Sticky Substrate Research Articles

Fabrication of encapsulated and sticky surface-enhanced Raman spectroscopy substrate coupling with thin layer chromatography for determination of pesticide

A sealed and sticky surface-enhanced Raman scattering (SERS) substrate was fabricated by screen-printed technology. The screen-printed ink was prepared by mixing poly(ethylene glycol) diacrylate (PEGDA), Ag nanoparticles (Ag-NPs) and photoinitiator. After printed on Supporting material, PEGDA can polymerize into film under UV light illumination. Ag-NPs were sealed and protected by this film. SERS signal of 10−12 M rhodamine 6G has been recorded on this substrate. The homogeneity of this substrate was examined by mapping experiments, and the relative standard deviation of the signals from 48 points was within 10 %, indicating high uniformity of this substrate. Upon coupling with thin layer chromatography (TLC), this sticky SERS substrate can be in thorough contact with the separated targets on TLC plates and stick to them firmly by pressing a cover, which was effective for improving the detection sensitivity. This coupling technology exhibited good performance for determination of thiabendazole in complex matrix with a detection limit of 0.01 μg/mL.

Dual-Functional Self-Attachable and Stretchable Interface for Universal Three-Dimensional Modular Electronics.

Stretchable electronics have become essential for custom-built electronics, self-assembling robotics, and wearable devices. Although many stretchable electronics contain integrated systems, they still limit bulky connection systems. We introduce a new dual-functioned self-attachable and stretchable interface (SASI), allowing a direct and instant interconnection between rigid and soft electronics. The SASI consists of a sticky and stretchable substrate and surface-embedded serpentine conductors with the single-sided polyimide fabricated using the embedded transfer process. The adhesion property of the SASI is controlled by the mixed elastomer ratio. The resulting sticky and conductive SASI can instantly adhere to a metal surface and create conductive paths. The SASI serpentine conductors exhibit high stretchability (∼290%) and provide self-attachable, re-attachable, and low-resistant electrical contacts (0.85 ohms in 0.25 mm2) between interfaces without pressure, heat, or extra solder. In addition, three-dimensional curved and modular electronics can be formed with the SASI by compiling functional blocks. SASI provides a novel strategy for assembling functional chips or modules for stretchable electronics, opening a path to onboard integrated electronics that are customizable by users for real-world stretchable electronics.

Metastability for expanding bubbles on a sticky substrate

We study the dynamical behavior of a one dimensional interface interacting with a sticky impenetrable substrate or wall. The interface is subject to two effects going in opposite directions. Contacts between the interface and the substrate are given an energetic bonus while an external force with constant intensity pulls the interface away from the wall. Our interface is modeled by the graph of a one-dimensional nearest-neighbor path on Z+, starting at 0 and ending at 0 after 2N steps, with the wall being the horizontal axis. At equilibrium each path ξ=(ξx)x=02N is given a probability proportional to λH(ξ)exp(σNA(ξ)), where H(ξ):=#{x:ξx=0} and A(ξ) is the area enclosed between the path ξ and the x-axis. We then consider the classical heat-bath dynamics which equilibrates the value of each ξx at a constant rate via corner-flip. Investigating the statics of the model, we derive the full phase diagram in λ and σ of this model, and identify the critical line which separates a localized phase where the pinning force sticks the interface to the wall and a delocalized one, for which the external force stabilizes ξ around a deterministic shape at a macroscopic distance of the wall. On the dynamical side, we identify a second critical line, which separates a rapidly mixing phase (for which the system mixes in polynomial time) to a slow phase where the mixing time grows exponentially. In this slowly mixing regime, we obtain a sharp estimate of the mixing time on the log scale, and provide evidences of a metastable behavior.

Rapid Trace Detection of Pesticide Residues on Tomato by Surface-Enhanced Raman Spectroscopy and Flexible Tapes

The non-judicious use of pesticides in agro-food poses a severe threat to food safety and human health. As an emerging chromatographic fingerprint provider, surface-enhanced Raman spectroscopy analysis (SERS) sheds bright light on sensitive and nondestructive detection of pesticide residues. This research proposed a novel strategy to detect three-pesticide residues (thiabendazole, carbendazim, and chlorpyrifos) on tomato peel based on the flexible and sticky SERS substrate. After selecting the best commercial adhesive tape (3M9080), the SERS substrate was constructed by optimizing the parameters in the preparation process of AuNPs. Therefore, a new simple “tape-wrapped SERS” way for pesticide residue analysis was established with a simple procedure of “absorption, separation, and drop addition.” Based on chemometrics method, the limit of semiquantitative detection was 20, 36, and 80 ng/cm2 for thiabendazole, carbendazim, and chlorpyrifos, respectively, on tomato surface, which indicated that the proposed method could meet the requirement of actual application with a large prospect in agro-food safety detection.

Design of an intelligent vibration screening system for armyworm pupae based on image recognition

Biological control is a green and effective pest management method to mitigate or inhibit pests and pest effects by introducing natural enemies. The stinkbug is one of the insects used for biological control and fed on armyworm. It is necessary to separate the farm-raised armyworm from the sticky substrate after pupation. At present, the work is done manually, with high labor intensity, low efficiency and high cost. In this paper, an intelligent vibration screening system of armyworm pupae based on image recognition is developed. The system can effectively separate the pupae from the sticky substrate without damaging the pupae. The system is comprised of vibration subsystem, separation subsystem, image recognition subsystem and control subsystem. The pupa material is sticky and cannot be shaken off by vibration alone. Therefore, the separation subsystem uses the reciprocating motion of the brush to separate the armyworm from the substrate. Then, the image recognition technology is used to adjust the feed quantity in real time to ensure the optimal screening effect. Finally, the optimal working parameters, including separation speed, vibration frequency and feed quantity, are determined by using the design method of linear regression and linear programming. The experimental results show that the screening rate of the screening system can reach 90%, and the damage rate can be controlled within 5%.

Electrochemical synthesis of AgNP and mechanical performance of AgNP-EG coatings on soft elastomer

Silver nanoparticles (AgNP) are being used extensively in medical and modern age stretchable and flexible electronics applications. In this article, we describe easy, cost-effective, and scalable synthesis of AgNP using electrolysis of pure silver metal in aqueous silver acetate solution. Size measurements and structural characterizations of the nanoparticles were performed using scanning electron microscopy coupled with image analysis and X-ray diffraction techniques, respectively. As-prepared nanoparticles were dispersed in pure ethylene glycol (EG) in a concentration of 50 wt%. The dispersion was coated on a soft, sticky, stretchable, and flexible elastomeric substrate polydimethylsiloxane (PDMS). Finally, the stretchability and flexibility tests on AgNP-EG/PDMS laminate were performed. The as-fabricated AgNP-EG/PDMS laminate is capable of stretching up to 18% without electrical failure. It was also found to remain electrically conductive when bent on curved surfaces. This behavior indicates that the AgNp-EG/PDMS laminate has good stretchability and flexibility and can be used as an electrically conductive platform for stretchable and flexible electronics.

Robust adhesion of droplets via heterogeneous dynamic petal effects

HypothesisBionics and dynamic interface wetting intensely appeal to many research communities due to their unique practical implications. The rose petals had a highly robust dynamic water-retaining capacity under heavy precipitation. We predicted that the roses became more “hydrophilic” at higher Weber numbers. ExperimentsFresh rose petals were directly impacted by droplets, and facile artificial petal-like substrates and superhydrophobic substrates were used in the comparative analysis. The wetting dynamics of the droplet (e.g., topography, bounce dynamics, contact time, three-phase contact lines, and oscillations) were investigated when interacting with four selected target substrates. FindingsThe present work first time investigated the dynamic wetting rule of the sticky superhydrophobic substrates (SSHS). Simulated and experimental investigations confirmed that the unique coupling synergy between the pinning effect and the inhomogeneous micropapillaes resulted in lopsided contact line velocities, which remarkably suppressed the lateral oscillation and rebounding. This may be a new strategy when designing dynamic water-repellent surfaces and open a promising avenue for emerging areas such as super-efficiency energy conversion and harvesting.

An illustrative case of endocardial fibroelastosis and recalcitrant intracardiac thrombosis: a case report

BackgroundEndocardial Fibroelastosis is diffuse, accentuated proliferation of ventricular endocardium causing a rare form of restrictive cardiomyopathy in both children and adults. It is an incompletely understood cause of heart failure predominantly in Sub-Saharan Africa associated with high morbidity and mortality. Atrial fibrillation and thrombus formation are common accompanying complications and portend a poor prognosis. Due to rarity of the condition in the developed countries and lack of evidence based options, the optimal strategy for anticoagulation is unclear.Case presentationHerein, we describe a relatively asymptomatic patient with endocardial fibroelastosis who has been found to have atrial fibrillation and a large thrombus in the right atrium. Currently, there is no evidence-based strategy in the management of endocardial fibroelastosis-associated intracardiac thrombus. This case report illustrates a scenario by which the use of apixaban potentially benefited or prevented the thrombus formation compared with warfarin as demonstrated by imaging findings.ConclusionsThe patients with endocardial fibroelastosis are at risk of developing intracardiac thrombus due to sticky substrate lining cardiac chambers while being relatively asymptomatic. No directed therapy is known for the management of heart failure and any complications of subsequent arrhythmias. The general recommendations follow those of same conditions in other hosts. Novel oral anticoagulant agents can be considered in the treatment of atrial thrombus in the appropriate settings.

Beyond coffee ring: Anomalous self-assembly in evaporating nanofluid droplet on a sticky biomimetic substrate

Evaporation induced self-assembly is of paramount importance in many fields ranging from optoelectronic devices, blood spatter analysis, food industry, and thin film deposition. In this article, we report the evaporative drying of a nanofluid droplet on an inclined biomimetic sticky substrate obtained by soft lithographically replicating the structures of Rose petals on crosslinked Polydimethylsiloxane and demonstrate the influence of substrate inclination on the transitions in morphodynamics of the final deposit patterns. Based on experimental data and agglomeration kinetics, we present three unique morphologies induced by substrate inclination. First, buckling from the side in an upright droplet due to air cavity in the substrate. Second, sedimentation induced side buckling in an inclined droplet. Finally, cavity from the bottom in an inverted droplet. We provide a detailed physical explanation of the transition in the morphologies by exploring the coupling among droplet-substrate orientation, evaporation, internal flow and particle agglomeration.

Robust, flexible, sticky and high sensitive SERS membrane for rapid detection applications

Up to date, many efforts have been done to improve the performance of surface-enhanced Raman scattering spectroscopy (SERS) substrates, but the fabrication of a stable, sensitive and uniform SERS substrate in a simple way also remains a challenge. In this work, we report a very convenient way to prepare a durable, uniform, flexible and sticky SERS substrate by dropping noble metal nanoparticles colloids on highly transparent fluorescent quantitative PCR sealing membranes, designated as HTFQ-PCR-M. HTFQ-PCR-M based SERS substrate exhibits high sensitivity, superior reproducibility, good stability and thermal stability. We apply such to directly collect thiram pesticide residues on the peel of fruit and do Raman measurement, to analyze dividually methylene blue and rhodamine B in mixture by the aid of thin layer chromatography plate via “paste and peel off” approach. Moreover, HTFQ-PCR-M based SERS substrate can keep its SERS activity at 90℃. As a perspective, HTFQ-PCR-M based SERS substrate could offer a great practical potential for on-spot identification of trace target molecules in various real samples.

An Inherent Multifunctional Sellotape Substrate for High‐Performance Flexible and Wearable Organic Single‐Crystal Nanowire Array‐Based Transistors

Sellotape, as a flexible, sticky, and lightweight substrate, can be integrated in electronic devices to realize unprecedented and low‐cost applications, such as biomedical devices, wearable electronics, smart clothes, and sensory skin for robotic system. However, very few works have successfully demonstrated fabricating devices on sellotape substrates, primarily because traditional microelectronic processing techniques, including photolithography, metallization, and lift‐off, are incompatible with sellotape. Here a novel tape‐stripping method is demonstrated for large‐area fabrication of high‐performance flexible and wearable organic nanowire array‐based field‐effect transistors (ONWFETs) on sellotape substrates. The copper phthalocyanine ONWFETs on the tapes exhibit high average mobility (≈1.02 cm2 V−1 s−1) as well as high bending and wearing stability. Furthermore, 3D ONWFET circuitry consisting of five vertically stacked layers is demonstrated. Device geometries and electronic properties are maintained with high fidelity after sequential stacking processes. This is so far the first study of ONWFETs on flexible tapes and their applications in wearable or 3D integrated devices. It is anticipated that the novel tape stripping method may help overcome upcoming difficulties for organic flexible electronics.

Thermodynamic and kinetic anisotropies in octane thin films.

Confinement breaks the translational symmetry of materials, making all thermodynamic and kinetic quantities functions of position. Such symmetry breaking can be used to obtain configurations that are not otherwise accessible in the bulk. Here, we use computer simulations to explore the effect of substrate-liquid interactions on thermodynamic and kinetic anisotropies induced by a solid substrate. We consider n-octane nano-films that are in contact with substrates with varying degrees of attraction, parameterized by an interaction parameter ϵS. Complete freezing of octane nano-films is observed at low temperatures, irrespective of ϵS, while at intermediate temperatures, a frozen monolayer emerges at solid-liquid and vapor-liquid interfaces. By carefully inspecting the profiles of translational and orientational relaxation times, we confirm that the translational and orientational degrees of freedom are decoupled at these frozen monolayers. At sufficiently high temperatures, however, free interfaces and solid-liquid interfaces close to loose (low-ϵS) substrates undergo "pre-freezing," characterized by mild peaks in several thermodynamic quantities. Two distinct dynamic regimes are observed at solid-liquid interfaces. The dynamics is accelerated in the vicinity of loose substrates, while sticky (high-ϵS) substrates decelerate dynamics, sometimes by as much as two orders of magnitude. These two distinct dynamical regimes have been previously reported by Haji-Akbari and Debenedetti [J. Chem. Phys. 141, 024506 (2014)] for a model atomic glass-forming liquid. We also confirm the existence of two correlations-proposed in the above-mentioned work-in solid-liquid subsurface regions of octane thin films, i.e., a correlation between atomic density and normal stress, and between atomic translational relaxation time and lateral stress. Finally, we inspect the ability of different regions of an octane film to explore the potential energy landscape by performing inherent structure calculations, and observe no noticeable difference between the free surface and the bulk in efficiently exploring the potential energy landscape. This is unlike the films of model atomic glass formers that tend to sample their respective landscape more efficiently at free surfaces. We discuss the implications of this finding to the ability of octane-and other n-alkanes-to form ultrastable glasses.

Remote Giant Multispectral Plasmonic Shifts of Labile Hinged Nanorod Array via Magnetic Field.

We report a remotely mediated and fast responsive plasmonic-magnetic nanorod array with extremely large variability in optical appearance (up to 100 nm shifts in scattering maxima) and concurrently for multiple wavelengths in a broad range from UV-vis to near-infrared (at 450, 550, and 670 nm) with an external magnetic field with variable direction. The observed phenomenon demonstrates a rapid, wide-range response controlled via a noninvasive remote stimulus. The remotely controlled system suggested here is a magnetic field-directed assembly of an ordered monolayer array of unipolar oriented magnetic-plasmonic nickel-gold nanorods flexibly hinged to a sticky substrate. The unique geometry of the mobile nanorod array allows for the instant alteration of the surface plasmon polariton modes in the gold segment of the controllably tilting nanorods. This design demonstrates the utility of hybrid bimetallic nanoparticles and gives a novel approach to the design of fast-acting, remotely controlled color-changing nanomaterials for sensing and interfacial transport.

Lamplighter model of a random copolymer adsorption on a line

We present a model of an AB-diblock random copolymer sequential self-packaging with local quenched interactions on a one-dimensional infinite sticky substrate. It is assumed that the A-A and B-B contacts are favorable, while A-B are not. The position of a newly added monomer is selected in view of the local contact energy minimization. The model demonstrates a self-organization behavior with the nontrivial dependence of the total energy, $E$ (the number of unfavorable contacts), on the number of chain monomers, $N$: $E\sim N^{3/4}$ for quenched random equally probable distribution of A- and B-monomers along the chain. The model is treated by mapping it onto the "lamplighter" random walk and the diffusion-controlled chemical reaction of $X+X\to 0$ type with the subdiffusive motion of reagents.

Sticky Substrates Snatch Bugs from Blood

Magnetic nanoparticles conjugated with a synthetic ligand remove bacteria from whole blood while sparing red blood cells.

Evaluation of a sticky trap (AedesTraP), made from disposable plastic bottles, as a monitoring tool for Aedes aegypti populations

BackgroundDengue virus, which is transmitted by Aedes aegypti mosquitoes is the most important emerging viral disease, infecting more than 50 million people annually. Currently used sticky traps are useful tools for monitoring and control of A. aegypti, despite differences in efficiency, labor requirements and cost. In the present work, a field assay was carried out to evaluate the performance of a sticky trap (AedesTrap), produced using disposable material, in capturing gravid Aedes spp. females. Additionally, conditions necessary for the improved performance of the device, such as number of traps per site and location (indoors or outdoors) were evaluated.MethodsDuring a one year period, traps were placed in a dengue endemic area in 28 day cycles. The trap, named AedesTrap, consisted of a disposable plastic soda bottle coated inside with colophony resin, which served as a sticky substrate. Disposable bottles were donated by restaurants, and traps were made by laboratory staff, reducing the cost of the sticky trap (less than U$3). Mosquito capture in indoor and outdoor areas was compared by placing the traps in laundry room, kitchen or bedroom (indoors) and front or back yard (outdoors). The relationship between the number of AedesTraps and quantity of captured mosquitoes was investigated by utilizing one or three traps/site.ResultsDuring a 28 day cycle, a single AedesTrap was capable of capturing up to 15 A. aegypti in a house, with a mean capture of 0.5 to 2.63 females per premise. The AedesTrap collected three times more outdoors versus indoors. Similarly, the capability of detecting Aedes spp. infestation, and of capturing females, was three times higher when using three AedesTraps per house, compared with one trap per house.ConclusionsAedesTrap was shown to be capable of capturing A. aegypti and other culicidae, providing information on the adult mosquito population, and allowing the identification of areas critically infested by mosquitoes. Low requirements for skilled labor together with easy maintenance and low cost are additional advantages of using this sticky trap.

A colloidal route to fabricate hierarchical sticky and non-sticky substrates

We present a facile and inexpensive bottom-up colloidal route to prepare sticky superhydrophobic surfaces and non-sticky ones. Either spin coating to assemble silica microspheres into random multilayered arrays or irreversible adsorption of gold nanoparticles is used to manufacture substrates with a single length scale roughness. Hierarchical roughness with multiple length scales is achieved by decorating the silica spheres with gold nanoparticles. The surface chemistry of the silica surfaces is modified by the adsorption of fluoroalkylsilane self-assembled monolayers, while gold nanoparticles are hydrophobized by dodecanethiol. The wetting properties, both static and dynamic, of surfaces in relation to the morphology of the substrates are addressed. We demonstrate the role of hierarchy in the roughness in converting a sticky into a non-sticky superhydrophobic surface and discuss the results in terms of existing models describing wetting characteristics.

A multi-sphere indentation method to determine Young's modulus of soft polymeric materials based on the Johnson–Kendall–Roberts contact model

Tissue cells can sense mechanical properties of their surroundings, which, in vitro, generally refer to substrates coated with proteins. The elastic moduli of soft polymers used as substrates have been proved to affect many cellular processes, such as migration, development, and even differentiation. In this note, we present a cost-effective experimental design by using multi-sphere indentations to find the relation between indentation depth and sphere radius, and then apply the Johnson–Kendall–Roberts (JKR) contact theory with consideration of adhesive work to fit the experimental results so as to assess the value of Young's modulus. Two compliant polymeric materials, polyacrylamide gels and polydimethylsiloxane elastomers, are tested with this method. The results are in good agreement with those reported by previous experiments. Comparisons between JKR and traditional Hertz fittings highlight the demand for taking adhesive forces into account to measure Young's modulus of soft sticky polymeric substrates in cell–substrate interaction studies.

Kinetics of Reactions of the Actinomadura R39 dd-Peptidase with Specific Substrates

The Actinomadura R39 DD-peptidase catalyzes the hydrolysis and aminolysis of a number of small peptides and depsipeptides. Details of its substrate specificity and the nature of its in vivo substrate are not, however, well understood. This paper describes the interactions of the R39 enzyme with two peptidoglycan-mimetic substrates 3-(D-cysteinyl)propanoyl-D-alanyl-D-alanine and 3-(D-cysteinyl)propanoyl-D-alanyl-D-thiolactate. A detailed study of the reactions of the former substrate, catalyzed by the enzyme, showed DD-carboxypeptidase, DD-transpeptidase, and DD-endopeptidase activities. These results confirm the specificity of the enzyme for a free D-amino acid at the N-terminus of good substrates and indicated a preference for extended D-amino acid leaving groups. The latter was supported by determination of the structural specificity of amine nucleophiles for the acyl-enzyme generated by reaction of the enzyme with the thiolactate substrate. It was concluded that a specific substrate for this enzyme, and possibly the in vivo substrate, may consist of a partly cross-linked peptidoglycan polymer where a free side chain N-terminal un-cross-linked amino acid serves as the specific acyl group in an endopeptidase reaction. The enzyme is most likely a DD-endopeptidase in vivo. pH-rate profiles for reactions of the enzyme with peptides, the thiolactate named above, and β-lactams indicated the presence of complex proton dissociation pathways with sticky substrates and/or protons. The local structure of the active site may differ significantly for reactions of peptides and β-lactams. Solvent kinetic deuterium isotope effects indicate the presence of classical general acid/base catalysis in both acylation and deacylation; there is no evidence of the low fractionation factor active site hydrogen found previously in class A and C β-lactamases.

Asymptotic theory of the elastohydrodynamic adhesion and gliding motion of a solid particle over soft and sticky substrates at low Reynolds numbers

This analysis makes use of asymptotic analyses and numerical methods to address, in the limit of small Reynolds and ionic Péclet numbers and small clearances, the canonical problem of the forces exerted on a small solid spherical particle undergoing slow translation and rotation in an incompressible fluid moving parallel to an elastic substrate, subject to electric double-layer and van der Waals intermolecular forces, as a representative example of particle gliding and the idealized swimming dynamics of more complex bodies near soft and sticky surfaces in a physiological solvent. The competition of the hydrodynamic, intermolecular and surface-deformation effects induces a lift force, and drag-force and drift-force perturbations, which do not scale linearly with the velocities, and produce a non-additivity of the intermolecular effects by reducing the intensity of the repulsive forces and by increasing the intensity of the attractive forces. The lift force enhances a reversible elastohydrodynamic adhesion regime in both ionized and deionized solvents, in which lateral motion and lift-off from the substrate can occur. An irreversible elastohydrodynamic adhesion regime, produced by elastic instabilities in the form of surface bifurcations in the substrate, is found to exist for both positive and negative lift forces and is enhanced by small gliding velocities and large substrate compliances, for which critical thresholds are calculated for both ionized and deionized solvents. Elastohydrodynamic corrections are derived for the critical coagulation concentration of electrolyte predicted by the Derjaguin–Landau–Verwey–Overbeek (DLVO) standard theory of colloid stabilization. The corrected DLVO critical concentration is unable to describe the adhesion process when the substrate is sufficiently compliant or when the solvent is deionized. These effects may have consequences on the lateral motility and adhesion of small particles and swimming micro-organisms to soft and sticky substrates, in which the reversible or irreversible character of the adhesion process may be influenced not only by the solvent ionic strength, as described by the DLVO theory, but also by the motion kinematics and the substrate mechanical properties.