Low Pressure Range Research Articles

Flexible and transparent leaf-vein electrodes fabricated by liquid film rupture self-assembly AgNWs for application of heaters and pressure sensors

The leaf veins with hierarchically interconnected network structures have great potential as self-assembly templates for transparent and flexible electrodes. In this paper, a liquid membrane ruptured assisted AgNWs self-assembly method was adopted to obtain conductive veins, which show a low sheet resistance of 3.6Ω/□ and a high transparency of 79 % at a minimal materials waste. The figure of merit of conductive veins was as high as 433Ω-1 and can be further increased by increasing the number of soaking because the light transmittance is nearly immune to the AgNWs layer number. The veins maintained a good electrical conductivity even after bending 10,000 times at a 2 mm radius of curvature and exhibited a good corrosion resistance under harsh conditions. Heaters based on the conductive veins are shown as application examples. A high temperature of 104 °C was achieved at a low voltage of 2 V, which is enough to heat cold water. They still have good heating properties even in the bending state or tensile state. Furthermore, pressure sensors based on the conductive veins were fabricated as examples of wearable devices. The sensor exhibits a high sensitivity of 3.8 kPa−1 in the low-pressure range (0–15 kPa) and 17.4 kPa−1 in the high pressure range (15–50.96 kPa). It can monitor human actions such as finger bending, finger taping, throat swallowing and wrist pulse in real-time, which has promising potential for motion monitoring and information encryption applications.

Surface-enhanced CO2 capture in ionic liquid-silica nanocomposites via sol-gel synthesis in the low partial pressure range

Surface-enhanced CO2 capture in ionic liquid-silica nanocomposites via sol-gel synthesis in the low partial pressure range

Design of superconducting compounds at lower pressure via intercalating XH$_4$ molecules (X = B, C, and N) into fcc lattices

Abstract Recently, many encouraging experimental processes have been achieved in ternary hydrides superconductors under high pressure. However, the extreme pressure required is indeed a challenge for practical application, which promotes a further exploration for high temperature (T c) superconductors at relatively low pressure. Herein, we performed a systematic theoretical investigation on a serious of ternary hydrides with stoichiometry AX$_2$H$_8$, which is constructed by interacting molecular XH$_4$ (B, C, and N) into the fcc metal A lattice under low-pressure range of 0-150 GPa. We uncovered five compounds which are dynamically stable below 100 GPa, e.g., AcB$_2$H$_8$ (25 GPa), LaB$_2$H$_8$ (40 GPa), RbC$_2$H$_8$ (40 GPa), CsC$_2$H$_8$ (60 GPa), and SrC$_2$H$_8$ (65 GPa). Among these, AcB$_2$H$_8$, which is energetically stable above 2.5 GPa, exhibits the highest T c value of 32 K at 25 GPa. The superconductivity originates mainly from the coupling between the electron of Ac atoms and the associated low-frequency phonons, distinct from the previous typical hydrides with H-derived superconductivity. Our results shed light on the future exploration of superconductivity among ternary compounds at low pressure.

Adsorption characteristics and separation behavior of binder and binderless zeolite LiX Pellets: O2, N2, and CO2

In adsorptive gas separation process design, optimal adsorbent selection acts as a critical factor in process efficiency. This study investigated the adsorption equilibria and kinetics of O2, N2, and CO2 (weak, medium and strong affinity, respectively) and the breakthrough performance of four commercial zeolite LiX pellets (one binderless and three binder zeolite LiX pellets) because the performance of pelletized zeolites becomes different by adding binders and pelletizing methods. The adsorption isotherms at 293–323 K and up to 100 kPa were correlated with the dual-site Langmuir and Sips models. For all adsorbents, the order of adsorption amount and isosteric heat of adsorption was CO2 ≫ N2 > O2. However, differences among the four zeolite pellets were also observed, showing the highest values of the binderless zeolite LiX pellet. Furthermore, the adsorption capacity was 20–25 % smaller for CO2 and 40–50 % smaller of N2 and O2 at 100 kPa compared to pure zeolite LiX powder. According to kinetic analysis using a non-isothermal diffusion model, the adsorption rate of N2 was faster than that of CO2 for all adsorbents, showing the order difference in the low-pressure range. The kinetic difference among the zeolite pellets resulted from the effects of heat of adsorption, heat dissipation, and thermal resistance. The breakthrough performance using N2 and O2 was mainly controlled by the adsorption capacity, showing almost constant breakthrough pattern regardless of the samples. This study suggests that detailed evaluation of pelletized adsorbent is essential before designing adsorptive processes because performance of adsorbent powder would lead to under-design of the process. (255 words)

Neuron-astrocyte interaction-inspired percolative networks with metal microdendrites and nanostars for ultrasensitive and transparent electronic skins

Biological systems provide innovative designs for electronic devices, optimizing network configurations for high-performance signal transmission with minimal energy consumption. The brain, as one of the most complex biological structures, demonstrates efficient network design through the multiscale radial networks of neurons and astrocytes. Emulating these brain networks offers a blueprint for the development of ultrasensitive pressure sensors for electronic skin, aiming to provide a more intuitive and sensitive mode of interaction between humans and machines. Herein, we propose a neuromorphic percolative network inspired by neuron-astrocyte interactions for ultrasensitive pressure sensors employing metal microdendrites and nanostars. Electromechanical investigation through representative volume elements simulation reveals that the optimized arrangement of microdendrites and nanostars in the neuromorphic percolative system enhances the percolation threshold and probability. Following these simulation results, we developed a neuromorphic percolative polyurethane (NP-PU) matrix utilizing the metal microdendrite-nanostar networks. The augmented quantum tunneling effect in the NP-PU matrix was investigated through electrochemical impedance spectroscopy and capacitance analysis. The fabricated piezoresistive pressure sensor with the NP-PU matrix shows ultrahigh sensitivity (160.3 kPa−1) at a low pressure range and a low limit of detection resolution (4 Pa), enabled by multi-channel quantum tunneling in the metal particle networks. Furthermore, the sensor maintains excellent mechanical flexibility and high optical transparency (75.4 %), improving its efficacy in applications like electronic skin and force touch panel. Our study highlights the potential of leveraging biological system-inspired network designs for crafting advanced electronic devices.

Effect of laser wavelength on ablation propulsion and plasma characteristics with acrylonitrile butadiene styrene target

Propulsion performance produced by laser ablation of polymer made of acrylonitrile butadiene styrene is experimentally investigated using the first, second, and third harmonics of a Nd: YAG laser. A ballistic pendulum is employed to assess the impulse and coupling coefficient for laser propulsion application. Fast photography, target ablation, and optical emission spectroscopy are proposed to analyze the energy coupling characteristic. The impulse and coupling coefficient under different pressures are demonstrated to depend on the target ablation and plasma properties which are relevant to laser wavelength. As the laser wavelength decreases, the crater depth and ablation mass are enhanced. Meanwhile, the plasma plume separates at atmospheric pressure and its length extends continuously in the low-pressure range. As a result, plasma including more ejected particles with higher velocity contributes to obtaining excellent impulse and coupling coefficient. In addition, the decreased electron density and temperature indicate higher collision frequency and photoionization dominate rather than inverse bremsstrahlung absorption at shorter laser wavelengths. This work provides a better understanding of the energy conversion mechanism and a reference for improving propulsion performance.

Wearable electronic device for X-ray warning and health monitoring

The well-developed multifunctional wearable electronic device has fed the demand for human medicine and health monitoring in complex situations. However, the advancement of nuclear technology, especially irradiation medicine and safety inspections, has increased the exposure risk of irradiation safety workers. Traditional irradiation detectors are stiff and incompatible with the skin, and lack human health monitoring function, thus it’s vital to apply these flexible sensors for irradiation warning. Here, we report a novel composite gel device synthesized through solution processes by combining the Cs3Cu2I5:Zn nano-scintillator with the pre-patterned biocompatible gel, exhibiting a bi-functional response to motion/vibration sensing and sensitive irradiation warning. These wearable devices achieve a pressure sensitivity of up to 34 kPa−1 in a low-pressure range (0–3 kPa), a low limit of detection (LoD) down to 1.4 Pa, enabling health monitoring functions of pulse monitoring, finger bending, and elbow bending. Simultaneously, the device scintillates under X-ray irradiation among a wide dose rate range of 54–1167 μGyair s−1. The robust device shows no obvious signal loss after 4000 compression cycles and also excellent irradiation resistance over 50 days, broadening the path for designing and realizing new functional wearable devices.

Semi-analytical calculation model for friction of polymers on the example of POM ∣ PE-UHMW and steel ∣ PE-UHMW

In this paper, a semi-analytical calculation model for the coefficient of friction (COF) of single spherical protrusions is presented. It allows the prediction of the deformative friction part (μdef) and adhesive friction part (μadh) of the friction pairings steel ∣ polyethylene with ultra-high molecular weight (PE-UHMW) and polyoxymethylene (POM) ∣ PE-UHMW. The experimental studies included unlubricated friction tests, which served to determine the total COF (μtot), as well as tests being lubricated with silicone oil, from which μdef is obtained. Based on the verification tests, it could be shown that both states of lubrication result in the same deformation and that the relationship between the rear angle (ω) and μdef postulated in the calculation model is valid. Therefore, friction tests with segmented spheres were carried out, which allow a specific variation of the ω.It can be concluded that for both pairings the μdef is generally of minor significance (approx. 1/3 μtot) and the influence of the μadh predominates (approx. 2/3 μtot) the friction process. Furthermore the μtot decreases with increasing contact pressure especially in the low pressure range and depends on the form of motion (continuous and discontinuous).

Microwave Corona Breakdown Suppression of Microstrip Coupled-Line Filter Using Lacquer Coating

Due to its potential harm to space payload, microwave corona breakdown of microstrip circuits has attracted much attention. This work describes an efficient way to suppress corona breakdown. Since the corona breakdown threshold is determined by the highest electric field intensity at the surface of microstrip circuits, lacquer coating with a thickness of tens of microns is sprayed on top of microstrip circuits. The applied dielectric coating is used to move the discharge location away from the circuit’s surface, which is equivalent to reducing the highest electric field intensity on the interface of solid/air of the circuit and thus results in a higher breakdown threshold. Two designs of a classic coupled-line bandpass filter were used for verification. Corona experimental results at 2.5 GHz show that in the low-pressure range of interest (100 to 4500 Pa), a 5.3 dB improvement of the microwave corona breakdown threshold can be achieved for a filter with a narrowest gap of 0.2 mm, while its electrical performances like insertion loss and Q-factor are still acceptable. A threshold improvement prediction method is also presented and validated.

Hydrovoltaic–piezoelectric hybridized device for microdroplet-pressure dual energy harvesting and piezo sensing

Previous droplet-based nanogenerators have made significant advancements in mechanical energy harvesting from liquid–solid contact electrification. However, these generators still face certain issues, such as neglecting substrate deformation energy, inability to store energy, and surface deterioration due to continuous impact of droplets, thus narrowing the scope of their potential applications. Here, a novel hydrovoltaic-piezoelectric hybridized device (HPeD) is reported that integrates hydrocapacitor, aluminum–air (Al–air) battery, and piezoelectric nanogenerator technologies through a green design strategy, which can effectively address the proposed problems. Impinged by a 40-μL water droplet, the HPeD yields a potential window of 1.54 V within approximately 1 min, further boosting to 1.86 V under external vertical pressure. The generated energy was greatly stored for up to 5.7 days. This all-solid-state device effectively inhibits electrolyte leakage during idle periods and controls reversible reactions to minimize corrosion, thereby extending its lifespan. Furthermore, the HPeD is successfully used as a piezoelectric nanogenerator/sensor that can operate continuously to detect external mechanical stimulus. In piezo sensor mode, the device demonstrated good sensitivity of 0.098 kPa−1 in the low-pressure range (0–8.2 kPa), a remarkable response/relaxation time of 0.3 s, and durability lasting over 8000 cycles. This study paves the way for the advancement of next-generation flexible hybrid devices capable of multifunctionality in both energy harvesting and sensing.

Pressure-Induced Re-Entrant Superconductivity in Transition Metal Dichalcogenide TiSe2.

Transition metal dichalcogenide TiSe2 exhibits a superconducting dome within a low pressure range of 2-4GPa, which peaks with the maximal transition temperature Tc of ≈1.8 K. Here it is reported that applying high pressure induces a new superconducting state in TiSe2, which starts at ≈16GPa with a substantially higher Tc that reaches 5.6 K at ≈21.5GPa with no sign of decline. Combining high-throughput first-principles structure search, X-ray diffraction, and Raman spectroscopy measurements up to 30GPa, It is found that TiSe2 undergoes a first-order structural transition from the 1T phase under ambient pressure to a new 4O phase under high pressure. Comparative ab initio calculations reveal that while the conventional phonon-mediated pairing mechanism may account for the superconductivity observed in 1T-TiSe2 under low pressure, the electron-phonon coupling of 4O-TiSe2 is too weak to induce a superconducting state whose transition temperature is as high as 5.6 K under high pressure. The new superconducting state found in pressurized TiSe2 requires further study on its underlying mechanism.

Efficient Low-Pressure CO2 capture via ZIF-8 modified by deep eutectic solvents

To enhance CO2 sorption efficiency under low-pressure conditions and effectively compete with N2 sorption in flue gas, modifications are implemented aimed at improving the adsorption capacity and selectivity of ZIF-8, renowned for their robust stability. Deep eutectic solvent (DES) comprising tetraethylammonium chloride (TEAC), tetrapropylammonium chloride (TPAC), and tetrabutylammonium bromide (TBAB) as hydrogen-bond acceptors, along with ethanolamine (MEA) as the hydrogen-bond donor, were meticulously prepared for this purpose. ZIF-8 underwent modification through DES loading, resulting in the distinctive emergence of a “core-membrane” structure. Characterization revealed that the DES effectively adhered to the surface of ZIF-8 in a membrane-like structure, without altering the chemical structure or pore size of ZIF-8. The most significant enhancement in sorption capacity was observed with TPAC&MEA modification. Considering the presence of N2 partial pressure in the flue gas, at 0.05 and 1 bar, the CO2 adsorption capacities reached 1.92 and 3.03 mmol g−1, respectively, increasing 71.11 and 4.00 times compared to pristine ZIF-8. The ZIF-8 exhibited a CO2/N2 separation coefficient of 72.77, which increased to a maximum of 997.50 after DES modification. Additionally, the modified material demonstrated exceptional cyclic and thermal stability during testing. This study significantly elevates the CO2 adsorption capacity and selectivity of solid materials within the low-pressure range, providing pivotal support for CO2 capture and decarbonization efforts.

Thermodynamic and economic analyses of the biomass gasification Allam cycle integrated with compressed carbon energy storage

The Allam cycle is a novel oxy-fuel power system that has the potential to achieve efficient negative carbon emissions. Compressed carbon energy storage (CCES) technology could improve the stability of power plants. A biomass gasification Allam cycle combined with the CCES system is proposed and evaluated in this research. The energy efficiency of the Allam-CCES cycle during the charge and discharge time is 36.43 % and 39.45 %, respectively. The round trip efficiency (RTE) of the CCES system is 62.04 %. The exergy destruction of the Allam-CCES system is 317.02 MW. Economic analysis shows that the proposed system has a net present value of 447347.97 k$, implying benefits in economic performance. The total cost rate of the Allam-CCES system is 6959.63 $/h. The influence of the storage pressure on the CCES system is evaluated. The RTE drops from 64.55 % to 61.12 % as the high storage pressure rises. The variation of RTE has a crest when the low storage pressure is near critical pressure. The highest RTE is 90.71 % in the research range of low storage pressure. This paper could provide information on biomass gasification Allam cycle integrated with CCES technology, and offer insights to realize efficient and economic carbon emissions reduction.

Wide-range, durable, and adaptable miniature pressure sensor based on planar capacitance

Capacitive pressure sensor (CPS) is widely used in the field of industrial equipment, because of the merits of fast dynamic response and high resolution. However, the traditional laminated CPS makes it difficult to achieve a wide detection limit in a small size, and this structure is susceptible to electromagnetic interference. Here we developed a miniature planar capacitive pressure sensor (MPCPS) with high performance, which can realize the response to external touching stimuli through the deformation of the packaging material and the change of the equivalent resistance. A metal shielding layer was added under the insulating substrate to effectively isolate the external interference. The thickness of the sensor is about 200 μm, and the diameter of the core sensing area is less than 1 mm. Two types of electrodes with different shapes were designed, among which the spiral electrode MPCPS (S-MPCPS) has better performance than the linear electrode MPCPS. The S-MPCPS has a sensitivity of 99.2% MPa−1 in the low-pressure range (0–0.1 MPa), fast response (20 ms), wide detection limit (>1 MPa), and high durability (>2000 cycles). In addition, MPCPS is proven to have good resistance to high temperature and oil contamination. Finally, practical applications such as contact pressure measuring on the meshing surface of spur gears and mechanical gripper clamping force monitoring were successfully demonstrated. These results shed light on the potential application of the MPCPS in the pressure detection of industrial equipment.

Rational Design of Amorphous Carbon-Coated Laminar-Structured Wood for Integrating Repeatable Early Fire Detection and High-Temperature Affordable Flexible Pressure Sensing in One System.

High-temperature affordable flexible polymer-based pressure sensors integrated with repeatable early fire warning service are strongly desired for harsh environmental applications, yet their creation remains challenging. This work proposed an approach for preparing such advanced integrated sensors based on silver nanoparticles and an ammonium polyphosphate (APP)-modified laminar-structured bulk wood sponge (APP/Ag@WS). Such integrated sensors demonstrated excellent fire warning performance, including a short response time (minimum of 0.44 s), a long-lasting alarm time (>750 s), and reliable repeatability. Moreover, it achieved high-temperature affordable flexible pressure sensing that exhibited an almost unimpaired working range of 0-7.5 kPa and a higher sensitivity (in the low-pressure range, maximum to 226.03 kPa-1) after fire. The high stability was attributed to reliable structural elasticity, and the wood-derived amorphous carbon is capable of repeatable fire warnings. Finally, a Ag@APP/WS-based wireless fire alarm system that realized reliable house fire accident detection was demonstrated, showing great promise for smart firefighting application.

Switching of n- and p-type doping with partial pressure of oxygen gas on few layers MoS2-field effect transistor

We examined the oxygen adsorption effect on the electric property of the field-effect transistor with an atomic layer MoS2 channel, whose experiment was executed in well-defined ultra-high vacuum conditions and with surface treatment. The threshold voltage change of the Id-Vg curve with the oxygen partial pressure shows n-type doping in the low-pressure range and p-type doping in the high-pressure range. In this report, the Vth vs. oxygen partial pressure uptake curve is well modeled with the Langmuir type adsorption/desorption. The deduced adsorption energy indicates that the adsorbed species are oxygen atoms on the pristine MoS2, suggesting a catalytic behavior of MoS2 for the oxygen reduction reaction. The oxygen adsorption at the S vacant site induces the initial n-type doping. DFT calculation illustrates that, despite the electron transfer from the substrate to the oxygen molecule, the electronic structure change causes the n-type doping.

Modeling of multilayer water adsorption and condensation in slits of cement minerals by molecule simulation and adsorption isotherm

The interactions between water and multiscale pores affect significantly most of the physical and chemical properties of cementitious materials such as cement mortar, paste, and concrete. In this paper, molecular mechanism of multilayer water adsorption and condensation in micropores of typical cementitious minerals, the dicalcium silicate (C2S) and calcium silicate hydrate (C-S-H), were investigated by molecular simulations. Classical adsorption isotherm models were examined for their applicability to describe the adsorption law in molecular scales. Besides, the Kelvin equation was modified to satisfy the description of condensation at the microscale. Calculation results show that the most commonly used Brunauer-Emmett-Teller (BET) model can only describe the isotherms within a limited range of low water vapor pressures. In comparison, the modified Brunauer-Emmett-Teller-Pickett (BETP) model can describe the adsorption of water molecular on the surface of C2S and C-S-H more precisely, due to considering the adsorption layers as finite at saturation pressure and the reduced escape probability of the outermost layer of adsorbed water molecules. As for the condensation of water molecules in C2S and C-S-H slits, the traditional Kelvin equation is not applicable. Therefore, a refined Kelvin equation was proposed to describe the relationship between pore size and the pressure required for condensation accurately by considering the critical pore size, adsorption thickness, and decay rate of adsorption potential energy. Further analysis suggests that C2S releases more first-layer adsorption heat and thus shows stronger adsorption of water molecules compared to C-S-H.

Two-Stage Micropyramids Enhanced Flexible Piezoresistive Sensor for Health Monitoring and Human-Computer Interaction.

High-performance flexible piezoresistive sensors are becoming increasingly essential in various novel applications such as health monitoring, soft robotics, and human-computer interaction. The evolution of the interfacial contact morphology determines the sensing properties of piezoresistive devices. The introduction of microstructures enriches the interfacial contact morphology and effectively boosts the sensitivity; however, the limited compressibility of conventional microstructures leads to rapid saturation of the sensitivity in the low-pressure range, which hinders their application. Herein, we present a flexible piezoresistive sensor featuring a two-stage micropyramid array structure, which effectively enhances the sensitivity while widening the sensing range. Owing to the synergistic enhancement effect resulting from the sequential contact of micropyramids of various heights, the devices demonstrate remarkable performance, including boosting sensitivity (30.8 kPa-1) over a wide sensing range (up to 200 kPa), a fast response/recovery time (75/50 ms), and an ultralong durability of 15,000 loading-unloading cycles. As a proof of concept, the sensor is applied to detect human physiological and motion signals, further demonstrating a real-time spatial pressure distribution sensing system and a game control system, showing great potential for applications in health monitoring and human-computer interaction.

High tensile properties, wide temperature tolerance, and DLP-printable eutectogels for microarrays wearable strain sensors

Due to good stretchability, conductive gels have significant advantages in the field of manufacturing wearable flexible electronic devices. However, hydrogel-based and ionogel-based conductive materials reported in previous studies are prone to solvent evaporation and leakage, which would seriously affect the gel electromechanical performance in extreme working environments. In addition, how to manufacture gel-based flexible devices with complex structures is also a significant challenge in this field. Based on this, a photocurable 3D-printed eutectogel system was designed in this work. The precursor solution was composed of N-hydroxymethyl acrylamide (NAM), hydroxyethyl methacrylate (HEMA), and DES solvents. The prepared eutectogel had excellent comprehensive properties, such as good transparency (>80 % in the visible region), high tensile performance (up to 648 %), strong mechanical strength (breaking strength up to 938 kPa), electrical conductivity (up to 78 mS/m at 25 ℃), environmental tolerance (-80 ℃ − 60 ℃), and so on. In addition, flexible wearable devices with complex microstructures can be constructed efficiently by DLP printing technology. In the low-pressure detection range (0–––2.5 kPa), the sensitivity of the printed eutectogel-based microarray was 8.78 times higher than that of the block or sheet gel structure, and various weak deformation signals can be timely and accurately detected. Therefore, the combination of photo-cured 3D printing and eutectic gels will provide new possibilities for the development and promotion of intelligent, flexible wearable devices.

Pressure Dependence of the Structural and Superconducting Properties of the Bi-Based Superconductor Bi2Pd3Se2.

The structural and superconducting properties of the Bi-based compound Bi2Pd3Se2 were investigated over a wide pressure range. The prepared Bi2Pd3Se2 sample was a superconductor with a superconducting transition temperature, Tc, of approximately 3.0 K, which differed from a previous report (Tc of less than 1.0 K). At ambient pressure, the powder X-ray diffraction (XRD) pattern of the Bi2Pd3Se2 sample was consistent with that previously reported for Bi2Pd3Se2. The Rietveld method was used to refine the crystal structure, which had a space group of C2/m (No. 12), as reported previously. This compound showed no clear anomaly due to the charge-density-wave (CDW) transition, as seen from the temperature dependence of magnetic susceptibility. However, the temperature dependence of electrical resistivity indicated a clear anomaly, presumably because of the CDW transition in the low-pressure range; the CDW transition temperature was approximately 230 K. The XRD patterns of the Bi2Pd3Se2 sample were measured at 0.160-22.7 GPa, and the patterns were well analyzed by both the Le Bail and Rietveld refinement methods, showing no structural phase transitions in the above pressure range. The pressure dependence of Tc of Bi2Pd3Se2 was recorded based on the temperature dependence of the electrical resistance, which showed an almost constant Tc at 0-13.7 GPa, and the Tc-pressure (p) behavior was fully discussed.