The increasing awareness of the importance of water for human and environmental health has prompted the need for developing fast, user-friendly and cost-effective analytical approaches for quality ...control and management. This work reports the fabrication and analytical assessment of a very simple sample-to-result electrochemical sensor for discrete and precise measurements of dissolved chemical oxygen demand (COD) in water samples of urban wastewater treatment plants (UWWTP). The device is fabricated by screen printing and shows a three-electrode cell configuration including a working electrode made of a composite material comprising a porous carbon matrix and copper nanoparticles, synthesized by a customized one-pot sol-gel process. The key feature of this device is the implementation of a paper disk loaded with sodium hydroxide covering the electrochemical cell area that allows sample filtering and pH conditioning. Thus, analytical measurements are carried out by casting a 20 µL sample drop without requiring any further user intervention. The overall sensor fabrication process can be scaled up for cost-effective mass manufacturing. The feasibility and performance of this integrated device are first evaluated using glucose as a standard analyte. A linear range up to 400 mg L− 1 O2 and a limit of detection of around 26 mg L− 1 O2 is achieved, this being well below the EU legal concentration limit of 125 mg L− 1 set for effluents of UWWTPs. Three real samples are analyzed in the lab as well as on-site and COD sensor values are in agreement with those obtained with the standard dichromate method at a certified laboratory, within the error limits. This miniaturized novel sensor platform greatly simplifies the standard analytical procedure for measuring COD, facilitating rapid decentralized analysis for precise control of urban wastewater treatment.
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•A sample-to-result sensor fabricated to monitor soluble COD in urban wastewater.•Screen-printed sensor approach to be of application for in-field analysis of COD.•COD sensor values in good correlation with those provided by the standard method.•Environmentally and user-friendly sensor approach.•Sensor fabrication potentially scaled up for low-cost industrial manufacturing.
The majority of existing medical diagnosis depends on the blood analysis in centralized sophisticated laboratories having bulky, complex, and time-consuming clinical instruments. Blood test involves ...invasive sample collection followed by plasma separation via centrifugation, and chemical analyses. This may prevent persons in need of urgent medical diagnosis and prompt medical attention. Wearable biosensor offers non-invasive monitoring of physiologically relevant biomarkers from biofluids and continuous tracking of real-time health status. Recent advances are much focused on electrochemical monitoring of various biomarkers from sweat samples. Such skin-interfaced sweat sensors require flexibility, stretchability and self-healing ability to match with the mechanical properties of the epidermis. The multiplexed sweat analysis coupled with wireless signal transduction provides vital information about health and fitness level of the wearer. This review focuses on the challenges, perspectives, recent advances and the technological aspects in the progress of wearable electrochemical sweat sensors.
•Wearable sweat sensors offer non-invasive monitoring of real-time health information.•Wearable sensors require skin-like flexibility, stretchability and self-healing ability.•Microfluidic integration facilitates real-time sample transport and eliminates dilution.•Multiplexed sweat analysis enables timely diagnosis and prompt clinical therapy.
Novel photochromic, thermochromic and gaseous ammonia sensing paper sheets were developed via screen-printing with a viologen-based covalent polymer, resulting in multi-stimuli responsive chromogenic ...paper substrates. The viologen-based covalent polymer was synthesized from the polymerization of a hydroxyl-substituted aryl-dihydrazide with a viologen-dialdehyde in an acidic aqueous medium. Translucent viologen/resin nanocomposite films prepared on the surface of the paper sheets were developed by the well-dispersion of the covalent organic viologen polymer as a chromogenic agent in a resin-based binder solution without aggregation. As shown by CIE coloration measurements, the translucent film immobilized on cellulose paper surface became green when exposed to UV light. Organic nanocomposite-containing a covalent organic polymer of viologen and a resin binder was used to make a new photochromic film for anti-counterfeiting papers. The photochromic impact was explored at various concentrations of the covalent organic viologen polymer. When exposed to ammonia gas, the viologen-coated paper strips changed color from yellow to green very rapidly. It recovered to yellow immediately after being removed away from the ammonia stimulus. The present paper strip demonstrated a detection limit for aqueous ammonia ranging between 15 and 350 ppm. In addition, heat (95 °C) was able to reversibly trigger the color transformation process. The thermal properties of the synthesized viologen-based covalent polymer were also investigated. Under UV irradiation, the screen-printed documents exhibited a reversible photochromism with high photostability. In addition to examining the rheologies of the generated nanocomposites, the screen-printed papers mechanical and morphological properties were also explored.
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•Novel multi-stimuli responsive viologen-based nanocomposite ink was developed.•Optical photochromism for anti-counterfeiting applications was introduced.•Colorimetric change from yellow to green was monitored between 399 and 585 nm.•Screen-printed strips showed thermochromism (25–95 °C) and NH3(g) sensing activity.•Durability, rheological and mechanical properties were explored.
Perovskite solar cells (PSCs) have already achieved comparable performance to industrially established silicon technologies. However, high performance and stability must be also be achieved at large ...area and low cost to be truly commercially viable. The fully printable triple-mesoscopic carbon perovskite solar cell (mCPSC) has demonstrated unprecedented stability and can be produced at low capital cost with inexpensive materials. These devices are inherently scalable, and large-area modules have already been fabricated using low-cost screen printing. As a uniquely stable, scalable and low-cost architecture, mCPSC research has advanced significantly in recent years. This review provides a detailed overview of advancements in the materials and processing of each individual stack layer as well as in-depth coverage of work on perovskite formulations, with the view of highlighting potential areas for future research. Long term stability studies will also be discussed, to emphasise the impressive achievements of mCPSCs for both indoor and outdoor applications.
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•A paperfluidic crossing-channel closed-BPE based electrochemiluminescence (P-3C-BPE-ECL) was firstly reported.•The glucose detection using the paperfluidic C-BPE-ECL method was ...firstly presented.•The proposed platform could be well applied for glucose determination in four complex samples.•The P-3C-BPE-ECL method was demonstrated to have the potential for multiplex detection.
In this work, we for the first time reported a paperfluidic crossing-channel closed-BPE based electrochemiluminescence (P-3C-BPE-ECL) platform where multiple “band”-shaped C-BPEs are situated perpendicular to two parallel channels, and multiplex detection can be achieved in the reporting channel. The paperfluidic devices are easily fabricated by wax and carbon ink-based screen-printing processes. Under optimized conditions, the P-3C-BPE-ECL is applied to the quantitative analysis of hydrogen peroxide (H2O2) and glucose, with corresponding linear ranges of 0.075–10 mM and 0.08–5 mM, and corresponding detection limits of 0.041 mM and 0.03 mM. To our knowledge, this is the first demonstration of paperfluidic C-BPE-ECL method for glucose determination. Based on its acceptable selectivity, the P-3C-BPE-ECL method is used for measurements of glucose in four complex samples (human serum and urine, wine, and glucose injection) and is compared with the traditional methods. The results indicate a good agreement and prove the reliability and accuracy of the proposed platform. Importantly, the proposed method is demonstrated to have the potential for duplex detection of glucose and uric acid, which intensively matches the requirement of those patients simultaneously suffering from diabetes and gout. Therefore, we believe that the P-3C-BPE-ECL could provide a new platform for wide biochemical applications.
The application of flexible sensors in the biomedical field is deepening. It is of great significance to develop flexible wearable sensors which are more in line with the needs of the public. A ...flexible polylactic acid membrane fabric was prepared by electrospinning method. The membrane was used as SERS active substrate by screen printing capture probe which combine Au nanoplates with antibodies to the target substance. Thioglycolic acid-labeled silver nanoparticles coupled with antibodies as SERS nanotags. The target substance can be fixed between the capture probe and SERS nanotags. Due to the high specific surface area between the spinning, the adhesion rate of the capture probe is higher than that of the rigid substrate, and the enrichment and hypersensitivity detection of the object to be tested could be realized. The membranes prepared are flexible, wearable, portable, highly biocompatible, and can be mass-produced for high-throughput detection. We then applied the sensor to the detection of SARS-CoV-2 with detection limits as low as 10 TU/mL. This membrane as a SERS substrate can offer a fast and non-invasive reference for the early diagnosis of respiratory infectious diseases similar to COVID-19.
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•It is the first device for detecting respiratory virus made of electrospun fiber film.•The sensor has a very low detection limit of 10 TU/mL for SARS-CoV-2.•The sensor is portable, flexible, biocompatible and inexpensive.•The sensor is suitable for mass production and high throughput testing.
Toward smart building and smart home, floor as one of our most frequently interactive interfaces can be implemented with embedded sensors to extract abundant sensory information without the ...video-taken concerns. Yet the previously developed floor sensors are normally of small scale, high implementation cost, large power consumption, and complicated device configuration. Here we show a smart floor monitoring system through the integration of self-powered triboelectric floor mats and deep learning-based data analytics. The floor mats are fabricated with unique "identity" electrode patterns using a low-cost and highly scalable screen printing technique, enabling a parallel connection to reduce the system complexity and the deep-learning computational cost. The stepping position, activity status, and identity information can be determined according to the instant sensory data analytics. This developed smart floor technology can establish the foundation using floor as the functional interface for diverse applications in smart building/home, e.g., intelligent automation, healthcare, and security.
A novel flexible capacitive pressure sensor based on hybrid micro-structured (HM) polydimethylsiloxane (PDMS) dielectric layer was developed. The HM-PDMS with M-tooth structured patterns was ...fabricated using a laser engraved acrylic master mold. The top and bottom electrodes were fabricated by depositing silver (Ag) on flexible polyethylene terephthalate PET) substrate using additive screen-printing process. The pressure sensor was assembled by sandwiching two HM-PDMS based dielectric layers between the top and bottom electrodes. The capability of the developed pressure sensor to detect a wide range of pressure was investigated by applying varying pressure from 0 to 1 kPa, 1 to 10 kPa, and 10 kPa to 40 kPa. A sensitivity of 51.36% kPa −1 , 8.37% kPa −1 , and 2.46% kPa −1 was obtained for the pressure ranges of 0 to 1 kPa, 1 to 10 kPa, and 10 to 40 kPa, respectively. The capacitive pressure sensor response, hysteresis, and repeatability of the fabricated pressure sensor is investigated and presented in this paper. To demonstrate the wide sensing range of the pressure sensor, the sensor was attached to face mask for breath monitoring applications that require low pressure sensing of ~20 Pa, and to the hand glove for fingertip pressure monitoring applications that require relatively high pressure sensing of ~3 kPa.
This review covers the current state of the art related to up-scaling and commercialization of dye solar cells (DSC). The cost analysis of the different components and manufacturing of DSC gives an ...estimate on the overall production costs. Moreover, it provides an insight in which areas improvement is needed in order to reach significant cost reductions. As a result of the cost analysis, transferring the technology to flexible substrates and employment of simple roll-to-roll production methods were found the key issues. The focus of this work was set accordingly. In this work, appropriate materials along with their unique fabrication processes and different design methods are investigated highlighting their advantages and limitations. The basic goal is to identify the best materials and preparation techniques suitable for an ideal roll-to-roll process of flexible dye solar module fabrication as well as the areas where further development is still needed.
A Prussian blue (PB) biosensor chip with the nanocubic crystals was fabricated in batch by a screen printing technique for the general detection of various physiological substances. Through a ...low-speed chemical synthesis approach, the nanostructure of PB slurry was well controlled to be a 100nm nanocube by the synthesis temperature and reactant concentration. Then, PB slurry was screen-printed as the working electrode to construct a microchip by the integration of the printed reference and counter electrodes. Due to the high electrocatalytic activity attributed by the regular nanostructure of PB electrode, the as-prepared chips exhibited the generally high sensitivities of 83.404, 31.642 and 6.379μAmM−1cm−2 for the respective detections of glucose, glutamate and lactate, as well as the excellent selectivity, reproducibility and stability under the low work potential of −0.05V.
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