properties of hydrogels could be controlled. Additionally, the hydrogels exhibited not only excellent self-healing and injectable properties but also pH and sugar dual-responsiveness. Moreover, the hydrogels could effectively inhibit the growth of both Escherichia coli and Staphylococcus aureus while exhibiting low toxicity. 3D cell encapsulation experiment results also demonstrated the potential use of these hydrogels as cell culture scaffolds. Taken together, the injectability, self-healing, and antimicrobial properties of the prepared hydrogels showed great promise for translational medicine, such as cell and tissue engineering applications.

Bottom-metal-printed thermo-optic waveguide switches based on low-loss fluorinated polycarbonate materials.

In this work, thermo-optic (TO) waveguide switches are designed and fabricated based on the bottom-metal-printed technique. Low-loss fluorinated polycarbonate (AF-Z-PC MA) and polymethyl methacrylate (PMMA) are used as core and cladding materials, respectively. The thermal stability and optical absorption characteristics of AF-Z-PC MA are analyzed. The optical and thermal field distributions of the TO switch are simulated. The insertion loss and extinction ratio of the device are found to be 4.5 dB and 19.8 dB, respectively, at a wavelength of 1550 nm. The on-off time of the switching chip is 80 µs. The electrical power consumption is approximately 8.8 mW. The proposed low-loss fluorinated polymer TO waveguide switch realized by bottom-metal-printed fabrication technology is suitable for large-scale integrated photonic circuit systems.

Synthesis, characterization, and aging resistance of the polyurethane dimethacrylate layer for dental restorations.

In this study, polyurethane dimethacrylate (PUDMA) was synthetized from different components and incorporated into a direct resin composite restoration system with the aim to buffer tooth-resin interfacial stresses and maintain the marginal adaptation. The tensile strength, elongation at fracture (ε), and thermal stability of the PUDMA layer were characterized, showing a tensile strength of 22 MPa, an ε of 112%, and a thermal decomposition temperature of about 282°C. In addition, the degree of conversion, water sorption/solubility, hydrophobicity, microtensile bond strength (µTBS), marginal leakage, and cytotoxicity in vitro were evaluated for the PUDMA layer. The data were analyzed using one-way ANOVA, except for leakage depths (which were analyzed using the Wilcoxon paired-rank test). The level of significance was set at 0.05. Compared with dental adhesives, PUDMA displayed a higher degree of conversion, lower water sorption/solubility, and improved hydrophobicity and biocompatibility in vitro. After thermocycling, the µTBS of the restoration system containing PUDMA had increased compared with the µTBS at 24 h. Restorations containing PUDMA showed lower leakage depths than those which did not contain PUDMA. In conclusion, because of its hydrophobic and elastic nature, the PUDMA layer, when used as an intermediate between tooth and resin restoratives, may buffer interfacial stresses, improve the stability and durability of the bonding interface, and reduce microleakage.

Fluorinated photopolymer cascaded MMI-based integrated optical waveguide switching matrix with encoding functions.

In this work, thermo-optic tunable 4 × 4 cascaded multimode interference based integrated optical waveguide switching matrices are designed and fabricated using photopolymer lightwave circuits. The materials of the waveguide core and cladding are fluorinated epoxy-terminated copolycarbonate and polymethylmethacrylate, respectively. The driving power that controls matrices for binary encoding of different optical switching states are simulated and analyzed. The measured insertion loss of the actual chip is < 7.1 dB and the maximum crosstalk in adjacent channels is <-30 dB. The switching time is approximately 220 µs and the extinction ratio is obtained as 21.5 dB. This flexible encoding technique can be applied for achieving optical code-division multiple-access network coders.

Ordered Micro/Nanostructures with Geometric Gradient: From Integrated Wettability "Library" to Anisotropic Wetting Surface.

Geometric gradients within ordered micro/nanostructures exhibit unique wetting properties. Well-defined and ordered microsphere arrays with geometric gradient (OMAGG) are successfully fabricated through combining colloidal lithography and inclined reactive ion etching (RIE). During the inclined RIE, the graded etching rates in vertical direction of etcher chamber are the key to generating a geometric gradient. The OMAGG can be used as an effective mask for the preparation of micro/nanostructure arrays with geometric gradient by selective RIE. Through this strategy, a well-defined wettability "library" with graded silicon cone arrays is fabricated, and the possibility of screening one desired "book" from the designated wettability "library" is demonstrated. Meanwhile, the silicon cone arrays with geometric gradient (SCAGG) can be applied to control the wetting behavior of water after being modified by hydrophilic or hydrophobic chemical groups. Based on this result, a temperature-responsive wetting substrate is fabricated by modifying poly n-isopropyl acrylamide (PNIPAM) on the SCAGG. These wettability gradients have great potential in tissue engineering, microfluidic devices, and integrated sensors.

Fluorinated photopolymer waveguide thermo-optic switches with loss-compensation function based on erbium-containing cladding structure.

In this work, a novel polymer thermo-optic switch with loss compensation function is successfully designed and fabricated by direct UV-writing technology. The waveguide core and cladding layer material of the switch are based on the low-loss fluorinated photopolymer and erbium-containing gain copolymer. The absorption loss characteristics and thermal stabilities of the core and cladding materials are studied. The optimal optical field distribution for loss-compensation structures is analyzed by modifying refractive index difference between the core and cladding. The thermo-optic modulation effect of the optical signal transmission for the device is simulated. The insertion loss of the switch device is about 6 dB. The switching rise and fall time are 396.2 µs and 461.2 µs applied by 500 Hz square-wave voltage, respectively. The switching power is 6.5 mW, the extinction ratio of the switch is about 14 dB. The loss-compensation value of the entire chip is obtained as 1.9 dB at 1530 nm wavelength. The flexible loss-compensation multi-functional waveguide switch is appropriate for incorporation in large-scale opti-electronic integrated circuits.

Improved performance of thermal-optic switch using polymer/silica hybrid and air trench waveguide structures.

By exploiting the polymer/silica hybrid and the air trench waveguide structures, we demonstrate a new type of low-power consuming and high-speed thermal-optic (TO) switch. Such a design provides an effective means to shorten the switching time of the TO switches, as well as to reduce the power consumption at the same time. This TO switch operated with less than 150 µs of switching time via a polymer/silica hybrid waveguide structure. Meanwhile, the power consumption was reduced to be 3.4 mW by introducing the air trench structure.

Reconfigurable optical interleaver modules with tunable wavelength transfer matrix function using polymer photonics lightwave circuits.

A transparent reconfigurable optical interleaver module composed of cascaded AWGs-based wavelength-channel-selector/interleaver monolithically integrated with multimode interference (MMI) variable optical attenuators (VOAs) and Mach-Zehnder interferometer (MZI) switch arrays was designed and fabricated using polymer photonic lightwave circuits. Highly fluorinated photopolymer and grafting modified organic-inorganic hybrid material were synthesized as the waveguide core and caldding, respectively. Thermo-optic (TO) tunable wavelength transfer matrix (WTM) function of the module can be achieved for optical routing network. The one-chip transmission loss is ~ 6 dB and crosstalk is less than ~25 dB for transverse-magnetic (TM) mode. The crosstalk and extinction ratio of the MMI VOAs were measured as -15.2 dB and 17.5 dB with driving current 8 mA, respectively. The modulation depth of the TO switches is obtained as ~18.2 dB with 2.2 V bias. Proposed novel interleaver module could be well suited for DWDM optical communication systems.

Monolithic multi-functional integration of ROADM modules based on polymer photonic lightwave circuit.

A transparent reconfigurable optical add-drop multiplexer (ROADM) module composed of AWG-based wavelength-channel-selectors monolithically integrated with Mach-Zehnder interferometer (MZI) thermo-optic (TO) waveguide switch arrays and arrayed waveguide true-time-delay (TTD) lines is designed and fabricated using polymer photonic lightwave circuit technology. Negative-type fluorinated photoresist and grafting modified organic-inorganic hybrid materials were synthesized as the waveguide core and cladding, respectively. The one-chip transmission loss is ~6 dB and the crosstalk is less than ~30 dB for the transverse-magnetic (TM) mode. The actual maximum modulation depths of different thermo-optic switches are similar, ~15.5 dB with 1.9 V bias. The maximum power consumption of a single switch is less than 10 mW. The delay time basic increments are measured from 140 ps to 20 ps. Proposed novel ROADM is flexible and scalable for the dense wavelength division multiplexing network.

Thermo-optic waveguide gate switch arrays based on direct UV-written highly fluorinated low-loss photopolymer.

Novel thermo-optic waveguide gate switch arrays were designed and fabricated based on the direct UV-written technique. Highly fluorinated low-loss photopolymers and organic-inorganic grafting materials were used as the waveguide core and cladding, respectively. The low absorption loss characteristics and excellent thermal stabilities of the core and cladding materials were obtained. The rectangular waveguides and arrayed electrode heaters have been theoretically designed and numerically simulated to realize single-mode transmission. The propagation loss of a 4-µm-wide straight waveguide was measured as 0.15 dB/cm. The insertion loss of the device was directly measured to be about 5.5 dB. The rise and fall times of the device applied 100 Hz square-wave voltage were obtained as 1.068 and 1.245 ms, respectively. The switching power was about 9.2 mW, and the extinction ratio was 17.8 dB. The low-loss integrated switch arrays are suitable for realizing large-scale photonic integrated circuits.

Emulsion-Templated Gelatin/Amino Acids/Chitosan Macroporous Hydrogels with Adjustable Internal Dimensions for Three-Dimensional Stem Cell Culture.

The demand for macroporous hydrogel scaffolds with interconnected porous and open-pore structures is crucial for advancing research and development in cell culture and tissue regeneration. Existing techniques for creating 3D porous materials and controlling their porosity are currently constrained. This study introduces a novel approach for producing highly interconnected aspartic acid-gelatin macroporous hydrogels (MHs) with precisely defined open pore structures using a one-step emulsification polymerization method with surface-modified silica nanoparticles as Pickering stabilizers. Macroporous hydrogels offer adjustable pore size and pore throat size within the ranges of 50 to 130 µm and 15 to 27 µm, respectively, achieved through variations in oil-in-water ratio and solid content. The pore wall thickness of the macroporous hydrogel can be as thin as 3.37 µm and as thick as 6.7 µm. In addition, the storage modulus of the macroporous hydrogels can be as high as 7250 Pa, and it maintains an intact rate of more than 92% after being soaked in PBS for 60 days, which is also good performance for use as a biomedical scaffold material. These hydrogels supported the proliferation of human dental pulp stem cells (hDPSCs) over a 30 day incubation period, stretching the cell morphology and demonstrating excellent biocompatibility and cell adhesion. The combination of these desirable attributes makes them highly promising for applications in stem cell culture and tissue regeneration, underscoring their potential significance in advancing these fields.

Enhancing glass-ionomer cements with flake-shaped glass: A new frontier in dental restoration.

This study aims to investigate whether the combined use of thin sheet glass (FSG) and polyurethane acrylate (PUA) can enhance the mechanical properties and biocompatibility of glass ionomer cements (GICs) to improve the overall performance of commercial GICs. In this study, an innovative approach was employed by incorporating diluents and photoinitiators into PUA to develop a novel light-curable PUA material. The PUA was then used to modify the GIC to obtain PUA-modified GIC. Subsequently, physical and chemical methods were employed to corrode and chemically modify the glass fiber surface to acquire dried thin sheet glass (FSG). Different proportions of FSG (10%, 20%, and 30% by mass) were mixed with PUA-GIC to obtain FSG-PUA modified GIC. Mechanical and biocompatibility tests were conducted on regular GIC, PUA-GIC, resin-modified glass ionomer cement (RMGIC), and various proportions of FSG-PUA-GIC materials, including flexural strength, surface hardness, water absorption rate, solubility, shear strength, compressive strength (CS), in vitro cytotoxicity, as well as short-term oral toxicity and subcutaneous implantation trials. A novel FSG-PUA modified GIC was successfully prepared, which not only retained the excellent biocompatibility and fluoride ion release capacity of the original GIC but also significantly enhanced its mechanical strength and durability. The application of this innovative method provides a new direction for the development of dental restorative materials, particularly in addressing the shortcomings of GICs in terms of mechanical performance. The addition of FSG notably increased the flexural strength and surface hardness of GICs, especially at a 20% additive level, demonstrating superior performance compared with standard Fuji IX (F9) and slightly better than RMGIC. Water absorption rate and solubility initially decreased and then increased with an increase in FSG content, and significantly outperformed F9 and RMGIC at 10% and 20% additive levels. Shear strength and CS decreased with an increase in FSG content but remained superior to commercial groups. Material incubation with cells in vitro for 24-48 h showed no significant impact on cell viability, with cell viability exceeding 90%. Short-term oral toxicity tests demonstrated good biocompatibility of the material, and subcutaneous implant trials did not observe any significant inflammation or pathological changes within 12 weeks of observation. The use of FSG-PUA materials effectively enhances the mechanical properties of GIC materials, demonstrating excellent biocompatibility and significant potential as dental restorative materials. Among them, the 20% FSG-PUA modified GICs exhibited significantly superior flexural strength, surface hardness, shear strength, water absorption, and solubility compared with F9 and slightly surpassing RMGIC, showcasing the best mechanical performance.

Application of modified aldehyde compounds in self-etching bonding of dentin.

OBJECTIVE: The aim of this study was to evaluate the ability of 4-formylphenyl acrylate (FA) to enhance the bond strength and stabilize the resin-dentin bonding interface of universal adhesives in self-etching mode over time. METHODS: Different concentrations of FA (1%, 3%, 5%, 7%, 9%) were prepared as primer. The optimal group was selected according to degree of conversion of 2 universal adhesives (Single Bond Universal (SBU)/All-Bond Universal (ABU)), and grouped according to the pre-treatment time (30s, 1min, 2min). The micro-tensile strength before and after 10,000 times thermocycling aging was used to evaluate the bonding performance. RESULTS: The 1min application of FA (5%) increased the conversion rate of the adhesive. The expressions of microtensile bond strength and nanoleakage in the FA treatment group did not decrease significantly compared with their immediate values even after 10,000 thermocycling of aging. In situ zymography results showed that the hydrolytic activity of endogenous proteins decreased significantly in FA-1min group. CONCLUSIONS: Treatment by FA primer can effectively enhance the bond stability at the bonding interface. CLINICAL RELEVANCE: FA can be used as a functional monomer in self-etching bonding system to dentin, which not only had high biocompatibility, but also can show good collagen cross-linking ability within clinically acceptable application time.

Polyphenol-Enriched Extract of Lacquer Sap Used as a Dentine Primer with Benefits of Improving Collagen Cross-Linking and Antibacterial Functions.

Commercial dentin adhesive systems are applied to restorations due to their resistant bonding properties, but they suffer from the lack of bioactivity and are prone to hydrolysis. Therefore, to overcome these limitations, an eco-friendly natural monomer, urushiol, was adopted to be a primer in dentin bonding due to its interaction with collagen and antibacterial activity, preventing further hydrolysis development. First, urushiol was determined to be capable of improving the biological stability of dentin collagen through cross-linking. Using high-fidelity analytical chemistry techniques, such as Fourier transform infrared spectroscopy, we quantified the effects of urushiol on collagen molecules. It could also effectively decrease weight loss after collagenase ingestion by improving the stability of dentin. Moreover, urushiol inhibited Streptococcus mutans growth as well as its biofilm formation. Finally, we demonstrated that the urushiol primer could improve the bonding strength, particularly after aging. The cross-linking and antibacterial functions of urushiol have provided promising developmental prospects for biomaterials in dentin adhesion.

Construction of antibacterial adhesion surfaces based on bioinspired borneol-containing glycopolymers.

Preparation of antibacterial coating materials is considered an effective strategy to prevent medical device-related infections. In the present study, by combining 2-lactobionamidoethyl methacrylamide with a uniquely structured borneol compound, new copolymers poly(2-lactobionamidoethyl methacrylamide-co-glycidyl methacrylate-co-isobornyl acrylate) (poly(LAEMA-co-GMA-co-BA)) were synthesized by a simple free-radical polymerization. An amine containing silane layer was first prepared on the substrate surface by a silanization reaction. The glycopolymers were grafted onto the silane layer through covalent bonding to obtain glycosylated coatings. X-ray photoelectron spectroscopy (XPS) confirmed the successful preparation of the APTES-functionalized surface and polymer layers. The surface wettability was measured by the contact angle (CA). The coated surfaces were relatively flat and smooth as confirmed by Atomic Force Microscopy (AFM). Moreover, the prepared coatings showed good antibacterial adhesion properties toward both E. coli and S. aureus. Furthermore, no significant cytotoxicity to the MRC-5 cells (lung fibroblasts) in vitro was observed, indicating the good biocompatibility of the antibacterial coatings. This study provides an excellent strategy for designing an antibacterial surface containing glycopolymers and natural antibacterial compounds, and these coatings may be suitable for medical devices.