Polymer Sensors Research Articles

SERS-based molecularly imprinted polymer sensor for highly sensitive norfloxacin detection

SERS-based molecularly imprinted polymer sensor for highly sensitive norfloxacin detection

Colorimetric Polymer Sensors for Smart Packaging

AbstractNowadays, consumers can estimate the condition of packaged foods only by checking the expiration date on the label. However, this approach is inefficient when it comes to assessing the actual edibility of fresh products, since the events that accelerate the onset of degradation phenomena, such as a rise in temperature, cannot be continuously assessed. In this context, the detection of a different parameter, such as low concentration of amines, can reveal the onset of degradation processes. Here, a colorimetric photonic multilayer sensor is reported for detecting low amine concentrations suitable for sealed packages. The sensor consists of alternating layers of poly(N‐vinylcarbazole) and polyacrylic acid, and its response is based on the selective interaction between the latter and amines. This interaction causes the polymer layers to swell and introduce disorder into the photon structure, resulting in fading its bright color. Since the reaction of these systems is usually reversible, manipulation or false readings are possible due to inapt sealing of the package. It is shown that the activation of carboxylic acid residues of the sensitive polymer with N‐hydroxysuccinimide produces an irreversible response to amine vapor concentrations as low as 3 parts per billion.

An oxygen-insensitive and minimally invasive polymeric microneedle sensor for continuous and wide-range transdermal glucose monitoring

Despite significant advances in diabetes management, particularly with the introduction of the most recent continuous glucose monitoring devices (CGMDs) that can monitor glucose actively in the transdermal interstitial fluid (ISF) in vivo, CGMDs still have significant disadvantages in terms of accuracy, low interference effect, precision, and stability. This is mostly because they detect hydrogen peroxide at higher potentials and require an oxygen-rich environment. First in its class, we developed an oxygen-insensitive polymeric glucose microneedle (MN) that was functionalized using a new electron-transfer mediator, 3-(3′-phenylimino)-3H-phenothiazinesulfonic acid-based enzyme cocktail for the NAD-GDH system. The inclusion of reduced graphene oxide aided in the absorption of the cocktail via the π−π interaction and enhanced the conductivity and sensor performance. The MN exhibited a dynamic linear range (1–30 mM) with a low detection limit of 26 μM, high sensitivity (18.05 μAmM−1 cm−2), stability (up to 7 days), high selectivity (due to a low oxidation potential of 0.15 V), and a fast response time (∼3 s). In vivo, deployment of the MN in a rabbit model demonstrated that the ISF glucose concentrations measured with the MN for up to 24 h correlate very well with the blood glucose concentrations measured with a commercial glucometer.

DPD simulation of the reciprocating translocation behaviour of polymer chain in a microchannel under variable external force

ABSTRACT In this study, an investigation has been carried out regarding the reciprocating translocation (i.e. back and forth motion) of a polymer chain in a microchannel. External force is one of the important factors in the movement of the polymer chain. In this investigation, variable forces are applied to the polymer chain and all fluid particles in which at a certain time, the direction of the force and the movement will change in this simulation. The behaviour and the properties of the chain, such as the radius of gyration, the centre of mass velocity and the amount of translocation, have been examined in this reciprocating movement. Based on the present results, when employing a longer polymer chain and especially applying the force on the polymer and fluid particles, due to the inertia effect, it would not be easily possible to stop the polymer chain. Consequently, changing the direction of polymer motion would not instantly occur by changing the force direction. In fact, some amount of displacement and lost time (LT) (around 6 dissipative particle dynamics units out of a total time of 40) will be associated with the case of applying force on just a polymer chain and imposing variable external force on all particles, LT has increased dramatically (dimensionless LT parameter is around 50%). The present method is a suitable tool for simulating the variable movement of polymer for the design of micro-actuators or polymer sensors.

Fatigue test on optical fiber angle sensors based on polymeric materials for flexion–extension applications

Polymer Optical Fiber (POF) and Cyclic Transparent Optical Polymer (CYTOP) based sensors present some advantages related to their light weight, flexibility, and reduced dimensionality for applications in assistive robotics compared to conventional sensors that are rigid and heavy. To ensure adequate functionality, usability, and controllability of the systems over time, the measurements made by the sensors must be maintained in optimal ranges of functionality. Considering that for most robotic assistance applications an adequate range of motion of the limbs is at approximately 80°, this study presents a fatigue test performed on three Polymeric Optical Fiber sensors for angle measurement in this range. The tests were performed on a bending system that generates variations at a frequency of 2 Hz recording the voltage variation. For fatigue measurement each sensor was instrumented into the system and set to perform a total of 40,000 cycles, repeating the tests two times per sensor. The results show that the CYTOP optical fiber-based sensor did not break during the trial; however, it is determined that this type of fiber is more sensitive to light variations in the environment. On the other hand, the other two sensors reached a time of approximately 70 min for a total of 8,360 cycles to rupture. These results have potential usability in characterizing systems incorporating angle sensors to estimate proper system performance.

Process Parameters and Geometry Effects on Piezoresistivity in Additively Manufactured Polymer Sensors.

The current work experimentally determined how the initial resistance and gauge factor in additively manufactured piezoresistive sensors are affected by the material, design, and process parameters. This was achieved through the tensile testing of sensors manufactured with different infill angles, layer heights, and sensor thicknesses using two conductive polymer composites. Linear regression models were then used to analyze which of the input parameters had significant effects on the sensor properties and which interaction effects existed. The findings demonstrated that the initial resistance in both materials was strongly dependent on the sensor geometry, decreasing as the cross-sectional area was increased. The resistance was also significantly influenced by the layer height and the infill angle, with the best variants achieving a resistance that was, on average, 22.3% to 66.5% lower than less-favorable combinations, depending on the material. The gauge factor was most significantly affected by the infill angle and, depending on the material, by the layer height. Of particular interest was the finding that increasing in the infill angle resulted in an increase in the sensitivity that outweighed the associated increase in the initial resistance, thereby improving the gauge factor by 30.7% to 114.6%, depending on the material.

Development of Levo-Lansoprazole Chiral Molecularly Imprinted Polymer Sensor Based on the Polylysine-Phenylalanine Complex Framework Conformational Separation.

The efficacies and toxicities of chiral drug enantiomers are often dissimilar, necessitating chiral recognition methods. Herein, a polylysine-phenylalanine complex framework was used to prepare molecularly imprinted polymers (MIPs) as sensors with enhanced specific recognition capabilities for levo-lansoprazole. The properties of the MIP sensor were investigated using Fourier-transform infrared spectroscopy and electrochemical methods. The optimal sensor performance was achieved by applying self-assembly times of 30.0 and 25.0 min for the complex framework and levo-lansoprazole, respectively, eight electropolymerization cycles with o-phenylenediamine as the functional monomer, an elution time of 5.0 min using an ethanol/acetic acid/H2O mixture (2/3/8, V/V/V) as the eluent, and a rebound time of 10.0 min. A linear relationship was observed between the sensor response intensity (ΔI) and logarithm of the levo-lansoprazole concentration (l-g C) in the range of 1.0 × 10-13-3.0 × 10-11 mol/L. Compared with a conventional MIP sensor, the proposed sensor showed more efficient enantiomeric recognition, with high selectivity and specificity for levo-lansoprazole. The sensor was successfully applied to levo-lansoprazole detection in enteric-coated lansoprazole tablets, thus demonstrating its suitability for practical applications.

Polyimide/Carboxylated Multi-walled Carbon Nanotube Hybrid Aerogel Fibers for Fabric Sensors: Implications for Information Acquisition and Joule Heating in Harsh Environments

Polymeric hybrid sensors have garnered great interest in health monitoring, human–computer interaction, and soft robotics for their lightweight, flexibility, and feasible fabrication process. However, polymeric hybrid sensors suitable for harsh environments remain a considerable challenge, limiting further application. Herein, polyimide (PI)/carboxylated multi-walled carbon nanotube (c-MWCNT) hybrid aerogel fibers with a micro-porous structure were fabricated via wet-spinning and chemical thermal imidization. The fabricated PI/c-MWCNT hybrid aerogel fibers’ conductivity and the change of current in response to the bending degree were tested, in which the relative current change achieved 4.78% with a bending degree of 150°. The fibers possessed a density of 0.41 ± 0.06 g/cm3, a conductivity of 17.8 ± 2.9 μS/m, and a tensile strength of 13.0 ± 1.1 MPa. In addition, they exhibited excellent heat/cold durability, whose decomposition temperature, cold resistance, and service life were 367 °C, −196 °C, and 300 cycles, respectively. Furthermore, the fabric sensor woven with PI/c-MWCNT hybrid aerogel fibers demonstrated two sensitivity stages of stage 1 (S1) = 6.04 and stage 2 (S2) = 0.55 under various pressures. Besides, it could be heated to 62 °C at a voltage of 30 V in 90 s with a changing resistance. The above properties demonstrate that the as-prepared fabric sensor exhibited great application potential for information acquisition and joule heating in harsh environments.

Temperature-responsive polymeric sensors based on triphenylamine linked naphthalimide with red aggregation-induced emission

Temperature-responsive fluorescence sensors have attracted great attention in recent years. Herein, we designed a series of AIE-based polymer sensors for monitoring the temperature in the physiological environment. In these polymers, a triphenylamine-naphthalimide chromophore (TPANIP) was used as the signal unit which can output the red emission in aggregated state. Different ratios of the temperature-responsive unit (NIPMAM) and the water-soluble unit (N-(2-(2-hydroxyethoxy)ethyl)methacrylamide, HEOEMA) were introduced to adjust the responsibility of the polymers in suitable temperature region and sensitivity. The structural and optical properties of all polymers were investigated by GPC, 1H NMR, FTIR, fluorescence spectroscopy and SEM. Among them, the polymer P1 (TPANIP/NIPMAM = 1/10) without the water-soluble unit shows the best sensing property. It performs a linear response to the temperature at the region of 15–50 °C in its aqueous solution with low concentration (0.5 mg/mL). By optimizing the work medium, polymer P1 can outputs the turn on signals with the increase of temperature. The enhanced emission mode is more suitable for the fluorescent detection that the turn off one.

Anti-fouling TiO2-Coated Polymeric Membrane Ion-Selective Electrodes with Photocatalytic Self-Cleaning Properties

Nowadays, using a polymeric membrane ion-selective electrode (ISE) to achieve reliable ion sensing in complex samples remains challenging because of electrode fouling. To address this challenge, we describe a polymeric membrane ISE with excellent anti-fouling and self-cleaning properties based on surface covalent modification of an anatase TiO2 coating. Under ultraviolet illumination, the reactive oxygen species produced by photocatalytic TiO2 can not only kill microorganisms but also degrade organic foulants into carbon dioxide and water, and a formed superhydrophilic film can effectively prevent the adsorption of foulants, thus inhibiting the occurrence of biofouling and organic fouling of the sensors. More importantly, residual foulants could be fully self-cleaned through the flow of water droplets. By using Ca2+-ISE as a model, an anti-fouling polymeric membrane potentiometric sensor has been developed. Compared to the unmodified electrode, the TiO2-coated Ca2+-ISE exhibits remarkably improved anti-biofouling properties with a low bacterial adhesion rate of 4.74% and a high inhibition rate of 96.62%. In addition, the proposed electrode displays unique properties of anti-organic dye fouling and a superior self-cleaning ability even after soaking in a concentrated bacterial suspension of 109 CFU mL-1 for 60 days. The present approach can be extended to improve the fouling resistance of other electrochemical or optical membrane sensors and is promising for the construction of contamination-free sensors.

Broadside‐Coupled Split Ring Resonators as a Model Construct for Passive Wireless Sensing

AbstractPassive and wireless Radio‐Frequency (RF) sensors are a unique, enabling modality for emerging applications in environmental sensing. These sensors exhibit several key features that may unlock new functionalities in complex environments: sensors are composed of zero electronic components, are wirelessly interrogated even in opaque media, and structures are often inherently biocompatible. Such capabilities make it unique in the realm of sensing architectures. Here, the broadside‐coupled, split‐ring resonator is studied as a compact and versatile model structure for RF sensing (of potentially mechanical and biochemical environments). A new analytical model is derived to assess resonator behavior—these yield a rapid, first‐order approximation of the resonator resonant frequency or sensitivity. Finally, experimental investigations into how sensors may be optimally designed, sized, and interrogated to enhance sensitivity or spectral intensity are performed. These studies encompass a wide variety of potential dimensional and dielectric modifications that may be relevant to emerging sensors. Last, hydrogel polymeric sensors are synthesized and studied to assess how practical sensors may deviate in response from expectations. Such investigations lay the groundwork for how such sensing architectures may be adapted to fit application needs.

3-Aminophenylboronic Acid Conjugation on Responsive Polymer and Gold Nanoparticles for Qualitative Bacterial Detection.

Because of their sensitive and selective responses to a wide variety of analytes, colorimetric sensors have gained widespread acceptance in recent years. Gold nanoparticles (AuNPs) are widely employed in visual sensor strategies due to their high stability and ease of use. Combining AuNPs with a responsive polymer can result in distinct surface plasmon resonance (SPR) changes that can be utilized as colorimetric biosensors. The purpose of this research is to develop a colorimetric-based sensor through the utilization of the optical properties of gold nanoparticles (AuNPs) crosslinked with pH-responsive polymers poly (acrylic acid) (PAA) conjugated to 3-aminophenyl boronic acid (APBA). The polymer (PAA) was synthesized via RAFT polymerization. The inversed Turkevic method was used to produce AuNPs, which were subsequently used in a self-assembly process using poly (acrylic acid)-aminophenyl boronic acid (PAA-APBA) to create the self-assembled AuNPs-APBA-PAA. The particle size, zeta potential, and reversibility of the polymer-modified gold nanoparticles were determined using a transmission electron microscope (TEM), a particle size analyzer (PSA), and an Ultraviolet-Visible spectrophotometer (UV-Vis spectrophotometer). Visual, UV-Vis spectrophotometer and TEM observations confirmed the system's ability to identify bacteria. Statistical analysis was performed using a one-way analysis of variance using Excel software. Using UV-Vis spectrophotometry, the particle size of AuNPs was determined to be 25.7 nm, and the maximum absorbance occurred at 530 nm. AuNPs PAA APBA colloid exhibited an absorbance maximum of 532 nm, a zeta potential of -41.53, and a pH transition point between 4 and 5. At E. coli concentrations of 4.5 x 107 CFU/mL, the color of the system sensors changed from red to blue after 15 hours of incubation, whereas at S. aureus concentrations of 1.2 x 109 CFU/mL, the color changed to purple immediately after mixing. The TEM confirmed that the detection mechanism is based on the boronate-polyol bonding of saccharides on the outer membranes of Escherichia coli and Staphylococcus aureus. The use of APBA in conjunction with pH-responsive PAA polymers containing AuNPs to detect E. coli and S. aureus bacteria induces a maximum wavelength transition, followed by a color change from red to blue. By the process of de-swelling of the responsive polymer, which induces the aggregation of the AuNPs, the established sensor system is able to alter the color. The conjugated polymer and gold nanoparticle-based sensor system demonstrated a promising method for bacterial detection.

Democratization of Copper Analysis in Grape Must Following a Polymer-Based Lab-on-a-Chip Approach

Quality control in the food industry is of the upmost importance from the food safety, organoleptic and commercial viewpoints. Accordingly, the development of in situ, rapid, and costless analytical tools is a valuable task in which we are working. Regarding this point, the copper content of grape must has to be determined by wineries along the wine production process. For this purpose, grape must samples are sent to laboratories where the copper content is measured usually by flame atomic absorption spectrometry or by inductively coupled plasma mass spectrometry. We herein propose a straightforward, rapid, and inexpensive methodology based both on a film-shaped colorimetric polymer sensor and a smartphone method that at the same time can be used by unskilled personnel. The sensory polymer films change their color upon dipping them on the grape must, and the color evolution is analyzed using the digital color parameters of a picture taken to the film with a smartphone. Furthermore, the analytical procedure is automatically carried out by a smartphone app. The limit of detection of copper of the polymer sensor is 0.08 ppm. Following this approach, 18 production samples coming from the French Groupe ICV company were studied. The copper content of the samples was analyzed by the usual procedure carried out by the company (flame atomic absorption spectrometry) and by the method proposed in this work, ranging this content from 0.41 to 6.08 ppm. The statistical study showed that the results of both methods are fully consistent, showing the validity of the proposed method for the determination of copper in grape must within the frame of wine production wineries and industries.

Electrochemical molecularly imprinted polymer sensor for ultrasensitive indoxacarb detection by tin disulfide quantum dots/carbon nitride/multiwalled carbon nanotubes as a nanocomposite

Unsuitable use of agricultural pesticides has caused excessive pollution of the environment. Therefore, it is very important to identify the remaining contamination in environmental samples. Indoxacarb (IDC) as an oxadiazine fungicide use on large part of corps. In this work, we reported voltammetric sensor-based molecularly imprinted polymers (MIP) film on a tin disulfide quantum dots-carbon nitride-multiwalled carbon nanotubes (MIP@SnS2 QDs/pg-C3N4/MWCNTs) nanocomposite for ultrasensitive detection of IDC. Cyclic and differential pulse voltammetry (CV and DPV), electrochemical impedance spectroscopy (EIS), UV-Vis absorption spectroscopy, photoluminescence spectroscopy, Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD), energy dispersive X-ray (EDX), elemental mapping used for characterization of the proposed electrode. Under optimum conditions, the current response for IDC was obtained in the linear range of 20.0 nmol L−1 to 10.0 µmol L−1 and a detection limit of 7.1 nmol L−1. Using this MIP sensor, IDC has been determined in samples of Zayandeh Rood river water and apple. Several advantages of the proposed sensor were demonstrated, including its sensitivity, selectivity, and simplicity.

Coupled Chemo-Mechanical Swelling Behavior of PH-Sensitive Hollow Cylinder Hydrogels under Extension–Torsion and Internal Pressure: Analytical and 3D FEM Solutions

The coupled transient chemo-mechanical behavior as well as the large deformation behavior under various complex load conditions must be taken into account when designing a functional responsive polymer actuator or sensor. One sort of deformation that can be used to characterize the properties of materials with complicated behavior, like soft hydrogels, is coupled extension and torsion with internal pressure. It is important to thoroughly research the complex kinetics of pH-hydrogels with coupled diffusion and massive deformation behavior. The transient behavior of cylindrical hydrogels under coupled extension–torsion with internal pressure under indifferent conditions is proposed in this work using a reliable semi-analytical method. In this regard, an analytical solution is offered to inspect this problem, which is used as a common experimental methodology for the characterization and modeling of polymeric materials. The results show that the rate of deformation and the physical characteristics of the material have a substantial impact on the cylindrical hydrogel’s transient behavior under coupled extension–torsion and internal pressure. For the same problem, a 3D finite element study was done to assess the analytical solution. The accuracy of our method is supported by the results’ agreement in both the FE analysis and the proposed approach. However, offering such a solution for this complex problem is of tremendous relevance given the significantly cheaper computational cost of analytical methods when compared to FEM. Additionally, the calculations indicate a complex reaction force and moment because the hydrogel experiences nonlinear Poynting-type effects in this deformation domain. The suggested semi-analytical procedure’s resilience behavior is demonstrated by the visualization of the effects of various material properties. This method can be used to calibrate constitutive models and to develop and improve hydrogel structures.

Electrospun Core–Sheath PVDF Piezoelectric Fiber for Sensing Application

In recent years, piezoelectric polymer sensors are used in energy harvesting and self-powered sensing due to their flexibility, low density, and high piezoelectric constant, and their performances may be improved through a careful architectural design. Herein, we reported a facile strategy for fabricating core-sheath piezoelectric fiber (C-PEF) by directly electrospinning poly(vinylidene fluoride) (PVDF) onto the stainless steel wires. Such C-PEF can well respond to bending deformation with different degrees, and therefore it can be assembled into a piezoelectric bending sensor for airflow speed sensing. Furthermore, spring-like structured C-PEF (S-C-PEF) can serve as a piezoelectric spring sensor and in a sophisticated manner monitor human sleep behavior. This work paves a way for developing multigeometric piezoelectric sensors though a low-cost, facile, and reliable method, showing potential applications including bending sensing and health monitoring.

Synthesis and characterization of nano-fibres graphene oxide for sensing humidity

Relative humidity is the prime parameter in industrial processes which are measured through ceramic, metal oxide and polymeric sensors. Ceramic and metal oxide sensors shows nonlinear resistive behaviours with increasing relative humidity and high sintering temperature for hydro-desorption. Transformation of ceramic and metallic sensors with the polymeric sensors is due to its eco-friendly synthesis fabrication, less heat intensive and high sensitivity. In this research work, a polymeric sensor of enhanced electric properties with sustainable captive and resistive response was synthesised from nano-fibres graphene oxide for sensing humidity. The synthesized graphene oxide through modified Hammer method was mixed with poly-vinyl alcohol (GO/PVA) in the ratio of 5 wt % for four hours at 90 ºC. Nano fibres of graphene oxide and poly-vinyl alcohol (GO/PVA) solutions were obtained at the 24V DC electric field; 0.5 ml/h feed rate and 10 cm tip-to-collector distance through electrospinnig. GO/PVA fibres were deposited on the silver inter-digited electrodes of 8mm and five combs of 20Îm consecutive distance. SEM analysis shows that the fibres were in nano-range with no major cracks while XRD and FTIR spectrum investigated the finger prints and functional groups of GO and GO/PVA respectively. Parametric study of resistive and capacitive were analysed at difference response and recovery time at various frequency in the range of 0 % to 82% relative humidity.

Polymer sensors for underwater robot proprioception

Polymer sensors for underwater robot proprioception

MIP-based electrochemical sensor for highly selective and sensitive determination of entacapone from the triple mixture in tablet dosage form

The aim of this study is to develop a molecularly imprinted polymer (MIP) sensor via photopolymerization for selective and sensitive analysis of entacapone (ENT), a catecholamine-o-methyl transferase (COMT) inhibitor. ENT is used for Parkinson’s disease treatment with levodopa (LEV) and carbidopa (CAR), and it is available in a triple combination tablet dosage form. For the MIP-based electrochemical sensor (4-AP@MIP/GCE) design, 4-aminophenol (4-AP) was selected as the functional monomer. Surface characterization of the 4-AP@MIP/GCE sensor was performed by scanning electron microscopy, electrochemical characterization by CV, and electrochemical impedance spectroscopy (EIS). The linear concentration range was between 1.0 pM and 10.0 pM under optimum conditions for ENT determination. The limit of detection (LOD) of 0.24 pM and the limit of quantification (LOQ) of 0.80 pM were calculated for ENT analysis using 4-AP@MIP/GCE. The accuracy was proven by performing a recovery study on the tablet sample that contains ENT, LEV, and CAR, and the recovery was found to be 99.32%. The selectivity of the 4-AP@MIP/GCE sensor for ENT has been proven by interference studies on LEV, CAR, and their binary mixtures. Looking at the results of the study, it has been proven that the 4-AP@MIP/GCE sensor is a highly selective, sensitive, and specific quantitative option for the analysis of ENT.

Molecularly imprinted sensor based on poly-o-phenylenediamine-hydroquinone polymer for β-amyloid-42 detection.

A sensitive and selective molecularly imprinted polymer (MIP) sensor was developed for the determination of amyloid-β (1-42) (Aβ42). The glassy carbon electrode (GCE) was successively modified with electrochemical reduction graphene oxide (ERG) and poly(thionine-methylene blue) (PTH-MB). The MIPs were synthesized by electropolymerization with Aβ42 as a template and o-phenylenediamine (o-PD) and hydroquinone (HQ) as functional monomers. Cyclic voltammetry (CV), electrochemical impedance spectroscopy(EIS), chronoamperometry (CC), and differential pulse voltammetry (DPV) were used to study the preparation process of the MIP sensor. The preparation conditions of the sensor were investigated in detail. In optimal experimental conditions, the response current of the sensor was linear in the range of 0.12-10μgmL-1 with a detection limit of 0.018ngmL-1. The MIP-based sensor successfully detected Aβ42 in commercial fetal bovine serum (cFBS) and artificial cerebrospinal fluid (aCSF).