Bioinspired Touch-Responsive Hydrogels for On-Demand Adhesion on Rough Surfaces.

Reversible adhesives are widely needed in our daily lives and industrial applications. However, robust and switchable adhesion on rough surfaces with on-demand attachment and detachment remains highly challenging. Here, we report a snail-mucus-inspired touch-responsive hydrogel (TRH), whose universal and robust adhesion is triggered by simple contact with the attaching surface. TRH is composed of a polymeric hydrogel and saturated sodium acetate (NaAc) and is prepared by one-pot synthesis. At room temperature, TRH remains in an amorphous and soft state, which allows it to conformally adapt to rough surfaces. The contact with the target surface triggers the crystallization of NaAc, which increases the modulus of TRH by an order of magnitude and interlocks with the target surfaces, achieving an adhesion of up to 204.84 ± 53.98 kPa. Upon heating, TRH returns to a soft state, facilitating easy detachment with adhesion of 5.12 ± 1.34 kPa. Meanwhile, the detached TRH is ready for the next adhesion without the need to be maintained at high temperature. TRH finds applications as a smart material for light-triggered adhesion switching, information encryption, and temperature sensors.

Naturally Crosslinked Biocompatible Carbonaceous Liquid Metal Aqueous Ink Printing Wearable Electronics for Multi-Sensing and Energy Harvesting.

Achieving flexible electronics with comfort and durability comparable to traditional textiles is one of the ultimate pursuits of smart wearables. Ink printing is desirable for e-textile development using a simple and inexpensive process. However, fabricating high-performance atop textiles with good dispersity, stability, biocompatibility, and wearability for high-resolution, large-scale manufacturing, and practical applications has remained challenging. Here, water-based multi-walled carbon nanotubes (MWCNTs)-decorated liquid metal (LM) inks are proposed with carbonaceous gallium-indium micro-nanostructure. With the assistance of biopolymers, the sodium alginate-encapsulated LM droplets contain high carboxyl groups which non-covalently crosslink with silk sericin-mediated MWCNTs. E-textile can be prepared subsequently via printing technique and natural waterproof triboelectric coating, enabling good flexibility, hydrophilicity, breathability, wearability, biocompatibility, conductivity, stability, and excellent versatility, without any artificial chemicals. The obtained e-textile can be used in various applications with designable patterns and circuits. Multi-sensing applications of recognizing complex human motions, breathing, phonation, and pressure distribution are demonstrated with repeatable and reliable signals. Self-powered and energy-harvesting capabilities are also presented by driving electronic devices and lighting LEDs. As proof of concept, this work provides new opportunities in a scalable and sustainable way to develop novel wearable electronics and smart clothing for future commercial applications.

Micropillar with Radial Gradient Modulus Enables Robust Adhesion and Friction.

The gradient modulus in beetle setae plays a critical role in allowing it to stand and walk on natural surfaces. Mimicking beetle setae to create a modulus gradient in microscale, especially in the direction of setae radius, can achieve reliable contact and thus strong adhesion. However, it remains highly challenging to achieve modulus gradient along radial directions in setae-like structures. Here, polydimethylsiloxane (PDMS) micropillar with radial gradient modulus, (termed GM), is successfully constructed by making use of the polymerization inhibitor in the photosensitive resin template. GM gains adhesion up to 84 kPa, which is 2.3 and 4.7 times of soft homogeneous micropillars (SH) and hard homogeneous micropillars (HH), respectively. The radial gradient modulus facilitates contact formation on various surfaces and shifts stress concentration from contact perimeter to the center, resulting in adhesion enhancement. Meanwhile, GM achieves strong friction of 8.1 mN, which is 1.2 and 2.6 times of SH and HH, respectively. Moreover, GM possesses high robustness, maintaining strong adhesion and friction after 400 cycles of tests. The work here not only provides a robust structure for strong adhesion and friction, but also establishes a strategy to create modulus gradient at micron-scale.

Washing antimony and arsenic from agricultural soil with eco-friendly organic acids and the relevant bioavailability assessment.

Antimony (Sb) and arsenic (As) contamination in agricultural soil poses human health risks through agricultural products. Soil washing with degradable low molecular weight organic acids (LMWOAs) is an eco-friendly strategy to remediate agricultural soils. In this study, three eco-friendly LMWOAs, oxalic acid (OA), tartaric acid (TA), and citric acid (CA), were used to treat Sb and As co-contaminated agricultural soil from Xikuangshan mine area. The OA, TA, and CA washed out 18.4, 16.8, and 26.6% of Sb and 15.3, 19.9, and 23.8% of As from the agricultural soil, with CA being the most efficient reagent for the soil washing. These organic acids also led to pH decline and macronutrients losses. Fraction analysis using a sequential extraction procedure showed that the three organic acids targeted and decreased the specifically sorbed (F2) (by 19.3-37.6% and 2.41-23.5%), amorphous iron oxide associated (F3) (by 49.1-61.2% and 51.2-70.2%), and crystallized iron oxide associated (F4) (by 12.3-26.0% and 26.1-29.1%) Sb and As. The leachability of Sb and As, as well as their concentrations and bioconcentration factor (BCF) in vegetables reduced due to the soil washing. It demonstrated that the bioavailability of both the elements was decreased by the organic acids washing. The concentrations of Sb and As in typical vegetable species cultivated in CA washed soil were less than the threshold value for consumption safety, while those in OA and TA washed soils were still higher than the value, suggesting that only CA is a potential washing reagent in soil washing for Sb- and As-contaminated agricultural soil.

The non-coevolution of DIC and alkalinity and the CO2 degassing in a karst river affected by acid mine drainage in Southwest China.

Dissolved inorganic carbon (DIC) in mine water generated during coal mining is a large and potential source of atmospheric CO2, however its geochemical behaviors under the influence of AMD in relation to CO2 degassing and carbonate buffering are not well known. In this study, water temperature, pH, DO, alkalinity, Ca2+ concentration, and the carbon isotope of DIC were measured monthly from November 2020 to November 2021 and carbonate chemistry and CO2 emission flux were calculated to reveal the processes of DIC evolution and CO2 degassing from the Chetian River draining a karst region, which is materially affected by the input of large quantities of AMD. The results showed that carbonate erosion, the mineralization of terrestrial organic matter, and domestic sewage input are all identified to contribute DIC to different degrees to the river. Throughout the year, the Chetian River undergoes high-intensity CO2 degassing, which is dominated by HCO3--neutralized degassing and proton-enhanced degassing in different reaches. The pCO2 in the river under the influence of AMD is as high as 237,482 µatm, while the F-CO2 approaches 316.9 g C m-2 d-1. Meanwhile, the carbonate system in the downstream karst river buffers an average of 85.2 % of DIC release at the river's outlet. The input of AMD significantly altered the carbon cycle of the surface watershed in the headwaters of tributaries, and greatly enhanced the release of CO2 from surface water to the atmosphere; meanwhile, the buffering of carbonates on acidity in the water of main streams causes pCO2 to rapidly reduce over a short distance. Obviously, the carbon emission effect generated by the interaction between AMD and carbonate mainly occurs in the tributary water system. Considering the huge amount of AMD worldwide, this large potential source of atmospheric CO2 requires a specific and precise quantitative analysis based on actual observations.

Natural Silkworm Cocoon-Based Hierarchically Architected Composite Triboelectric Nanogenerators for Biomechanical Energy Harvesting.

Silk-based triboelectric nanogenerators (TENGs) have been demonstrated as an ideal platform for self-powered systems. The source of silk, Bombyx mori, entails a valuable ingredient, sericin (SS), viewed as a binder in composites. Interestingly, SS is rich in the amorphous region, possibly resulting in triboelectrification enhancement between the amorphous region and the crystallization region when subject to external pressure. However, most researchers remove the SS component when designing silk-TENGs to eliminate immunological responses as implantation in vivo through complicated degumming, rehydration, and dialysis procedures. Herein, integral SS retention was utilized to fabricate silk-TENGs without affecting the output performance. We designed, for the first time, an ultra-robust and natural silkworm cocoon layer (SCL)/polydimethylsiloxane (PDMS)-TENG as an energy harvester to scavenge waste energy from human motions. The working mechanisms and influence of operational parameters are explored and studied. Working in the contact-separation mode, the electrical outputs of the SCL/PDMS-TENG in terms of open-circuit voltage, short-circuit current, and power density reaches 126 V, 3 µA, and 216 mW/m2, respectively. The integrated self-charging TENG is demonstrated to power small electronic electronics and monitor human motions. This work widens a new dielectric material selection with SS retention to boost the output performance of TENGs for practical applications.

Gradient Micropillar Array Inspired by Tree Frog for Robust Adhesion on Dry and Wet Surfaces.

The strong adhesion on dry and wet surfaces and the durability of bioinspired hierarchical fibrillar adhesives are critical for their applications. However, the critical design for the strong adhesion normally depends on fine sub-micron structures which could be damaged during repeat usage. Here, we develop a tree frog-inspired gradient composite micropillars array (GP), which not only realizes a 2.3-times dry adhesion and a 5.6-times wet adhesion as compared to the pure polydimethylsiloxane (PDMS) micropillars array (PP), but also shows excellent durability over 200 repeating cycles of attachment/detachment and self-cleaning ability. A GP consists of stiffer tips and softer roots by incorporating gradient dispersed CaCO3 nanoparticles in PDMS micropillar stalks. The modulus gradient along the micropillar height facilitates the contact formation and enhances the maximum stress during the detaching. The study here provides a new design strategy for robust adhesives for practical applications in the fields of robotics, electronics, medical engineering, etc.

Physiological Roles of Carnosine in Myocardial Function and Health.

Carnosine is a pleiotropic histidine-containing dipeptide synthesized from ß-alanine and l-histidine, with the intact dipeptide and constituent amino acids being available from the diet. The therapeutic application of carnosine in myocardial tissue is promising, with carnosine playing a potentially beneficial role in both healthy and diseased myocardial models. This narrative review discusses the role of carnosine in myocardial function and health, including an overview of the metabolic pathway of carnosine in the myocardial tissue, the roles carnosine may play in the myocardium, and a critical analysis of the literature, focusing on the effect of exogenous carnosine and its precursors on myocardial function. By so doing, we aim to identify current gaps in the literature, thereby identifying considerations for future research.

Switchable Adhesion on Curved Surfaces Mimicking the Coordination of Radial-Oriented Spatular Tips and Motion of Gecko Toes.

Bio-inspired structured adhesives have promising applications in many fields, like biomedicine, robotics, and aerospace. However, achieving robust and switchable adhesion in structured adhesives on non-planar surfaces remains highly challenging. Inspired by the gripping and rolling motions of gecko toes, a strong and switchable adhesive, which comprises a pillar array with radial-oriented spatular tips and is named as PROST, is developed. PROST possesses a robust adhesion on flat surfaces and doubles its adhesion on curved surfaces. Moreover, in situ and fast adhesion switching of PROST on flat/curved surfaces in dry and wet conditions has been realized by solvent stimulation, mimicking the bending locomotion of gecko toes. The work here provides a new strategy for designing controllable adhesion on curved substrates.

Fast Self-Assembly of Photonic Crystal Hydrogel for Wearable Strain and Temperature Sensor.

Structural colors from photonic crystals (PCs) have attracted emerging attention in the research area of wearable sensors. Conventional self-assembly of PC takes days to weeks. Here, a fast self-assembly method of PC with horizontal precipitation of silica nanoparticles (NPs) in a polydimethylsiloxane fence, which can be completed within 1-4 h depending on the fence parameters, is introduced. The resultant PC exhibits tunable structural colors in the entire visible spectrum. With infiltration of composite hydrogels containing acrylic acid, acrylamide, chitosan, and carbon nanotubes (CNTs) into the gaps of NPs to form an inverse opal PC, a structural color hydrogel that can quickly respond to different stimuli, including strain and temperature, is obtained. Moreover, with the addition of CNTs, the composite PC hydrogel can also output an electronic signal together with optical color changes. Based on these extraordinary responsive behaviors, the PC hydrogel sensor for quantitative feedback to external stimuli of stretching, bending, pressing, and thermal stimuli, with brilliant color change and electronic signal outputs simultaneously, is demonstrated. This fast-assembled PC hydrogel with excellent responsive properties has great potential for applications in wearable devices, mechanical sensors, temperature sensors, and colorimetric displays.

Improvement in Mechanical Properties of 3D-Printed PEEK Structure by Nonsolvent Vapor Annealing.

The broad applications of 3D-printed poly-ether-ether-ketone (3D-PEEK) structures are largely hampered by their inadequate mechanical properties that can be improved by post treatments. At present, thermal annealing is generally used to improve the mechanical properties of 3D-PEEK. However, it cannot simultaneously improve strength and ductility. Here, a cost-effective postprocessing method is developed to improve the mechanical properties of 3D-PEEK, based on annealing in nonsolvent vapor at room temperature. The annealing in nonsolvent vapor at room temperature simultaneously improves the strength, ductility, and fracture energy of as-printed 3D-PEEK by 22.6%, 151.3%, and 109.1%, respectively. The improved mechanical properties are attributed to enhanced interfacial bonding, increased crystallinity, decreased pinhole defects, and stress relaxation in the 3D-PEEK. Moreover, the annealing in both polar solvents (such as acetone and chloroform) and nonpolar solvents (such as n-hexane) are demonstrated to be effective for improving the mechanical properties of 3D-PEEK. The nonsolvent vapor-annealed 3D-PEEK can thus have potential applications in the fields of medical implants, automotive, aerospace, and more.

The leaching of antimony and arsenic by simulated acid rain in three soil types from the world's largest antimony mine area.

A simulated acid rain (SAR) experiment on leaching of antimony (Sb) and arsenic (As) in three soil types including paddy soils (PS), vegetable soils (VS) and slag based soils (SS) from Xikuangshan (XKS) Sb mine area was conducted. The SAR at pH 2.5, 3.5, 4.5 and 5.6 were sprayed to soil columns with intermittent pattern in a period of 50 days. Through the spraying duration, leaching Sb in PS, VS and SS showed decreasing trends regardless of pH values in SAR and were in the ranges of 0.026-0.064 mg L-1, 0.19-2.18 mg L-1 and 11.8-32.4 mg L-1, respectively. By contrast, leaching As in these three soil types continuously increased at the initial five spraying times and then deeply decreased afterward, with ranges being 0-0.007 mg L-1, 0.001-0.071 mg L-1 and 0.17-1.07 mg L-1, respectively. The leaching Sb in all the three soil types were extremely higher than the reference value in grade IV (0.01 mg L-1) for groundwater quality of China (GB/T 14,848-2017). For leaching As, peck values in VS and all the values in SS were also greater than the corresponding reference value (0.05 mg L-1). This indicated that leaching Sb and As could pollute the groundwater in XKS Sb mine area, especially those in slag based soils. The total leaching losses of Sb and As were affected by pH ambiguously, such as SAR at pH 2.5, 5.6 and 2.5 induced the greatest losses of Sb in PS, VS and SS, and pH 3.5, 5.6 and 2.5 resulted in the greatest leaching losses of As in these soils. After SAR treatment, the specific sorbed and Fe/Mn oxide-associated Sb and As significantly decreased. It demonstrated that these two fractions of both Sb and As were involved in leaching losses. The present study also found that the SAR treatment resulted in soil acidification in all the three soil types. In addition, available N, P and K in all the SAR treatments decreased regardless of pH values, except for available N and P in PS.

Heavy metal characteristics in porewater profiles, their benthic fluxes, and toxicity in cascade reservoirs of the Lancang River, China.

The construction of cascade reservoirs on the Lancang River (the upper Mekong) has an important influence on the distribution and accumulation of heavy metals. Heavy metal contents in porewater provide vital information about their bioavailability, studies on this aspect are rare until now. In this study, sediment cores were collected from four adjacent cascade reservoirs in the upper Mekong River to study the distribution, potential sources, diffusive fluxes and toxicity of heavy metals in porewater. The findings indicated that the average contents of Mn, Fe, As, Ni, Cu, Zn, Cd, and Pb in the sediment porewater were 6442, 644, 11.50, 2.62, 1.23, 3.95, 0.031, and 0.24 µg/L, respectively; these contents varied as the sediment depth increased. Correlation analysis and principal component analysis showed that Cu, Zn, Cd and Pb were mainly associated with anthropogenic sources, As, Mn and Fe were primarily affected by natural inputs, and Ni was affected by a combination of natural and anthropogenic effects. The diffusive fluxes of Mn, Fe, As, Ni, Cu, Zn, Cd, and Pb in the cascade reservoirs of the Lancang River were 919 - 35,022, 2.12 - 2881, 0.17 - 750, 0.71 - 7.70, 2.30 - 31.18, (-3.35) - 6.40, 0.06 - 0.54, and (-0.52) - 4.08 µg/(m2 day), respectively. The results of toxic units suggested that the contamination and toxicity of heavy metals in porewater were not serious. Overall, in the cascade reservoirs, the content and toxicity of heavy metals in porewater of the upstream reservoirs were higher than that of the downstream reservoirs. The operation of the cascade reservoirs enabled greater accumulation of contaminants in sediments of the upstream reservoirs. This research gives strong support for the prevention of heavy metal contamination and the sustainability of water resources under the running condition of cascade reservoirs on such a large international river (the Lancang-Mekong River).

3D printing of bioinspired compartmentalized capsular structure for controlled drug release.

Drug delivery with customized combinations of drugs, controllable drug dosage, and on-demand release kinetics is critical for personalized medicine. In this study, inspired by successive opening of layered structures and compartmentalized structures in plants, we designed a multiple compartmentalized capsular structure for controlled drug delivery. The structure was designed as a series of compartments, defined by the gradient thickness of their external walls and internal divisions. Based on the careful choice and optimization of bioinks composed of gelatin, starch, and alginate, the capsular structures were successfully manufactured by fused deposition modeling three-dimensional (3D) printing. The capsules showed fusion and firm contact between printed layers, forming complete structures without significant defects on the external walls and internal joints. Internal cavities with different volumes were achieved for different drug loading as designed. In vitro swelling demonstrated a successive dissolving and opening of external walls of different capsule compartments, allowing successive drug pulses from the capsules, resulting in the sustained release for about 410 min. The drug release was significantly prolonged compared to a single burst release from a traditional capsular design. The bioinspired design and manufacture of multiple compartmentalized capsules enable customized drug release in a controllable fashion with combinations of different drugs, drug doses, and release kinetics, and have potential for use in personalized medicine.

Bph30 confers resistance to brown planthopper by fortifying sclerenchyma in rice leaf sheaths.

Phloem-feeding insects cause massive losses in agriculture and horticulture. Host plant resistance to phloem-feeding insects is often mediated by changes in phloem composition, which deter insect settling and feeding and decrease viability. Here, we report that rice plant resistance to the phloem-feeding brown planthopper (BPH) is associated with fortification of the sclerenchyma tissue, which is located just beneath the epidermis and a cell layer or two away from the vascular bundle in the rice leaf sheath. We found that BPHs prefer to feed on the smooth and soft region on the surface of rice leaf sheaths called the long-cell block. We identified Bph30 as a rice BPH resistance gene that prevents BPH stylets from reaching the phloem due to the fortified sclerenchyma. Bph30 is strongly expressed in sclerenchyma cells and enhances cellulose and hemicellulose synthesis, making the cell walls stiffer and sclerenchyma thicker. The structurally fortified sclerenchyma is a formidable barrier preventing BPH stylets from penetrating the leaf sheath tissues and arriving at the phloem to feed. Bph30 belongs to a novel gene family, encoding a protein with two leucine-rich domains. Another member of the family, Bph40, also conferred resistance to BPH. Collectively, the fortified sclerenchyma-mediated resistance mechanism revealed in this study expands our understanding of plant-insect interactions and opens a new path for controlling planthoppers in rice.

Diel variation of CH4 emission fluxes in a small artificial lake: Toward more accurate methods of observation.

Lakes are significant sources in global methane (CH4) budgets. However, estimations of the magnitude of global CH4 emissions from lakes may be highly biased owing to the uncertainties in data originating from observation times, methods, and parameterizations of the gas transfer velocity (k). Here, we conducted continuous 48-hour measurements of CH4 fluxes using the floating chamber method seasonally at Lake Baihua, a small reservoir in southwestern China, and compared the results with estimates derived from boundary layer models. Results showed that there was a weak dependency of k on wind speed, indicating that wind speed was not the major factor regulating gas exchange in such small lakes. It is thus concluded that the wind speed-dependent boundary layer model method is not suitable for CH4 flux observations in small and medium-sized lake, and that the floating chamber method is recommended for use instead. The measured CH4 fluxes displayed remarkably diurnal patterns, therefore the use of single observations to represent daily average values comes with unacceptably large uncertainties. A reasonable alternative is averaging observations made at sunrise and at sunset to represent daily values, which has a much smaller uncertainty (ranging from 0.8% to 13.6%). The coincident peaks of CH4 and chlorophyll concentrations in the subsurface indicate that CH4 originated mainly from aerobic methanogenesis. Solar radiation is likely one of the major factors regulating CH4 production and emissions in the lake through enhancing CH4 production, inhibiting CH4 oxidation, and probably changing hydrodynamics conditions. Therefore, irradiation should be taken into consideration as a key factor in observing CH4 fluxes in lakes. As sampling times are limited, observations during both sunny and cloudy weather should be proportionally included. This is the first time, to the best of our knowledge, that solar radiation has been proposed as a key driver of CH4 emissions from lakes.

Tree frog-inspired nanopillar arrays for enhancement of adhesion and friction.

Bioinspired structure adhesives have received increasing interest for many applications, such as climbing robots and medical devices. Inspired by the closely packed keratin nanopillars on the toe pads of tree frogs, tightly arranged polycaprolactone nanorod arrays are prepared by mold process and chemical modification. Nanorod arrays show enhanced adhesion and friction on both smooth and rough surfaces compared to the arrays with hexagonal micropillars. The bonding of nanorods results in a larger stiffness of the nanorod surface, contributing mainly to friction rather than adhesion. The results suggest the function of closely packed keratin nanopillars on the toe pad of tree frogs and offer a guiding principle for the designing of new structured adhesives with strong attaching abilities.

Adhesion Enhancement of Micropillar Array by Combining the Adhesive Design from Gecko and Tree Frog.

It has long been demonstrated the gecko-inspired micropillar array with T-shape tips possesses the best adhesion performance of a given material. The further enhancement of the adhesion performances of T-shape micropillars can offer redundant adhesion to compensate for the inevitable improper contacts. Here, the array of T-shape polydimethylsiloxane (PDMS) micropillars is incorporated with gradient dispersed calcium carbonate nanoparticles in the micropillar stalk, termed as T-shape gradient micropillars (TG), possessing the modulus gradient with stiff tip and soft root. The gradient modulus in TG facilitates the contact formation and regulates the stress at the detaching interface, resulting in a 4.6 times adhesion and 2.4 times friction as compared with the pure PDMS T-shape micropillar arrays. The study here provides a new design strategy for the super-strong structured dry adhesives.

A dissolving and glucose-responsive insulin-releasing microneedle patch for type 1 diabetes therapy.

Diabetes and its complications have become crucial public health challenges worldwide. In this study, we aim to develop a dissolving and glucose-responsive insulin-releasing microneedle (MN) patch system, for minimally invasive and glucose-responsive insulin delivery for type 1 diabetes therapy. The MNs were composed of dissolving and biodegradable gelatin and starch materials, which encapsulated glucose-responsive insulin-releasing gold nanocluster (AuNC) nanocarriers. The fabricated MNs had a complete and uniform structure, consisting of an array of 11 × 11 conical needles, with a needle height of 756 µm, a bottom diameter of 356 µm, a tip diameter of 10 µm, and a tip-to-tip distance of 591 µm. The encapsulated AuNC nanocarriers as additives in the MNs enhanced the mechanical strength of the MNs, and facilitated the penetration of the MNs into the skins of mice. Moreover, the AuNC nanocarrier drugs in the MNs enabled MN patches with a glucose-responsive insulin releasing behavior. With one transdermal application of MN patches on the dorsal skin of mice, the MN patches effectively regulated the BG levels of mice in normoglycemic ranges for 1 to 2 days, and effectively alleviated the diabetic symptoms in type 1 diabetic mice. This dissolving and glucose-responsive insulin-releasing MN patch system realized a closed-loop administration of insulin with minimal invasion, providing great potential applications for type 1 diabetes therapy.

Reversible Structure Engineering of Bioinspired Anisotropic Surface for Droplet Recognition and Transportation.

Surfaces with tunable liquid adhesion have aroused great attention in past years. However, it remains challenging to endow a surface with the capability of droplet recognition and transportation. Here, a bioinspired surface, termed as TMAS, is presented that is inspired by isotropic lotus leaves and anisotropic butterfly wings. The surface is prepared by simply growing a triangular micropillar array on the pre-stretched thin poly(dimethylsiloxane) (PDMS) film. The regulation of mechanical stress in the PDMS film allows the fine tuning of structural parameters of the micropillar array reversibly, which results in the instantaneous, in situ switching between isotropic and various degrees of anisotropic droplet adhesions, and between strong adhesion and directional sliding of water droplets. TMAS can thus be used for robust droplet transportation and recognition of acids, bases, and their pH strengths. The results here could inspire the design of robust sensor techniques.