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Graphical abstract Enzyme-linked immunosorbent assay (ELISA) is widely used for the detection of disease biomarkers. However, it utilizes time-consuming procedures and expensive instruments, making it infeasible for point-of-care (POC) analysis especially in resource-limited settings. In this work, a multicolorimetric ELISA biosensor integrated on a paper/polymer hybrid microfluidic device was developed for rapid visual detection of disease biomarkers at point of care, without using costly equipment. This multicolormetric ELISA platform was built on multiple distinct color variants resulted from the catalytic oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) and the etching of gold nanorods (AuNRs). The vivid color changes could be easily distinguished by the naked eye, and their red mean values allowed quantitative biomarker detection, without using any sophisticated instruments. When this multicolorimetric ELISA was integrated on a paper/polymer hybrid analytical device, it not only provided integrated processing and high portability but also enabled fast assays in about 50 min due to the unique advantages of paper/polymer hybrid devices. The limit of detection of 9.1 ng/μL of the hepatitis C virus core antigen, a biomarker for hepatitis C, was achieved using this multicolorimetric ELISA platform. This multicolor ELISA analytical device provides a new versatile, user-friendly, affordable, and portable immunosensing platform with high potential for on-site detections of various viruses, proteins, and biomarkers for low-resource settings such as at home, public venues, rural areas, and developing nations. Supplementary Information The online version contains supplementary material available at 10.1007/s00216-021-03359-8.

The development of industry and of the Internet of Things (IoTs) have brought energy issues and huge challenges to the environment. The emergence of triboelectric nanogenerators (TENGs) has attracted wide attention due to their advantages, such as self-powering, lightweight, and facile fabrication. Similarly to paper and other fiber-based materials, which are biocompatible, biodegradable, environmentally friendly, and are everywhere in daily life, paper-based TENGs (P-TENGs) have shown great potential for various energy harvesting and interactive applications. Here, a detailed summary of P-TENGs with two-dimensional patterns and three-dimensional structures is reported. P-TENGs have the potential to be used in many practical applications, including self-powered sensing devices, human–machine interaction, electrochemistry, and highly efficient energy harvesting devices. This leads to a simple yet effective way for the next generation of energy devices and paper electronics.

Edible oils form an integral component in the human diet as well as in the industrial preparations. Any adulteration in oil is concerning from nutritional as well as economical perspective. Although analytical techniques exist for detection of adulterants in oil, most of them require sophisticated instruments, and trained professionals. Microfluidic based lab-on-a-chip technologies have rapidly progressed over the recent years and offer promising alternatives in this regard. In this work, we report development of a paper-based microfluidic lab-on-a-chip for detection of palm oil contamination in sunflower oil. We use the paper-based microfluidic colorimetric detection approach that indicates the presence of adulteration in a visual manner. The data is analyzed using digitally acquired images along with ultraviolet–visible spectrophotometry. The paper-based microfluidic device is fabricated and tested for 10–50% (v/v) palm oil adulteration in sunflower oil. Further, we employ the device for free fatty acid content tests in oil samples. Visual signal acquired from the device is optimized by varying phenolphthalein proportions. The stability of visual colorimetric signal is examined over time and is found to remain steady over the trial period of six days considered in this work. The integration of the detection device with smartphone imaging can prove to be useful for onsite data collection. We believe the approach presented here can be extended to food quality monitoring portable platforms.

Introduction We developed low-cost, portable paper-based diagnostic devices for detection of human immunoglobulin M (IgM) and immunoglobulin G (IgG) in serum without any sample preparation. These devices can be used to help identify presence of diseases, used to provide rapid results ( Materials and Methods We successfully accomplished colorimetric detection of human IgG and human IgM using a sandwich-style assay within the microfluidic paper device via vertical flow immunoassay configuration. The reaction zone in the wax printed paper layer is a small circular pattern. Gold nanoparticles conjugated with anti-human IgG and IgM antibodies have been used for colorimetric detection of IgG or IgM by naked eye. Colorimetric signal can be precisely quantified through implementation of image analysis software which can be developed as an app for a smartphone. The size of the device is 2 cm × 2 cm × 1 mm. Results Colorimetric detection of human IgG was accomplished at 100 fg/mL concentration using a gold nanoparticle–conjugated anti-human IgG antibody. The developed platform has a dynamic range of IgM and IgG concentrations between 0.1 pg/mL and 100 μg/mL. These devices provided a color readout in Conclusions Because of the inherent simplicity of the device operation and their ease of use, there is no variation between samples and users of the device. This low-cost approach enables multiplexing with >1 measurement performed in parallel at the same time. We anticipate that because of the sensitivity, specificity, ease of use, and overall reliability, this approach will become a standard for diagnosis of diseases and health conditions.

The waste of paper or the paper dump is a serious problem and its occurrence is widespread in various institutions. Wastepaper can be recycled to produce some important and usable products that are ecological and biodegradable. For example, it is used to extract new paper from the old by chemical decomposition. Other products such as paper plates, paper cups, paper spoons, tiles, toys, crafts, etc. can be formed from the slurry. This project also initiates a mould that makes cups and plates from the wastepaper management circuit. With learning institutions being the main consumers, most paper are usually eliminated after its use. The waste remains undeveloped and unused, although is a valuable resource. Studying the design of a manual, economical and efficient paper recycling machine, it can be surmised that the design uses the integration of the knowledge gained about the recycling technology that exists manually from the paper recycling machines used to form a cheap but effective paper recycling system. The advantages of the machine are not only of recycled paper, but also the advantages of the interaction of the manual drive system, which will also reduce the high cost. As the design is not 100% effective, the transmission, belt and chain transmission correspond to the estimated 90% efficiency using the 90% for the design. The power consumption for the design is 450 W and since an average user can produce 100 W constant, it takes 5 people to drive the machine.

Process-monitoring laboratories in the pulp and paper industry generally use a combination of wet chemical analyses and physical measurements to certify the fitness of a production pulp for a specific end-use. These laboratory tests require time and the effort of trained personnel, limiting their utility for real-time process control. Here we show that Raman probes of unrefined cellulosic pulps, well-suited to the online measurement of in-process materials, can predict the quality attributes of manufactured papers. The accuracy of prediction improves when the covariance is modelled in a reduced measurement space selected by a data-driven, feature-selection technique referred to as a Template Oriented Genetic Algorithm (TOGA). TOGA, combined with discrete wavelet transform (DWT), isolates functional-group features that correlate best with mechanical properties paper derived from refined pulp. Paper makers refine market pulps to build sheet strength using a beating process that decreases freeness as it increases fibre-fibre bonding. Methods demonstrated here predict manufactured sheet properties obtainable after any specified degree of refining from the Raman spectrum of an unrefined pulp. This analysis capacity will enable both vendors of market pulp and makers of sheet paper to specify in advance the amount of beating required to produce a desired product, thereby saving cost and conserving resources.

Tissue paper conversion consists of the transformation of base tissue papers into finished tissue products to meet specific demands. When base tissue paper arrives at the converting line, it already holds different requirements that were met during its manufacture in the paper machine (e.g., grammage, bulk, tensile index, etc.). However, what happens during converting can still influence the performance and quality of the finished products. The current work addresses this topic and aims to evaluate the influence of converting conditions on the final softness. For that, two 5-ply finished tissue products were analyzed using different methodologies for their proper characterization in terms of softness and surface analysis. The analyzed products are composed by the same base tissue papers, but some changes were applied on their settings in the converting line. In particular, the base tissue papers arrangement and the embossing pressure affected the finished products, resulting in one of them being softer and more pleasant to touch, with a global handfeel (HF) value of 75.3 units, and the other revealed to be rougher and less pleasant, with a global handfeel (HF) value of 68.0 units.

Development of paper-based microfluidic devices that perform colorimetric measurements requires quantitative image analysis. Because the design geometries of paper-based microfluidic devices are not standardized, conventional methods for performing batch measurements of regularly spaced areas of signal intensity, such as those for well plates, cannot be used to quantify signal from most of these devices. To streamline the device development process, we have developed an open-source program called ColorScan that can automatically recognize and measure signal-containing zones from images of devices, regardless of output zone geometry or spatial arrangement. This program, which measures color intensity with the same accuracy as standard manual approaches, can rapidly process scanned device images, simultaneously measure identified output zones, and effectively manage measurement results to eliminate requirements for time-consuming and user-dependent image processing procedures.

The spread of invasive alien plant species (IAPS) is a leading reason for worldwide environmental change due to their effects on biodiversity and humans. Some valued goods from IAPS have been produced, e.g. paper that consists of cellulose fibres from Japanese knotweed. Therefore, the aim of this study was to establish the usability of this paper grade as a printing substrate, since it does not have ideal optical properties as it is expected from commercial office paper. Because it is widely used, inkjet printing technology was employed. Print permanence is essential, especially when printing documents. However, typographic characteristics must be considered to make a text more legible. Two widely used typefaces (Arial and Times) were tested in three commonly used type sizes (8 pt, 10 pt, and 12 pt). The results showed that the paper made from Japanese knotweed could have valuable properties and suitable legibility, especially when using typefaces with a moderate counter size, high x-height, and minimal differences in the letter stroke width to obtain an appropriate typographic tonal density with an adequate type size. Even after exposure to light, the texts printed in a proper type size and stroke width remained visible.

Microfluidic paper-based analytical devices (μPADs) allow user-friendly and portable chemical determinations, although they provide limited applicability due to insufficient sensitivity. Several approaches have been proposed to address poor sensitivity in μPADs, but they frequently require bulky equipment for power and/or read-outs. Universal serial buses (USB) are an attractive alternative to less portable power sources and are currently available in many common electronic devices. Here, USB-powered μPADs (USB μPADs) are proposed as a fusion of both technologies to improve performance without adding instrumental complexity. Two ITP USB μPADs were developed, both powered by a 5 V potential provided through standard USB ports. The first device was fabricated using the origami approach. Its operation was analyzed experimentally and numerically, yielding a two-order-of-magnitude sample focusing in 15 min. The second ITP USB μPAD is a novel design, which was numerically prototyped with the aim of handling larger sample volumes. The reservoirs were moved away from the ITP channel and capillary action was used to drive the sample and electrolytes to the separation zone, predicting 25-fold sample focusing in 10 min. USB μPADs are expected to be adopted by minimally-trained personnel in sensitive areas like resource-limited settings, the point-of-care and in emergencies. Fil: Schaumburg, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina Fil: Kler, Pablo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones en Métodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones en Métodos Computacionales; Argentina Fil: Carrell, Cody S.. State University of Colorado - Fort Collins; Estados Unidos Fil: Berli, Claudio Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina Fil: Henry, Charles S.. State University of Colorado - Fort Collins; Estados Unidos

The dissemination of emerging electronic devices increases considerably alongside with the Internet of Things (IoT) paradigm. Some key elements considered in these devices (e.g. rare-earth) are becoming critical materials and are associated with serious environmental concerns. Therefore, there is a major requirement for designing differently our electronic technologies at the early stages of the research process. Many reports present the promising properties of paper-based electronics as meant to address this challenge. Through technical and life cycle assessments, this article discusses the main design levers in terms of material and fabrication process choices for the eco-design of paper-electronics water quality sensors. Our results suggest conscientious choices of conductive nanomaterials and additive fabrication techniques.

Recently, portable sensing devices with point of care testing (POCT) capability have attracted great attention due to their inherent affordability and accessibility in low resource areas. Paper sensors possess excellent potential as POCT platforms because of low cost, ease of operation, disposability and high-volume manufacturing. Paper sensors that incorporate functional nucleic acids (FNAs) as recognition elements are particularly attractive given that FNAs can be isolated from random-sequence nucleic acid pools to recognize, or respond to, virtually any target of interest. In this review, the advantages of FNAs, particularly DNA aptamers and DNAzymes, as recognition elements for the design of paper sensors are first discussed. This is followed by reviewing three specific types of FNA based paper sensors: dot blots, lateral flow assays, and microfluidic paper-based analytical devices. Furthermore, advances in the signal reporting methods used by FNA based paper sensors are summarized. Finally, limitations of current FNA based paper sensors are discussed along with considerations of future research directions.

The development of diagnostic tools for measuring a wide spectrum of target analytes, from biomarkers to other biochemical parameters in biological fluids, has experienced a significant growth in the last decades, with a good number of such tools entering the market. Recently, a clear focus has been put on miniaturized wearable devices, which offer powerful capabilities for real-time and continuous analysis of biofluids, mainly sweat, and can be used in athletics, consumer wellness, military, and healthcare applications. Sweat is an attractive biofluid in which different biomarkers could be noninvasively measured to provide rapid information about the physical state of an individual. Wearable devices reported so far often provide discrete (single) measurements of the target analytes, most of them in the form of a yes/no qualitative response. However, quantitative biomarker analysis over certain periods of time is highly demanded for many applications such as the practice of sports or the precise control of the patient status in hospital settings. For this, a feasible combination of fluidic elements and sensor architectures has been sought. In this regard, this paper shows a concise overview of analytical tools based on the use of capillary-driven fluidics taking place on paper or fabric devices integrated with solid-state sensors fabricated by thick film technologies. The main advantages and limitations of the current technologies are pointed out together with the progress towards the development of functional devices. Those approaches reported in the last decade are examined in detail.

Advancements in technology have led to the use of smartphones as biosensor detectors. However, it is difficult to obtain stable color information of colorimetric sensors using multiple smartphones owing to different light conditions and image correction operations. In this study, we attempted color detection of the colorimetric paper chip using smartphone-embedded light-emitting diode (LED) and simple transformation calculation. This method enables the acquisition of stable color information using different smartphones by reducing the influence of external light sources. Moreover, we studied characteristics such as convergence and distinction of detection result details by the manufacturers and smartphones. These findings suggested the necessity of classification criteria for the use of smartphones to achieve optimal detection. In addition, white and black references were used to set the standard for color correction of various light sources. Based on our results, we conclude that this approach presents the possibility of smartphone-based colorimetric detection in practical applications.

We developed a portable device for blood detection as well as blood typing assay, using a microfluidic paper-based analytical devices (µPADs) which proves to be sensitive, cost-effective, user-frie...

The wide spread of smartphones and QR codes for various end-user applications has had an impact beyond traditional fields of use, recently also reaching point-of-care testing (POCT). This work presents the integration of QR code recognition into paper-based analytical devices (PADs) with "distance-based" colorimetric signalling, resulting in semiquantitative readout fully relying on straightforward barcode reader solutions. PADs consist of an array of QR codes arranged in series inside a paperfluidic channel. A mask dye concept has been developed, which enables utilisation of colour changing indicators by initially hiding QR codes. The colour change of the indicator induced by the presence of an analyte of interest results in gradual unmasking of QR codes, which become recognisable by the smartphone barcode reader app. To reproducibly fabricate devices, all fabrication steps were performed by commercial desktop solid ink and inkjet printing. The QR code masking function was optimised by controlling the amount of printed mask dye through adjusting the opacity of printing patterns during the inkjet deposition process. For proof-of-concept, a model assay in the form of colorimetric copper ion (Cu2+) detection in the concentration range of 0.4 mM to 3.2 mM was evaluated. Consistent results independent of the smartphone model and environmental light condition were achieved with a free barcode reader app. To the best of our knowledge, this work is the first demonstration of a semiquantitative assay approach fully relying on QR code readout without digital colour analysis, customised app or hardware modification.

This paper presents a new approach towards the design of paper based autonomous microfluidic devices. Autonomy in the device operation is achieved through the incorporation of mechanically actuated microfluidic switches that are versatile in their design and may be configured to be simple time triggered ON or OFF switches or more complex switches that can be timed to be in multiple states (timed ON, followed by timed OFF). These switches are self-contained and require no external power for their operation, deriving their functionality solely through stored elastic energy. This paper presents the design and fabrication of these switches as fluidic analogs of electronic transistors, and their integration into microfluidic paper based circuit demonstrating their operation as a programmable paper-based microfluidic device.

Background In recent times, the use of thermal papers has increased exponentially and the fingerprints on thermal papers are frequently encountered. Although fingerprint development on paper has been standardized, that on thermal paper is complicated. Thermal papers turn black on the application of heat which poses a problem in the visualization of fingerprints which makes it difficult to visualize. Main body One solution to this problem is to use heat or steam for the development of white fingerprints on darker backgrounds. Second solution might be to dissolve the chemicals present on the surface of the thermal papers using acetone. Many studies to develop fingerprints on thermal papers using iodine fuming, ninhydrin, 1,8-diazofluorene-9-one, and p-dimethylaminocinnamaldehyde have been performed. In the present review, an attempt has been made to summarize the problem posed to fingerprint development on thermal papers and the probable solutions attempted by different authors. Conclusion Although the development of fingerprints is difficult on thermal papers, it can be achieved either by subjecting the thermal paper to controlled heat or by removing the temperature-sensitive layer before treating it with other fingerprint development methods.

The combination of smartphone technology and colorimetric paper-based microfluidics can enable simple, inexpensive diagnostics. However, imaging colorimetric diagnostic results via smartphones currently requires accessories to mitigate the influence of variability in surrounding lighting conditions. Here, we present an accessory-free smartphone-based colorimetric imaging method that enlists the built-in LED light source to dominate ambient lighting in combination with background and colour rescaling. This simple approach enables quantitative measurements from paper-based tests by compensating for different environmental lighting conditions and is universally applicable with respect to phone models and manufacturers. We demonstrate the method with three dominant phone makes and models in a cell counting application with a paper-based yeast detection device. The detection results are in good agreement with cell counting using automated cell counters. Eliminating the need for make/model specific accessories, this approach helps realize the potential for low-cost, broadly applicable paper-based diagnostics.

This work reports on fully integrated “sample‐in‐signal‐out” microfluidic paper‐based analytical devices (μPADs) relying on bioluminescence resonance energy transfer (BRET) switches for analyte recognition and colorimetric signal generation. The devices use BRET‐based antibody sensing proteins integrated into vertically assembled layers of functionalized paper, and their design enables sample volume‐independent and fully reagent‐free operation, including on‐device blood plasma separation. User operation is limited to the application of a single drop (20–30 μL) of sample (serum, whole blood) and the acquisition of a photograph 20 min after sample introduction, with no requirement for precise pipetting, liquid handling, or analytical equipment except for a camera. Simultaneous detection of three different antibodies (anti‐HIV1, anti‐HA, and anti‐DEN1) in whole blood was achieved. Given its simplicity, this type of device is ideally suited for user‐friendly point‐of‐care testing in low‐resource environments.

Escherichia coli has been known to cause a variety of infectious diseases. The conventional enzyme-linked immunosorbent assay (ELISA) is a well-known method widely used to diagnose a variety of infectious diseases. This method is expensive and requires considerable time and effort to conduct and complete multiple integral steps. We previously proposed the use of paper-based ELISA to rapidly detect the presence of E. coli. This approach has demonstrated utility for point-of-care (POC) urinary tract infection diagnoses. Paper-based ELISA, while advantageous, still requires the execution of several procedural steps. Here, we discuss the design and experimental implementation of a turntable paper-based device to simplify the paper-based ELISA protocols for the detection of E. coli. In this process, antibodies or reagents are preloaded onto zones of a paper-based device and allowed to dry before use. We successfully used this device to detect E. coli with a detection limit of 105 colony-forming units (colony-forming unit [CFU])/mL.

Paper-based devices have a wide range of applications in point-of-care diagnostics, environmental analysis, and food monitoring. Paper-based devices can be deployed to resource-limited countries and remote settings in developed countries. Paper-based point-of-care devices can provide access to diagnostic assays without significant user training to perform the tests accurately and timely. The market penetration of paper-based assays requires decreased device fabrication costs, including larger packing density of assays (i.e., closely packed features) and minimization of assay reagents. In this review, we discuss fabrication methods that allow for increasing packing density and generating closely packed features in paper-based devices. To ensure that the paper-based device is low-cost, advanced fabrication methods have been developed for the mass production of closely packed assays. These emerging methods will enable minimizing the volume of required samples (e.g., liquid biopsies) and reagents in paper-based microfluidic devices.

Development of wearable devices for in situ monitoring biological analytes in sweat has been fueled up in the past few years. Although microfluidic thread/paper-based analytical device (μTPAD) fulfills the requirements of wearable systems on flexibility and biocompatibility, it has not been employed as a sensing system for the in situ sweat analysis. In this work, we developed a wearable μTPAD containing a cotton thread and a functionalized filter paper for non-invasive, quantitative and in situ monitoring of human sweat glucose with the assistance of a smartphone. The oxygen plasma was applied to tailor the wicking property of the cotton thread. Amounts of enzymes and reagents on the filter papers were optimized to achieve the high-performance colorimetric sensing of glucose. The as-prepared device possesses a dynamic range of 50–250 μΜ and a detection limit of ~ 35 μΜ. Because of its great wearability and compatibility with conventional textile industry, the μTPAD was integrated with an arm guard to sensitively detect glucose in human sweat. This work may provide a low-cost, easy to use wearable device based on the cotton thread and filter paper for human sweat analysis.

Paper-based microfluidics is a rapidly developing field with applications for point-of-care disease and environmental diagnostics. In parallel, printed electronics has grown swiftly, particularly for wearable technologies. By combining these fields, fluidic sample processing and control, as well as automated sensing and readout can be integrated on a single device. Towards this goal, this work highlights the design, manufacture, and testing of paper-based electrochemical sensors, with focus on photo paper and chromatography paper substrates. These substrates are typically used for printed electronics and paper-based fluidics, respectively. The electrochemical sensors were screen printed using manual techniques. For chromatography paper sensors, wax-printed fluidic barriers were used to illustrate the potential integration of the sensors with typical paper-based microfluidic device formats. As an initial example, the detection of heavy metals (Cd(II) and Pb(II)) in buffer solution was demonstrated. Commercial DropSens sensors were used as reference with the limit of detection (LOD) of Cd(II) and Pb(II) on chromatography sensors showing comparable results to commercial DropSens sensors. It is worth noting that the chromatography paper sensors showed a higher repeatability than the commercial DropSens sensors. Tap water samples spiked with Cd(II) and Pb(II) were also tested and showed promising results. Future work will include sensor optimization and exploration of scale-up to provide low-cost solutions for effective point-of-need diagnostics—ranging from environmental monitoring to healthcare applications.

Brain-machine interfaces (BMIs) decode neural activity in real-time, allowing control of sensors and actuators. However, real-time neural decoding requires high computational resources. Recently developed paper-based electronics (e.g., transistors) are likely to reduce the cost of computing devices. In this theoretical study, we propose a roadmap to develop BMIs that take advantage of cellulose based supercomputers. Major milestones will include: 1) an initial prototype with a small number of elements capable of forming a simple brain-controlled On/Off switch, and 2) scaling up the capabilities of the new computing device, such that paper-based electronics lined in the walls of people’s homes will form a supercomputer. The initial prototype will be used to control the lights in a room, but more advanced devices are expected to decode more complex brain commands. As paper-based electronics are very low cost, it is proposed here that paper-based supercomputing capabilities may significantly improve BMIs.

One of the benefits of Internet of Vehicles (IoV) is improved traffic safety and efficiency, for example due to the capability to share vehicular messages in real-time. While most of the vehicular messages only need to be shared by nearby vehicles, some messages (e.g., announcement messages) may need to be more broadly distributed, for example to vehicles in a wider region. Finding a single trusted entity to store and distribute such messages can be challenging, and vehicles may not be inclined to participate (e.g., generation and distribution of announcement messages) unless they can benefit from such participation. In addition, achieving both security and privacy can be challenging. In this paper, we propose a blockchain based secure data sharing system to address the above challenges in an IoV setting. Specifically, in our system, announcement messages are stored using blockchain. To encourage/incentivize participation, vehicles that faithfully broadcast the announcement messages and/or contribute to the block generation will be rewarded by some cryptocurrency. Our system is also designed to be privacy-preserving and realizes both priori and posteriori countermeasures.

Foodborne pathogens are responsible for hundreds of thousands of deaths around the world each year. Rapid screening of agricultural products for these pathogens is essential to reduce and/or prevent outbreaks and pinpoint contamination sources. Unfortunately, current detection methods are laborious, expensive, time-consuming and require a central laboratory. Therefore, a rapid, sensitive, and field-deployable pathogen-detection assay is needed. We previously developed a colorimetric sandwich immunoassay utilizing immuno-magnetic separation (IMS) and chlorophenol red-β-D-galactopyranoside for Salmonella detection on a paper-based analytical device (μPAD); however, the assay required many sample preparation steps prior to the μPAD as well as laboratory equipment, which decreased user-friendliness for future end-users. As a step towards overcoming these limitations in resource-limited settings, we demonstrate a reusable 3D-printed rotational manifold that couples with disposable μPAD layers for semi-automated reagent delivery, washing, and detection in 65 minutes. After IMS to clean the sample, the manifold performs pipette-free reagent delivery and washing steps in a sequential order with controlled volumes, followed by enzymatic amplification and colorimetric detection using automated image processing to quantify color change. Salmonella was used as the target pathogen in this project and was detected with the manifold in growth media and milk with detection limits of 4.4 × 102 and 6.4 × 102 CFU mL−1 respectively. The manifold increases user friendliness and simplifies immunoassays resulting in a practical product for in-field use and commercialization.

In recent times, it has been witnessed that wireless systems based on IoT-based have developed rapidly in various sectors. The IoT (Internet of Things) is the network in which physical devices, equipment, sensors and other objects can communicate among themselves without human involvement. The WSN (Wireless Sensor Network) is a central component of the IoT, which has proliferated into several different applications in real-time. The IoT and WSNs now have various critical and non-critical applications impacting nearly every area of our everyday life. WSN nodes are usually small and battery-driven machines. Thus, the energy effective data aggregation techniques that increase the lifespan of the network are highly significant. Various approaches and algorithms for energy-efficient data aggregation in IoT-WSN systems were presented. This paper reviews the literature with specific attention to aspects of wireless networking for the preservation of energy and aggregation of data.

A novel strategy for fabricating the paper-based valves on microfluidic paper-based analytical devices (μPADs) was described to control fluid in a user-friendly way. Initial prototypes of 3D μPADs manipulate the spatial distribution of fluid within the device. The movable paper channel in a different layer could be achieved using the channel's connection or disconnection to realize the valve function using plastic comb binding spines (PCBS). The entire valve manipulation process was similar to a desk calendar that can be flipped over and turned back. It is notable that this kind of PCBS valve can control a fluid in a simple and easy way without the timing setting or any trigger, and this advantage makes it user-friendly for untrained users to carry out the complex and high throughput operations. The reusable plastic comb binding spines greatly reduce the cost of fabricating paper-based valves. To evaluate the performance, the actual samples of Fe (II) and nitrite were successfully analyzed. We hope this method will introduce a new approach to fabrication of paper-based valves on μPADs in the future.

At present, the tissue paper manufacturing is mostly based on the dry crepe technology. During the last decade, the manufacturers have introduced new tissue machines concepts that increase the softness, bulk, and absorption capacity. Such machines produce a strong regular three-dimensional (3D) structure to the sheet before the Yankee cylinder. At present, the quality of the 3D structure is not evaluated, or it is evaluated only subjectively at the mill. This is mostly because of the difficulties to separate reliably the regular 3D pattern from other variations. This paper introduces a frequency analysis based method which separates the surface profile variances in tissue paper to the creping, to the regular 3D pattern and to the residual variation. The 3D surface profiles and their variances were determined online with the photometric stereo method. We show that the introduced analysis method evaluates the variance portions reliably and the results are consistent with the visual perception of the 3D surfaces. In one particular product, the regular 3D pattern explains 74 % of total surface variance; the creping explains 10 % and residual variations 16 %. Furthermore, the creping and residual variances are quite stable over time whereas the variance of the regular 3D pattern fluctuates significantly.

Synthetic cannabinoid receptor agonists (SCRAs), colloquially known as "spice," are commonly used in prisons and enter establishments via the mail in the form of infused papers. Many prisons use benchtop ion mobility spectroscopy (IMS) instruments to screen mail and seized materials for the presence of SCRAs and other controlled substances. The selectivity and sensitivity of Rapiscan Itemiser® 3E and Itemiser® 4DN Ion Trap Mobility Spectroscopy™ (ITMS™) systems were evaluated using 21 SCRA reference standards. Some differences in the SCRA reduced mobility (K0 ) values were observed between this study and those reported previously using IMS detection systems, particularly for cumyl and quinolinyl SCRAs (e.g., 5F-PB-22, Cumyl-4CN-BINACA, and 5F-Cumyl-PEGACLONE), although this was found to have little effect at an operational level. Operational reliability of the systems was evaluated by analyzing 392 paper and card samples with known drug content. ITMS™ system results (e.g., detect or nondetect) were in agreement with gas chromatography-mass spectrometry (GC-MS) analysis in up to 95% of samples tested. Overall, this study found the ITMS™ systems tested to be effective instruments when deployed for the rapid detection of SCRA-infused papers. Used effectively and with up-to-date substance libraries, they will help reduce the supply of SCRAs into prisons and identify emerging threats as they arise. Several emerging SCRAs (5F-MPP-PICA, 5F-EMB-PICA, and 4F-MDMB-BICA) were detected for the first time in Scottish prisons between May and August 2020 as a result of routine monitoring, and all were detected using the ITMS™ systems tested.

This paper presents the main disadvantages of receipts printed on thermal paper, underlining the impact that BPA (component of thermal paper) has on the environment and human health. The conceptual solution proposes to use the near-field communication (NFC) protocol available in smartphones, integrating a virtual receipt printing device (called e-receipt) at the end of the contactless payment chain.

Made available in DSpace on 2020-12-10T19:54:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-03-04 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) We present a capacitive smart sensor based on printed circuit board (PCB) technology to measure the amount of water content in a paper pulp at the wet end of a paper machine. The developed sensor incorporates in the same PCB the signal processing circuits. It is a handheld portable device, and its output is sent to the reading equipment using a Bluetooth wireless connection, providing to the sensor's operator ease of mobility around the wet end of a paper machine. The prototype was tested in a laboratory, using a wire mesh to emulate the end of a paper machine, and we were able to measure and easily detect when it reaches the water content in the range of 90% to 92%, as required in the paper fabrication process. Standard deviation of the capacitance measurements at various moisture levels is four orders of magnitude smaller than the mean. The smart sensor was tested in the 20 degrees C to 40 degrees C temperature range, in a paper pulp with a gravimetric water content of 91%. Since the variation of capacitance with temperature is practically linear, we propose a simple linear compensation equation to correct the observed sensitivity with the temperature. To keep the signal processing circuits small, low cost, simple, and robust, a novel direct interface sensor to microcontroller circuit technique was used to make the capacitive measurement, allowing for measuring small capacitance deviations without high-frequency oscillators. It was shown that it is possible to integrate the signal processing circuits in the top layer of the PCB interdigitated sensor without adding noise or degrading the performance of the capacitive sensor. Sao Paulo State Univ Julio de Mesquita Filho, Fac Sci & Engn, Tupa, SP, Brazil Parana Fed Univ Technol UTFPR, Cornelio Procopio, PR, Brazil FEEC UNICAMP, Dept Semicond Instrumentat & Photon, Campinas, SP, Brazil Uninove Campus Vergueiro, Sao Paulo, SP, Brazil Sao Paulo State Univ Julio de Mesquita Filho, Fac Sci & Engn, Tupa, SP, Brazil CAPES: 001

For a suspected forgery that involves the falsification of a document or its contents, the investigator will primarily analyze the document&rsquo, s paper and ink in order to establish the authenticity of the subject under investigation. As a non-destructive and contactless technique, Hyperspectral Imaging (HSI) is gaining popularity in the field of forensic document analysis. HSI returns more information compared to conventional three channel imaging systems due to the vast number of narrowband images recorded across the electromagnetic spectrum. As a result, HSI can provide better classification results. In this publication, we present results of an approach known as the t-Distributed Stochastic Neighbor Embedding (t-SNE) algorithm, which we have applied to HSI paper data analysis. Even though t-SNE has been widely accepted as a method for dimensionality reduction and visualization of high dimensional data, its usefulness has not yet been evaluated for the classification of paper data. In this research, we present a hyperspectral dataset of paper samples, and evaluate the clustering quality of the proposed method both visually and quantitatively. The t-SNE algorithm shows exceptional discrimination power when compared to traditional PCA with k-means clustering, in both visual and quantitative evaluations.

The analysis of complex systems requires an integrated application of different assessment methods also taking into account different scales and points of view to gain a systemic understanding of the investigated case study. Life Cycle Assessment (LCA) and Emergy Accounting (EMA) are both environmental assessment methods, showing many similarities in the way they are performed, especially with respect to the inventory construction and to the interpretation of results. They also show great differences, the main residing in the different perspectives they give. LCA applies a consumer side perspective, and its space and time scales are set at a boundary capable to include all the process phases in terms of location and durability and their direct impacts on the investigated areas. On the other hand, throughout its donor side perspective, EMA expands the boundaries of the system over the entire biosphere space and time scales. Differences and similarities between LCA and EMA may gain added value by their implementation within a procedural framework which exploits the characteristics of the two methods. The present work proposes a methodological procedure based on the sequential and integrated application of LCA and EMA methods, called LEAF (LCA & EMA Applied Framework). The traditional Amalfi paper production is used as a test case study. The procedure stems include: (i) an ex-ante LCA analysis, to identify the hotspots of the investigated case study; (ii) the assessment of the environmental performance of the system through the development of different EMA-based improvement scenarios built around the chosen hotspots; and (iii) an ex-post LCA application built on each scenario results in order to detect the different environmental burdens. The application of LEAF to the traditional Amalfi paper production shows that the use of a more sustainable energy source is an effective solution (among the set of proposed options) to increase the sustainability of the investigated system.

With the surging energy price and environmental concerns, measures to improve energy efficiency have attracted increasing concerns of the manufacture sector, especially energy-intensive manufacturing industries such as tissue paper mills. Energy-efficiency scheduling, as a novel energy-efficient method, has attracted the attention of an increasing number of researchers in recent years. Drying process is the most energy-intensive production process in tissue paper mills, which has a great energy-saving potential. This paper aims to reduce the energy costs for the tissue paper mill, consisting of processing energy cost and set-up energy cost, through integrating drying process optimization with energy-efficient scheduling. First, the energy cost model and the scheduling model were built. Then, the energy cost of the drying process of every job in a given scheduling problem was optimized using particle swarm optimization (PSO). Afterwards, the energy cost was further optimized using energy-efficiency scheduling. In addition, a hybrid non-dominated sorting genetic algorithm II (NSGA-II) was utilized to solve the energy-efficiency scheduling problem. Finally, several real scheduling problems from a real tissue paper mill were addressed using the proposed approach to demonstrate its effectiveness in energy saving. The experiment result showed that there is a great energy-saving potential in the drying process, accounting for up to 12.53% of the total energy consumption. Moreover, the maximum energy saving ratio of the proposed approach could reach 9.03%. On the whole, the proposed approach can provide a new energy-saving method for tissue paper mills or other manufacturing industries.

Paper-based technologies have been drawing increasing attentions in the biosensor field due to their economical, ecofriendly, and easy-to-fabricate features. In this paper, we present a time-delay valve mechanism to automate a series of procedures for conducting competitive enzyme-linked immunosorbent assay (ELISA) on a paper-based device. The mechanism employs a controllable time-delay valve, which has surfactants to dissolve the hydrophobic barriers, in a fluid pathway. The valves can regulate the liquid and sequentially deliver the sample flow for automating ELISA procedures in microchannels. Competitive ELISA is achieved in a single step once the sample, or small molecule pesticide (e.g., Imidacloprid), is applied onto the paper-based device with a comparable sensitivity to plate-based competitive ELISA. The results further demonstrate the appositeness of using paper-based devices with the valve designs for on-the-go ELISA detection in agriculture and biomedical applications.

The increasing presence of e-books (electronic books) has become a major focus in countries around the world. In the United States, e-books represented 28% of the total book sales for 2012. In Japan, the conversion from paper books to e-books is expected to accelerate by the prevalent use of smartphones and tablet PCs. It is therefore important to quantitatively evaluate the environmental load of paper books and e-books for a sustainable society. In this study, paper books are compared to e-books read on different electronic devices (e-ink tablets, tablets, cell phones, smartphones, laptop computers, desktop computers and portable music players) through a case study on a 224-page book. The study is based on key primary data such as use time and reading speed for each device and aims to minimize assumptions made in other studies. GHG emissions for paper books are 1.24 kg-CO2e/book, and are reduced to 1.11 kg-CO2e/book when the effect of paper recycling is taken into consideration. The results for e-books under average use-time conditions range from 0.25 to 0.91 kg-CO2e/book with the e-ink tablet having the lowest emissions. When the average use time of each e-book device is applied, the paper book has a higher impact than all the e-books. However, sensitivity analysis shows that the impact of paper books can be lower than that of e-books for larger screen devices such as tablets, laptops and desktops when the reuse of books is considered or the e-book reading device is hardly used during its life cycle.

icrofluidic paper-based analytical devices (mu PADs) have attracted much attention over the past decade because they offer clinicians the ability to deliver point-of-care testing and onsite analysis. Many of the advantages of mu PADs, however, are limited to work in a laboratory setting due to the difficulties of processing data when using electronic devices in the field. This review focuses on the use of mu PADs that have the potential to work without batteries or with only small and portable devices such as smartphones, timers, or miniaturized detectors. The mu PADs that can be operated without batteries are, in general, those that allow the visual judgment of analyte concentrations via readouts that are measured in time, distance, count, or text. Conversely, a smartphone works as a camera to permit the capture and processing of an image that digitizes the color intensity produced by the reaction of an analyte with a colorimetric reagent. Miniaturized detectors for electrochemical, fluorometric, chemiluminescence, and electrochemiluminescence methods are also discussed, although some of them require the use of a laptop computer for operation and data processing.

In the last decade, much effort has been invested in using methanol as an oil-soluble chemical marker for assessing the condition of insulating paper. The use of this marker as paper life index presents many advantages particularly with new transformers insulated with thermally upgraded papers. However, until now, no interpretation model has been available for its extensive use by the transformer community. In this paper, a methanol-based interpretation model is presented for the first time using postmortem paper analysis on core-type transformers. This model allows the evaluation of the average degree of polymerization of a transformer's cellulose winding. Furthermore, threshold values based on the methanol concentration are given using this approach. Finally, model validation was performed on a limited number of papers taken from transformers being assessed in the repair shop.

The urgent demand for portable electronics has promoted the development of high-efficiency, sustainable, and even stretchable self-charging power sources. In this work, we propose a flexible self-charging power unit based on folded carbon (FC) paper for harvesting mechanical energy from human motion and power portable electronics. The present unit mainly consists of a triboelectric nanogenerator (FC-TENG) and a supercapacitor (FC-SC), both based on folded carbon paper, as energy harvester and storage device, respectively. This favorable geometric design provides the high Young’s modulus carbon paper with excellent stretchability and enables the power unit to work even under severe deformations, such as bending, twisting, and rolling. In addition, the tensile strain can be maximized by tuning the folding angle of the triangle-folded carbon paper. Moreover, the waterproof property of the packaged device make it washable, protect it from human sweat, and enable it to work in harsh environments. Finally, the as-prepared self-charging power unit was tested by placing it on the human body to harvest mechanical energy from hand tapping, foot treading, and arm touching, successfully powering an electronic watch. This work demonstrates the impressive potential of stretchable self-charging power units, which will further promote the development of high Young’s modulus materials for wearable/portable electronics.

This letter presented a pencil-on-paper-based ecofriendly capacitive touchpad fabricated through a low-cost lab- and solvent-free fabrication process. Economical, readily available, and biodegradable materials, such as pencil and paper, have been used for sensor fabrication. A touchpad based on five such sensors has been developed and evaluated by using it as a user control interface to on/off LEDs and displaying results on LCD and mobile app. The graphite sensors in the user interface have been shielded from the direct interaction of humans and the environment using changeable cling film to make the interface reliable and reusable. The interface can be used in different conditions and users by changing the shielding film. Simultaneously, the system's functionality will remain consistent and functioned similarly to the conventional touch sensors and buttons. These recyclable and easily arrayed touch sensor-based keypads can contribute to future developments in disposable and lightweight interfaces for human–machine interface, medical and healthcare applications, smart packaging, security monitoring, and consumer products.

To date, 55% of inhabitants of the developing world still live in rural regions and they have a very urgent need to improve the level of disease diagnosis, especially in resource-limited settings. Herein, we present a microfluidic system that centrifuges whole blood and quantifies contained biomarkers in a rapid, feasible and integrated way. Such a device provides a blood-in/answer-out capability and is small enough to be carried by any individual in any environment. The successful integration a hand-powered centrifuge and immunoassay unit within a rotational paper-based device allows for diagnostic application by untrained users and in environments where access to electricity cannot be assumed. In addition, the low cost (~$ 0.5), light weight and small instrumental footprint make the device ideally suited for rapid on-site detection. To validate the applicability of the system in a clinical diagnostic testing, we successfully perform enzyme-linked immunosorbent assay (ELISA) analysis of carcinoembryonic antigen and alpha fetoprotein from human blood samples. We expect that this powerful platform technology will provide the opportunities for point-of-care diagnosis in resource-limited settings.

Although fabrication of colorimetric paper-based analytical devices (PADs) has drawn increasing attention recently, the signal readout method is still a crucial challenge on the way to practical exploitations. We herein introduce an integration of digital image processing with a model PAD for easing and improving the signal readout procedure. The colorimetric detection mechanism of PAD relies on in-situ induced yellowish silver nanoparticles via the interaction of silver ions, poly(vinyl alcohol), and ammonia with isoniazid. The observed color value is related with the concentration of isoniazid. The proposed algorithm is based on mathematical morphology recognition, and minimizes the errors arising from manual area selection. Besides, it allows the recognition of both circle and square shapes in 96-well plate and A4 size array designs. Since this algorithm automatically provides the blank-corrected numerical matrixes and image profiles of red, green and blue channels, further investigations such as outlier classification, construction of regression/prediction models and calculation of detection limit can be easily performed. Comparison of signal readout results of the developed algorithm with ImageJ software demonstrates significant improvements in analysis speed, reproducibility, accuracy and color values. Therefore, application of the proposed algorithm is promising as a robust technique for practical applications.

As a rapidly developing field, paper-based microfluidic devices (μPADs) are expected to have profound implications, especially for in vitro diagnosis. In particular, integrated μPADs, with the merits of capillary-driven force, cost effectiveness, mass production and ease of use, are emerging as ideal tools for personal diagnosis; sample collection/pretreatment, signal transduction and results output can be simplified into one μPAD with minimal need for complex operation. In this review, we emphasize the latest developments of integrated μPADs and highlight the accomplishments and challenges of each component, including sample collection/pretreatment, signal transduction and amplification, and results output. Moreover, we give an overview of the growing trend of novel integrated μPADs and analyze existing challenges as well as potential directions for integrated μPADs for point-of-care testing (POCT).

There is a need for an accurate end-of-life indicator for packaged food (meat, seafood, dairy food etc.) beyond a simple “best use by” date on the food package. In this work, we propose a low cost solution by repurposing the food’s barcode as a colorimetric sensor array to monitor food condition. A smart phone camera is used to read color information from the sensor barcode for quantitative estimate of the food aging and quality. The sensor is based on cross-reactive vapor sensitive dyes encapsulated in resin microbeads, which are impregnated onto a low cost paper substrate in a barcode pattern. The entire sensor platform is validated by accurately monitoring chicken aging and eventual spoilage under different temperature conditions. The proposed food diagnostics platform has the potential to reduce food waste and eliminate food-borne illness.

Objective This study examines the validity of optical mark recognition, a novel user interface, and crowdsourced data validation to rapidly digitize and extract data from paper COVID-19 assessment forms at a large medical center. Methods An optical mark recognition/optical character recognition (OMR/OCR) system was developed to identify fields that were selected on 2,814 paper assessment forms, each with 141 fields which were used to assess potential COVID-19 infections. A novel user interface (UI) displayed mirrored forms showing the scanned assessment forms with OMR results superimposed on the left and an editable web form on the right to improve ease of data validation. Crowdsourced participants validated the results of the OMR system. Overall error rate and time taken to validate were calculated. A subset of forms was validated by multiple participants to calculate agreement between participants. Results The OMR/OCR tools correctly extracted data from scanned forms fields with an average accuracy of 70% and median accuracy of 78% when the OMR/OCR results were compared with the results from crowd validation. Scanned forms were crowd-validated at a mean rate of 157 seconds per document and a volume of approximately 108 documents per day. A randomly selected subset of documents was reviewed by multiple participants, producing an interobserver agreement of 97% for documents when narrative-text fields were included and 98% when only Boolean and multiple-choice fields were considered. Conclusion Due to the COVID-19 pandemic, it may be challenging for health care workers wearing personal protective equipment to interact with electronic health records. The combination of OMR/OCR technology, a novel UI, and crowdsourcing data-validation processes allowed for the efficient extraction of a large volume of paper medical documents produced during the COVID-19 pandemic.

Recent advanced paper-based microfluidic devices provide an alternative technology for the detection of biomarkers by using affordable and portable devices for point-of-care testing (POCT). Programmable paper-based microfluidic devices enable a wide range of biomarker detection with high sensitivity and automation for single- and multi-step assays because they provide better control for manipulating fluid samples. In this review, we examine the advances in programmable microfluidics, i.e., paper-based continuous-flow microfluidic (p-CMF) devices and paper-based digital microfluidic (p-DMF) devices, for biomarker detection. First, we discuss the methods used to fabricate these two types of paper-based microfluidic devices and the strategies for programming fluid delivery and for droplet manipulation. Next, we discuss the use of these programmable paper-based devices for the single- and multi-step detection of biomarkers. Finally, we present the current limitations of paper-based microfluidics for biomarker detection and the outlook for their development.

Near Infrared Spectroscopy (NIRS), as one of analysis technologies, has shown promisingly industrial applications for significant properties for recent decades such as fast response, preciseness, non-intrusion etc. Here, the authors employed NIRS coupled with a series of physical and chemical tests to assess the ageing condition of oil-paper insulation, which is responsible for the main insulation type of high-voltage power transformer. Among these procedures, the data analytic algorithms are of utmost importance to determine the evaluation precision. After plenty of trial-and-error, Savitzky-Golay (S-G) convolution was finally utilised to de-noise samples and improve the spectral data quality. The competitive adaptive reweighted sampling (CARS) was used to select the optimal wavelength combination of NIRS, which is found able to fully extract the effectively spectral information and reduce dimensions of spectral data. Based on the above-mentioned techniques, the quantitative analysis model of NIRS was established by partial least squares (PLS), which could synthetically process the spectral data and the degree of polymerisation (DP) of paper samples. The results indicated that compared with the traditional detection methods, the NIRS analysis is a powerful and informative tool to characterise the condition of oil-paper insulation without intrusion or damage to transformers.