Sustainable Oily Liquid-Proof Passive Cooling (SOC) Textile for Personal Thermal Management.

Sweat passive-cooling textiles with asymmetric wettabilities on different sides offer an effective and low-energy consumption solution to personal thermal management in extreme thermal environments. However, the sweat-wicking and the cooling abilities decrease when the textile is contaminated by low-surface tension oily liquid fouling. The integration of anti-oily liquid fouling and sweat-wicking abilities on textile involves resolving the contradiction between hydrophilic and oleophobic properties and seeking eco-friendly short-chain fluorides to reduce the surface energy. Herein, a sustainable oily liquid-proof passive cooling (SOC) textile for personal thermal management is proposed. The SOC textile is obtained by applying a fluoride-free hydrophobic coating layer to one side of the high thermal conductive superoleophobic/superhydrophilic basal textile, which is fabricated using eco-friendly short-chain fluoride. The SOC textile preserves the anti-oily liquid fouling property even after 2000 abrasion cycles. Experimental test revealed that the SOC textile exhibits a cooling effect of ≈5 °C compared with the cotton textile, and the up to 70% reduction in sweating rate under the constant metabolic heat production rates. The configuration of the SOC textile would inspire the future design of intelligent textiles for personal thermal management, and the proposed strategy have implications for fabrication of eco-friendly oil-water separation materials.

Seaweed-inspired underwater anti-oil-fouling and anti-fogging coating with mechanical durability.

Ecofriendly fabrication of anti-oil-fouling materials is of interest. Surfaces with underwater superoleophobicity have been fabricated which exhibit limited mechanical durability and water resistance. In this study, we report on a bioinspired bilayer design of a transparent anti-oil-fouling coating. Seaweed surfaces show anti-oil-fouling in the sea due to its high surface hydration ability. Mussels can adhere tightly onto a surface with good stability in the sea by virtue of its levodopa-containing secretions. The surface layer was fabricated using a crosslinked combination of carboxymethyl cellulose (CMC) and sodium alginate (AlgS) inspired by seaweed, with the addition of calcium ions. Polydopamine (PDA), a derivative of levodopa, was used as the underlayer to enhance bonding strength and water resistance. Oil that adhered to the coated surface was spontaneously detached upon immersion in water. The mechanism underlying this anti-oil-fouling effect was elucidated using Gibbs free energy theory. The coating exhibited mechanical durability and water resistance. The coating is transparent and preserves the original color of the substrate. The coated glass showed stable anti-fogging and anti-frost performance. These coatings hold promise for a wide range of anti-oil-fouling applications.

Bioinspired claw-engaged and biolubricated swimming microrobots creating active retention in blood vessels.

Swimming microrobots guided in the circulation system offer considerable promise in precision medicine but currently suffer from problems such as limited adhesion to blood vessels, intensive blood flow, and immune system clearance-all reducing the targeted interaction. A swimming microrobot design with clawed geometry, a red blood cell (RBC) membrane-camouflaged surface, and magnetically actuated retention is discussed, allowing better navigation and inspired by the tardigrade's mechanical claw engagement, coupled to an RBC membrane coating, to minimize blood flow impact. Using clinical intravascular optical coherence tomography in vivo, the microrobots' activity and dynamics in a rabbit jugular vein was monitored, illustrating very effective magnetic propulsion, even against a flow of ~2.1 cm/s, comparable with rabbit blood flow characteristics. The equivalent friction coefficient with magnetically actuated retention is elevated ~24-fold, compared to magnetic microspheres, achieving active retention at 3.2 cm/s, for >36 hours, showing considerable promise across biomedical applications.

Monitoring Cd2+ in oily wastewater using an aptamer-graphene field-effect transistor with a selective wetting surface.

The discharge of oily industrial wastewater containing heavy metal ions with the development of industry severely threatens the environment and human health. Therefore, it is of great significance to monitor the concentration of heavy metal ions in oily wastewater quickly and effectively. Here, an integrated Cd2+ monitoring system consisting of an aptamer-graphene field-effect transistor (A-GFET), oleophobic/hydrophilic surface and monitoring-alarm circuits was presented for monitoring the Cd2+ concentration in oily wastewater. In the system, oil and other impurities in wastewater are isolated by an oleophobic/hydrophilic membrane before detection. The concentration of Cd2+ is then detected by a graphene field-effect transistor with a Cd2+ aptamer modifying the graphene channel. Finally, the detected signal is collected and processed by signal processing circuits to judge whether the Cd2+ concentration exceeds the standard. Experimental results demonstrated that the separation efficiency of the oleophobic/hydrophilic membrane to an oil/water mixture was up to 99.9%, exhibiting a high oil/water separation ability. The A-GFET detecting platform could respond to changes in the Cd2+ concentration within 10 min with a limit of detection (LOD) of 0.125 pM. The sensitivity of this detection platform to Cd2+ near 1 nM was 7.643 × 10-2 nM-1. Compared with control ions (Cr3+, Pb2+, Mg2+, Fe3+), this detection platform exhibited a high specificity to Cd2+. Moreover, the system could send out a photoacoustic alarm signal when the Cd2+ concentration in the monitoring solution exceeds the preset value. Therefore, the system is practical for monitoring the concentration of heavy metal ions in oily wastewater.

Durable Superoleophobic Janus Fabric with Oil Repellence and Anisotropic Water-Transport Integration toward Energetic-Efficient Oil-Water Separation.

Porous materials with opposing superwettability toward oil and water have aroused widespread interest for their selective-wetting advantage in oil-water separation. The separation process, however, requires constant energy input to maintain the driving force. Further reducing the external energy consumption or accelerating the liquid transport during separation is still a challenge. The Janus membrane is an emerging porous material with opposing wettability toward a specific liquid on each side. The asymmetric wettability distribution leads to a surface energy gradient-driven liquid-transport behavior through the thickness, which significantly facilitates liquid transportation. It is conceived that porous materials possessing both Janus features and selective superwettability would reduce energy consumption and strengthen the efficiency in oil-water separation. Herein, a novel durable superoleophobic (SOHB) Janus fabric which possesses oil-repellent and surface energy gradient-driven water-transport properties was developed through one-side superoleophobic/superhydrophilic modification of the superamphiphobic fabric. The SOHB Janus fabric exhibits high mechanical durability and significant superior capacity than the homogeneous superoleophobic/superhydrophilic fabric in separating various oil-water mixtures. Moreover, the SOHB Janus fabric repels oil contaminants and pumps perspiration from the human skin, exhibiting prospects in physical moisture regulation and comfort improvement. Our novel Janus fabric, along with the fabrication principle, provides a feasible solution for energetic-efficient oil-water remediations and would have implications for the fabrication of advanced separation membranes and intelligent functional clothing.

Ultrasensitive Graphene-Based Nanobiosensor for Rapid Detection of Hemoglobin in Undiluted Biofluids.

Detection of hemoglobin (Hb), a critical part of the biological system that is responsible for oxygen transportation, is of great significance on clinical diagnosis of various diseases. Particularly, time-efficient Hb detection under nanomole levels has drawn much attention in recent years. Herein, we present a graphene field effect transistor (GFET)-based aptameric nanobiosensor for rapid detection of Hb in undiluted biofluids including serum and urine and for the first time use polyethylenimine (PEI), a kind of comparatively low-cost polymer consisting of numerous amino groups, which can be directly linked with the anchor molecule without any pretreatment as the graphene surface passivation agent. Experimental results indicate the PEI-modified graphene aptameric nanobiosensor can respond to the Hb concentration change in a few minutes (6-8 min) with estimated detection limits of 10.6 fM in 1× PBS, 14.2 fM in undiluted serum, and 11.9 fM in undiluted urine, respectively. Further, considering the potential use of our sensor for implantable and wearable applications, we also examine the sensing performance of the sensor fabricated on an ultrathin flexible polyethylene terephthalate (PET) substrate. The Hb detection results are almost invariable even after 100 cycles of cyclic extension by 120% or 100 cycles of bending with a radius of 1 mm. Hence, our sensor holds great potential for accurate monitoring of nanomole levels of Hb in clinical applications.

Hygro-responsive, Photo-decomposed Superoleophobic/Superhydrophilic Coating for On-Demand Oil-Water Separation.

The superoleophobic/superhydrophilic material has attracted considerable interest due to the incomparable property of it for the oil-water separation. However, it is a challenge to make the prepared surface superoleophobic and superhydrophilic at the same time since the oleophobic surface tends to repel water. Herein, a hygro-responsive superoleophobic/superhydrophilic coating was fabricated by liquid-phase deposition of TiO2 with perfluorooctanoic acid. The wettability of the coating could complete the transformation from superoleophobicity/superhydrophilicity to superhydrophobicity/superoleophilicity, both of which exhibit excellent selective superwettability under the air, underwater, salt, alkali, and acid conditions. The hygro-responsive coating can separate different types of oil-water mixtures, and the separation efficiency could be over 99% using different capillary forces acting on the oil and water phases before and after wettability transformation. Last but not least, long-chain perfluoroalkyl substances on the coating could be decomposed by UV irradiation, which could reduce the harm to the environment and human beings. It is anticipated that the developed superoleophobic/superhydrophilic coating provides a feasible solution for the application of oil-water separation.

An Intelligent Graphene-Based Biosensing Device for Cytokine Storm Syndrome Biomarkers Detection in Human Biofluids.

Abnormal elevated levels of cytokines such as interferon (IFN), interleukin (IL), and tumor necrosis factor (TNF), are considered as one of the prognosis biomarkers for indicating the progression to severe or critical COVID-19. Hence, it is of great significance to develop devices for monitoring their levels in COVID-19 patients, and thus enabling detecting COVID-19 patients that are worsening and to treat them before they become critically ill. Here, an intelligent aptameric dual channel graphene-TWEEN 80 field effect transistor (DGTFET) biosensing device for on-site detection of IFN-γ, TNF-α, and IL-6 within 7 min with limits of detection (LODs) of 476 × 10-15 , 608 × 10-15 , or 611 × 10-15 m respectively in biofluids is presented. Using the customized Android App together with this intelligent device, asymptomatic or mild COVID-19 patients can have a preliminary self-detection of cytokines and get a warning reminder while the condition starts to deteriorate. Also, the device can be fabricated on flexible substrates toward wearable applications for moderate or even critical COVID-19 cases for consistently monitoring cytokines under different deformations. Hence, the intelligent aptameric DGTFET biosensing device is promising to be used for point-of-care applications for monitoring conditions of COVID-19 patients who are in different situations.

Superhydrophilic Al2O3 Particle Layer for Efficient Separation of Oil-in-Water (O/W) and Water-in-Oil (W/O) Emulsions.

The separation of oil-water emulsion using superliquiphobic/philic porous coated materials has attracted considerable attention for dealing with environmental pollution and resource recycling issues. The coatings used may lack adequate surface mechanical and chemical durability. This paper proposes a simple method without other modifications for separating the oil-water emulsion. A porous layer was fabricated by superhydrophilic Al2O3 particles, which could separate oil-water emulsions. The particle layer has the property of underwater superoleophobicity after prewetting. For the oil-in-water (O/W) emulsion separation, a 0.3 µm Al2O3 particle layer was used. This layer had a pore size less than about 1 µm to minimize oil flow and to obtain a purity of oil recovery greater than 99 wt %. For the water-in-oil (W/O) emulsion separation, a 40 µm Al2O3 superhydrophilic particle layer was used. Larger particles were used to provide a more porous surface to facilitate oil flow through the layer, resulting in a purity of water recovery purity greater than 99 wt %.

A Wearable and Deformable Graphene-Based Affinity Nanosensor for Monitoring of Cytokines in Biofluids.

A wearable and deformable graphene-based field-effect transistor biosensor is presented that uses aptamer-modified graphene as the conducting channel, which is capable of the sensitive, consistent and time-resolved detection of cytokines in human biofluids. Based on an ultrathin substrate, the biosensor offers a high level of mechanical durability and consistent sensing responses, while conforming to non-planar surfaces such as the human body and withstanding large deformations (e.g., bending and stretching). Moreover, a nonionic surfactant is employed to minimize the nonspecific adsorption of the biosensor, hence enabling cytokine detection (TNF-α and IFN-γ, significant inflammatory cytokines, are used as representatives) in artificial tears (used as a biofluid representative). The experimental results demonstrate that the biosensor very consistently and sensitively detects TNF-α and IFN-γ, with limits of detection down to 2.75 and 2.89 pM, respectively. The biosensor, which undergoes large deformations, can thus potentially provide a consistent and sensitive detection of cytokines in the human body.

Modulating the Linker Immobilization Density on Aptameric Graphene Field Effect Transistors Using an Electric Field.

Aptameric graphene-based field-effect transistors (A-GFETs) always employ linkers, which could immobilize on graphene through π-π stacking between contained pyrenyl groups and graphene, to anchor aptamers. Aptamer density is closely associated with the A-GFET sensitivity and determined by the linker density. Using known linker immobilization methods, the linker density is random, uncontrollable, and limited. In this work, we propose a novel linker immobilization method which can be used to effectively modulate the linker density using an electric field and further bridge the relationship between the linker density and the A-GFET sensitivity. Here, polar molecule 1-pyrenebutanoic acid succinimidyl ester (PASE) is used as a linker representative. In the electric field, PASE is arranged regularly with the electron-rich pyrenyl group forced toward graphene in the solution due to electrostatic repulsion, thereby making it possible to modulate the quantity of PASE molecules that could interact with graphene by tuning the electric field application and then realizing the regulation of the A-GFET sensitivity. Experimental results indicate that the limits of detection (LODs) of A-GFETs for detecting interleukin-6 (IL-6) and insulin can be significantly improved to be 618 and 766 fM, respectively, by applying an electric field at -0.3 V for 3 h during PASE immobilization.

Multifunctional TiO2-Based Superoleophobic/Superhydrophilic Coating for Oil-Water Separation and Oil Purification.

Materials that possess distinguishable superwettability toward oil and water have aroused widespread attention for their application in oil-water separation. Among them, a superoleophobic/superhydrophilic material is considered as the ideal candidate because of its antioil-fouling and water-wetting behavior; however, the fabrication is a challenge and there has been insufficient attention given to multipurpose applications in treating intricate mixtures. Herein, for the first time, a multifunctional superoleophobic/superhydrophilic coating integrated with a photocatalysis property was fabricated by the combination of polarity component-enhanced fluorosurfactant and titanium dioxide (TiO2) nanoparticles. The coating applied on stainless steel mesh preserves the ability to separate immiscible oil-water mixtures, whereas the coated cotton preserves the ability to separate both surfactant-stabilized oil-in-water and water-in-oil emulsions. Notably, benefiting from the photocatalysis property of titanium dioxide, the coating also can be used in liquid purification. Contaminated oil can be separated and purified by a separation-purification process, during which the oil-soluble contamination is degraded under ultraviolet (UV) irradiation. The multipurpose coating provides an alternative solution for oil-water remediations, which has prospects in intricate liquid treatment in industrial and domestic applications.

Ultraviolet-driven switchable superliquiphobic/superliquiphilic coating for separation of oil-water mixtures and emulsions and water purification.

Materials with switchable wettability by external stimuli are of interest in on-demand oil-water separation. Among these materials, ultraviolet (UV) light-stimuli TiO2-based materials are considered as predominant candidates due to the photoinduced superliquiphilicity of TiO2. Besides the photoinduced superliquiphilic property, the photocatalysis is another important intrinsic property of TiO2 which has applications in liquid purification. Therefore, TiO2-based material with these two properties can achieve both separation of diverse oil-water mixtures and liquid purification. In this study, a substrate-independent, UV-driven switchable superliquiphobic/superliquiphilic coating was developed by a facile one-pot method. The wettability of the coating can be rapidly switched between superhydrophobicity/superoleophilicity and superhydrophilicity/underwater superoleophobicity by UV irradiation and heating process, which can be used for on-demand separation of both immiscible oil-water mixtures and emulsions. Such a coating can also be used for the degradation of soluble contamination in water during UV irradiation due to the photocatalysis property of TiO2. The coating provides an effective solution for both on-demand oil-water separation and water purification, which is of interest in both industrial and domestic applications.

Sensitive detection of lung cancer biomarkers using an aptameric graphene-based nanosensor with enhanced stability.

We present an electrolyte-gated graphene field effect transistor (GFET) nanosensor using aptamer for rapid, highly sensitive and specific detection of a lung cancer biomarker interleukin-6 (IL-6) with enhanced stability. The negatively charged aptamer folds into a compact secondary conformation upon binding with IL-6, thus altering the carrier concentration of graphene and yielding a detectable change in the drain-source current Ids. Aptamer has smaller size than other receptors (e.g. antibodies), making it possible to bring the charged IL-6 more closely to the graphene surface upon affinity binding, thereby enhancing the sensitivity of the detection. Thanks to the higher stability of aptamer over antibodies, which degrade easily with increasing storage time, consistent sensing performance was obtained by our nanosensor over extended-time (>24 h) storage at 25 °C. Additionally, due to the GFET-enabled rapid transduction of the affinity recognition to IL-6, detection of IL-6 can be achieved in several minutes (<10 min). Experimental results indicate that this nanosensor can rapidly and specifically respond to the change in IL-6 levels with high consistency after extended-time storage and a detection limit (DL) down to 139 fM. Therefore, our nanosensor holds great potential for lung cancer diagnosis at its early stage.

Rapid, ultraviolet-induced, reversibly switchable wettability of superhydrophobic/superhydrophilic surfaces.

Controllable wettability is important for a wide range of applications, including intelligent switching, self-cleaning and oil/water separation. In this work, rapid switching and extreme wettability changes upon ultraviolet (UV) illumination were investigated. TiO2 nanoparticles were modified in solutions of trimethoxy(alkyl)silane, and the suspensions were sprayed on glass substrates. For such samples, the water contact angle (WCA) was shown to transition from a superhydrophobic (WCA ≈ 165°) to a superhydrophilic (WCA ≈ 0°) state within 10 min upon UV illumination and subsequent recovery to superhydrophobicity occurred after heat treatment. It was found that the changes in the trimethoxy(alkyl)silane upon UV illumination can explain the rapid decrease of the WCA from more than 165° to almost 0°. To further investigate the wettability transition, trimethoxy(alkyl)silane and Al2O3 nanoparticles (which are not photocatalytic) were mixed and spray-coated onto the glass substrates as the control samples. Then the unrecoverable change of trimethoxy(alkyl)silane under UV illumination can be confirmed. It was found that the presence of trimethoxy(alkyl)silane in the TiO2-trimethoxy(alkyl)silane coating served to speed up the super-wettability transition time from superhydrophobicity to superhydrophilicity, but also limited the number of wettability recycle times. With this understanding, the effect of the trimethoxy(alkyl)silane concentration on the number of recycle cycles was investigated.

Bioinspired superoleophobic/superhydrophilic functionalized cotton for efficient separation of immiscible oil-water mixtures and oil-water emulsions.

Oil contamination is pressing environmental and natural resource issues. Oil-water separation technology can be used for water purification. Traditional methods are either time consuming or energy intensive. Bioinspired materials with combination of affinity and/or repellence towards oil and water in mesh-based methods have attracted widespread attention in the oil-water separation. Among existing materials, superhydrophobic/superoleophilic materials are prone to contamination by oil. Superhydrophilic/underwater superoleophobic materials can only operate underwater which restricts the practical use. In contrast, superoleophobic/superhydrophilic materials are desirable for oil-water separation. However, traditional mesh-based method cannot be used for separation of emulsions since the dispersed microdroplets can easily pass through the mesh pores. Superhydrophobic/superoleophilic cotton has been used for separation of water-in-oil emulsions. In this study, a facile method to fabricate bioinspired superoleophobic/superhydrophilic cotton was developed. The functionalized cotton exhibits an oil-repellent and water-wetting behavior and is capable of separating both immiscible oil-water mixtures and also oil-in-water emulsions without oil contamination. This developed cotton is of interest for various applications.

Graphene-based fully integrated portable nanosensing system for on-line detection of cytokine biomarkers in saliva.

Saliva has been reported to contain various cytokine biomarkers which are associated with some severe diseases such as cancers. Non-invasive saliva diagnosis using wearable or portable devices may pave a new avenue for monitoring conditions of the high risk population. Here, a graphene-based fully integrated portable nanosensing system, the entire size of which is smaller than a smart-phone and can be handheld, is presented for on-line detection of cytokine biomarkers in saliva. This miniaturized system employs an aptameric graphene-based field effect transistor (GFET) using a buried-gate geometry with HfO2 as the dielectric layer and on-line signal processing circuits to realize the transduction and processing of signals which reflect cytokine concentrations. The signal can be wirelessly transmitted to a smart-phone or cloud sever through the Wi-Fi connection for visualizing the trend of the cytokine concentration change. Interleukin-6 (IL-6) is used as a representative to examine the sensing capability of the system. Experimental results demonstrate that the nanosensing system responds to the change of IL-6 concentration within 400s in saliva with a detection limit down to 12 pM. Therefore, this portable system offers the practicality to be potentially used for non-invasive saliva diagnosis of diseases at early stage.

Mechanochemical robust, magnetic-driven, superhydrophobic 3D porous materials for contaminated oil recovery.

HYPOTHESIS: Research on the fabrication of superwettable adsorbents based on 3D porous materials has been attracting considerable attention due to the large storage space presented in their inner bodies. However, it is rare to present a facile, eco-friendly and ultralow-cost approach to modify the 3D porous materials with magnetism thereby obtaining a remotely controllable superhydrophobic/superoleophilic material. EXPERIMENTS: Based on this, the 3D magnetic superhydrophobic porous materials (MSPM) based on adsorbent cotton and sponge as substrates were fabricated by a simple dip-coating method using non-hazardous chemical reagents as raw materials. Changes in pristine materials' wettability during the fabrication process were illustrated gradually by SEM micrographs and XPS characterization. FINDINGS: The prepared 3D MSPM exhibits fast magnetic responsivity while the superwettable property of water contact angle reached to 162°, and demonstrated oil/water separation and demulsification with excellent adsorption capacity, high separation efficiency and good reusability. Moreover, the 3D MSPM maintains the superhydrophobicity even if compressed with 50% strain for 200 cycles, or immersed in a harsh chemical environment for more than 3 days. As a result, all these features make the as-prepared 3D MSPM possess a large range of applications in contaminated oil recovery.

Measurement of cytokine biomarkers using an aptamer-based affinity graphene nanosensor on a flexible substrate toward wearable applications.

We present an approach for the label-free detection of cytokine biomarkers using an aptamer-functionalized, graphene-based field effect transistor (GFET) nanosensor on a flexible, SiO2-coated substrate of the polymer polyethylene naphthalate (PEN). The nanosensor conforms to the underlying nonplanar surface and performs GFET-based rapid transduction of the aptamer-biomarker binding, thereby potentially allowing the detection of cytokine biomarkers that are sampled reliably from human bodily fluids (e.g., sweat) in wearable sensing applications. In characterizing the suitability of the nanosensor for wearable applications, we investigate the effects of substrate bending on the equilibrium dissociation constant between the aptamer and the biomarker as well as the graphene transconductance. The utility of the nanosensor is demonstrated by the detection of tumor necrosis factor-α (TNF-α), an inflammatory cytokine biomarker. Experimental results show that the flexible nanosensor can specifically respond to changes in the TNF-α concentration within 5 minutes with a limit of detection as low as 26 pM in a repeatable manner.

Humanoid Identification of Fabric Material Properties by Vibration Spectrum Analysis.

In daily contexts, fabrics embodied in garments are in contact with human body all the time. Since fabric material properties-such as softness or fineness-can be easily sensed by human fingertips, fabric materials can be roughly identified by fingertip sliding. Identification by simply touching and sliding is convenient and fast, although the room for error is always very large. In this study, a highly discernible fabric humanoid identification method with a fingertip structure inspired tactile sensor is designed to investigate the fabric material properties by characterizing the power spectrum integral of vibration signal basing on fast Fourier transform integral S(FFT), which is generated from a steel ball probe rubbing against a fabric surface at an increasing sliding velocity and normal load, respectively. kv and kw are defined as the slope values to identify the fabric surface roughness and hardness. A sample of 21 pieces of fabric categorized by yarn weight, weave pattern, and material were tested by this method. It was proved that the proposed humanoid sensing method has more efficient compared with fingertip sliding while it is also much more accurate for fabric material identification. Our study would be discussed in light of textile design and has a great number of potential applications in humanoid tactile perception technology.