Wide Pressure Research Articles

3D-Printed Multi-Axis Alignment Airgap Dielectric Layer for Flexible Capacitive Pressure Sensor

Flexible pressure sensors are increasingly recognized for their potential use in wearable electronic devices, attributed to their sensitivity and broad pressure response range. Introducing surface microstructures can notably enhance sensitivity; however, the pressure response range remains constrained by the limited volume of the compressible structure. To overcome this limitation, this study implements an aligned airgap structure fabricated using 3D printing technology. This structure, designed with a precisely aligned triaxial airgap configuration, offers high deformability under pressure, substantially broadening the pressure response range and improving sensitivity. This study analyzes the key structural parameters—the number of axes and pore size—that influence the compressibility and stability of the dielectric material. The results indicate that the capacitive pressure sensor with an aligned airgap structure, manufactured via 3D printing, exhibits a wide operating pressure range (50 Pa to 500 kPa), rapid response time (100 ms), wide limit of detection (50 Pa), and approximately 21 times enhancement in sensitivity (~0.019 kPa−1 within 100 kPa) compared with conventional bulk structures. Furthermore, foot pressure monitoring trials for wearable sensor applications demonstrated exceptional performance, indicating the sensor’s suitability as a wearable device for detecting plantar pressure. These findings advocate for the potential of 3D printing technology to supplant traditional sensor manufacturing processes.

Improvement of Thermal Stability of Charges in Polylactic Acid Electret Films for Biodegradable Electromechanical Sensors.

Eco-friendly sensors fabricated from biocompatible and biodegradable materials are promising candidates for wearable and implantable electronics due to their environmental sustainability and biosafety. This article reports a fully biodegradable electromechanical sensor (FBES) utilizing a sandwich structure with macro ripple structured polylactic acid (PLA) electret films acting as sensitive layers and molybdenum (Mo) sheets serving as electrodes for a wearable device application. The stability of the space charge stored within the PLA film has been enhanced by introducing an internal cellular structure and improving the polarization process. A macro ripple structure of the PLA layer with higher deformation is a great guarantee for boosting the pressure sensitivity. The results indicate that inserting cell microstructures and optimizing the polarization process significantly improve the charge storage stability of PLA films by nearly 55%. This enhancement is attributed to several factors, including the extended charge drift path of the charges in cellular films, a synergy effect of surface charges, and "macroscopic" dipole charges distributed in the cells. The fabricated sensor achieves a high sensitivity of 1000 pC/kPa, a wide pressure detection range of 0.03-62.4 kPa, and satisfactory stability. Such sensors are not only sensitive to body movements but also to subtle physiological signals, satisfying the diverse needs of wearable healthcare. Importantly, all the composition materials of the sensor can be completely degraded after their service, aligning with the environmentally friendly principles of green development.

Structural and Superconducting Properties of Bi2Rh3(Se1-xSx)2 (x = 0-1.0).

The structural and superconducting properties of the Bi-based superconductor Bi2Rh3(Se1-xSx)2 were investigated over a wide pressure range. Bi2Rh3Se2 is a superconductor with a superconducting transition temperature, Tc, of less than ∼1.0 K, whereas Bi2Rh3S2 is a nonsuperconductor. The former shows a clear charge density wave (CDW) phase transition at 240 K and the latter shows a first-order structural phase transition at 165 K, providing the supercell structure. Both compounds have the same crystal structure at ambient temperature and pressure (monoclinic, space group of C2/m (No. 12)). This implies the possible formation of solid solution-like phases Bi2Rh3(Se1-xSx)2. In this study, we prepared Bi2Rh3(Se1-xSx)2 (x = 0-1.0) and investigated its superconducting properties and phase transitions at different x values. Because the superconducting properties and temperature causing the phase transition (Tpt) are quite different between Bi2Rh3Se2 and Bi2Rh3S2, their variation against x is quite intriguing from the viewpoint of the pursuit of physical properties via the replacement of Se with S. In this study, the features of the superconductivity and crystal structure against x were fully explored to depict the phase diagram. Moreover, we investigated the pressure (p) dependence of superconductivity and phase transition (CDW or the first-order structural transition) to clarify the interplay between the two ordered states.

Investigating the Potential of Cr3+-Doped Pyroxene for Highly Sensitive Optical Pressure Sensing.

Luminescent manometry has gained significant popularity in recent years due to its capability to provide in situ pressure measurements in a remote manner. Therefore, there is a growing need to identify phosphors with pressure-dependent spectroscopic properties that can be utilized to develop highly sensitive pressure sensors operating over a wide pressure range. Hence, we present a novel temperature-invariant luminescent manometer based on Cr3+ ion emission in pyroxene Ca0.8Sr0.2MgSi2O6:Cr3+. We utilized two readout modes, including an innovative luminescent pressure sensing ratiometric approach based on the broad emission band associated with the 4T2g → 4A2g electronic transition of Cr3+ ions. This approach provided an exceptionally high sensitivity of SR = 50.7 ± 0.5% GPa-1 and ensured temperature-independent pressure measurements, thus offering highly reliable readouts. Furthermore, the proposed readout mode, which leverages changes in luminescence kinetics, demonstrated high sensitivity at high pressure at around 5 GPa (SR ∼ 8 ± 0.2% GPa-1) surpassing the performance of luminescence kinetics-based manometers reported to date. Consequently, Ca0.8Sr0.2MgSi2O6:Cr3+ emerges as a highly promising phosphor with significant application potential for pressure sensing across a broad pressure range.

Nationwide trends in blood pressure control among those with and without diabetes in England over last 2 decades: Health Survey of England 2003-2019

Abstract Diabetes and hypertension are both risk factors for cardiovascular disease (CVD), and often co-exist. Over recent decades practice guidance and health policy efforts have been made to improve population wide blood pressure (BP) control, particularly amongst those with diabetes, to reduce CVD. However, the nationwide impact of these ongoing efforts is yet to be documented comprehensively in England. We used data from 11 serial nationally representative health surveys of England between 2003 and 2019 and compared BP control and presence of untreated hypertension amongst those with and without diabetes. These cross-sectional, randomly sampled surveys included 94,100 individuals cumulatively. We applied sample weights, accounting for oversampling and survey nonresponse, and transformations mitigating for survey equipment changes during this period. We used ‘period definitions’ to define those with diabetes and quantify BP control at the time of each coinciding survey, facilitating accurate comparison of trends over the sixteen-year period, while accounting for changes in understanding, variations in definitions, and shifts in medical practices. Python and STATA were used to conduct analyses and Join Point regression software was used to develop and compare trends. In England, from 2003-2019, the prevalence of hypertension amongst those with diabetes and without diabetes decreased from 74.4% to 66.5% and from 32.6% to 27.1% (7.9% vs. 5.5%), respectively. This corresponded to reductions in population-wide mean systolic (S) and diastolic (D) BPs: compared to those without diabetes, those with diabetes had greater reduction in both SBP (7.9mmHg vs. 4.8mmHg) and DBP (2.7mmHg vs. 1.9mmHg) (Figure1). Both groups showed similar temporal improvement in BP-control amongst those with diagnosed hypertension, with those with diabetes showing better improvement in BP control compared to those without diabetes (14% vs. 12%). There was a significant difference in proportions of those with undiagnosed (unaware) hypertension amongst those with and without diabetes (11.4% vs. 30.0% respectively) (Figure2). Notably, there was no change in proportion of those with hypertension unaware about the condition (i.e. detection rate for hypertension in either of the group did not show any improvement over time). These results suggest that we have been able to improve BP control over this period amongst those with and without diabetes, however, those without diabetes (more than 90% of population) have shown significantly poorer improvement. In addition, around one third of hypertensive patients amongst the no-diabetes group are unaware of the condition, and overall, the detection rates for hypertension in both groups have not improved in the last two decades. Lessons learnt from improving BP control amongst those with diabetes should be applied across the entire population, and newer strategies need to develop to improve detection of those with hypertension and are unaware.

Congelation- and dehydration-tolerant, mechanically robust hydrogel electrolyte for durable iontronic sensors operating in open air and freezing temperatures over wide strain and pressure ranges

Conventional hydrogels have limitations in mechanical properties and are susceptible to loss of elasticity and conductivity caused by congelation and dehydration, limiting their practical uses for application in high-stress environments, open air, and freezing temperatures. This study introduces a mechanically robust, dehydration- and congelation-tolerant, and ionically conductive hydrogel electrolyte, practical for iontronic sensors working in wide pressure and strain ranges under open-air and freezing temperatures. This hydrogel electrolyte is fabricated through a reconstruction process comprising a drying-induced densification of double-network hydrogel of alginate and polyacrylamide, a structure fixation by Fe3+ crosslinking, and a Li+ infiltration. The resultant hydrogel electrolyte is tolerant to dehydration and congelation and mechanically robust, with strength and elastic modulus of a few mega-pascals comparable to those of non-conductive elastomers/rubbers used as dielectric materials. Therefore, the hydrogel electrolyte-based iontronic sensors demonstrate exceptional sensitivity and stability under compression and tension and across a wide temperature range. Further, the sensor demonstrates their practical applicability in high-stress environments from kg-range human weight to ton-range car weight. These achievements evince that iontronic sensors, based on mechanically robust and ionically conductive hydrogel electrolytes tolerant to congelation and dehydration, can be employed for practical applications.

Tobacco consumption influencing the prevalence of hypertension among Indian women aged above 15 years: An in-depth analysis using National Family Health Survey (NFHS - 5), 2019–2021

Objectives: Globally, hypertension associated with tobacco consumption is one of the leading causes of death. The aim of this study is to explore the possible association between tobacco consumption and hypertension among women aged 15 years and above in India. Methods: Data available from the National Family Health Survey (NFHS 5) survey was used for the study. The study examined the relationship between tobacco consumption and hypertension by analysing blood pressure indices among women aged above 15 years in India. The weighted proportion was computed with 95% CI for the cross-tabulations. Multivariable logistic regression was used to determine the risk factors for hypertension, high mean arterial pressure, and wide pulse pressure. Results: Among 625116 women aged 15 years and above, 41181 (6.6%) of them were tobacco consumers; among them, 3.4% had wide pulse pressure, 6% had hypertension, and 20.2% had high mean arterial pressure. Tobacco consumers were 1.11 times (1.03-1.20) and 1.09 (1.05-1.14) times more likely to have hypertension and high mean arterial pressure respectively, compared to those who didn't consume tobacco. Smokeless tobacco consumers were 1.12 (1.04-1.21) times more likely to develop hypertension. Conclusion: From this study, we found that factors like older age, mixed diet, alcohol use, and obesity have contributed to the risk of hypertension. Smokeless tobacco users were at risk of developing hypertension compared to users of other forms of tobacco.

High-Performance Membranes Based on Spherical-Beaded Nanofibers and Nanoarchitectured Networks for Water-in-Oil Emulsion Separation.

High-performance separation materials for oil-water emulsions are crucial to environmental protection and resource recovery; however, most existing fibrous separation materials are subject to large pore size and low porosity, resulting in limited separation performance. Herein, we create high-performance membranes consisting of spherical-beaded nanofibers and nanoarchitectured networks (nano-nets) using electrostatic spinning/netting technology, for water-in-oil emulsion separation. By manipulating the nonequilibrium stretching of jets, spherical-beaded nanofibers capable of generating a robust microelectric field are fabricated as scaffolds, on which charged droplets are induced to eject and phase separate to self-assemble nano-nets with small pores. Benefiting from 3D undulating networks with cavities originating from 2D nano-nets supported by 1D spherical-beaded nanofibers, the membranes exhibit under-oil superhydrophobicity (>152°), a striking separation performance with an efficiency of >99.2% and a flux of 5775 L m-2 h-1, together with wide pressure applicability, antifouling, and reusability. This work may open up new horizons in developing fibrous materials for separation and purification.

Sulfur dioxide absorption by novel green solvents of deep eutectic solvents: Modeling screening

Sulfur dioxide (SO2), produced mainly from the combustion of coal, is the most important cause of acidic rain, skin diseases, and environmental issues. To overcome the environmental problems, SO2 must be captured on an industrial scale before it is released into the air. In chemical industries, organic solvents are used for partial absorption of SO2. However, those organic solvents have negative environmental effects. Thus, proposing environmentally friendly and green solvents for SO2 absorption is vital for industries. Recently, increased attention has been paid to capturing SO2 using Deep Eutectic Solvents (DESs) as the most recently introduced category of green solvents. This study performed a comprehensive screening study on the investigation of the performance of various simple and complicated models for SO2 solubilities in a wide range of different nature DESs. For this purpose, the most updated and largest SO2 solubility data bank in DESs involving 976 data points for 63 different nature DESs over wide temperature and pressure ranges has been gathered from open literature. For model screening, for the physical absorption models, the performances of SRK and CPA as the simple cubic and complicated sophisticated equations of state, NRTL and UNIQUAC as the well-known activity coefficient models, and for the chemical absorption models, RETM were investigated and compared. For physical absorption models, coupling an equation of state with the UNIQUAC activity coefficient model i.e. CPA-UNIQUAC, SRK-UNIQUAC, and also using simple SRK-SRK models led to the best performances. Compared to all investigated models, RETM as the chemical absorption model showed the best performance with the AARD% value of 12.95. This shows the importance of considering the chemical absorption mechanism for SO2 absorption by DESs. Finally, general guidelines for using different modeling approaches were proposed to be considered by the researchers.

Cleanroom-free fabrication of flexible capacitive pressure sensors using paintable silver electrodes on stationery paper and random microstructured polydimethylsiloxane dielectric layer

Abstract In this work, we propose a facile, low-cost, and cleanroom-free approach for fabricating flexible capacitive pressure sensors based on paintable Ag electrodes on stationery paper substrates (Ag–paper electrodes) and a random microstructured polydimethylsiloxane (PDMS) dielectric layer transferred from emery paper. COMSOL Multiphysics simulations and experimental investigations suggest that the pressure sensor with random microstructured PDMS dielectric layer performs better than the sensor with ordered micropyramidal dielectric layer. The developed Ag–paper electrode and random microstructured PDMS dielectric layer-based pressure sensors are workable in a wide pressure range (up to 630 kPa) and exhibit a high sensitivity of 0.132 kPa−1 up to 1 kPa, low hysteresis (6.6%) with loading–unloading of ∼500 kPa pressure, high stability during a ∼5250 cyclic test, and the ability to sense a low pressure of ∼27 Pa. The developed sensor also successfully transduces arterial pulse wave forms when it is properly attached to the wrist. Using the proposed process, a flexible capacitive pressure sensor matrix of 4 × 4 array is also successfully developed for single- and multiple-point pressure mapping with minimal cross-talk. The proposed sensor process is simple and inexpensive to implement, and offers spatial pressure mapping for e-skin applications.

Diffusive nature of different gases in graphite: Implications for gas separation membrane technology

Graphite membranes have gained attention in membrane technology for gas separation due to their high stiffness, strength, and stability in corrosive and high-temperature environments. Graphite exists naturally in geologic media and can also be prepared by synthetic processes. In- situ hydrogen (H2) production in petroleum reservoirs or H2 storage in depleted gas reservoirs results in contamination with CH4 and CO2. To address the separation challenge at the surface, a sustainable downhole wellbore membrane must be available to separate H2, leaving behind CO2 and other gases to improve operational economics. Currently, there are no studies in the literature on the self-diffusivity of gases (CO2, H2, and CH4) in graphite as a function of pore size. To overcome time constraints in diffusivity experiments, this work utilized mathematical models and molecular simulations to delineate the self-diffusivity of gases in graphite of different pore sizes.To acknowledge subsurface operational conditions during in situ hydrogen production, we considered a temperature of 360 K and a wide pressure spectrum from 2 MPa to 20 MPa. In this study, we explored the diffusive nature of H2, CH4, and CO2 gases in different nanopore-sized graphite using analytical and molecular simulation approaches. We validated the results by presenting unrestricted case density calculations. First, effective diffusivity was calculated using the mean free pore path, followed by gas adsorption at high pressures (10–20 MPa) and a temperature of 350 K. The study utilized theoretical models and molecular dynamics (MD) simulations to determine the self-diffusivity of gases in graphite systems with various structures.

Efficient fabrication of conductive sponges for wearable flexible sensors

In recent years, flexible and wearable sensors, particularly piezoresistive sensors, have been widely used in various fields such as human–computer interface, soft robotics, and artificial electronic skin. Three-dimensional (3D) conductive sponges have attracted widespread attention due to their excellent sensor performance, ease of manufacture, and seamless integration into circuits. Polydimethylsiloxane (PDMS) is widely used as an ideal substrate for these 3D conductive sponges due to its excellent chemical stability, good biocompatibility, and ideal mechanical properties. In this study, we synthesize a series of conductive silicone sponges (PCSs) by the one-pot thiol oxidative coupling reaction using commercially available multi-walled carbon nanotubes and poly((thiopropyl)methyl dimethylsiloxane). The PCSs possess controllable density and electrical conductivity. Moreover, the PCS-a sponge exhibits a wide pressure sensing range from 0.5 to 230 kPa with high-pressure sensitivity along with excellent mechanical and sensing stability. Pressure sensors fabricated using PCSs can be utilized in speech recognition systems and human activity monitoring such as arm/finger bending or walking while attached to joint positions. Additionally, they can also function as compressible switching devices for pressure alarms and LEDs.

Ligand extension of aluminum fumarate metal-organic framework in transferring higher water for adsorption desalination

This article presents the synthesis and characterization of a new microporous metal organic framework (MOF) for adsorption desalination for the first time. The new MOF, designated as “Al-t,t-Ma”, is an analogue of aluminum fumarate (Al-Fum) and is fabricated via ligand extension method. Firstly, the MOF is synthesized, and then characterized by XRD, FTIR spectroscopy, TEM, SEM, TGA and N2 adsorption techniques. Secondly, the water adsorption experiments on the pristine Al-Fum and Al-t,t-Ma are performed for a wide temperature (30 °C ≤ T ≤ 80°C) and pressure (0 < P/Ps ≤ 0.9) ranges. The water adsorption isotherms, kinetics, hydro-thermal stabilities as well as the isosteric heat of adsorption (Qst) are evaluated. Thirdly, based on the experimentally confirmed isotherms, kinetics and isosteric heats data, the adsorption assisted desalination (AD) system is modelled and simulated. Finally, the performances of AD system employing Al-Fum and Al-t,t-Ma MOFs are calculated in terms of the performance ratio (PR) and specific daily water production (SDWP) under various half cycle times (100 s ≤ tcycle ≤ 1000 s) and regeneration temperatures (55°C ≤ Tregen ≤ 80°C). As compared with the pristine Al-Fum, the pore volume of Al-t,t-Ma MOF is found 115 % higher. The proposed Al-t,t-Ma MOF possesses higher water transfer (+57.5 % more) with promising hydro-thermal stability. Employing Al-t,t-Ma MOF as porous adsorbent, the SDWP is achieved 28 m3 per tonne of MOFs per day at the regeneration temperature of 55°C. These results confirm that Al-t,t-Ma MOF is a competent candidate for adsorption desalination.

In Silico-Directed Design and Experimental Validation of an IL/UiO-66 Nanocomposite with Exceptional CO2 Selectivity across a Wide Pressure Range

In Silico-Directed Design and Experimental Validation of an IL/UiO-66 Nanocomposite with Exceptional CO₂ Selectivity across a Wide Pressure Range

Synergistic ionic liquid encapsulated MIL-101 (Cr) metal-organic frameworks for an innovative adsorption desalination system

The transformations of brackish water into freshwater employing porous materials such as metal-organic frameworks (MOFs) show a great potential for a green environment. But the adsorption-based desalination slows down due to slow water adsorption/desorption rates and inadequate water storage capacity in conventional adsorbents. Therefore, the restructuring of porous MOFs increases water storage and transfer rates. This paper presents a comprehensive investigation on the fabrication of ionic liquid encapsulated MIL-101 (Cr) MOFs (metal-organic frameworks), and its interactions with water for desalination applications. Firstly, the pristine MIL-101 (Cr) is encapsulated with various types/amounts of ionic liquids. Next, these MOFs are characterized via SEM (Scanning electron microscope), FTIR (Fourier transform infrared), XRD (X-ray diffraction), TGA (Thermal gravimetric analysis), N2 adsorption techniques. The water adsorption on these MOFs is performed experimentally for a wide temperature (30–80 °C) and pressure (0 < P/Ps < 0.95) ranges. The effects of the size (or type) as well as the encapsulation ratio of ionic liquids on water adsorption behaviors are conducted. Based on the experimentally proven water adsorption (isotherms and kinetics) data, an AD (adsorption desalination) system is modelled and simulated. Finally, the AD performances in terms of the specific daily water production (SDWP) and performance ratio (PR) are parametrically studied with respect to various regeneration temperature (50–80 °C) and cycle times (100 s–1000 s). It is found that by ionic liquid encapsulation, the water uptakes/offtake rates are expedited up to 48% (for adsorption)/55% (for desorption), respectively. In addition, the water transfer (Δq) improves up to 45% more than the parent MIL-101(Cr) MOFs. Furthermore, the SDWP increases from 38 to 56 m3 of water per tonne of MOFs per day at the regeneration temperature of 70 °C. The simulation results also show that the ionic-liquid-encapsulated MIL-101 (Cr) MOFs generates water (>25 m3 water per tonne of IL-MOFs) at the regeneration temperature of 50 °C and is potential for the next generation desalination applications.

Thermochemical and kinetic study of the recombination and dissociation reactions R + Br (+M) ⇄ RBr (+M) (R = CH3, CH2Cl, CHCl2, CHClBr, CH2Br and CHBr2)

The kinetics of the recombination and thermal dissociation reactions R + Br (+M) ⇄ RBr (+M) with R = CH3, CH2Cl, CHCl2, CHClBr, CH2Br and CHBr2 were theoretically studied over wide temperature and pressure ranges employing unimolecular reaction rate theory combined with potential energy surfaces derived at the ab initio G4//B3LYP/6-311++G(3df,3pd) level. The resulting rate constants are in good agreement with the available experimental information. Rate constant values for the reactions of CH2Cl, CHCl2, CHClBr, CH2Br and CHBr2 radicals with Br atoms are for a first time reported. Standard enthalpies of formation for the above and related molecules have been calculated.

Model for predicting oil testing fluid rheological parameters of Bohai Bay oilfield in wide temperature and pressure range

The rheological parameters of oil testing fluids play a crucial role in safely conducting oil testing operations, protecting reservoirs, and maintaining wellbore integrity, which are greatly influenced by temperature and pressure. This article conducted rheological experiments on commonly used potassium salt polymer systems and organic salt systems for oil testing fluids in the Bohai Bay Oilfield under 4–200 °C and 30–150 MPa. The experiments revealed the variation of rheological parameters with temperature and pressure. Nine commonly used rheological models were evaluated for their applicability to the two types of oil testing fluids. It was found that the Ross model was suitable for the potassium salt polymer system, while the power-law model was suitable for organic salt oil testing fluids. A new rheological parameter prediction model suitable for wide range of temperature and pressure and different testing fluid systems was proposed based on the optimized results. The average error for the potassium salt polymer system for oil testing fluids was 0.101%, and the error for the organic salt system for oil testing fluids was 0.113%. Both were superior to known rheological models and can meet the requirements of oil testing operations within the wide temperature and pressure range in the Bohai Bay Oilfield.

Multimodal Intelligent Flooring System for Advanced Smart-Building Monitoring and Interactions.

The floor constitutes one of the largest areas within a building with which users interact most frequently in daily activities. Employing floor sensors is vital for smart-building digital twins, wherein triboelectric nanogenerators demonstrate wide application potential due to their good performance and self-powering characteristics. However, their sensing stability, reliability, and multimodality require further enhancement to meet the rapidly evolving demands. Thus, this work introduces a multimodal intelligent flooring system, implementing a 4× 4 floor array for multimodal information detection (including position, pressure, material, user identity, and activity) and human-machine interactions. The floor unit incorporates a hybrid structure of triboelectric pressure sensors and a top-surface material sensor, facilitating linear and enhanced sensitivity across a wide pressure range (0-800 N), alongside the material recognition capability. The floor array is implemented by an advanced output-ratio method with minimalist output channels, which is insensitive to environmental factors such as humidity and temperature. In addition to multimodal sensing, energy harvesting is co-designed with the pressure sensors for scavenging waste energy to power smart-building sensor nodes. This developed flooring system enables multimodal sensing, energy harvesting, and smart-sport interactions in smart buildings, greatly expanding the floor sensing scenarios and applications.

Trace element partitioning in a deep magma ocean and the origin of the Hf-Nd mantle array.

Crystallization in Earth's deep magma ocean could have caused trace element fractionation in the lower mantle that might be inherited to the isotopic compositions of the present-day mantle. However, the trace element partitioning has been experimentally investigated only up to the uppermost lower-mantle pressures. Here, we determined the bridgmanite/melt partition coefficients D of La, Nd, Sm, Lu, and Hf from 24 to 115 gigapascals, covering the wide pressure range of the lower mantle. Results demonstrate substantial reductions in DLu and DHf from >1 to ≪1 with increasing pressure to 91 gigapascals. We also found DLu/DHf > 1 and DSm/DNd < 1 under deep lower-mantle conditions, evolving melts toward low Lu/Hf and high Sm/Nd ratios by crystallizing bridgmanite. If residual melts form a dense hidden reservoir in the lowermost mantle, the complementary accessible mantle has the Hf and Nd isotopic compositions matching the observed terrestrial mantle array that deviates from the bulk silicate Earth reference.

Sensitivity enhancement of an all-solid FPE sensor via a programmable Vernier effect.

All-solid, open-cavity fiber optic Fabry-Perot etalon (FPE) sensors possess a wide static pressure detection range, yet their low sensitivity significantly restricts their application. This study proposes a programmable Vernier effect to improve the gas pressure sensitivity of FPE sensors substantially. By effectively modulating the emission spectrum of a widely tunable laser using a variable optical attenuator (VOA), the emission spectrum at different modulation lengths is expected to produce an optical beating in conjunction with the transmission spectrum of the FPE sensor, thereby realizing the Vernier effect. Experimental results indicate that by utilizing the proposed programmable Vernier effect, the pressure sensitivity of the FPE sensor has increased to -612.21 pm/kPa, demonstrating an amplification in sensitivity of approximately -153 times, consistent with the theoretical results. Owing to the programmable Vernier effect, which flexibly enhances the sensitivity of the FPE sensor, this sensor demonstrates considerable potential for gas pressure monitoring under various extreme conditions.