There is increased usage of flexible electronics recently in various applications such as wearable devices, flexible displays and sensors. Studies on the durability of conductive metal traces under cyclic mechanical loading is crucial since these conductors will be subjected to repeated bending. In this work, the mechanical and electrical behavior of silver printed conductors was tested using cyclic three-point bend test. The samples were flexible polymer thick film (PTF) silver (Ag) ink printed on a flexible polyethylene terephthalate (PET) substrate. The durability of this PTF Ag ink, which has a hyper-elastic binder and Ag flakes, was studied by performing cyclic bending tests. Four-point resistivity measurements and imaging of the sample both before and after bending were performed. A custom tester machine was used to apply strain to the circuit and measure the resistivity of the silver trace. The results of the bending test show that the silver trace does not undergo significant deformation and the change in resistance is less than 0.6% under both tensile and compressive tests. Fatigue tests were also performed by cyclic bending tests for three trials in which batches of 10,000 cycles were completed. The printed silver wire withstood 30,000 cycles of bend tests and produced only 2.64% change in resistance. This indicates that the printed wires are very durable even after 30,000 cycles of outer bending. Imaging was also conducted on these samples to study the effect of repeated bending on the morphology of the silver conductive trace. Although there was an increase in surface roughness before and after cyclic bending, there was no obvious deformation or delamination observed in the samples.

A photonic crystal fiber (PCF) is presented for milk sensing; sensing liquid compounds are injected in core region one by one and various sensing properties are studied numerically. The PCF sensor's performance is examined for different strut sizes and for a variety of frequencies (e.g., 1.0THz ≤ f ≤ 3.0THz). When f = 2.8THz, the relative sensitivity is attained 94.586%, 94.696%, and 94.751% for water, camel milk, and buffalo milk; also, the effective area is obtained 186020um2, 187210um2, and 187870um2 for water, camel milk, and buffalo milk; furthermore, the effective material loss is noticed 0.00790 cm−1, 0.00796 cm−1, and 0.00799 cm−1 for water, camel milk, and buffalo milk, respectively. Moreover, extrusion and 3D-printing methods are potentially capable to fabricate the presented PCF sensor.

Early detection, diagnosis and treatment of cattle disease is very important for any livestock farming enterprise, to remain viable. Improved cattle health and productivity through advanced and innovative smart farming technologies will pave the way for the United Arab Emirates in achieving its national agenda of food security. Advanced livestock health care bio-capsules were administered through mouth into the rumen of cattle in a private dairy farm to a group of cattle to monitor their health. The effect of using such biosensors on the animal health was not previously described by any other researchers. Hence, in the current study, we tried to understand the effects of the bio-capsules on the cattle health, if any. This was done through collecting and screening blood samples from the test animals for different hemato-biochemical parameters and our results showed that there were no harmful effects of using such bio-capsules for livestock health monitoring.

Excessive protein excretion in human urine is an early and sensitive marker of diabetic nephropathy, primary and secondary renal disease. Kidney problems, particularly chronic kidney disease, remain among the few growing causes of mortality in the world. Therefore, it is important to develop efficient, expressive, and low-cost method for protein determination. Surface-enhanced Raman spectroscopy (SERS) methods are potential candidates to achieve those criteria. In this paper, the SERS method was developed to distinguish patients with proteinuria and the healthy group. Two types of commercial gold nanoparticles with a diameter of 60 nm and 100 nm were employed to prepare substrates for the analysis of 78 samples of unique patients. Data analysis by the PCA-LDA algorithm, and the ROC curves, gave results for diagnostic figures of merits. Sensitivity, specificity, accuracy, and AUC were 0.79, 0.89, 0.85, and 0.90 for the set with 60 nm Au NPs, respectively. Sensitivity, specificity, accuracy, and AUC were 0.79, 0.98, 0.90, and 0.91 for the set with 100 nm Au NPs, respectively. The results show the potential of SERS spectroscopy in differentiating between patients with proteinuria and healthy individuals for clinical diagnostics.

In this study, a simple, ultrasensitive, inexpensive, and environmentally friendly sensor was developed for the electrochemical determination of ciprofloxacin (CPRO) using a choline chloride-modified carbon paste electrode (ChCl/CPE). The electrochemical properties of ChCl/CPE were examined by square wave voltammetry (SWV). Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), ultraviolet-visible (UV–Vis) spectroscopy, and Fourier transform infrared (FT-IR) spectrometry were used for electrochemical and morphological characterizations. The sensor exhibits excellent conductivity and superior electrocatalytic activity, within the linear range of 0.005–200 μM, for the detection of CPRO in citrate buffer solution (CBS) at pH 5, with detection and quantification limits of 0.36 nM and 1.2 nM. The electroactive surface area of ChCl/CPE was calculated to be 0.123 cm3, which is four times higher than that of the bare CPE (0.037 cm2). The ChCl/CPE is not only simple, inexpensive and time-saving, but also has the lowest detection limit and widest linear range compared to the recently reported sensors for the determination of CPRO. The developed sensor also showed excellent reproducibility, repeatability, long-term stability, and exceptional selectivity against potentially interfering organic, inorganic, and antibiotic species. In addition, ChCl/CPE was successfully applied for the determination of ciprofloxacin in eye drops, river water, and egg samples with very good recoveries of 97–102% and relative standard deviations (RSD) of 0.27–3.85%. Therefore, the proposed electrochemical sensor is a potential candidate for the determination of ciprofloxacin in various matrices.

A novel non-invasive system has been developed to measure transdermally emitted hydrogen sulfide (H2S) from the upper and lower limbs of human subjects. The transdermal arterial gasotransmitter sensor (TAGS™) has previously been shown to detect low levels of H2S ranging between 1 and 100 ppb considered relevant for physiological measurements (Shekarriz et al. 2020). This study was designed to compare its measurement precision in detecting transdermal H2S to a commercially available chemiluminescent device, the H2S-selective Ecotech Serinus 55 TRS™. Although TAGS™ does in-situ and real-time sampling, the comparative studies in this paper collected gases emitted from the lower arm of 10 heathy human subjects between the ages of 30 and 60. Three replicate samples of each individual were collected for 30 min in a sealed 10 L Tedlar® bag to allow readings from the same sample by both devices. Readings from the TAGS™ system correlated strongly with the values obtained from the Serinus™ device, both ranging between 0.31 ppb/min and 2.21 ppb/min, with a correlation coefficient of R2 = 0.8691, p < 0.0001. These results indicate that TAGS™ measures transdermal H2S specifically and accurately. Because vascular endothelial cells are a known source of H2S, TAGS™ measurements may provide a non-invasive means of detecting endothelial dysfunction, the underlying cause of peripheral artery disease (PAD) and microvascular disease. TAGS™ has potential clinical applications such as monitoring skin vascular perfusion in individuals with suspected vascular disease or to monitor progression of wound healing during treatment, which is of particular value in diabetic patients with calcified arteries limiting detection options.

This study presents a new method for simple, selective and sensitive electrochemical determination of lead(II) using N1-hydroxy-N1,N2-diphenylbenzamidine (HDPBA) modified carbon paste electrode. HDPBA was easily prepared in the laboratory from common chemicals. Morphological characterizations and spectroscopic analyses of the developed electrode were conducted using various analytical techniques such as electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), Fourier transform infrared (FTIR), and ultraviolet-visible (UV–Vis) spectroscopic techniques. The electrochemical determination of Pb(II) was performed using square wave anodic stripping voltammetry (SWASV) and cyclic voltammetry (CV). The effects of several experimental parameters such as modifier composition in the carbon paste, composition and pH of supporting electrolyte solutions, accumulation time, accumulation potential, and other instrumental parameters were studied for the analytical application. Pb(II) was accumulated for 270 s on the surface of the modified electrode using 0.1 M sodium acetate (NaAc) pH 5 at −0.90 V vs Ag/AgCl, followed by electrochemical stripping with SWASV in the same solution after a resting time of 10 s. The linear range was found to be 0.0001–2.5000 μM Pb(II) with a limit of detection of 0.0094 nM which are better than most of the reported method based on 2–4 different modifiers in a single electrode. The proposed method was found to be highly sensitive and selective. In addition, the developed electrode showed good reproducibility (with RSDs of 4.3%), long-term stability, and fast response. The proposed method has been successfully applied to the determination of trace levels of Pb(II) in various environmental samples such as wastewater, vegetable, fish, and cigarette samples.

The rapid bio-sensing of the synthetic cannabinoids, AB-Fubinaca y AB-Pinaca, was developed and validated using six different electrode platforms. Screen-printed electrodes containing 3% tetrathiafulvalene (TTF) ink on the carbon electrode were modified with gold nanoparticles and carbon nanotubes. Then, acetylcholinesterase and glucuronyl transferase were immobilized on the surface of these carbon electrodes. A quantitative response was obtained by measuring the enzymatic inhibition caused by increasing concentrations of the target drugs. Acetylthiocholine iodide, serotonin, and β-D- phenolphthalein glucuronide were used as enzymatic substrates. Optimal pH, peak potential, and substrate concentration of each biosensor were studied. Analytical performance parameters and figures of merit, including LODs (< 1.5 × 10–4 mg/L), precision and reproducibility (< 10%), trueness (< 3%), demonstrate that the developed biosensors were able to interrogate low concentration of AB-Fubinaca y AB-Pinaca in a buffer environment. Michaelis Menten's apparent constants were estimated from inhibition calibration curves. They were lower than 2.0 × 10–3 M. Km inhibition values, and an interference study concluded which biosensor was the most selective for both drugs. AChE/AuNPs/SPCTTFEs with ATI, for AB-Fubinaca, pH = 7.00; ATI = 0.450 mM y Eap = +0.70 V; UDPGT/CNTNPs/SPCTTFEs with Serotonin substrate, AB-Pinaca, pH = 6.64; Cn Serotonin = 0.45 mM y Eap = +0.58 V. Performance parameters of the developed biosensors are acceptable as proof of concept, which opens an opportunity for their future application in forensic and chemical analysis.

Expensive, time-consuming and labour-intensive solvent-extraction and liquid-chromatography methods are the industry's current gold standard for antibiotic residue quantification. A novel immunoassay methodology and system for the rapid detection of clinically relevant levels of tetracycline residues found in food-producing animal tissues is described. Anti-tetracycline antibody-coated paramagnetic particles were used for the specific capture of tetracycline in spiked buffer (with and without a 1% pork muscle tissue suspension) and quantified via an analytically-sensitive in-house magnetometer instrument. Detection of tetracycline between 0.1 μg/mL - 1 μg/mL was achieved, with a readout time (including sample treatment) presented in 20 min. The magneto-immunoassay described provides a rapid, low-cost, de-skilled and analytically-sensitive solution for tetracycline screening at the point-of-sampling, with potential applications for other prevalent antibiotic families used in the international farming and food industry.

A photonic crystal fibre (PCF)-based sensor has been proposed and thoroughly investigated for the identification of blood components, including red blood cells, haemoglobin, white blood cells, plasma, and water. To evaluate the sensor's sensing and propagation properties, a numerical analysis was performed using the COMSOL Multiphysics software. The proposed sensor design features an octagonal core and two layers of cladding with octagonal and circular air holes. At the optimal wavelength of 7.0 μm, the extensive simulation results confirms that the proposed sensor achieves high relative sensitivity of 99.89%, 99.13%, 97.95%, 97.77%, and 96.68% for red blood cells, haemoglobin, white blood cells, plasma, and water, respectively. Furthermore, the design demonstrates favourable confinement loss, propagation constant, V-parameter, spot size, and beam divergence. Therefore, the proposed PCF-based sensor holds great promise not only for medical sensing applications but also for optical communications. Its advanced design and highly sensitive capabilities make it a valuable tool for a wide range of potential applications in the biomedical and telecommunications fields.

The importance of rapid detection of Mycobacterium tuberculosis (MTB) has become greater than ever. Among biosensors as a rapid test, gold nanoparticles (GNPs) can play an important role in accelerating the diagnosis of TB. This systematic review and meta-analysis study were conducted to evaluate the diagnostic accuracy of GNPs for the diagnosis of MTB. All cross sectional and case control studies as original article about rapid detection of MTB using GNPs combined with molecular methods published in PubMed, Web of Science, and Scopus databases were selected, retrieved and appraised up to September 2021. The sensitivity and specificity of GNPs in different studies ranges from 83.7% to 100% for sensitivity and from 86.6% to 100% for specificity. The highest sensitivity and specificity of GNPs combined with molecular methods was related to the LAMP method. Therefore, GNPs are a simpler, low cost and more efficient way in the clinical diagnosis of TB.

BackgroundA non-invasive method capable of promptly detecting clinically important blood potassium changes could benefit care and safety for significant patient populations, including those with end-stage kidney disease.MethodsA total of 96 patients receiving maintenance hemodialysis participated in service evaluations of a wearable biosensor across four renal centers (two in UK, one in US and one in Saudi Arabia). All the patients had standard blood tests taken before and after their routine hemodialysis sessions and the results were used as reference potassium measurements for simultaneous, photoplethysmography-based, non-invasive digital samples obtained by the wearable biosensor. These digital samples were subsequently analyzed utilizing a machine learning model designed to identify excursions in serum potassium concentration by quantifying changes across a ternary classification strategy— hyperkalemia (K+ > 5.2 mEq/L), normokalaemia (K+ 3.5–5.2 mEq/L) or hypokalemia (K+  5.2 mEq/L) or normokalemia (3.5 ≥ K+ ≤ 5.2). The total weighted recall of the biosensor and model was 86%. The overall weighted precision of the model was 86% with an F1-score of 0.86 indicating that the model achieved both high sensitivity and a low rate of false positivesConclusionsThis evaluation demonstrates wearable technology capable of identifying important blood potassium changes outside of the normal reference range, in a group of patients receiving hemodialysis.

Antibiotics have been effectively used in the last decades to prevent bacterial infections in humans and animals. In this study an electrochemical sensor based on poly(diphenylamine sulfonic acid) (poly(DPASA)) modified glassy carbon electrode was prepared by electropolymerization of 1.0 mM DPASA in 0.1 M KCl in the potential window of −1.2 to +1.80 V for 20 cycles and characterized using cyclic voltammetry and electrochemical impedance spectroscopy using [Fe(CN)6]3−/4-. In contrast to GCE, the poly(DPASA)/GCE showed catalytic activity towards the reduction of tinidazole, which attributed to increase in its surface area. A good linear relationship between the reductive peak current and square root of scan rate indicated that tinidazole reduction at poly(DPASA)/GCE was diffusion controlled process. The peak current response of tinidazole reduction at the poly(DPASA)/GCE was linearly related with its concentration ranged from 0.05 to 300 μM with detection limit and quantification of 0.00427 μM and 0.0142 μM, respectively. The tinidazole content of drug samples claimed 300 mg/tablet in three tablets (China, Cyprus, and India) were detected in the range 96% (Cyprus 20) to 101.78% (India 40) of the expected with %RSD value below 2.0%. The poly(DPASA)/GCE was successfully applied for tinidazole detection in drugs and urine samples, where recovery between 96.0 and 101.78% and 98.45 to 101.11% were obtained, respectively. The selectivity of poly(DPASA)/GCE was evaluated in the presence of amoxicillin, ciprofloxacin, paracetamol, glucose and uric acid in drug samples and there were no significant change in the current response of tinidazole, indicated the excellent selectivity of the poly(DPASA)/GCE.

The redox behaviours of three dibenzo-18-crown-6 hydrazones were investigated via cyclic and square wave voltammetries, prior to their electropolymerization onto a platinum working electrode to yield three novel Ion Selective Electrodes (ISEs) whose lead sensing behaviours were investigated via Differential Pulse Anodic Stripping Voltammetry (DPASV) and Electrochemical Impedance Spectroscopy (EIS), subsequent to their characterization via Scanning Electron Microscopy (SEM). For all three ISEs, the electrosynthesized polymeric Ion Selective Membranes (ISM) are multi-layered with pores of diverse dimensions; a feature which allows wide linear ranges (4–107 ppm) in all cases, relative to Flame Atomic Absorption Spectroscopy (FAAS); one of the traditional “go-to” methods for metal ion quantification. Additionally, these ISEs allow selective detection of Pb2+ at concentrations below 20 ppm even in the presence of high concentrations of competing metal ions, except when excess Al3+ is present. Overall, given the relative ease of modification and low cost of these hydrazonic dibenzo-18-crown-6 ISEs, coupled with their performance, they represent a viable starting point for the development of high quality, low cost lead ISEs.

Human axillary odours taken by an electronic nose (e-nose) device that uses a Metal Oxide Semiconductor (MOS) sensor not only contains a gas signal from the pure source of the axillary odour but also has the potential to contain other substances such as perfume and deodorant. This situation requires noise reduction so that dirty data can be cleaned and produce better predictions without wasting a lot of data. The approach taken in this study is to detect data clusters and data centroids from each reference data. Dimensional reduction using Linear Discriminant Analysis (LDA) on the reference data is carried out, then look for the centroid of each data using K-Means Clustering and use it to be a good signal estimate and process using Kalman Filtering so that it can be used to process axillary odour data containing deodorant. The proposed method was tested by a stacked Deep Neural Network (DNN) approach and can increase accuracy by 18.95% and balanced accuracy by 11.865% compared to original invalid data before filtering. The proposed method is also tested by other classification methods and able to produce the highest accuracy with 79.29% in Support Vector Classifier (SVC) and Multi-Layer Perception (MLP), while other filtering methods only get the highest accuracy with 69.03% also in SVC and MLP. We also analysed the execution time of each tested methods.

2D materials raised extensive attention for physical-, chemical- and wearable-sensors, among others. The principal reason is the outstanding capability of 2D materials to detect specific analytes and physical stimuli through diverse responses. After a short introduction to 2D materials, a critical explanation of sensors containing 2D materials is provided to justify their applications. Following by a description of the most relevant transduction mechanisms of 2D materials employed for sensing. This review explores their advancement and implementation in sensing during the last decade in several areas, such as physical, chemical, bio and wearable sensors. Different types of 2D materials, including graphene, transition metal dichalcogenides (TMDs), hexagonal boron nitride (h-BN), 2D carbides and nitrides of transition metals (MXenes) and black phosphorus (BP), are considered.

In this study, an efficient non-enzymatic glucose sensor is proposed based on a bimetal-oxide-modified carbon fiber microelectrode (CFME). The NiO-CuO/CFME nanocomposite was synthesized by consecutive electro-deposition of CuO and NiO nanoparticles on the CFME. The morphology and structure of NiCuCFME were studied with scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). NiCuCFME provides both a large surface area and electrocatalytic properties to improve electrochemical reactivity toward glucose oxidation. The electrocatalytic behavior of the sensing microelectrode is analyzed with cyclic voltammetry (CV) and amperometric techniques in an alkaline medium. The fabricated glucose microsensor exhibits a linear range from 1.32 μM to 570 μM, a sensitivity of 0.07 mA μM−1 cm−2, and a low limit of detection of 0.40 μM. The NiCuCFME shows long-term stability, good reproducibility, favorable repeatability, excellent selectivity, and satisfactory applicability for glucose detection which is a promising candidate for the development of non-enzymatic glucose sensors.

In this study, a sensitive square wave voltammetric method using poly(resorcinol) modified glassy carbon electrode (poly(reso)/GCE) was prepared for the determination of aspirin (ASA) in pharmaceutical tablet and biological fluid samples. CV and EIS were verify the modification of the GCE by a biosensor polymer that raised the electrocatalytic activity of poly(reso)/GCE towards an oxidation of ASA. Appearance of a single irreversible oxidative peak for ASA with fivefold current enhancement and much reduced potential at poly(reso)/GCE compared to bare GCE demonstrated catalytic property of the modifier. The peak current response with optimized experimental conditions at the poly(reso)/GCE exhibited a linear dependence with ASA concentration within the range 0.05–400.0 μM, with LoD 2.0 nM. The levels of ASA in four tablet brands ranged from 94.65 to 100.00% of their assigned values revealed the effectiveness of the developed method. The spike recovery results in pharmaceutical samples were ranged from 99.60 to 101.43% and urine samples 98.95% to 102.7%. Wider dynamic range, lower LoD, excellent spike recovery, and interference recovery results with errors <4.82% and good stability of the modifier, validated the potential applicability of the method based on poly(reso)/GCE for determination of ASA in real samples.

In this study, a novel photonic crystal fiber (PCF) based drug sensor has been introduced. The core and cladding area of the hexagonal fiber structure (H-PCF) has round air holes. We examined the model in the THz regime using the FEM and the COMSOL Multiphysics Software platform. With this updated model, the sensitivity to detect amphetamine (n = 1.518), cocaine (n = 1.5022), and ketamine (n = 1.562) at 1 THz is 89.50%, 90.20%, and 85.50% accordingly. Furthermore, the suggested fiber, operating at 1 THz, generated a vast effective area of Ketamine (n = 1.562), cocaine (n = 1.5022), and amphetamine (n = 1.518) of 1.37 × 10−7 m2, 1.40 × 10−7 m2, 1.39 × 10−7 m2 and relatively low confinement loss of 6.40 × 10−8 dB/m, 7.10 × 10−8 dB/m, 6.20 × 10−8 dB/m and negligible effective material loss of the structure of 0.02 cm−1. After all, we can say that abuse of drugs produces not only short-term effects but also long-term, catastrophic consequences for human health, including the potential for death. Therefore, it is essential to identify illegal drugs with high efficiency and precision. So, this H-PCF structure that we have proposed will be ideal for illegal drug detection.

Viral outbreaks, which include the ongoing coronavirus disease 2019 (COVID-19) pandemic provoked by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), are a major global crisis that enormously threaten human health and social activities worldwide. Consequently, the rapid and repeated treatment and isolation of these viruses to control their spread are crucial to address the COVID-19 pandemic and future epidemics of novel emerging viruses. The application of cost-efficient, rapid, and easy-to-operate detection devices with miniaturized footprints as a substitute for the conventional optic-based polymerase chain reaction (PCR) and immunoassay tests is critical. In this context, semiconductor-based electrical biosensors are attractive sensing platforms for signal readout. Therefore, this study aimed to examine the electrical sensing of patient-derived SARS-CoV-2 samples by harnessing the activity of DNA aptamers directed against spike proteins on viral surfaces. We obtained rapid and sensitive virus detection beyond the Debye length limitation by exploiting aptamers coupled with alkaline phosphatases, which catalytically generate free hydrogen ions which can readily be measured on pH meters or ion-sensitive field-effect transistors. Furthermore, we demonstrated the detection of the viruses of approximately 100 copies/μL in 10 min, surpassing the capability of typical immunochromatographic assays. Therefore, our newly developed technology has great potential for point-of-care testing not only for SARS-CoV-2, but also for other types of pathogens and biomolecules.