Polymer Sensors Research Articles

A differential strategy to enhance the anti-interference ability of electrochemical molecularly imprinted polymers sensors for the determination of sulfamerazine and 4-acetamidophenol

Herein, we report a differential strategy to enhance the anti-interference ability of the electrochemical molecularly imprinted polymers (MIP) based sensors for the determination of 4-acetamidophenol (AP) and sulfamerazine (SMR). Polypyrrole MIP membranes for AP or SMR were grown independently on the surface of Ni2P/GCE, with the imprinting factors of 6.13 for MIPAP and 5.82 for MIPSMR. At the potentials of 0.42 V and 0.89 V (vs. Ag/AgCl), MIPAP/Ni2P/GCE and MIPSMR/Ni2P/GCE exhibit sensitive current responses to AP and SMR, respectively. However, the non-specific adsorption of various interferents on the surface of MIP suppresses the selectivity of the MIP sensors. For example, 20 μM ascorbic acid (AA) and sulfamethoxazole (SMZ) were determined falsely as 5.2 μM AP and 4.7 μM SMR, respectively. In the proposed differential strategy using the current differences between MIPAP/Ni2P/GCE and MIPSMR/Ni2P/GCE as the signal indicators, 20 μM of AA and SMZ are equivalent only to 0.25 μM AP and 0.33 μM SMR, respectively, enhancing significantly the anti-interference ability of MIP sensors. Moreover, the limit of detection for AP and SMR are 0.011 and 0.019 μM, respectively. AP and SMR in actual urine samples were determined with the recoveries from 94% to 105%.

Carbazole-siloxane based polymers for the selective detection of 4-nitrophenol and Fe3+

Silicone-containing polymers have broad application prospects in the detection of many analytes due to their unique fluorescence properties. Environmental pollutants are very complex, which have prompted researchers to explore different detection methods. In this report, two kinds of polymers were synthesized via Heck-reaction between tetramethyltetravinylcyclotetrasiloxane (D4vi) and carbazole derivatives. The polymers showed excellent fluorescent properties and exhibited high sensitivity to 4-nitrophenol (4-NP) and Fe3+ in solution. Furthermore, the polymers still showed high sensitivity for Fe3+ in living cells. We estimate that the cyclic structure of D4vi and carbazole structure will serve as responsive sites for Fe3+ and 4-NP, respectively. The frontier molecular orbitals of polymers were calculated by Materials Studio and the effect of the cyclic structure of D4vi on their responsiveness had been discussed. The design idea of the polymer sensors can provide a new direction for the synthesis of multi-response polymer fluorescent probes.

Electropolymerized, Molecularly Imprinted Polymer on a Screen-Printed Electrode-A Simple, Fast, and Disposable Voltammetric Sensor for Trazodone.

In recent years, analytical chemistry has been facing new challenges, particularly in developing low-cost, green, and easy-to-reproduce methods. In this work, a simple, reproducible, and low-cost electrochemical (voltammetric) molecularly imprinted polymer (MIP) sensor was designed specifically for the detection of trazodone (TZD). Trazodone (TZD) is an antidepressant drug consumed worldwide since the 1970s. By combining electropolymerization (surface imprinting) with screen-printed electrodes (SPCEs), the sensor is easy to prepare, is environmentally friendly (uses small amounts of reagents), and can be used for in situ analysis through integration with small, portable devices. The MIP was obtained using cyclic voltammetry (CV), using 4-aminobenzoic acid (4-ABA) as the functional monomer in the presence of TZF molecules in 0.1 M HCl. Non-imprinted control was also constructed in the absence of TZD. Both polymers were characterized using CV, and TZD detection was performed with DPV using the oxidation of TZD. The polymerization conditions were studied and optimized. Comparing the TZD signal for MIP/SPCE and NIP/SPCE, an imprinting factor of 71 was estimated, indicating successful imprinting of the TZD molecules within the polymeric matrix. The analytical response was linear in the range of 5–80 µM, and an LOD of 1.6 µM was estimated. Selectivity was evaluated by testing the sensor for molecules with a similar structure to TZD, and the ability of MIP/SPCE to selectively bind to TZD was proven. The sensor was applied to spiked tap water samples and human serum with good recoveries and allowed for a fast analysis (around 30 min).

Detection of progesterone in aqueous samples by molecularly imprinted photonic polymers.

A label-free molecular imprinted polymer (MIP) sensor was fabricated for the detection of progesterone in aqueous solutions, by polymerization inside the void spaces of colloidal crystals, which gave them photonic properties. The prepolymerization mixture was prepared fromacrylic acid as the functional monomer, ethylene glycol as thecross-linker agent, ethanol as solvent, and progesterone as the imprinted template. After polymerization, the colloidal crystal was removed by acid etching and the target eluted with a solvent. Material characterization included as follows: attenuated total reflectance-Fourier-transform infrared spectroscopy, dynamic light scattering, swelling experiments, and environmental scanning electron microscopy. MIPs were investigated by equilibrium binding, kinetics experiments, and UV-visible spectra to investigate Bragg diffraction peak shift that occurs with the rebinding at different progesterone concentrations in deionized water and 150-mM NaCl solutions. The MIP response was investigated with progesterone concentration in the 1-100μg L-1 range, with LOD of 0.5μg L-1, reaching the detected range of hormone in natural waters. Furthermore, hydrogel MIP films were successfully tested in various real water matrices with satisfactory results. Moreover, the MIP film exhibited good selectivity toward the progesterone hormone evidenced by a larger response than when exposed to structurally similar molecules. Computational studies suggested that size along with surface potential influenced the binding of analog compounds. Due to their ease of use and low cost, the sensors are promising as screening tools for the presence of progesterone in aqueous samples.

Conformal 3D printing of a polymeric tactile sensor

• Conformal additive manufacturing of soft tactile sensors on a curved surface is new. • Sensors printed by conformal and conventional additive manufacturing were compared. • Conformal printing of sensors on non-flat surfaces can avoid manufacturing errors. • Conformal printing of sensors can be employed in future robotics and prosthetics. Conventional additive manufacturing processes are generally inadequate for printing electronics on a curved surface. When printing a curved functional structure, the typical way of generating the extrusion path only in a horizontal plane could cause various issues such as impreciseness and disconnect in the printed part. In this work, conformal 3D printing of a soft tactile sensor is presented in which curvilinear extrusion paths were generated for the printing of a curved sensor. An extrusion-based multi-material direct printing system was employed to print the sensor, and ultraviolet light was used to polymerize the printed layers. An ionic liquid–based pressure-sensitive polymer membrane, carbon nanotube-based conductive electrodes, and a soft polymeric insulation layer were conformally 3D printed to fabricate the curved sensor on a fingertip model. The conformally printed sensor was evaluated under different conditions. Sensors 3D-printed using conformal and planar slicing processes were compared to investigate the effect of curvilinear slicing on the printed parts. The results show that conformal 3D printing is able to overcome the fabrication limitations of conventional planar processing while also retaining the functionality of the printed structures.

Highly Efficient Multi‐Tasking Porphyrin‐Based Chemosensor for Mercury Ions

AbstractPorphyrin‐based monomeric and polymeric sensors are emerging as a desirable alternative to efficient sensors due to their unique optical properties and biocompatibility. An efficient new sensor Acpmono and Acppoly were designed and synthesized for selective and efficient mercury detection at ppm‐level. UV‐visible and fluorescence spectroscopic techniques were studied for the sensing performance of both the monomeric and the polymeric sensors. Mechanism of interaction between sensors was confirmed by proton nuclear magnetic resonance (NMR) titration, Ultraviolet‐visible and fluorescence spectroscopic titration, mass spectrometry, time‐correlated single‐photon count (TCSPC) study. Furthermore, a “turn‐off” mode has been established to detect noble heavy metal mercury (Hg2+) by quenching the red fluorescence of sensor molecules. The real‐time application of Acpmono and Acppoly were studied by preparing paper strips and detecting Hg2+ from beauty products in a facile way. Cell viability was evaluated for sensors Acpmono and Acppoly to living HeLa cells using the MTT assay technique to investigate the applicability of the sensors in a biological medium. Based on the MTT assay data of both monomeric and polymeric sensors, the cell imaging of endogenous Hg2+ ions was explored in living HeLa cells.

Comparison of the performance of metal oxide and conducting polymer electronic noses for detection of aflatoxin using artificially contaminated maize

The electronic nose offers potential as a rapid and cost effective field portable diagnostic device that would allow for quick screening of produce for aflatoxin contamination at the market entry level. This study aimed to compare the performance of three electronic nose sensor technologies: metal oxide semiconductor sensors (Fox 3000), conducting polymer sensors (Cyranose 320) and doped metal oxide semiconductor sensors with thermocycling (DiagNose), for the detection of volatiles associated with maize contaminated with aflatoxins. Australian maize (variety DK703w) samples were artificially inoculated with aflatoxigenic and non-aflatoxigenic Aspergillus flavus isolates and 2 % v/v Tween 20 as a control. Mutual information was used to select features from the electronic nose sensor signals for classification of the samples. The effectiveness, of selected features to discriminate between the different classes of samples was evaluated by support vector machines and k-nearest neighbour with leave-one-out cross-validation. Cross-validated classification accuracy for the different sample classes ranged from 81 % to 94 % for DiagNose, 76 to 79 % for Fox 3000 and 68 to 75 % for Cyranose. The results suggest that an electronic nose equipped with doped metal oxide semiconductor sensors and thermocycling is more effective for detection of aflatoxin contamination of maize.

Facile Synthesis of Water-Soluble Rhodamine-Based Polymeric Chemosensors via Schiff Base Reaction for Fe3+ Detection and Living Cell Imaging.

Quantitative and accurate determination of iron ions play a vital role in maintaining environment and human health, but very few polymeric chemosensors were available for the detection of Fe3+ in aqueous solutions. Herein, a water-soluble rhodamine-poly (ethylene glycol) conjugate (DRF-PEG), as a dual responsive colorimetric and fluorescent polymeric sensor for Fe3+ detection with high biocompatibility, was first synthesized through Schiff base reaction between rhodamine 6G hydrazide and benzaldehyde-functionalized polyethylene glycol. As expected, the introduction of PEG segment in DRF-PEG significantly improved the water solubility of rhodamine derivatives and resulted in a good biosensing performance. The detection limit of DRF-PEG for Fe3+ in pure water is 1.00 μM as a fluorescent sensor and 3.16 μM as a colorimetric sensor at pH 6.5. The specific sensing mechanism of DRF-PEG toward Fe3+ is proposed based on the intramolecular charge transfer (ICT) mechanism, in which the O and N atoms in rhodamine moiety, together with the benzene groups from benzaldehyde-modified PEG segment, participate in coordination with Fe3+. Furthermore, DRF-PEG was applied for the ratiometric imaging of Fe3+ in HeLa cells and showed the potential for quantitative determination of Fe3+ in fetal bovine serum samples. This work provides insights for the design of water-soluble chemosensors, which can be implemented in iron-related biological sensing and clinical diagnosis.

A suspended polymeric microfluidic sensor for liquid flow rate measurement in microchannels

In this study, a microfluidic cantilever flow sensor was designed and manufactured to monitor liquid flow rate within the range of 100–1000 µl/min. System simulation was also performed to determine the influential optimal parameters and compare the results with experimental data. A flowmeter was constructed as a curved cantilever with dimensions of 6.9 × 0.5 × 0.6 mm3 and a microchannel carved with a CO2 laser inside the cantilever beam. The fabrication substance was Polydimethylsiloxane. Different flow rates were injected using a syringe pump to test the performance of the flowmeter. Vertical displacement of the cantilever was measured in each flowrate using a digital microscope. According to the results, the full-scale overall device accuracy was up to ± 1.39%, and the response time of the sensor was measured to be 6.3 s. The microchip sensitivity was 0.126 µm/(µl/min) in the range of measured flow rates. The sensor could also be utilized multiple times with an acceptable error value. The experimental data obtained by the constructed microchip had a linear trend (R2 = 0.995) and were of good consistency with simulation results. Furthermore, according to the experimental and the simulation data, the initially curved cantilever structure had a higher bending and sensitivity level than a perfectly straight cantilever construction.

Piezoresistive 3D graphene–PDMS spongy pressure sensors for IoT enabled wearables and smart products

Recently, 3D porous graphene–polymer composite-based piezoresistive sensors have gained significant traction in the field of flexible electronics owing to their ultralightweight nature, high compressability, robustness, and excellent electromechanical properties. In this work, we present an improved facile recipe for developing repeatable, reliable, and linear 3D graphene–polydimethylsiloxane (PDMS) spongy sensors for internet of things (IoT)-enabled wearable systems and smart consumer products. Fundamental morphological characterization and sensing performance assessment of the piezoresistive 3D graphene–polymer sensor were conducted to establish its suitability for the development of squeezable, flexible, and skin-mountable human motion sensors. The density and porosity of the sponges were determined to be 250 mg cm−3 and 74% respectively. Mechanical compressive loading tests conducted on the sensors revealed an average elastic modulus as low as ∼56.7 kPa. Dynamic compressive force-resistance change response tests conducted on four identical sensors revealed a linear piezoresistive response (in the compressive load range 0.42–2.18 N) with an average force sensitivity of 0.3470 ± 0.0794 N−1. In addition, an accelerated lifetime test comprising 1500 compressive loading cycles (at 3.90 N uniaxial compressive loading) was conducted to demonstrate the long-term reliability and stability of the sensor. To test the applicability of the sensors in smart wearables, four identical graphene–PDMS sponges were configured on the fingertip regions of a soft nitrile glove to develop a pressure sensing smart glove for real-time haptic pressure monitoring. Similarly, the sensors were also integrated into the Philips 9000 series electric shaver to realize smart shaving applications with the ability to monitor shaving motions. Furthermore, the readiness of our system for next-generation IoT-enabled applications was demonstrated by integrating the smart glove with an embedded system software utilizing the an open source microcontroller platform. The system was capable of identifying real-time qualitative pressure distribution across the fingertips while grasping daily life objects, thus establishing the suitability of such sensors for next-generation wearables for prosthetics, consumer devices, and personalized healthcare monitoring devices.

Aggregation-induced emission-active fluorescent polymer sensors for the detection of water in organic solvents, Cu2+ and hemolysis

The hydrophobic polymer HDDA-EDT-SADA with aggregation-induced emission (AIE) property was synthesized via the thiol-ene click copolymerization of salicylaldehyde azine (SA) derivative diacrylate monomer SADA and commercially available 1,2-ethanedithiol (EDT) and 1,6-hexanediol diacrylate (HDDA). HDDA-EDT-SADA was found to display unexpected intense fluorescence in acetone and DMSO compared to that in other good solvents, which dramatically decreased by adding small amount of water. We demonstrate that HDDA-EDT-SADA can be used as a fluorescent sensor for water detection in acetone and DMSO. To improve the water solubility of the AIE-active polymer, SADA was copolymerized with dithiothreitol (DTT) and poly(ethylene glycol) diacrylate (PEGDA) to give an amphiphilic AIE polymer PEGDA-DTT-SADA. Similar fluorescence phenomenon was also found in DMF, suggesting that PEGDA-DTT-SADA could serve as an indicator for water detection in DMF. Thanks to the PEG segments and DTT units, the PEGDA-DTT-SADA was able to well-disperse in water via the formation of stable micelles. The PEGDA-DTT-SADA selectively complexed with Cu2+ and thus could be used as a fluorescent sensor for Cu2+ detection in aqueous media. Moreover, the PEGDA-DTT-SADA could be utilized as a fluorescent sensor for hemolysis ratio detection of red blood cells (RBCs) due to the inner filter effect.

Application-Specific Adaptable Coatings for Sensors: Using a Single Polymer-Plasticizer Pair to Detect Aromatic Hydrocarbons, Mixtures, and Interferents in Water with Single Sensors and Arrays.

A relatively simple design procedure is presented for new, adaptable chemical sensor coatings made from a single polymer-plasticizer pair to detect single or a mixture of chemical compounds (e.g., BTEX, the small aromatic hydrocarbon family). Affinity between coating components and target analytes, expressed through Hansen solubility parameters and relative energy difference values, describes the sensitivity of the resultant coatings to each analyte. While analyte affinity is paramount for plasticizer selection, for the aqueous-phase sensing application described here, it must be traded off with the permanence in the host polymer, i.e., resistance to leaching into the ambient aqueous phase; deleterious effects including coating creep must also be minimized. By varying the polymer:plasticizer mixing ratio, the physical and chemical properties of the resultant coatings can be tuned across a range of sensing properties, in particular the differential response magnitude and rate, for multiple analytes. Together with the measurement of multiple sensor response parameters (relative sensitivity and response time constant) for each coating, this approach allows for identification and quantification of target analytes not previously separable using commercial off-the-shelf (COTS) polymer sensor coatings. Sensing results using a five-sensor array based on five different mixing ratios of a single plasticizer polymer pair (plasticizer: ditridecyl phthalate; polymer: polystyrene) demonstrate unique identification of mixtures of BTEX analytes, including differentiation of the chemical isomers ethylbenzene and total xylene (or "xylenes"), something not previously feasible for separation-free liquid-phase sensing with commercially available polymer coatings. Ultimately, the response of a single optimized sensor coating identified and quantified the components of various mixtures, including identification of likely interferents, using a customized estimation-theory-based multivariate signal-processing technique.

Prediction of Carbonate Selectivity of PVC-Plasticized Sensor Membranes with Newly Synthesized Ionophores through QSPR Modeling

Developing a potentiometric sensor with required target properties is a challenging task. This work explores the potential of quantitative structure-property relationship (QSPR) modeling in the prediction of potentiometric selectivity for plasticized polymeric membrane sensors based on newly synthesized ligands. As a case study, we have addressed sensors with selectivity towards carbonate—an important topic for environmental and biomedical studies. Using the logKsel(HCO3−/Cl−) selectivity data on 40 ionophores available in literature and their substructural molecular fragments as descriptors, we have constructed a QSPR model, which has demonstrated reasonable precision in predicting selectivities for newly synthesized ligands sharing similar molecular fragments with those employed for modeling.

Recent developments in textile based polymeric smart sensor for human health monitoring: A review

In the modern age, the most important and prevailing issue is the monitoring of human health. To address this, several devices have been developed and a need new materials investigated. The idea of textile-based smart sensors is emerging rapidly. In this regard, ICPs and ECPs have attracted the attention of researchers due to their mechanical adaptability to suit the characteristics of textile fabric. The lighter weight, stretchability and wearability, etc. are considered an advantage while selecting the material for developing sensors not only in health monitoring but also in biomedical, sports, and military fields. The idea behind wearable sensing devices is to enable easy integration of the sensor device into daily life routines. Such wearable sensors also have the potential for real time and online monitoring of human health and integrate with smart monitoring devices. The purpose of this review is to discuss the recent developments in smart monitoring sensors.

A highly temperature- and pressure-sensitive soft sensor self-powered by a galvanic cell design

A new design of self-powered and highly sensitive polymeric soft sensor that can be used for contactless temperature detecting and spatial pressure monitoring.

A Novel Terpolymer Membrane-Based Electrode Sensor for Selective Determination of Cd(II) Ions

A new polymeric membrane sensor for Cd(II) ion based on methyl acrylate-acrylonitrile-methyl methacrylate terpolymer as membrane carrier has been synthesized via atom transfer radical polymerization (ATRP) method at 60 ºC. Preliminary investigation with the membrane exhibited promising selectivity for Cd(II) ion with a slope of 32.02 mV/decade and the same could be estimated in the concentration range of 1 × 10-6 − 1 × 10-1 M in the working pH range of 4-6 for up to 90 days. The potentials generated across the membrane were reproducible and the response time was less than one minute. The electrode works well even in a partially non-aqueous media. The effect of surfactant and detergent on the working of Cd(II) selective electrode was also studied. A decrease in potential was observed in the presence of appreciable amount of surfactant and detergent. Addition of plasticisers was found to greatly improve the performance of membrane, best results being obtained with the membrane ratio (NaTPB:TP:TBP::1:100:06), exhibiting a working concentration range of 1 × 10-6 − 1 × 10-1 mol L-1 with a short response time of 10 s. The proposed sensor shows significantly good selectivity toward Cd(II) ion in comparison with some alkali, alkaline earth, transition and heavy metal ions. It was successfully employed as an indicator electrode in potentiometric titration of cadmium(II) ions against EDTA solution.

Novel Electrophoresis Device with a Molecularly Imprinted Polymer Sensor for High-Performance Sensing

Novel Electrophoresis Device with a Molecularly Imprinted Polymer Sensor for High-Performance Sensing

New composite polymer sensor for vehicle weighing

The work presented in this paper describes a new concept of the sensor for weighing-in-motion of vehicles. This sensor has small dimensions and can be used for weighing the vehicles. The sensor has four strain gauges, two of them are external and two are embedded into polymer. It’s well known that the influence of temperature can affect the measurement process and also can change the output signal of strain gauges. The hysteresis and linearity graphics of strain gauges are compared in order to establish which one has higher values. The measurements lead to interesting results which are presented in this paper.

Direct discrimination of cell surface glycosylation signatures using a single pH-responsive boronic acid-functionalized polymer.

Cell surface glycans serve fundamental roles in many biological processes, including cell-cell interaction, pathogen infection, and cancer metastasis. Cancer cell surface have alternative glycosylation to healthy cells, making these changes useful hallmarks of cancer. However, the diversity of glycan structures makes glycosylation profiling very challenging, with glycan 'fingerprints' providing an important tool for assessing cell state. In this work, we utilized the pH-responsive differential binding of boronic acid (BA) moieties with cell surface glycans to generate a high-content six-channel BA-based sensor array that uses a single polymer to distinguish mammalian cell types. This sensing platform provided efficient discrimination of cancer cells and readily discriminated between Chinese hamster ovary (CHO) glycomutants, providing evidence that discrimination is glycan-driven. The BA-functionalized polymer sensor array is readily scalable, providing access to new diagnostic and therapeutic strategies for cell surface glycosylation-associated diseases.

Fatigue Resistant Aerogel/Hydrogel Nanostructured Hybrid for Highly Sensitive and Ultrabroad Pressure Sensing (Small 1/2022)

High-Resolution Sensing In article number 2104706, Jingbin Zeng, Zifeng Yan, Yadong Yin, and co-workers fabricate a hybrid pressure aerogel/hydrogel sensor by integrating a polypyrrole nanotube-structured aerogel into a polyacrylamide hydrogel. With high stretchability and self-healing property, the hybrid polymer sensor exhibits stable performance in high-resolution sensing of a wide range of pressure from human physiological signals to significant stress caused by car rolling.