Low Dielectric Constant Research Articles

1D/2D Heterostructures: Synthesis and Application in Photodetectors and Sensors

Two-dimensional (2D) semiconductor components have excellent physical attributes, such as excellent mechanical ductility, high mobility, low dielectric constant, and tunable bandgap, which have attracted much attention to the fields of flexible devices, optoelectronic conversion, and microelectronic devices. Additionally, one-dimensional (1D) semiconductor materials with unique physical attributes, such as high surface area and mechanical potency, show great potential in many applications. However, isolated 1D and 2D materials often do not meet the demand for multifunctionality. Therefore, more functionality is achieved by reconstructing new composite structures from 1D and 2D materials, and according to the current study, it has been demonstrated that hybrid dimensional integration yields a significant enhancement in performance and functionality, which is widely promising in the field of constructing novel electronic and optoelectronic nanodevices. In this review, we first briefly introduce the preparation methods of 1D materials, 2D materials, and 1D/2D heterostructures, as well as their advantages and limitations. The applications of 1D/2D heterostructures in photodetectors, gas sensors, pressure and strain sensors, as well as photoelectrical synapses and biosensors are then discussed, along with the opportunities and challenges of their current applications. Finally, the outlook of the emerging field of 1D/2D heterojunction structures is given.

Theoretical insights into the ultrahigh piezoelectric performance of (BiFeO3)n/(BaTiO3)n (n = 1–5) superlattices

Perovskite structures have attracted extensive attention in microelectromechanical systems and nanoelectromechanical systems devices due to the high piezoelectric response and the low dielectric constant. The piezoelectric and dielectric properties of the tetragonal BiFeO3/BaTiO3 superlattices grown along the c-axis direction are investigated using density functional theory (DFT) and density functional perturbation theory. The calculated results demonstrate that the (BiFeO3)n/(BaTiO3)n (n = 1–5) superlattices exhibit a profoundly increased piezoelectric response compared to their bulk structures. The (BiFeO3)2/(BaTiO3)2 possesses the highest piezoelectric d33 of 697 pC/N among known lead-free perovskite systems. Furthermore, the (BiFeO3)2/(BaTiO3)2 superlattice possesses a low dielectric ɛ33, and its d33 at 2% tensile strain is 16 times larger than that of an unstrained equilibrium structure. This demonstrates that biaxial tensile strain significantly enhances the piezoelectric response. Combining the special quasirandom structure method with DFT, the structures of a 0.5BiFeO3–0.5BaTiO3 solid solution are predicted, and its calculated d33 is 58 pC/N, which is much smaller than that of a (BiFeO3)2/(BaTiO3)2 superlattice. The results suggest that the (BiFeO3)2/(BaTiO3)2 superlattice might be a potential candidate for nonvolatile random access memory, transducers and actuators, and nanoscale electronic devices.

Superhydrophobic Electrospun PI/PTFE Membranes with Ultralow Dielectric Constants for High-Frequency Telecommunication.

High-frequency, high-power, and high-speed telecommunication in a complex environment promotes the development of dielectric materials toward a low dielectric constant, low dielectric loss, good thermal properties, and long-term reliability. Here, polyimide/polytetrafluoroethylene (PI/PTFE) nanofiber membranes with an inherent super hydrophobicity, excellent dielectric properties, good thermal stability, and enhanced tensile strength were prepared via a simple electrospinning strategy and an imidization reaction. The obtained PI/PTFE membranes demonstrate a superlow average dielectric constant of 1.22-1.27 and a dielectric loss of 0.032-0.048 in high frequency, together with an enhanced tensile strength, benefiting from the special nanofiber-bead structure formed in the composite membrane. The mixing of polyamic acid (PAA) and PTFE in the electrospinning solution endows the obtained PI/PTFE nanofiber membrane with a uniform distribution of PTFE and thus an inherent superhydrophobicity with a water contact angle of 156.1 and 159.2° for PI/PTFE-30% and PI/PTFE-40%, respectively. Besides, the hydrophobicity could be kept even after standing more than 10,000 water drops, and the thermal properties exhibited promising results with Tmax = 587 °C and Td5% = 423 °C, rendering these PI/PTFE membranes favorable alternatives for prospective telecommunication.

Self-healable epoxy/graphene oxide vitrimers and their recyclable glass fiber reinforced composites

Glass fiber-reinforced polymers (GFRPs) made from thermoset polymers have been widely used across various industries. However, these composites have significant drawbacks, including poor interfacial adhesion between the fiber and matrix, as well as a substantial contribution to waste and environmental pollution due to the challenges in recycling, reprocessing, and reuse. Herein, firstly graphene oxide (GO) was incorporated in vitrimer matrix to fabricate recyclable vitrimer nanocomposites with improved interfacial interaction, high thermal stability, low dielectric constant, fast stress relaxation as well as rapid self-healing ability. The nanocomposite with 0.2 wt% GO is optimized to achieve excellent remoulding (89% of flexural strength) and self-healing (60 min for a 48 μm scratch) properties due to dynamic disulfide bond exchange mechanism. Furthermore, epoxy/GO matrix was used to develop glass fiber reinforced composites via vacuum assisted resin infusion molding process (VARIM). The developed composites demonstrate tremendous mechanical strength (250 MPa), shape-memory, weldability, and degradable properties. Due to the rapid chemical degradation of epoxy vitrimer under mild conditions in the thiol (2-mercaptoethanol and 1-otanethiol), facilitated by thiol disulfide exchange reaction, glass fibers (GFs) can be effectively recycled. The performance of recycled glass fibers closely matches that of original fibers, exhibiting nearly identical woven structure and mechanical properties. The single yarn of recycled glass fibers can achieve tensile strength of 85% (1-octanethiol) and 72% (2-mercaptoethanol) of the original glass fibers, thus, the recycling of glass fibers would be highly advantageous in terms of achieving the sustainability goals.

Investigation on barrier layers of Pt/BaTiO3/Pt based thin film capacitors

Barium titanate is a ferroelectric material used as a dielectric in thin film capacitors owing to its high dielectric constant. Barrier layers are utilized in these capacitors to improve the capacitors' performance. In this paper, zinc oxide and aluminium oxide are kept on both sides of BaTiO3 as barrier layers in Pt/BT/Pt capacitors and different dielectric properties are studied. The parameters such as capacitance density, leakage current, ESR, dielectric loss and dielectric strength of Pt/BT/Pt capacitors with barrier layers of different sizes are simulated using COMSOL Multiphysics modeling software. Aluminum oxide of 2 nm thickness as a barrier layer gives optimal performance. The leakage current, dielectric loss, capacitance density, equivalent series resistance and dielectric strength of Pt/BT/Pt capacitor are found to be 0.519 mA, 9.62x10‐12, 172.8 fF/µm2, 9.62 kΩ, 108 V/m respectively whereas that of Pt/ALO/BT/ALO/Pt capacitor are found to be 1.56x10‐18A, 7.81x10‐18, 11.6 fF/µm2, 9.01x1015 Ω, 5.05x109 V/m respectively. The low capacitance in Pt/ALO/BT/ALO/Pt capacitor is due to the low dielectric constant of Al2O3 layer. The reduced leakage current and increased equivalent series resistance is due to the low conductivity of the Al2O3 layer. The use of aluminium layer can reduce the electric field leading to improved dielectric strength.

Mechanically strong, transparent polyimide composite thin films with a low dielectric constant

Aromatic polyimide is widely used in microelectronics as dielectric packaging layers. There is a high demand to reduce its dielectric constant to meet the fast development of communication technology. Here we report a simple and eco-friendly approach to preparing polyimide films with a lowered dielectric constant by adding silica hollow nanospheres with an average size of 100 nm in an aqueous solution of poly(amic acid) salt, and subsequent film casting and thermal imidization. The silica hollow nanospheres present a uniform distribution in polyimide matrix after surface modification with 3-aminopropyltriethoxysilane. The dielectric constant of the resulting composite films decreases linearly with particle loading till 15 wt% and reaches the lowest value of 2.5. The surface hardness and elastic modulus of the films improve by adding hollow nanospheres, while maintaining high optical transparency, high flexibility and a low coefficient of thermal expansion.

Synthesis and properties of modified polyimides containing multiple side methyl and biphenyl structures

With the rapid development of 5 G technology and microelectronics, there is an urgent demand to design and develop modified polyimide films with low dielectric constant as flexible matrix materials. In this work, a diamine containing multiple side methyl and biphenyl groups was synthesized by aromatic nucleophilicsubstitution reaction and oxidation-reduction reaction, respectively. Furthermore, this monomer was used to polymerize with four different commercially available dianhydrides (ODPA, BTDA, BPDA, and PMDA) to produce a class of polyimides (PI 3a∼3d). The structures of the diamine and its PIs are characterized, and the relationship between the structure and properties of the obtained PI films is investigated. These modified PIs are easy to cast into films and have low dielectric constants and water absorption. Their dielectric constants and dielectric losses are in the range of 2.66–2.91 and 0.00579–0.00677 at 1 MHz, respectively. Meanwhile, these PIs also maintains good thermal stability, with glass transition temperatures (T g) higher than 284 °C and 10% weight loss temperatures in the range of 496–505 °C at N2.

Thermosetting boron-nitride-filled polybutadiene composites with enhanced thermal conductivity and good dielectric properties

Low dielectric materials with high heat dissipation, low dielectric constant (Dk), and dielectric loss (Df) are urgently needed to address the issues of signal cross-talk and heat accumulation arising from the rapid development of modern communication technology and the integration of microelectronics. Polyolefins, as hydrocarbon polymers, have shown significant potential due to their excellent low dielectric properties. However, their low polarity and flexible structures limit their thermal conductivity and thermomechanical properties. In this study, we developed a method to prepare thermosetting polybutadiene composites with enhanced thermal conductivity and good dielectric performance by modifying hexagonal boron nitride (h-BN) and hydroxyl-terminated polybutadiene (HTPB) with thermally cross-linkable benzocyclobutene (BCB) groups. The properties of the resulting composites were tailored by varying the filler content. With 30 wt% of the BCB-modified filler, the composite (HB-30) displayed excellent dielectric properties (Dk = 2.70; Df = 1.67 × 10−3 @10 GHz). Meanwhile, it exhibited a thermal conductivity of 0.615 W/mK at 35 °C, which was 7.1 times that of pristine HTPB. It also showed significantly enhanced mechanical properties and thermal stability with a storage modulus of 2.7 GPa and a glass transition temperature (Tg) of 208.5 °C. This method proved effective for preparing polymer composites with enhanced thermal conductivity, heat resistance, mechanical properties and good dielectric properties, making them suitable for high-frequency communication applications.

Epoxy-imine vitrimer having low dielectric constant and high wave transmission efficiency for mobile communication applications

The rapid growth of telecommunication technology calls for express evaluation and development for low dielectric constant (Dk) materials with higher performance requirements. At mean time, the extensive use of these dielectric materials generates increasing concerns over their crosslinking structures that cannot be readily recycled without causing environment pollution. Herein, a curing agent comprising dynamically exchangeable imine bonds was synthesized via the condensation of terephthalaldehyde (TPA) and isophorondiamine (IPDA). Epoxy vitrimers cured by this curing agent exhibited low Dk (2.75–2.79) and excellent wave transmission efficiency (>90.5 %) at high frequency range of 8.2–12.4 GHz. The cured resins can also be recycled through chemical degradation, producing reusable monomers. The cured resins demonstrate vitreous properties and its dielectric, thermal properties and wave transmission efficiency maintained unchanged after reprocessing. This work offers a strategy to prepare low Dk epoxy vitrimer used in communication field.

Photo‐Curable Fluorinated High‐k Polyimide Dielectrics by Polar Side Substitution Effect for Low‐Voltage Operating Flexible Printed Electronics

AbstractPolyimide‐based dielectric films are widely used in various thin film devices including organic field‐effect transistors (OFETs) owing to their promising thermal/chemical stability, mechanical flexibility, and insulating properties. On the other hand, considerable attention is paid to lowering the process temperature to allow coating on plastic substrates because high‐temperature annealing (≈200 °C) is usually required to convert precursors to polyimide films with those excellent properties. In addition, polyimide‐based dielectric films have low dielectric constants (k) (<4). Therefore, modifying the k properties of polyimide is a critical issue for applications as an insulating thin film for practical transistors. This paper reports a new type of polyimide‐based gate dielectric comprising methacryloyl moiety (PI‐MA) as a side chain for photo‐pattern/processability and high‐k properties. This study shows that the photocured PI‐MA thin films show excellent insulating properties (leakage current densities < 10−8 A cm⁻2 at 4 MV cm⁻1) and high‐k properties (≈8) even without a post‐annealing process. Finally, the use of PI‐MA in printed field‐effect transistors results in high performance with low‐voltage operation (within 5 V) and integrated logic‐gate devices (NOT, NAND, and NOR gates).

Enhanced performance of low-dielectric siloxane-polyimide copolymers: Synthesis and properties

Low-dielectric polyimides (PI) films with outstanding overall performance are attractive for next generation microelectronic applications. Herein, a series of two different FPIs and BPIs derived from 4,4′-diaminodiphenyl ether (ODA) and two different functional dianhydrides, 4,4'-(hexafluoroisopropylidene) biphthalic anhydride (6FDA) and 4,4′-(4,4′-isopropyldiphenoxy) biphthalic anhydride (BPADA), respectively, were synthesized by a conventional two-step methodology that included thermoimidatization. Additionally, employing aminopropyl-terminated polydimethylsiloxane PDMS (molecular weight = 1000) as the source of siloxane-oxygen bonds, a series of polyimide siloxane (SiFPIs and SiBPIs) copolymers were synthesized by varying the siloxane content (ranging from 0 to 5 wt%) within the copolymer structure. The effects of siloxane bond on the thermal, solubility, water resistance, dielectric and mechanical properties of polyimide were investigated systematically. The integration of siloxane significantly enhanced the solubility of these copolymers in polar aprotic solvents (DMAC, DMF, NMP), expanding their applicability in diverse processing environments. Crucially, these copolymers exhibited remarkably low dielectric constants—2.90 for SiFPI at 3% PDMS and 2.92 for SiBPI at 4% PDMS—coupled with low loss values, positioning them as prime candidates for advanced microelectronic applications. All the composite films have high thermal stability near pure PI. The introduction of PMDS into PI can improve the elongation at break and at the same time, the composite films still remained with higher modulus and tensile strength. Extensive hydrophobicity assessments through contact angle and water absorption studies underscored the copolymers’ superior moisture resistance, a critical parameter for their potential deployment in high-performance, environmentally sensitive electronic components.

New developments in intrinsic black photosensitive polyimide for advanced display applications

To meet the requirements of low power consumption, long endurance, and cost-efficiency for mobile phones, a polarizer-less technology (Pol-Less) OLED with a color-on-encapsulation (COE) structure has been proposed. In this groundbreaking technology, black photosensitive polyimide (PSPI) serves as the pixel definition layer (PDL) and plays a crucial role. However, the addition of inorganic pigments, such as carbon black, significantly compromises the dielectric insulation properties of the PDL. Therefore, exploring intrinsic black photosensitive polyimide with outstanding light shielding performance and high dielectric insulation properties has garnered increasing attention. In this study, a derivative of anthraquinone, namely 2,4,5,7-tetraamino-1,8-dihydroxyanthraquinone (4NADA) is incorporated into the photosensitive polyimide chains, successfully producing an intrinsic black photosensitive polyimide with broad absorption in the visible light range. Experimental results revealed that by copolymerizing 50 % moles of 4NADA in the diamines in the photosensitive polyamide acid ester, a black photosensitive polyimide with a high optical density (OD) of 0.89 and a relatively low dielectric constant of 3.6 at 1000 kHz was obtained. Furthermore.

Flexible and Transparent Electrovibration-Based Haptic Display with Low Driving Voltage.

Electrovibration haptic technology, which provides tactile feedback to users by swiping the surface with a finger via electroadhesion, shows promise as a haptic feedback platform for displays owing to its simple structure, ease of integration with existing displays, and simple driving mechanism. However, without electrical grounding on a user's body, the frequent requirement of a high driving voltage near 50 V limits the use of electrovibration haptic technology in practical display applications. This study introduces materials and fabrication strategies that considerably reduce the driving voltage. We used a transparent poly(vinylidene fluoride) (PVDF) thin film deposited on transparent conductive polymers through a simple spin-coating process, thereby enabling easy integration with existing display technologies. The high dielectric constant characteristics of PVDF enabled the production of tactile cues at low voltages (approximately 15 V), which are within the safety limits of common electronics. We verified the feasibility of our electrovibration haptic feedback system on the basis of the absolute threshold voltage through two-alternative forced choice psychological tests. The results revealed that the PVDF dielectric layer exhibited a relatively lower absolute threshold than commonly used polymer films, which possess a relatively lower dielectric constant. To validate the tactile attributes, a Likert five-point scale survey was conducted, considering flat, concave, and convex curvatures. The results indicated that our haptic device can render diverse surface textures, such as "hairy" and "groovy", on the fingertips through the control of applied pulse width modulated voltage signals.

Characterizing the Cooperative Effect of PROTAC Systems with End-Point Binding Free Energy Calculation.

Proteolytic targeting chimeras (PROTACs), as an emerging type of drug, function by proximity-based modalities that narrow the distance between a target protein and the E3 ubiquitin ligase to facilitate the ubiquitination labeling of the target protein for degradation. Although it is evidenced that the cooperativity of the PROTAC ternary interaction is one of the key factors affecting the degradation rate of a target protein, PROTAC design utilizing this indicator is still challenging because of the complicated/flexible interactions in a target-PROTAC-E3 ternary system. Therefore, developing reliable and practicable computational methods is of great interest for PROTAC design. Hence, in this study, we investigate the feasibility of using the end-point binding free energy calculation method, represented by molecular mechanics/Poisson-Boltzmann (generalized-Born) surface area (MM/PB(GB)SA), for characterizing cooperativity (including the stabilization and hook effects) of the PROTAC systems. The result shows that MM/GBSA is a good predictor in characterizing these effects under a relatively long molecular dynamics adjustment (50-100 ns) and low dielectric constant (εin = 1), with the Pearson correlation coefficient (rp) > 0.5 and 0.6 for the stabilization and hook effect, respectively. This study provides a feasible strategy for characterizing the cooperativity of the PROTAC systems, facilitating the rational design of PROTAC molecules.

Protocatechualdehyde-based epoxy vitrimer with low dielectric, excellent flame retardancy, and recyclability

Conventional bisphenol A epoxy resins cannot meet the requirements of the new generation of electronic/electrical industries in terms of dielectric properties and flame retardancy and are challenging to reprocess after molding, resulting in waste of resources and environmental hazards. Therefore, a tetrafunctional active ester curing agent (TIE) was successfully synthesized by a one-pot method using biomass protocatechualdehyde as raw materials, followed by curing DGEBA to prepare an epoxy vitrimer (TIE/DGEBA). MHHPA/DGEBA was chosen for comparison since the –OH was also absent after curing. The results showed that TIE/DGEBA had good combinatorial performance, thanks to the unique structure of TIE, including active ester units, siloxane chains, and aromatic Schiff base groups. TIE/DGEBA possessed a lower dielectric constant (2.9 vs. 4.0) compared to MHHPA/DGEBA, which was attributed to the synergistic effect of the less-polar siloxane chain segments, bulky benzene structure, and lower cross-linking density (1971 vs. 733 mol/cm3) of TIE/DGEBA. The aromatic Schiff base not only imparted good thermal stability (T30% = 418.0 vs. 422.2 °C) to TIE/DGEBA but ensured that it allowed for recycling and reprocessing. After solvent recycling, the resin can be remolded without significant change in tensile strength (53.0 vs. 46.3 MPa). TIE/DGEBA displayed better flame retardancy with higher residual weight (28.2 % vs. 5.5 %), lower total heat release (29.6 vs. 43.5 kJ/g), and good resistance to thermal oxidization. The structural and performance characteristics of TIE/DGEBA offer a strategy for designing multifunctional epoxy-based materials in electrical/electronic applications.

Structural designs and synthesis of co-polycarbonates with cyclohexyl and fluorene structures: Low-dielectric constant, high solubility, and superior mechanical properties

The rapid developments of high-speed communication and large-scale integrated circuits have accelerated the research for insulating dielectric materials with low dielectric constant, low dielectric loss, and good mechanical properties. In this study, a series of polycarbonate resins containing cyclohexyl and fluorene structures are synthesized by melt transesterification, which is low dielectric, highly thermally resistant, and soluble. The effects of fluorene structure contents on the properties of a co-polycarbonate resin were studied systematically. The results showed that the non-polar fluorene group could reduce the molecular polarization of co-polycarbonate, resulting in low permittivity of co-polycarbonate are 2.41-2.71@1MHz. In addition, the resin has excellent solubility and can be dissolved in NMP, CH2Cl2, THF, and other solvents at room temperature. Furthermore, the co-polycarbonate resins also exhibit superior heat resistance with glass transition temperature (Tg) of 160.6-173.1 °C as well as admirable mechanical properties with a tensile strength of 50.54-70.72 MPa. This makes it a promising candidate for high-speed communications and large-scale integrated circuits.

TFE Terpolymers: Once Promising - Are There Still Perspectives in the 21st Century? Part II: Processing, Properties, Applications.

Tetrafluoroethylene (TFE) terpolymers have emerged as advantageous substitutes for polytetrafluoroethylene (PTFE). Therefore, they are being considered as alternatives to PTFE in many application areas. The advantages of TFE terpolymers include their facile processability at elevated temperatures, their solubility in some polar organic solvents, their inertness against aqueous acids, aqueous bases and a large number of mostly nonpolar organic solvents, their low dielectric constant, their low refractive index as well as useful electro- and thermochemical properties. This review on TFE terpolymers focuses on their processing including shaping and surface modification as well as on selected properties including wettability, dielectric properties, mechanical response behavior, chemical stability, and degradability. Applications including their use as elastomeric sealing material, liner and cladding layer as well as their use as material for membranes, microfluidic devices, photonics, photovoltaics, energy storage, energy harvesting, sensors, and nanothermitic composites will be discussed. The review concludes with a discussion of the future potential of TFE terpolymers and scientific challenges to be addressed by future research on TFE terpolymers.

Mainchain and Sidechain-involving H-bonded Asymmetric Polyimides Containing Rigid Amide and Flexible Ether Linkages

Hydrogen bonds (H-bonds), usually mainchain amide H-bonds, have been well recognized to play important roles in modulating the properties of polyimides (PIs) by strengthening macromolecular interaction. While the structure-properties relationships of symmetric mainchain amide H-bonded PIs have been extensively researched, the asymmetric H-bonded PIs, particularly those containing rigid-flexible backbone structure, and sidechain-involving H-bonds, have been rarely explored. Herein, starting from designed synthesis of diamine monomers, we present two series of asymmetric PIs containing rigid amide and flexible ether linkages that form mainchain amide-amide and amide-imide H-bonds, lacking or bearing pendent trifluoromethyls (-CF3) that form sidechain-involving amide-CF3 H-bonds. The presence of these three types of H-bonds were revealed by RDF simulation and confirmed by FTIR. Mainchain H-bonded PIs (PI-Ax) show higher Tg than sidechain-involving H-bonded PIs (PI-Tx), while PI-Tx series exhibit higher optical transparency and hydrophobicity, lower dielectric constant (ε') and better mechanical properties than PI-Ax. The general researches on the PIs’ solubility, WAXD spectra, thermal properties, fluorescence emission and optical transparency, the dihedral angles (φ), fractional free volume (FFV), theoretical gas transport properties, chain geometry optimization and HOMO-LUMO energy gap (ΔE) values have been comprehensively carried out from the aspects of both experiments and theoretical calculation.

Insight and assessment of CO2 capture using diethylenetriamine/2-(diethylamino)ethanol/n-propanol water-lean biphasic solvent: Experimental and quantum chemical calculation

Biphasic solvents hold immense promise for CO2 capture, but often struggle to maintain stable performance over long-term cyclic use. Alcohols possess low dielectric constants, which can provide protons for amine-CO2 reaction products, enhancing the regeneration performance of absorbents while maintaining stability. In this study, diethylenetriamine (DETA) + 2-(diethylamino)ethanol (DEEA) + H2O was used as the biphasic solvent, with n-propanol (PrOH) serving as the regulator to develop the DETA + DEEA + PrOH water-lean biphasic solvent. Replacing half of the water with PrOH improved the cyclic stability of the absorbent, reduced the rich phase ratio (46 %) and energy consumption (2.05 GJ·ton−1 CO2), while effectively enhanced corrosion resistance and thermal stability, confirming the feasibility of PrOH as the regulator. The detailed reaction mechanism of the absorbent for CO2 absorption was elucidated through 13C NMR and DFT calculations. Quantum chemical calculations have provided the first compelling evidence for PrOH’s involvement in the absorption reaction: PrOH stores the reaction products in the form of PrOCOOH/PrOCOO−. By regenerating DETA, it restores its CO2 absorption capacity. Through polarity and hydrogen bonding, the reaction products aggregate in one phase, enhancing CO2 loading. In summary the PrOH regulated water-lean biphasic solvent presents a highly promising absorbent for industrial use.

Microwave Frequency Analysis of Dielectric Properties in Biological Tissues: Insights into Dielectric Constant, Conductivity, and Resistivity at 9.4 GHz

This study investigates the dielectric properties of various biological tissues at microwave frequencies, specifically focusing on their dielectric constant, conductivity, resistivity, and loss tangent. Using methods such as Von Hippel’s and Yadav Gandhi’s techniques, the dielectric characteristics of heart, liver, brain, and muscle of chicken tissues were analysed at 9.4 GHz. It is found that tissues with higher water content exhibit greater dielectric constants and conductivities, while those with higher solid content, like liver, display higher resistivity. It has also been observed that tissues with lower dielectric constants and conductivities are those with greater absorption indices, which are typically associated with increased energy dissipation as heat. An increasing amount of energy dissipation may result from tissues with higher absorption rates being less effective at transferring microwave energy, as suggested by this inverse connection, which also emphasizes the complexity of electromagnetic wave interaction within tissues. This work provides critical insights into the interaction of electromagnetic waves with biological tissues, which is essential for applications in medical diagnostics, therapeutic technologies, and electromagnetic exposure safety standards.