Commercial Tape Research Articles

The geometry, purity, and grain orientation database of the Cu stabilizer layer and the effect on the electrical and thermal properties of commercial REBCO tapes

Abstract Building upon our previous database of the thermal, electrical, and mechanical properties of commercial REBCO tape, we have constructed a subsequent database focusing on the Cu layer of such tapes from eight distinct manufacturers. This database encompasses information pertaining to the geometry, purity, and grain orientation of the Cu layer. The primary objective of this database is to not only elucidate the material science of the Cu layer across various commercial tapes but also to establish correlations between the thermal, electrical, and mechanical properties and the aforementioned geometry, purity, and grain orientation parameters. After analysis, three significant findings have been validated. Firstly, the non-uniformity of geometry plays a critical role in the electrical resistivity in the radial direction, primarily through altering the actual contact surface area. Secondly, it has been observed that the total grain boundary length per micrometer thickness exhibits a nearly linear correlation with the thermal conductivity in the circumferential direction. Thirdly, the purity of the Cu layer in all the commercial REBCO tapes is lower than anticipated. It is our aspiration that this database will facilitate enhanced comprehension of the Cu layer in REBCO tapes among a broader spectrum of researchers.

Manufacturing the current flow diverter architecture in REBCO tapes using silver inkjet printing

Abstract A low normal zone propagation velocity (NZPV) combined with critical current inhomogeneities favor the nucleation of destructive hot spots in rare-earth barium copper oxide (REBCO) tapes. Increasing the NZPV using the current flow diverter (CFD) concept is a promising solution to mitigate the risk of developing hot spots. The fabrication method of CFD REBCO tapes implies several steps consisting in masking, silver etching, mask removal, and silver deposition, which takes time and remains a barrier to the implementation of a low-cost industrial production of long-length CFD REBCO tapes. This work presents a cost-effective and maskless CFD fabrication approach that relies on inkjet printing (IJP) of silver patterns directly on top of the REBCO layer to create a non-uniform interfacial resistance between the silver and the REBCO surface, along the width of the tape. The parameters of IJP and oxygen annealing were optimized to obtain highly conductive silver patterns deposited on the surface of the REBCO layer. CFD REBCO tapes were successfully fabricated using commercial REBCO tapes and the proposed method without degrading the superconducting properties. Experimental measurements revealed an increase of the NZPV by a factor of 6-7 compared to commercial REBCO tapes.

Measuring linear birefringence via rotating-sample transmission Stokes spectropolarimetry

Linear birefringence is a fundamental property of optically anisotropic media, defined by the difference in refractive index experienced by light polarized along orthogonal directions. It is usually manifested in microscopically aligned molecular systems, where a preferential direction of light–matter interaction is created. For instance, the anisotropic structure of calcite crystal causes the famous double-refraction phenomenon. Another common example is commercial adhesive tapes, which are polymeric materials possessing birefringent properties due to their manufacturing processes. The intrinsic relation between birefringence and molecular alignment forges a new analytical route to study materials such as polymeric thin films. Therefore, the capacity of measuring linear birefringence and its fast axis is of paramount importance for the science of anisotropic molecular systems. In this contribution, a comprehensive approach to acquire linear birefringence using rotating-sample transmission Stokes spectropolarimetry is presented and applied to transparent adhesive tapes as a case study. The experimental setup comprises a thermal light source and a spectropolarimeter capable of determining wavelength distributions of Stokes parameters. The samples are carefully aligned in a rotating mount and subjected to a fixed broadband vertically polarized light beam. Then, the transmitted light is analyzed using a rotating retarder type of spectropolarimeter. Through systematic variation of the sample’s angular position, the Stokes parameters of transmitted light are measured for each transmitted wavelength as a function of the sample’s angular position. The linear retardance and fast axis direction relative to the tape’s long axis are then determined from the modulation of Stokes parameters over sample rotation. The model derivation, experimental procedure, and signal processing protocol are described in detail, and the approach is verified with a simple correlation between linear retardance and the number of stacked layers of tape.

Endocytosis-Inspired Zwitterionic Gel Tape for High-Efficient and Sustainable Underoil Adhesion.

Marine oil exploration is important yet greatly increases the risk of oil leakage, which will result in severe environment pollution and economic losses. It is an urgent need to develop effective underoil adhesives. However, realizing underoil adhesion is even harder than those underwater, due to the stubborn attachment of a highly viscous oil layer on target surface. Here, inspired by endocytosis, a tough gel tape composed of zwitterionic polymer network and zwitterionic surfactants is developed. The amphiphilic surfactants can form micelle to capture the oil droplets and transport them from the interface to gel via electrostatic attraction of polymer backbone, mimicking the endocytosis and achieving robust underoil adhesion. Benefiting from the oil-resistance of polymer backbone, the gel further realizes a combination of i) long-term adhesion with high durability, ii) repeated adhesion in oil, and iii) renewable adhesion efficiency after exhausted use. The tape exhibits an ultra-high adhesive toughness of 2446.86 J m-2 to stainless steel in silicone oil after 30 days' oil-exposure; such value of adhesive toughness surpasses many of those achieved in underwater adhesion and is greater than underoil adhesion performance of commercial tape. The strategy illustrated here will motivate the design of sustainable and efficient adhesives for wet environments.

High Current Measurement of Commercial REBCO Tapes in Liquid Helium: Experimental Challenges and Solutions

Recent advances in high-temperature superconductors (HTS) have made them extremely attractive for low-temperature, high-magnetic-field-power applications such as in fusion technology, where the advantages over traditional low-temperature superconductors (LTS) allow for the design of fusion reactors operating in different and more convenient regimes. However, the performance enhancement exhibited by novel conductors poses several challenges for the measurement of their superconducting properties. The high critical currents coupled with the relatively low thermal stability of the conductors and their mechanical fragility render this task a challenge, as the angular anisotropies complicate the experimental setup. In this work, we describe the development of our novel high-current measurement facility, focusing on the solutions introduced regarding critical aspects such as the superconducting leads and the sample holder design. We show how simple but effectively designed solutions can be adopted to combat the complexity of the measurement. The results reported in this work guide the development of a measurement system able to withstand high critical currents (I > 1500 A) at high magnetic fields (µ0H > 12 T) by evaluating the angular response of 4 mm wide short samples (L ~ 7.5 cm) in a robust and reproducible manner.

Characterization of residual-resistance-ratio of Cu stabilizer in commercial REBCO tapes

Residual-resistance-ratio (RRR) of Cu stabilizer in REBCO coated conductor is an important design parameter for REBCO magnets. Cu stabilizer with high RRR is especially beneficial for quench protections of REBCO magnets. In this work, we study RRR of electroplated Cu stabilizer in commercial REBCO tapes. We present RRR of over 180 samples measured for the quality assurance programs of REBCO magnet projects at the National High Magnetic Field Laboratory, USA (NHMFL). To investigate the factors that influence RRR, several samples were analyzed extensively by using scanning electron microscopy, secondary ion mass spectroscopy, and inductively coupled plasma mass spectroscopy. We found that RRR is strongly correlated with the grain size of Cu, which suggests that resistivity at low temperatures is dominated by grain boundary resistivity. In addition, low RRR corresponds to high concentration of chlorine impurity. This is explained by that higher chlorine impurity hindered the grain growth in the self-annealing process at room temperature which resulted in smaller grain size and low RRR. Annealing at 300C significantly enlarged the grain size and enhanced RRR. Due to the concern of critical current degradation, however, annealing is not recommended as a practical method to improve RRR of Cu in REBCO tapes.

Electrochemical detection of nitrofurazone using laser-engraved three-electrode graphene array

BackgroundNitrofurazone (NFZ) is a widely-used antimicrobial agent in aquaculture. The NFZ residue can be transmitted to humans through the food chain, and cause adverse health effects including carcinogenesis and teratogenesis. Until now, a number of modified electrodes have been developed for NFZ detection, however, there are some issues that need to be improved. For example, the reported detection sensitivity is relatively low, the modification procedure is complicated, and conventional three-electrode system is used. Therefore, it is quite important to develop new NFZ detection method with higher sensitivity, simplicity and practicality. ResultsHerein, a kind of integrated three-electrode array consisted with porous graphene is easily prepared through laser engraving of commercial polyimide tape. Five kinds of graphene arrays were prepared at different laser power percentage (i.e. 30 %, 40 %, 50 %, 60 % and 70 %). It is found that their structure, morphology, fluffiness and porosity show great difference, consequently affecting the electrochemical performance of graphene arrays such as conductivity, active area and electron transfer ability. The engraved graphene array at 50 % laser power percentage (LIG-50 array) is superior owing to uniform 3D structure, abundant pores and high stability. More importantly, LIG-50 array is more active for NFZ oxidation, and significantly enhances the detection sensitivity. The linear range of LIG-50 sensor is from 0.2 to 8 μM, and the detection limit is 0.035 μM, which is successfully used in fish meat samples. SignificanceA sensitive, portable and practical electrochemical sensor has been successfully developed for NFZ using laser-engraved graphene array. The demonstration using fish meat samples manifests this new sensor has good accuracy and great potential in application. This study could provide a new possibility for the design and fabrication of other high-performance electrochemical sensor for various applications in the future.

A facility for cryogenic ion irradiation and in situ characterization of rare-earth barium copper oxide superconducting tapes.

Superconducting magnets based on Rare Earth Barium Copper Oxides (REBCO) offer transformative capabilities in the fields of fusion energy, high energy physics, and space exploration. A challenge shared by these applications is the limited lifetime of REBCO due to radiation damage sustained during operation. Here we present a new ion-beam facility that enables simultaneous cryogenic irradiation and in situ characterization of commercial REBCO tapes. The ion source provides spatially uniform fluxes up to 1018protons/m2s with kinetic energies up to 3.4MeV, in addition to helium and higher-Z species. Using this facility, we can induce uniform damage profiles in the first 10-20 µm of REBCO tapes with less than 0.25 appm of hydrogen implanted in REBCO after a dose of 1020protons/m2. The tape can be held between 20 and 300K with an accuracy of ±0.1K and is connected to a four-point probe measuring the critical current, Ic, and critical temperature, Tc, before, during, and after irradiation with transport current ranging from 100 nA to 100A, and a typical voltage noise less than 0.1 μV. These capabilities are presently used to study the effect of irradiation temperature on REBCO performance change during and after proton bombardment, to assess the possibility of Ic and Tc recovery after irradiation through thermal annealing, and to explore the instantaneous and recoverable suppression of Ic and Tc observed during irradiation.

Flexible dual-mode ammonia-impedance sensing patch (FDP) based on Ti3C2Tx MXene/graphene material and symmetric structure

The pursuit of simple, cost-effective, and efficient flexible ammonia sensors is an area of keen interest. This study aimed to create a highly sensitive, affordable flexible sensing patch (FDP) for immediate ammonia and impedance monitoring. Using a laser direct writing technique, symmetrical graphene patterns were crafted onto commercial kapton tape. These patterns were folded in half, allowing the lower layer to serve as an impedance sensor and the upper layer as an electrode for ammonia detection. The modified Ti3C2Tx MXene solution was introduced as the sensitive layer in response to ammonia gas, and we also explored how varying thicknesses of this sensitive layer affected the response results. Notably, the results highlighted that FDPs with two thicknesses (50 μL solution) offered optimal ammonia detection. With a detection limit of 150 ppb, impressive sensitivity (18.08%/ppm), exceptional linearity (0.996), and stability within the 0.5 ppm–20 ppm range, the overall performance of the FDP surpassed that of most reported ammonia sensor devices based on graphene materials. FDP was able to better characterize the shelf life of lamb at a cost of no more than $1.5. This study provides solutions for rapid ammonia detection and food quality assessment.

Low insertion loss interposer approach for RF applications based on commercial LTCC tape, alkaline-free glass and printed metallization

Materials with high RF performance are in increasing demand due to the needs of modern telecommunications. Glass and low-temperature co-fired ceramics (LTCCs) are both interesting candidates for the design of complex signal transmission systems. Glass can be processed in large panels, and has suitable structure dimensions for silicon processing, but its multilayer capability is limited. LTCC is a mature technology for complex multilayer assemblies, but the structure dimensions and conductor line resolution are restricted by the need to use screen printing technology. The approach presented here combines the advantages of both technological domains: a thin glass sheet is bonded with no additional material to a LTCC multilayer ceramic and sintered to form a tight joint. Metallization of the glass is created using printable pastes and electroplating. Two fabrication routes are compared: etching of printed thick film metal layers, and semi-additive structuring. The results of RF measurements show a low attenuation per unit length for both types of metallization, indicating that our approach is a promising one for the integration of heterogeneous systems of RF transmission modules.

Analysis of Experimental Biaxial Surface Wrinkling Pattern Based on Direct 3D Numerical Simulation.

This paper presents a direct 3D numerical simulation of biaxial surface wrinkling of thin metal film on a compliant substrate. The selected compliant substrate is a commercial Scotch tape on which a gold metal thin film has been transferred by using low adhesion between the thin metal film and polyimide substrate. Compared with the previous fabrication of a cylindrical thin-film wrinkling pattern, an undulated wrinkling pattern has been implemented by increasing the width of the thin metal film in order to create biaxial straining in the thin film. To understand the wrinkling behavior due to biaxial loading, a simple direct numerical simulation based on material imperfections defined in the compliant substrate has been conducted. Through modeling and simulation, it was found that the wrinkling mode is determined by the biaxiality ratio (BR), the ratio between transversal strain and longitudinal strain. Depending on the BR, the wrinkling mode belongs to one of the cylindrical, undulated (or herringbone), checkerboard, or labyrinth modes as a function of applied strain. The cylindrical wrinkling is dominant at the input of BR less than 0.5, while the undulated (or herringbone) ones become dominant just after the onset of the wrinkling pattern at BR greater than 0.9. Through the comparison of the wrinkling patterns between simulation and experiment, the applied BR of the fabricated thin film has been successfully estimated.

Tension-free artisan tape: a low-cost option for cure of pelvic organ prolapse and stress incontinence.

The Lancet PROSPECT Trial has shown that vaginal repair has dismal cure rates of some 20% at 12 months. Meanwhile 10-year data from collagen creating ligament repair methods (implanted mini-sling tapes), with no vaginal excision, report very high, long-term cure rates. The reason for conserving the vagina, is that the vagina's main function is to transmit the muscle forces for external urethral closure or opening. Ligaments provide the main structural support for the organs, much like a suspension bridge. Collagen is the key structural component of the ligaments which structurally support the organs. However, collagen breaks down after the menopause and is excreted as hydroxyproline. If sufficient collagen breaks down, the ligaments weaken, and this explains the 80% failure rates for native ligament in the Lancet PROSPECT Trial. Whereas satisfactory results for pelvic organ prolapse (POP) and symptoms have been obtained with native ligament repair in premenopausal women, it has been shown that collagen-creating ligament repair method, for example, precisely inserted tapes, is required in older women. Tension-free" artisan tapes work in the same way as commercial tape kits which have been used to cure stress urinary incontinence (SUI) and POP. The "tension-free" artisan tape results for POP at three years were encouraging, but were applied only in a small number of cases. Very recently, long-term (5.7 years) tension-free artisan tape data has become available from artisan SUI surgery. Results from 93 women using an artisan transobturator tape (TOT) achieved a cure rate of 91.3% at a mean of 5.7 years postoperatively. The only significant complication was a 4.3% erosion rate. The implications are that tension-free artisan tape for POP is also likely to be long-lasting. Another implication is the cost, which, for each tape, is a few Euros. The low cost allows the artisan method to be applied even in the poorest nations.

Optical properties optimization of carbon fiber reinforced thermoplastic tapes by micro surface texturing for enhanced laser heating efficiency and in-situ consolidation quality during AFP process

The laser-assisted automated fiber placement (L-AFP) process of carbon fiber-reinforced thermoplastic composites suffers from insufficient heating efficiency and in-situ consolidation quality caused by significant reflection on the tape surface. Here, we propose a novel strategy to increase the heating efficiency by refocusing the reflected light, initially scattered to the environment and wasted, onto the tapes for multiple and full absorptions. The method for laser concentration is first validated through light-tracing simulation. Then, three kinds of tapes with different micro textures on the surface are prepared by the hot-embossing process. The transverse V-grooved texture tapes and flat surface tapes absorb 25% more laser energy than the longitudinal V-grooved and commercial tapes due to the reduction in transverse scattering angle from 180° to 2.72°. This leads to a temperature increase of 130 °C at the nip point during the L-AFP process at the lay-down rate of 500 mm/s with 1 kW laser power. Improved in-situ consolidation quality leads to a significant increase in the flexural and shear strength of L-AFP-prepared carbon fiber reinforced polyetheretherketone (CF/PEEK) laminates, with a reduction in porosity to around 2%.

Preliminary Validity and Acceptability of Motion Tape for Measuring Low Back Movement: Mixed Methods Study.

Low back pain (LBP) is a significant public health problem that can result in physical disability and financial burden for the individual and society. Physical therapy is effective for managing LBP and includes evaluation of posture and movement, interventions directed at modifying posture and movement, and prescription of exercises. However, physical therapists have limited tools for objective evaluation of low back posture and movement and monitoring of exercises, and this evaluation is limited to the time frame of a clinical encounter. There is a need for a valid tool that can be used to evaluate low back posture and movement and monitor exercises outside the clinic. To address this need, a fabric-based, wearable sensor, Motion Tape (MT), was developed and adapted for a low back use case. MT is a low-profile, disposable, self-adhesive, skin-strain sensor developed by spray coating piezoresistive graphene nanocomposites directly onto commercial kinesiology tape. The objectives of this study were to (1) validate MT for measuring low back posture and movement and (2) assess the acceptability of MT for users. A total of 10 participants without LBP were tested. A 3D optical motion capture system was used as a reference standard to measure low back kinematics. Retroreflective markers and a matrix of MTs were placed on the low back to measure kinematics (motion capture) and strain (MT) simultaneously during low back movements in the sagittal, frontal, and axial planes. Cross-correlation coefficients were calculated to evaluate the concurrent validity of MT strain in reference motion capture kinematics during each movement. The acceptability of MT was assessed using semistructured interviews conducted with each participant after laboratory testing. Interview data were analyzed using rapid qualitative analysis to identify themes and subthemes of user acceptability. Visual inspection of concurrent MT strain and kinematics of the low back indicated that MT can distinguish between different movement directions. Cross-correlation coefficients between MT strain and motion capture kinematics ranged from -0.915 to 0.983, and the strength of the correlations varied across MT placements and low back movement directions. Regarding user acceptability, participants expressed enthusiasm toward MT and believed that it would be helpful for remote interventions for LBP but provided suggestions for improvement. MT was able to distinguish between different low back movements, and most MTs demonstrated moderate to high correlation with motion capture kinematics. This preliminary laboratory validation of MT provides a basis for future device improvements, which will also involve testing in a free-living environment. Overall, users found MT acceptable for use in physical therapy for managing LBP.

From waste to tape: Inverse vulcanization of sulfur and solvent-based depolymerization for preparation of pressure-sensitive adhesives

Upcycling is an eco-friendly method that turns waste into valuable items. Elemental sulfur, a waste substance produced in large amounts (70 million tons per year), can be converted into valuable polymers using inverse vulcanization. However, the traditional method had significant limitations, such as limited consumption and weak strength. To address this problem, we newly fabricated sulfur-based pressure-sensitive adhesives (PSAs). PSAs are soft and tacky materials that should have low modulus, and they are used extensively (3.1 million tons per year). We prepared sulfur-based PSAs in four steps: polymerization, dissolution, coating/drying, and curing. In the polymerization step, castor oil and oleic acid were employed to facilitate inverse vulcanization. The resulting polymer then underwent solvent-based depolymerization to be coated in a film form. After drying and ultra-violet (UV)-induced curing, the tapes were successfully produced. Significantly, we adjusted the PSA's crosslinking density by changing the oleic acid content and UV dose. As the amount of mono-functional oleic acid decreased or the UV dose increased, the resulting PSA's crosslinking density increased. The best conditions led to PSAs with excellent adhesion performances and creep resistance, similar to commercial tapes. Moreover, the prepared PSAs exhibited self-healing properties, suggesting the feasibility of high-performance PSAs like remoldable PSAs and conductive sensors.

Development of a wearable surface enhanced Raman scattering sensor chip based on silver nanowires for rapid detection of urea, lactate and pH in sweat

A wearable sweat sensor chip based on surface-enhanced Raman spectroscopy (SERS) is here presented. The plasmonic core of the chip, obtained by deposition of silver nanowires on a polytetrafluoroethylene (PTFE) porous membrane, permits the direct and label-free detection of urea and lactate at physiologic concentrations in combination with the pH measurement in the range between 5 and 9. Once integrated with commercial biocompatible and adhesive tape layers, the as produced SERS-active chip provides a low-cost, flexible and wearable sensing device for rapid and reliable human sweat analysis. The chip was finally tested on real sweat samples to estimate lactate and urea during medium-intense exertions.

40-meter-long REBCO tapes with critical current over 4,000 A/12 mm at 4.2 K and 13 T by advanced MOCVD

REBa2Cu3O7−δ (REBCO, RE = rare earth) tapes doped with 5% and 15% Zr have been scaled up to lengths more than 40 m in a pilot-scale advanced metal organic chemical vapor deposition (A-MOCVD) tool. The precursor compositions used for the long tapes were guided by a study of the influence of (Ba + dopant)/Cu content on the critical current density (Jc) of 5 and 15 mol.% Hf- and Zr-added tapes at 4.2 K and 13 T. The 40-m-long tapes exhibited a critical current (Ic) over 4,000 A/12 mm at 4.2 K and 13 T as well as over 1,400 A/12 mm at 20 K and 20 T. The critical current densities of a 40-m-long tape doped with 5% Zr at 4.2 K measured at the National High Magnetic Field Laboratory (NHMFL) were > 10 MAcm−2 and >5 MAcm−2 at 14 T and 30 T, respectively, which are over three times those of commercial REBCO tapes. The infield Jc of 5% Zr-added 40-m-long tapes was similar to those of previously-reported high-performance short samples made with 15% Zr or Hf. These results demonstrate the excellent potential of A-MOCVD for manufacturing high Ic REBCO tapes for use in ultrahigh-field magnet applications.

Effect of molecular weight and its modality on pressure-sensitive adhesives behavior of plant oil-based latexes

Semibatch emulsion polymerization of high oleic soybean oil-based monomer (HO-SBM), 2–ethylhexyl acrylate (2-EHA), and styrene (St) was applied to synthesize pressure-sensitive latex adhesives with up to 40 wt% of plant oil-based content. Ternary latex copolymers with similar chemical composition and broadly different molecular weight distribution (MWD) and modality were synthesized at varying temperatures and the mechanism of free-radical initiation. Conventional thermal initiation with ammonium persulphate at 80 °C and ascorbic acid/tert-butyl hydroperoxide redox system of lower reaction temperature up to 20 °C were employed. Linear, short-chain, and long-chain branched macromolecules are formed due to chain-breaking reactions of HO-SBM (chain transfer on allyl groups) and 2-EHA (inter- and intramolecular chain transfer on the polymer). The dominant effect of chain transfer on allyl group protons and subsequent decrease in molecular weight was observed at higher reaction temperatures, while extensively branched polymer with high molecular weight was obtained at reaction temperature close to 20 °C.The effect of MWD and branching on the PSAs performance of synthesized biobased latexes was studied using loop tack and peel strength and lap shear testing and compared to two commercial PSA tapes as a benchmark. A significant increase in shear strength (up to 0.23 MPa) was observed for latex adhesives due to high molecular weight fractions, maintaining satisfactory level of tack (3–7 N) and peel (3–6 N/in). Broad MWD of the copolymers can be beneficial for providing materials with high shear strength (0.25–0.33 MPA) while preserving the significant level of tack (2–4 N) and peel strength (9–12 N/in) on both glass and steel substrates.

Electro‐Driven, Predefined Carbon Nanotube‐Based Phase Change Composite as a Lifting‐Jack

AbstractShape change materials or actuators that are capable of shrinking, bending or rotation under external stimuli (especially, by electricity), have attracted tremendous research interest in past years. Controlled shape change with large output capacity under low excitation voltage remains a challenging task in this field. Here, an electro‐driven carbon nanotube sponge/paraffin wax bulk composite (CS@PW) that can perform various shape change functions such as, in particular, jacking and lifting heavy objects (up to 668.3 times of composite weight) under lower voltages (4–8 V) with fast response and high reversibility is presented. This unique and superior jacking performance is attributed to the predefined original CS shape, the deformability and resilience derived from 3D porous CS@PW, and efficient Joule heat transfer from conductive CS to the coaxially wrapped PW layer; the latter, by reversible phase change solidification/melting, can fix or release carbon nanotube network to enable controlled fixation/motion. Additional advantages include hydrophobicity, anti‐leakage, wide operating temperature, and diverse reversible shape change modes based on CS@PW and commercial polyethylene tapes, are also demonstrated. The designed electro‐driven nanocomposites, combining resilient carbon nanotube networks with low‐cost organic phase‐change material, have wide applications in areas such as robust artificial muscles, intelligent morphing, and energy management.

Rapid and sensitive detection of 2,4‐dichlorophenoxyacetic acid residual on fruit surface via SERS‐tape sampling

AbstractThe residual 2,4‐dichlorophenoxyacetic acid (2,4‐D) in fruits poses a serious threat to human health. The continuous deposition of 2,4‐D in the body may cause symptoms such as cancer or Alzheimer's disease, therefore, it is of great significance for the detection of 2,4‐D traces on fruits. In this paper, we proposed a simple “paste‐collect‐test” strategy based on surface‐enhanced Raman spectroscopy via tape sampling (SERS‐tape sampling). The flexibility and stickiness of commercial tapes were combined with the excellent activity of optimized silver nanoparticles (Ag NPs) for rapid trace detection of pesticides in cherry tomatoes. The first two steps of “paste” and “collect” were completed by the tape to simplify the sampling procedure of the analyte molecules, and the “test” step was accomplished by deposing Ag NPs on the surface of the tape after analyte collection. The whole process was completed in a few minutes. The results showed that the limit of detection (LOD) of 2,4‐D in cherry tomatoes was 3.63 × 10−10 M with the SERS‐tape sampling approach, which is much lower than the maximum residue limit specified by the European Union (EU). This simple and easy‐to‐operate method is highly sensitive and could be a promise of 2,4‐D for food safety.