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1.
J Integr Neurosci ; 22(2): 47, 2023 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-36992589

RESUMO

OBJECTIVE: This study aimed to observe the clinical efficacy of long-term spinal nerve posterior ramus pulsed radiofrequency (PRF) in treating subacute herpes zoster neuralgia (HZN). METHODS: A total of 120 patients with subacute HZN in the thoracolumbar region and back were equally randomized to the conventional PRF group (P group, n = 60), with a pulse of 180 s, or to the long-term PRF group (LP group, n = 60), with a pulse of 600 s. The patients' baseline characteristics, the incidence rate of postherpetic neuralgia (PHN), and the dose of analgesics were compared between the two groups. RESULTS: Based on the pain-rating index (PRI), the PRI-sensory, PRI-affective, visual analogue scale, and present pain intensity scores in the two groups were lower at T2, T3, and T4 time points than at the T1 time point after treatment (p < 0.05). After 2 months, the dose of analgesics was significantly lower in the LP group than in the P group (p < 0.05), and the incidence of PHN was considerably lower. CONCLUSIONS: Long-term spinal nerve posterior ramus PRF is a more effective treatment strategy for subacute HZN than conventional PRF. It can effectively prevent the occurrence of PHN.


Assuntos
Herpes Zoster , Neuralgia Pós-Herpética , Neuralgia , Tratamento por Radiofrequência Pulsada , Humanos , Estudos Prospectivos , Neuralgia/terapia , Neuralgia Pós-Herpética/terapia , Herpes Zoster/terapia , Analgésicos , Nervos Espinhais
2.
Small ; 14(35): e1801657, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-30058286

RESUMO

Nature has long offered human beings with useful materials. Herein, plant materials including flowers and leaves have been directly used as the dielectric material in flexible capacitive electronic skin (e-skin), which simply consists of a dried flower petal or leaf sandwiched by two flexible electrodes. The plant material is a 3D cell wall network which plays like a compressible metamaterial that elastically collapses upon pressing plus some specific surface structures, and thus the device can sensitively respond to pressure. The device works over a broad-pressure range from 0.6 Pa to 115 kPa with a maximum sensitivity of 1.54 kPa-1 , and shows high stability over 5000 cyclic pressings or bends. The natural-material-based e-skin has been applied in touch sensing, motion monitoring, gas flow detection, and the spatial distribution of pressure. As the foam-like structure is ubiquitous in plants, a general strategy for a green, cost-effective, and scalable approach to make flexible e-skins is offered here.


Assuntos
Eletricidade , Plantas/química , Dispositivos Eletrônicos Vestíveis , Plantas/ultraestrutura , Maleabilidade
3.
Langmuir ; 33(40): 10577-10587, 2017 10 10.
Artigo em Inglês | MEDLINE | ID: mdl-28930633

RESUMO

The effect of particle parameters [aspect ratio (AR) and concentration] and flow conditions (gap spacing and shear rate) on droplet orientation deformation behavior in polystyrene (PS) particle-filled binary polymeric emulsions is investigated by using a rheo-optical technique and confocal microscopy. Interesting vorticity orientation behavior is achieved by tailoring experimental conditions to yield rigid anisotropic droplets during slow confined shear flow. PS ellipsoids with a high AR are found to reside both at the fluid interface in a monolayer side-on state and inside droplets, leading to the formation of rigid anisotropic droplets because of the interfacial/bulk jamming effect at appropriate particle concentrations. In unconfined bulk samples, droplets with a vorticity orientation can also be observed under the wall migration effect and confinement effect arising from nearby droplets. However, the overly strong wall confinement effect remarkably facilitates the coalescence of vorticity-aligned droplets during slow shear, eventually leading to the formation of a long stringlike phase aligning along the flow direction. High shear rates generate refined droplets with lower particle coverage and weak rigidity, which restrain the formation of anisotropic droplets and thus suppress the droplet vorticity orientation.

4.
Nanoscale ; 16(14): 6961-6972, 2024 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-38362794

RESUMO

The complex hybrid nanostructure combining a two-dimensional (2D) conductive material and a hierarchical nanoscale skeleton plays an important role to enhance its piezoresistive sensitivity. To construct such a novel hybrid nanostructure, a piezoresistive sensor was designed with the following strategy to take the full advantages of 2D MXene and nanoscale fibrils: ethylene oxide propylene oxide random copolymer (EOPO) was grafted to ethylene-vinyl alcohol (EVOH) molecular chains and was foamed by an environmentally-friendly supercritical CO2 (scCO2) foaming technology to fabricate abundant nanoscale EVOH fibrils surrounding micropores; MXene featured as a 2D structure of nanoscale size that strongly interacted with this hierarchical nanoscale skeleton, and MXene not only convolved on nanoscale fibrils to generate bumps but also MXene covered the end of broken fibrils to build spots, and furthermore, MXene adhered on the soft EOPO embedded EVOH fibrils to form wrinkles, in which these bumps, spots and wrinkles assembled by highly conductive 2D MXene offered sufficient contacts when the hierarchical nanoscale skeleton was compressed (these contacts would then destruct when the skeleton recovered). Such an elaborated hybrid nanostructural design exploits the full potential of 2D MXene and hence achieves an ultra-high sensitivity of 6895.0 kPa-1 for this fabricated MXene piezoresistive sensor.

5.
Ying Yong Sheng Tai Xue Bao ; 35(4): 909-916, 2024 Apr 18.
Artigo em Chinês | MEDLINE | ID: mdl-38884225

RESUMO

The stoichiometric characteristics of leaves can reflect environmental adaptation of plants, and thus the study of the relationship between them is helpful for exploring plant adaptation strategies. In this study, taking the national second-level key protection species, Ammopiptanthus mongolicus, as the research object, we set up 26 plots to collect samples, and measured the content of carbon (C), nitrogen (N), phosphorus (P) and water use efficiency (WUE) of leaves. We analyzed the relationship between leaf stoichiometric characteristics and WUE, and quantified the contributions of soil, climate, and water use efficiency to the variations of leaf stoichiometry. The results showed that C, N, and P contents in the leaves were (583.99±27.93), (24.31±2.09), and (1.83±0.06) mg·g-1, respectively. The coefficients of variation were 4.8%, 8.6%, and 3.2%, respectively, all belonging to weak variability, indicating that foliar contents of C, N and P tended to a certain stable value. The average value of N:P was 13.3, indicating that the growth of A. mongolicus was mainly limited by N. WUE was not correlated with leaf C content, but was significantly positively correlated with leaf N and P contents and N:P, and significantly negatively correlated with C:N and C:P, indicating that there was a linear synergistic trend between WUE and leaf nutrient content. The main factors influencing leaf C content and C:P were climatic factors, the leaf N content and N:P were mainly affected by soil factors, and the water use efficiency mainly affected leaf P content and C:N, indicating that the driving factors of different stoichiometric characteristics were different. The results could help eva-luate the habitat adaptation of desert plants, which would provide a theoretical basis for the conservation and management of A. mongolicus.


Assuntos
Carbono , Nitrogênio , Fósforo , Folhas de Planta , Folhas de Planta/química , Folhas de Planta/metabolismo , Folhas de Planta/crescimento & desenvolvimento , China , Nitrogênio/análise , Nitrogênio/metabolismo , Fósforo/análise , Fósforo/metabolismo , Carbono/análise , Carbono/metabolismo , Ecossistema , Água/análise , Água/metabolismo , Água/química , Adaptação Fisiológica , Solo/química
6.
ACS Nano ; 18(22): 14672-14684, 2024 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-38760182

RESUMO

Flexible sensing systems (FSSs) designed to measure plantar pressure can deliver instantaneous feedback on human movement and posture. This feedback is crucial not only for preventing and controlling diseases associated with abnormal plantar pressures but also for optimizing athletes' postures to minimize injuries. The development of an optimal plantar pressure sensor hinges on key metrics such as a wide sensing range, high sensitivity, and long-term stability. However, the effectiveness of current flexible sensors is impeded by numerous challenges, including limitations in structural deformability, mechanical incompatibility between multifunctional layers, and instability under complex stress conditions. Addressing these limitations, we have engineered an integrated pressure sensing system with high sensitivity and reliability for human plantar pressure and gait analysis. It features a high-modulus, porous laminated ionic fiber structure with robust self-bonded interfaces, utilizing a unified polyimide material system. This system showcases a high sensitivity (156.6 kPa-1), an extensive sensing range (up to 4000 kPa), and augmented interfacial toughness and durability (over 150,000 cycles). Additionally, our FSS is capable of real-time monitoring of plantar pressure distribution across various sports activities. Leveraging deep learning, the flexible sensing system achieves a high-precision, intelligent recognition of different plantar types with a 99.8% accuracy rate. This approach provides a strategic advancement in the field of flexible pressure sensors, ensuring prolonged stability and accuracy even amidst complex pressure dynamics and providing a feasible solution for long-term gait monitoring and analysis.


Assuntos
Pressão , Humanos , Análise da Marcha/instrumentação , Análise da Marcha/métodos , Dispositivos Eletrônicos Vestíveis , Marcha/fisiologia , Pé/fisiologia
7.
Nat Commun ; 14(1): 1382, 2023 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-36914642

RESUMO

Olivine is the dominant phenocryst or xenocryst of Hawaiian tholeiitic basalts, and the general consensus is that lavas with MgO concentrations from 7.5 to about 15 weight percent were derived from their primary magmas, which contain ~18-20 weight percent MgO, by only olivine crystallization. However, the major element composition of estimated primary magmas through olivine crystallization correction is inconsistent with direct partial melting of either mantle peridotite or its hybrid with subducted oceanic crust. Our melting experiments on peridotite-derived melt composition show that this discrepancy can be resolved if the primary magmas experienced two other processes before abundant olivine fractionation. First, the primary magmas experienced crystallization of clinopyroxene and garnet in the chamber at the base of the lithosphere (approximately the depths of 90-100 km). Second, the evolved magmas re-equilibrated with harzburgite when passing through the lithospheric mantle (approximately the depths of 60-10 km). Different from the isotopic evidence, the major and rare earth element compositions of Hawaiian post-shield alkali basalts and shield tholeiites suggest that they form from the same source by assimilating different amounts of orthopyroxene.

8.
Int J Mol Med ; 52(1)2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37232339

RESUMO

Osteoarthritis (OA) is a progressive joint disorder, which is principally characterized by the degeneration and destruction of articular cartilage. The cytoskeleton is a vital structure that maintains the morphology and function of chondrocytes, and its destruction is a crucial risk factor leading to chondrocyte degeneration and OA. Hyaluronan synthase­2 (HAS­2) is a key enzyme in synthesizing hyaluronic acid (HA) in vivo. The synthesis of high molecular weight HA catalyzed by HAS­2 serves a vital role in joint movement and homeostasis; however, it is unclear what important role HAS­2 plays in maintaining chondrocyte cytoskeleton morphology and in cartilage degeneration. The present study downregulated the expression of HAS­2 by employing 4­methylumbelliferone (4­MU) and RNA interference. In vitro experiments, including reverse transcription­quantitative PCR, western blotting, laser scanning confocal microscopy and flow cytometry were subsequently performed. The results revealed that downregulation of HAS­2 could activate the RhoA/ROCK signaling pathway, cause morphological abnormalities, decrease expression of the chondrocyte cytoskeleton proteins and promote chondrocyte apoptosis. In vivo experiments, including immunohistochemistry and Mankin's scoring, were performed to verify the effect of HAS­2 on the chondrocyte cytoskeleton, and it was revealed that inhibition of HAS­2 could cause cartilage degeneration. In conclusion, the present results revealed that downregulation of HAS­2 could activate the RhoA/ROCK pathway, cause abnormal morphology and decrease chondrocyte cytoskeleton protein expression, leading to changes in the signal transduction and biomechanical properties of chondrocytes, promotion of chondrocyte apoptosis and the induction of cartilage degeneration. Moreover, the clinical application of 4­MU may cause cartilage degeneration. Therefore, targeting HAS­2 may provide a novel therapeutic strategy for delaying chondrocyte degeneration, and the early prevention and treatment of OA.


Assuntos
Cartilagem Articular , Osteoartrite , Humanos , Cartilagem Articular/metabolismo , Condrócitos/metabolismo , Citoesqueleto/metabolismo , Regulação para Baixo , Hialuronan Sintases/metabolismo , Osteoartrite/metabolismo , Proteína rhoA de Ligação ao GTP/metabolismo , Transdução de Sinais
9.
Polymers (Basel) ; 15(3)2023 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-36771893

RESUMO

Bismaleimide (BMI) resin is an excellent performance resin, mainly due to its resistance to the effect of heat and its insulating properties. However, its lack of toughness as a cured product hampers its application in printed circuit boards (PCBs). Herein, a branched structure via Michael addition was introduced to a BMI system to reinforce its toughness. Compared with a pure BMI sample, the flexural strength of the modified BMI was enhanced, and its maximum value of 189 MPa increased by 216%. The flexural modulus of the cured sample reached 5.2 GPa. Using a scanning electron microscope, the fracture surfaces of BMI samples and a transition from brittle fracture to ductile fracture were observed. Furthermore, both the dielectric constant and the dielectric loss of the cured resin decreased. The breakdown field strength was raised to 37.8 kV/mm and the volume resistivity was improved to varying degrees. Consequently, the resulting modified BMI resin has the potential for wide application in high-frequency and low-dielectric resin substrates, and the modified BMI resin with a structure including three different diamines can meet the needs of various applications.

10.
Ying Yong Sheng Tai Xue Bao ; 34(3): 664-670, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37087649

RESUMO

To explore the stoichiometric characteristics of C, N and P and adaptive mechanism of mosses in mountain forest ecosystems, we set up 15 plots along the altitude gradient in Picea crassifolia forest in Helan Mountains, Ningxia. We analyzed the C:N:P stoichiometry of moss aboveground tissues and its relationship with environmental factors. The results showed the mean values of C, N and P concentration in moss aboveground tissues were 336.67, 20.31 and 0.66 mg·g-1, respectively. The mean value of aboveground tissue N:P was 33.4, indicating that the growth of mosses was limited by P. The C concentration in the aboveground tissues of mosses was positively correlated with soil total nitrogen concentration and negatively correlated with soil total phosphorus concentration. The N concentration in aboveground tissues of mosses was significantly negatively correlated with soil organic carbon and soil total nitrogen concentrations. Results of redundancy analysis showed that the interpretation rate of environmental factors on the stoichiometry was 48.5%, with canopy closure, soil total nitrogen and soil total phosphorus as the main factors. Canopy closure was the main environmental factor affecting the growth of mosses in P. crassifolia forest in Helan Mountains. High canopy closure facilitated the growth of mosses.


Assuntos
Briófitas , Picea , Ecossistema , Carbono/análise , Solo , Florestas , China , Nitrogênio/análise , Fósforo/análise
11.
Ying Yong Sheng Tai Xue Bao ; 33(1): 219-228, 2022 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-35224944

RESUMO

To reveal the effects of plantations on soil microbial environment,the composition and diversity of soil fungi and bacterial communities in five restoration models (Robinia pseudoacacia, Populus hopeiensis, Pinus tabuliformis, Picea crassifolia, natural restoration) in the mountainous area of southern Ningxia were compared by using high-throughput sequencing technology. The correlation between soil physical-chemical properties and dominant microbial groups was analyzed. The results showed that: 1) Dominant fungi in different restoration models were Ascomycota, Basidiomycota, Mortierellomycota, and unclassified fungi, which accounted for 90% of total fungal community. The dominant soil bacteria were Actinobacteria, Proteobacteria, Acidobacteriota, Chloroflexi, and other bacteria, accounting for more than 80% of total bacterial community. 2) The diversity of soil fungi in P. tabuliformis forest was the highest, with Shannon index, and Simpson index being 3.72±0.37 and 0.07±0.04, respectively. The richness of fungi in naturally restored forest land was the highest, with Ace and Chao1 index of 708.19±137.25 and 706.26±125.34, respectively. The bacterial diversity and richness of species in P. tabuliformis forest land was the highest. The Shannon, Simpson, Ace and Chao1 indices were 6.57±0.04, 0.004±0.00, 3439.81±41.67, 3463.14±32.16, respectively. 3) The fungus with significant difference among restoration models were Solicoccozyma, Cladosporium, and Alternaria. Bacteria from Norank_f_67-14, Rubrobacter_f_Rubrobacteraceae, Sphingomonas_f_Sphingomonadaceae had significant difference among restoration models. 4) The RDA ordination of the dominant microbial flora and soil physical-chemical properties showed that soil bulk density (BD), carbon to nitrogen ratio (C/N), and pH were the major factors affecting the dominant fungal flora. BD, nitrogen to phosphorus ratio (N/P), total phosphorus (TP), and total carbon (TC) were the main factors affecting the dominant bacterial flora. In general, the difference of composition and diversity in the fungal community of different restoration models was higher than that of the bacterial community, indicating that the fungal communities were more sensitive to the changes of tree species and soil environment than bacterial communities. Our results could provide the theoretical foundation for vegetation restoration measures and the maintenance of ecosystem function stability in southern Ningxia.


Assuntos
Emigrantes e Imigrantes , Microbiota , China , Emigração e Imigração , Fungos , Humanos , Solo/química , Microbiologia do Solo
12.
Micromachines (Basel) ; 13(5)2022 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-35630161

RESUMO

Flexible wearable pressure sensors play a pivotal role in healthcare monitoring, disease prevention, and humanmachine interactions. However, their narrow sensing ranges, low detection sensitivities, slow responses, and complex preparation processes restrict their application in smart wearable devices. Herein, a capacitive pressure sensor with high sensitivity and flexibility that uses an ionic collagen fiber material as the dielectric layer is proposed. The sensor exhibits a high sensitivity (5.24 kPa-1), fast response time (40 ms), long-term stability, and excellent repeatability over 3000 cycles. Because the sensor is resizable, flexible, and has a simple preparation process, it can be flexibly attached to clothes and the human body for wearable monitoring. Furthermore, the practicality of the sensor is proven by attaching it to different measurement positions on the human body to monitor the activity signal.

13.
Nat Commun ; 13(1): 1317, 2022 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-35273183

RESUMO

Electronic skins (e-skins) are devices that can respond to mechanical stimuli and enable robots to perceive their surroundings. A great challenge for existing e-skins is that they may easily fail under extreme mechanical conditions due to their multilayered architecture with mechanical mismatch and weak adhesion between the interlayers. Here we report a flexible pressure sensor with tough interfaces enabled by two strategies: quasi-homogeneous composition that ensures mechanical match of interlayers, and interlinked microconed interface that results in a high interfacial toughness of 390 J·m-2. The tough interface endows the sensor with exceptional signal stability determined by performing 100,000 cycles of rubbing, and fixing the sensor on a car tread and driving 2.6 km on an asphalt road. The topological interlinks can be further extended to soft robot-sensor integration, enabling a seamless interface between the sensor and robot for highly stable sensing performance during manipulation tasks under complicated mechanical conditions.

14.
Ying Yong Sheng Tai Xue Bao ; 32(3): 819-824, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33754546

RESUMO

We analyzed the relationship between carbon stable isotope characteristics of 131 Hippophae populations and environmental factors by measuring the foliar δ13C value in Hippophae. The results showed that the foliar δ13C values of Hippophae ranged from -24.65‰ to -29.11‰, with an average of -26.97‰. Hippophae species were C3 plants. For the foliar δ13C values, the coefficient variation at intraspecific level was higher than that at interspecific level, indicating that environmental factors should be main factors driving the variations of leaf δ13C. The δ13C values had no significant correlation with latitude and longitude, but were negatively correlated with altitude. The regression equation was δ13C(‰)=0.118VAP-0.007GST-0.000028RDA-20.721 (R2=0.212,P<0.0001). Water vapor pressure (VAP), growing season temperature (GST), and radiation (RDA) were the major factors affecting foliar δ13C values. Our results could provide a theoretical basis to understand the responses of Hippophae species to global climate change.


Assuntos
Carbono , Hippophae , Isótopos de Carbono , Folhas de Planta , Plantas
15.
Adv Mater ; 33(7): e2003464, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33346388

RESUMO

Over the past decade, a brand-new pressure- and tactile-sensing modality, known as iontronic sensing has emerged, utilizing the supercapacitive nature of the electrical double layer (EDL) that occurs at the electrolytic-electronic interface, leading to ultrahigh device sensitivity, high noise immunity, high resolution, high spatial definition, optical transparency, and responses to both static and dynamic stimuli, in addition to thin and flexible device architectures. Together, it offers unique combination of enabling features to tackle the grand challenges in pressure- and tactile-sensing applications, in particular, with recent interest and rapid progress in the development of robotic intelligence, electronic skin, wearable health as well as the internet-of-things, from both academic and industrial communities. A historical perspective of the iontronic sensing discovery, an overview of the fundamental working mechanism along with its device architectures, a survey of the unique material aspects and structural designs dedicated, and finally, a discussion of the newly enabled applications, technical challenges, and future outlooks are provided for this promising sensing modality with implementations. The state-of-the-art developments of the iontronic sensing technology in its first decade are summarized, potentially providing a technical roadmap for the next wave of innovations and breakthroughs in this field.


Assuntos
Pele Artificial , Técnicas Biossensoriais , Técnicas Eletroquímicas , Eletrólitos/química , Desenho de Equipamento , Humanos , Gotículas Lipídicas , Modelos Moleculares , Concentração Osmolar , Relação Estrutura-Atividade , Propriedades de Superfície , Tato , Dispositivos Eletrônicos Vestíveis
16.
Sci Bull (Beijing) ; 66(11): 1091-1100, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-36654343

RESUMO

Electronic skins and flexible pressure sensors are important devices for advanced healthcare and intelligent robotics. Sensitivity is a key parameter of flexible pressure sensors. Whereas introducing surface microstructures in a capacitive-type sensor can significantly improve its sensitivity, the signal becomes nonlinear and the pressure response range gets much narrower, significantly limiting the applications of flexible pressure sensors. Here, we designed a pressure sensor that utilizes a nanoscale iontronic interface of an ionic gel layer and a micropillared electrode, for highly linear capacitance-to-pressure response and high sensitivity over a wide pressure range. The micropillars undergo three stages of deformation upon loading: initial contact (0-6 kPa) and structure buckling (6-12 kPa) that exhibit a low and nonlinear response, as well as a post-buckling stage that has a high signal linearity with high sensitivity (33.16 kPa-1) over a broad pressure range of 12-176 kPa. The high linearity lies in the subtle balance between the structure compression and mechanical matching of the two materials at the gel-electrode interface. Our sensor has been applied in pulse detection, plantar pressure mapping, and grasp task of an artificial limb. This work provides a physical insight in achieving linear response through the design of appropriate microstructures and selection of materials with suitable modulus in flexible pressure sensors, which are potentially useful in intelligent robots and health monitoring.

17.
ACS Nano ; 15(3): 5752-5761, 2021 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-33683874

RESUMO

Interfacial solar evaporators (ISEs) for seawater desalination have garnered enormous attention in recent decades due to global water scarcity. Despite the progress in the energy conversion efficiency and production rate of ISE, the poor portability of large-area ISE during transportation as well as the clogging of water transport pathways by precipitated salts during operation remain grand challenges for its fielded applications. Here, we designed an ISE with high energy conversion efficiency and shape morphing capability by integrating carbon nanotube (CNT) fillers with a light-responsive shape memory polymer (SMP, cross-linked polycyclooctene (cPCO)). Utilizing the shape memory effect, our ISE can be folded to an origami with 1/9 of its original size to save space for transportation and allow for on-demand unfolding upon sunlight irradiation when deployed in service. In addition, the ISE is equipped with a real-time clogging monitoring function by measuring the capacitance of the electric double layer (EDL) formed at the evaporator/seawater nanointerface. Due to its good energy conversion efficiency, high portability, and clogging monitoring capability, we envisage our ISE as a promising selection in solar evaporation technologies.

18.
Adv Healthc Mater ; 9(17): e2001023, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32729260

RESUMO

The pulse is a key biomedical signal containing various human physiological and pathological information highly related to cardiovascular diseases. Pulse signals are often collected from the radial artery based on Traditional Chinese Medicine, or by using flexible pressure sensors. However, the wrist wrapped with a flexible pressure sensor exhibits unstable signals under hand motion because of the concave surface of the wrist. By contrast, fingertips have a convex surface and therefore show great promises in stable and long-term pulse monitoring. Despite the promising potential, the fingertip pulse signal is weak, calling for highly sensitive detecting devices. Here, a highly sensitive and flexible iontronic pressure sensor with a linear sensitivity of 13.5 kPa-1 , a swift response, and remarkable stability over 5000 loading/unloading cycles is developed. This sensor enables stable and high-resolution detection of pulse waveform under both static condition and finger motion. Fingertip pulse waveforms from subjects of different genders, age, and health conditions are collected and analyzed, suggesting that fingertip pulse information is highly similar to that of the radial artery. This work justifies that fingertip is an ideal platform for pulse signals monitoring, which would be a competitive alternative to existing complex health monitoring systems.


Assuntos
Dedos , Pulso Arterial , Feminino , Frequência Cardíaca , Humanos , Masculino , Monitorização Fisiológica , Movimento (Física)
19.
Adv Sci (Weinh) ; 7(10): 2000348, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32440489

RESUMO

Human-computer interfaces, smart glasses, touch screens, and some electronic skins require highly transparent and flexible pressure-sensing elements. Flexible pressure sensors often apply a microstructured or porous active material to improve their sensitivity and response speed. However, the microstructures or small pores will result in high haze and low transparency of the device, and thus it is challenging to balance the sensitivity and transparency simultaneously in flexible pressure sensors or electronic skins. Here, for a capacitive-type sensor that consists of a porous polyvinylidene fluoride (PVDF) film sandwiched between two transparent electrodes, the challenge is addressed by filling the pores with ionic liquid that has the same refractive index with PVDF, and the transmittance of the film dramatically boosts from 0 to 94.8% in the visible range. Apart from optical matching, the ionic liquid also significantly improves the signal intensity as well as the sensitivity due to the formation of an electric double layer at the dielectric-electrode interfaces, and improves the toughness and stretchability of the active material benefiting from a plasticization effect. Such transparent and flexible sensors will be useful in smart windows, invisible bands, and so forth.

20.
Nat Commun ; 11(1): 209, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31924813

RESUMO

Sensitivity is a crucial parameter for flexible pressure sensors and electronic skins. While introducing microstructures (e.g., micro-pyramids) can effectively improve the sensitivity, it in turn leads to a limited pressure-response range due to the poor structural compressibility. Here, we report a strategy of engineering intrafillable microstructures that can significantly boost the sensitivity while simultaneously broadening the pressure responding range. Such intrafillable microstructures feature undercuts and grooves that accommodate deformed surface microstructures, effectively enhancing the structural compressibility and the pressure-response range. The intrafillable iontronic sensor exhibits an unprecedentedly high sensitivity (Smin > 220 kPa-1) over a broad pressure regime (0.08 Pa-360 kPa), and an ultrahigh pressure resolution (18 Pa or 0.0056%) over the full pressure range, together with remarkable mechanical stability. The intrafillable structure is a general design expected to be applied to other types of sensors to achieve a broader pressure-response range and a higher sensitivity.

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