Mobile phone-based biosensing: An emerging “diagnostic and communication” technology

Advanced technologies in biodegradable packaging using intelligent sensing to fight food waste

The limitation of conventional packaging in demonstrating accurate and real-time food expiration dates leads to food waste and foodborne diseases. Real-time food quality monitoring via intelligent packaging could be an effective solution to reduce food waste and foodborne illnesses. This review focuses on recent technological advances incorporated into food packaging for monitoring food spoilage, with a major focus on paper-based sensors and their combination with smartphone. This review paper offers a comprehensive exploration of advanced macromolecular technologies in biodegradable packaging, a general overview of paper-based probes and their incorporation into food packaging coupled with intelligent sensing mechanisms for monitoring food freshness. Given the escalating global concerns surrounding food waste, our manuscript serves as a pivotal resource, consolidating current research findings and highlighting the transformative potential of these innovative packaging solutions. We also highlight the current intelligent paper-based food freshness sensors and their various advantages and limitations. Examples of implementation of paper-based sensors/probes for food storage and their accuracy are presented. Finally, we examined how intelligent packaging can be an alternative to reduce food waste. Several technologies discussed here have good potential to be used in food packaging for real-time food monitoring, especially when combined with smartphone diagnosis.

Low-tech vs. high-tech approaches in μPADs as a result of contrasting needs and capabilities of developed and developing countries focusing on diagnostics and point-of-care testing

Paper-based analysis has captivated scientists' attention in the field of analytical chemistry and related areas for the last two decades. Arguably no other area of modern chemical analysis is so broad and diverse in its approaches spanning from simple 'low-tech' low-cost paper-based analytical devices (PADs) requiring no or simple instrumentation, to sophisticated PADs and microfluidic paper-based analytical devices (μPADs) featuring elements of modern material science and nanomaterials affording high selectivity and sensitivity. Correspondingly diverse is the applicability, covering resource-limited scenarios on the one hand and most advanced approaches on the other. Herein we offer a view reflecting this diversity in the approaches and types of devices. The core idea of this article rests in dividing μPADs according to their type into two groups: A) instrumentation-free μPADs for resource-limited scenarios or developing countries and B) instrumentation-based μPADs as futuristic POC devices for e-diagnostics mainly aimed at developed countries. Each of those two groups is presented and discussed with the view of the main requirements in the given area, the most common targets, sample types and suitable detection approaches either implementing high-tech elements or low-tech low-cost approaches. Finally, a socioeconomic perspective is offered in discussing the fabrication and operational costs of μPADs, and, future perspectives are offered.

Emerging trends in nanomaterial design for the development of point-of-care platforms and practical applications

Nanomaterials and nanotechnology offer promising opportunities in point-of-care (POC) diagnostics and therapeutics due to their unique physical and chemical properties. POC platforms aim to provide rapid and portable diagnostic and therapeutic capabilities at the site of patient care, offering cost-effective solutions. Incorporating nanomaterials with distinct optical, electrical, and magnetic properties can revolutionize the POC industry, significantly enhancing the effectiveness and efficiency of diagnostic and theragnostic devices. By leveraging nanoparticles and nanofibers in POC devices, nanomaterials have the potential to improve the accuracy and speed of diagnostic tests, making them more practical for POC settings. Technological advancements, such as smartphone integration, imagery instruments, and attachments, complement and expand the application scope of POCs, reducing invasiveness by enabling analysis of various matrices like saliva and breath. These integrated testing platforms facilitate procedures without compromising diagnosis quality. This review provides a summary of recent trends in POC technologies utilizing nanomaterials and nanotechnologies for analyzing disease biomarkers. It highlights advances in device development, nanomaterial design, and their applications in POC. Additionally, complementary tools used in POC and nanomaterials are discussed, followed by critical analysis of challenges and future directions for these technologies.

Coupling ELISA to smartphones for POCT of chronic and congenital Chagas disease

Chagas disease (CD) affects about 7 million people worldwide, presents a large prevalence in Latin America, and is growing in the rest of the world, where congenital CD is the main mode of transmission. Point-of-care testing (POCT) methods are increasingly required to ease early diagnostics and increase treatment success. This work presents the development and validation of a smartphone-integrated ELISA-based POCT system for the detection of both chronic and congenital CD. Expensive and bulky equipment used for ELISA in conventional laboratories was replaced as follows. A miniaturized device was fabricated for incubation of commercial ELISA plates, achieving ∼±1 °C uniformity and stability. The ELISA plate reader was replaced by smartphone camera and image processing, comprising algorithms to account for variability sources and spatial light non-uniformity; thus, additional hardware like a dark-box is not required. The agreement between samples classified with this novel reading method vs. ELISA plate reader was found to be 99.7% and 95.4% for chronic and congenital CD, respectively. Furthermore, a smartphone application was designed and implemented to guide the user during the assay, provide connectivity, and access databases, facilitating patient monitoring and health-policy making. The whole system is aimed to be used as a practical diagnostic tool in primary health care settings, as well as to facilitate patients' follow-up to provide better treatment. Concerning the technology itself, the proposed POCT platform is versatile enough to be readily adapted for the detection of other infectious diseases.

Smartphone-based 3D-printed electrochemiluminescence enzyme biosensor for reagentless glucose quantification in real matrices

Three-dimensional (3D) printed electrochemical devices are increasingly used in point-of-need and point-of-care testing. They show several advantages such as simple fabrication, low cost, fast response, and excellent selectivity and sensitivity in small sample volumes. However, there are only a few examples of analytical devices combining 3D-printed electrodes with electrochemiluminescence (ECL) detection, an electrochemical detection principle widely employed in clinical chemistry analysis. Herein, a portable, 3D-printed miniaturized ECL biosensor for glucose detection has been developed, based on the luminol/H₂O₂ ECL system and employing a two-electrode configuration with carbon black-doped polylactic acid (PLA) electrodes. The ECL emission is obtained by means of a 1.5V AA alkaline battery and detected using a smartphone camera, thus providing easy portability of the analytical platform. The ECL system was successfully applied for sensing H₂O₂ and, upon coupling the luminol/H₂O₂ system with the enzyme glucose oxidase, for glucose detection. The incorporation of luminol and glucose oxidase in an agarose hydrogel matrix allowed to produce ECL devices preloaded with the reagents required for the assay, so that the analysis only required sample addition. The ECL biosensor showed an excellent ability to detect glucose up to 5 mmol L^-1, with a limit of detection of 60 μmol L^-1. The biosensor was also used to analyse real samples (i.e., glucose saline solutions and artificial serum samples) with satisfactory results, thus suggesting its suitability for point-of-care analysis. Coupling with other oxidases could further extend the applicability of this analytical platform.

Polyoxometalate-cyclodextrin supramolecular entities for real-time in situ monitoring of dopamine released from neuroblastoma cells

Optimized and sensitive biomarker detection has recently been shown to have a critical impact on quality of diagnosis and medical care options. In this research study, polyoxometalate-γ-cyclodextrin metal-organic framework (POM-γCD MOF) was utilized as an electrocatalyst to fabricate highly selective sensors to detect in-situ released dopamine. The POM-γCD MOF produced multiple modes of signals for dopamine including electrochemical, colorimetric, and smartphone read-outs. Real-time quantitative monitoring of SH-SY5Y neuroblastoma cellular dopamine production was successfully demonstrated under various stimuli at different time intervals. The POM-CD MOF sensor and linear regression model were used to develop a smartphone read-out platform, which converts dopamine visual signals to digital signals within a few seconds. Ultimately, POM-γCD MOFs can play a significant role in the diagnosis and treatment of various diseases that involve dopamine as a significant biomarker.

Moving toward smart biomedical sensing

The development of novel biomedical sensors as highly promising devices/tools in early diagnosis and therapy monitoring of many diseases and disorders has recently witnessed unprecedented growth; more and faster than ever. Nonetheless, on the eve of Industry 5.0 and by learning from defects of current sensors in smart diagnostics of pandemics, there is still a long way to go to achieve the ideal biomedical sensors capable of meeting the growing needs and expectations for smart biomedical/diagnostic sensing through eHealth systems. Herein, an overview is provided to highlight the importance and necessity of an inevitable transition in the era of digital health/Healthcare 4.0 towards smart biomedical/diagnostic sensing and how to approach it via new digital technologies including Internet of Things (IoT), artificial intelligence, IoT gateways (smartphones, readers), etc. This review will bring together the different types of smartphone/reader-based biomedical sensors, which have been employing for a wide variety of optical/electrical/electrochemical biosensing applications and paving the way for future eHealth diagnostic devices by moving towards smart biomedical sensing. Here, alongside highlighting the characteristics/criteria that should be met by the developed sensors towards smart biomedical sensing, the challenging issues ahead are delineated along with a comprehensive outlook on this extremely necessary field.

Smartphone-controlled biosensor for viral respiratory infectious diseases: Screening and response

Outbreaks of emerging viral respiratory infectious diseases (VRIDs) including coronavirus disease 2019 (COVID-19) seriously endanger people's health. However, the traditional nucleic acid detection required professionals and larger instruments and antigen-antibody detection suffered a long window period of target generation. To facilitate the VRIDs detection in time for common populations, a smartphone-controlled biosensor, which integrated sample preparation (electromembrane extraction), biomarker detection (red-green-blue model) and remote response technology (a built-in APP), was developed in this work. With the intelligent biosensor, VRIDs could be recognized in the early stage by using endogenous hydrogen sulfide as the biomarker. Importantly, it only took 15 min to accomplish the whole process of screening and response to VRIDs. Moreover, the experimental data showed that this smartphone-controlled biosensor was suitable for ordinary residents and could successfully differentiate non-communicable respiratory diseases from VRIDs. To the best of our knowledge, this is the first time that a smartphone-controlled biosensor for screening and response to VRIDs was reported. We believe that the present biosensor will help ordinary residents jointly deal with the challenges brought by COVID-19 or other VRIDs in the future.

Single-Molecule Optical Biosensing: Recent Advances and Future Challenges

In recent years, the sensitivity and specificity of optical sensors has improved tremendously due to improvements in biochemical functionalization protocols and optical detection systems. As a result, single-molecule sensitivity has been reported in a range of biosensing assay formats. In this Perspective, we summarize optical sensors that achieve single-molecule sensitivity in direct label-free assays, sandwich assays, and competitive assays. We describe the advantages and disadvantages of single-molecule assays and summarize future challenges in the field including their optical miniaturization and integration, multimodal sensing capabilities, accessible time scales, and compatibility with real-life matrices such as biological fluids. We conclude by highlighting the possible application areas of optical single-molecule sensors that include not only healthcare but also the monitoring of the environment and industrial processes.

Analysis of Polarization Images in the Microphysical Blood Parameters Research for the Hematocrit Diagnostics

The development of non-invasive optoelectronic technologies for human blood monitoring is one of the important research areas for medicine. A critical analysis of optoelectronic methods of blood research and the micromechanical systems based on them is carried out in this article. A design realization of a polarizing portable system for non-invasive monitoring of hematocrit as one of the basic homeostatic constants of the human body containing information about the microphysical parameters of blood cells has been substantiated. A physical model of polarized radiation conversion in a video information system of laser sensing of a biological research object has been formed. Visual and quantitative differences in the spatial distribution of polarization parameters of the scattered radiation for the states of the body with different hematocrit levels have been revealed. A scheme of a multichannel imaging portable system, based on a smartphone using miniature optical and microelectronic components of information conversion for non-invasive monitoring of microphysical blood parameters, has been created. The system implements the principle of polarimetric blood photometry and a multiparametric analysis of the polarization properties of the laser radiation scattered by blood. The developed portable optoelectronic system, based on a smartphone, can be used for rapid blood diagnostics in disaster medicine and the presence of clinical contraindications to the formation of invasive tests. The proposed polarization-based approach is a promising automated alternative to traditional devices and systems for the research of microphysical blood parameters.

Computer vision enabled funnel adapted sensing tube (FAST) for power-free and pipette-free nucleic acid detection

A simple, portable, and low-cost microfluidic system-funnel adapted sensing tube (FAST) is developed as an integrated, power-free, and pipette-free biosensor for viral nucleic acids. This FAST chip consists of four reaction chambers separated by carbon fiber rods, and the reagents in each chamber are transferred and mixed by manually removing the rods. Rather than using electrical heaters, only a hand warmer pouch is used for an isothermal recombinase polymerase amplification (RPA) and CRISPR-Cas12a reaction. The signal produced by the RPA-CRISPR reaction is observed by the naked eye using an inexpensive flashlight as a light source. The FAST chip is fabricated using water-soluble polyvinyl alcohol (PVA) as a sacrificial core, which is simple and environmentally friendly. Using a SARS-CoV-2 fragment as a target, a ∼10 fM (6 × 10³ copies per μL) detection limit is achieved. To generalize standard optical readout for individuals without training, a linear kernel algorithm is created, showing an accuracy of ∼100% for identifying both positive and negative samples in FAST. This power-free, pipette-free, disposable, and simple device will be a promising tool for nucleic acid diagnostics in either clinics or low-resource settings.

Smartphone Digital Image Colorimetry for the Determination of Aluminum in Antiperspirant Products

Objectives

This study aims to present a method for the determination of the aluminum in antiperspirant products (APPs) by chelating it with quercetin before its detection by smartphone digital image colorimetry (SDIC).

Materials and Methods

Samples were prepared by closed-vessel acid digestion in PTFE cups. This was followed by complexation of aluminum in the sample solution using quercetin as a chelating agent. Sample solutions were transferred into a quartz ultraviolet/visible detection microcuvette for detection in a homemade colorimetric box designed for capturing images of the yellow complex with a smartphone camera. The pixel intensity of the images was converted to numbers for quantitation using ImageJ software for a personal computer. An independent study using high-performance liquid chromatography-diode-array detection was conducted to check the accuracy of the proposed method.

Results

Optimum SDIC conditions included a Samsung C9 smartphone as the detection camera, a cropped region of interest of 6400 px², and the side position of the colorimetric box were selected for capturing the images of the sample solutions placed 10.0 cm from the detection camera, whereas optimum complexation conditions were found to be as sample pH of 5.5, sample volume of 3.0 mL, complexation time of 1.0 min and a ligand concentration of 0.28 mmol L^-1. Analytical performance of the method included a limit of detection of 0.5 μmol L^-1 and a coefficient of determination (R²) of the calibration graph of 0.9981.

Conclusion

The proposed method was successfully applied for the determination of aluminum in APPs with percentage recoveries ranging from 80.0 to 109.6%.

“Natural Laboratory Complex” for novel primate neuroscience

We propose novel strategies for primate experimentation that are ethically valuable and pragmatically useful for cognitive neuroscience and neuropsychiatric research. Specifically, we propose Natural Laboratory Complex or Natural Labs, which are a combination of indoor-outdoor structures for studying free moving and socially housed primates in natural or naturalistic environment. We contend that Natural Labs are pivotal to improve primate welfare, and at the same time to implement longitudinal and socio-ecological studies of primate brain and behavior. Currently emerging advanced technologies and social systems (including recent COVID-19 induced “remote” infrastructures) can speed-up cognitive neuroscience approaches in freely behaving animals. Experimental approaches in natural(istic) settings are not in competition with conventional approaches of laboratory investigations, and could establish several benefits at the ethical, experimental, and economic levels.

Toward Next Generation Lateral Flow Assays: Integration of Nanomaterials

Lateral flow assays (LFAs) are currently the most used point-of-care sensors for both diagnostic (e.g., pregnancy test, COVID-19 monitoring) and environmental (e.g., pesticides and bacterial monitoring) applications. Although the core of LFA technology was developed several decades ago, in recent years the integration of novel nanomaterials as signal transducers or receptor immobilization platforms has brought improved analytical capabilities. In this Review, we present how nanomaterial-based LFAs can address the inherent challenges of point-of-care (PoC) diagnostics such as sensitivity enhancement, lowering of detection limits, multiplexing, and quantification of analytes in complex samples. Specifically, we highlight the strategies that can synergistically solve the limitations of current LFAs and that have proven commercial feasibility. Finally, we discuss the barriers toward commercialization and the next generation of LFAs.

When smartphone enters food safety: A review in on-site analysis for foodborne pathogens using smartphone-assisted biosensors

Pathogens are one of the supreme threats for the public health around the world in food supply chain. The on-site monitoring is an emerging trend for screening pathogens during the food processing and preserving. Traditional analytical tools have been unable to satisfy the current demands. Smartphones have enormous potentials for achieving on-site detection of foodborne pathogens, with intrinsic advantages such as small size, high accessibility, fast processing speed, and powerful imaging capacity. This review aims to synthesize the current advances in smartphone-assisted biosensors (SABs) for sensing foodborne pathogens, and briefly put forward the problem that consist in the research. We present the role of nanotechnology and recognition modes targeting foodborne pathogens in SABs, and discuss the signal conversion platforms coupling with smartphone. The challenges and perspectives in SABs are also proposed. The smartphone analytics area is moving forward, and it much be subject to careful quality standards and validation.

Virus Detection: From State-of-the-Art Laboratories to Smartphone-Based Point-of-Care Testing

Infectious virus outbreaks pose a significant challenge to public healthcare systems. Early and accurate virus diagnosis is critical to prevent the spread of the virus, especially when no specific vaccine or effective medicine is available. In clinics, the most commonly used viral detection methods are molecular techniques that involve the measurement of nucleic acids or proteins biomarkers. However, most clinic-based methods require complex infrastructure and expensive equipment, which are not suitable for low-resource settings. Over the past years, smartphone-based point-of-care testing (POCT) has rapidly emerged as a potential alternative to laboratory-based clinical diagnosis. This review summarizes the latest development of virus detection. First, laboratory-based and POCT-based viral diagnostic techniques are compared, both of which rely on immunosensing and nucleic acid detection. Then, various smartphone-based POCT diagnostic techniques, including optical biosensors, electrochemical biosensors, and other types of biosensors are discussed. Moreover, this review covers the development of smartphone-based POCT diagnostics for various viruses including COVID-19, Ebola, influenza, Zika, HIV, et al. Finally, the prospects and challenges of smartphone-based POCT diagnostics are discussed. It is believed that this review will aid researchers better understand the current challenges and prospects for achieving the ultimate goal of containing disease-causing viruses worldwide.

A free customizable tool for easy integration of microfluidics and smartphones

The integration of smartphones and microfluidics is nowadays the best possible route to achieve effective point-of-need testing (PONT), a concept increasingly demanded in the fields of human health, agriculture, food safety, and environmental monitoring. Nevertheless, efforts are still required to integrally seize all the advantages of smartphones, as well as to share the developments in easily adoptable formats. For this purpose, here we present the free platform appuente that was designed for the easy integration of microfluidic chips, smartphones, and the cloud. It includes a mobile app for end users, which provides chip identification and tracking, guidance and control, processing, smart-imaging, result reporting and cloud and Internet of Things (IoT) integration. The platform also includes a web app for PONT developers, to easily customize their mobile apps and manage the data of administered tests. Three application examples were used to validate appuente: a dummy grayscale detector that mimics quantitative colorimetric tests, a root elongation assay for pesticide toxicity assessment, and a lateral flow immunoassay for leptospirosis detection. The platform openly offers fast prototyping of smartphone apps to the wide community of lab-on-a-chip developers, and also serves as a friendly framework for new techniques, IoT integration and further capabilities. Exploiting these advantages will certainly help to enlarge the use of PONT with real-time connectivity in the near future.

Solving Color Reproducibility between Digital Devices: A Robust Approach of Smartphones Color Management for Chemical (Bio)Sensors

In the past twelve years, digital image colorimetry (DIC) on smartphones has acquired great importance as an alternative to the most common analytical techniques. This analysis method is based on fast, low-cost, and easily-accessible technology, which can provide quantitative information about an analyte through the color changes of a digital image. Despite the fact that DIC is very widespread, it is not exempt from a series of problems that are not fully resolved yet, such as variability of the measurements between smartphones, image format in which color information is stored, power distribution of the illuminant used for the measurements, among others. This article proposes a methodology for the standardization and correction of these problems using self-developed software, together with the use of a 3D printed light box. This methodology is applied to three different colorimetric analyses using different types and brands of smartphones, proving that comparable measurements between devices can be achieved. As color can be related to many target analytes, establishing this measurement methodology can lead to new control analysis applicable to diverse sectors such as alimentary, industrial, agrarian, or sanitary.

A visual chiroptical system with chiral assembly graphene quantum dots for D-phenylalanine detection

Chirality is a fundamental phenomenon of nature, and the enantioselective recognition of amino acids isomers is especially important for life science. In this study, chiroptical system based on chiral assembly graphene quantum dots (GQDs) was developed for visual testing of D-phenylalanine (D-Phe). Here, GQDs were used as the fluorescent element, and chiral functional moieties of 1,3,5-triformylphloroglucinol-functionalized chiral ( +)-diacetyl-L-tartaric anhydride (TPTA) were used as the chiral recognition elements. Based on the formed chiral microenvironment, the fluorescence intensity of TPTA-assembled GQDs had a good linear relationship with D-Phe in the concentration range of 0.1-5 μM, and the detection limit was 0.023 μM. According to the variation in luminance of TPTA-assembled GQDs, visual testing to D-Phe was realized using a smartphone-assisted chiroptical system with a detection limit of 0.050 μM. The spiked recoveries of both chiroptical sensing methods based on TPTA-assembled GQDs from the food matrix ranged from 86.20 to 110.0%. Furthermore, TPTA-assembled GQDs were successfully applied to intracellular chiroptical imaging in response to D-Phe in vitro. The developed chiral nanomaterial TPTA-assembled GQDs with excellent photochemical stability, optical properties, and bioimaging capabilities provide a promising technique for the visual detection of amino acid isomers in the field of smart devices.

A novel score for mobile health applications to predict and prevent mortality: Further validation and adaptation to US population using the US NHANES dataset

Background

The C-Score, which is an individual health score, is based on a predictive model validated in the UK and US populations. It was designed to serve as an individualized point-in-time health assessment tool that could be integrated into clinical counseling or consumer-facing digital health tools to encourage lifestyle modifications that reduce the risk of premature death.

Objective

Our study aimed to conduct an external validation of the C-Score in the US population and expand the original score to improve its predictive capabilities in the US population. The C-Score is intended for mobile health apps on wearable devices.

Methods

We conducted a literature review to identify relevant variables that were missing in the original C-Score. Subsequently, we used data from the 2005 to 2014 US National Health and Nutrition Examination Survey (NHANES; N=21,015) to test the capacity of the model to predict all-cause mortality. We used NHANES III data from 1988 to 1994 (N=1440) to conduct an external validation of the test. Only participants with complete data were included in this study. Discrimination and calibration tests were conducted to assess the operational characteristics of the adapted C-Score from receiver operating curves and a design-based goodness-of-fit test.

Results

Higher C-Scores were associated with reduced odds of all-cause mortality (odds ratio 0.96, P<.001). We found a good fit of the C-Score for all-cause mortality with an area under the curve (AUC) of 0.72. Among participants aged between 40 and 69 years, C-Score models had a good fit for all-cause mortality and an AUC >0.72. A sensitivity analysis using NHANES III data (1988-1994) was performed, yielding similar results. The inclusion of sociodemographic and clinical variables in the basic C-Score increased the AUCs from 0.72 (95% CI 0.71-0.73) to 0.87 (95% CI 0.85-0.88).

Conclusions

Our study shows that this digital biomarker, the C-Score, has good capabilities to predict all-cause mortality in the general US population. An expanded health score can predict 87% of the mortality in the US population. This model can be used as an instrument to assess individual mortality risk and as a counseling tool to motivate behavior changes and lifestyle modifications.

A Self-Powered Triboelectric Hybrid Coder for Human-Machine Interaction

Human-machine interfaces have penetrated various academia and industry fields such as smartphones, robotic, virtual reality, and wearable electronics, due to their abundant functional sensors and information interaction methods. Nevertheless, most sensors' complex structural design, monotonous parameter detection capability, and single information coding communication hinder their rapid development. As the frontier of self-powered sensors, the triboelectric nanogenerator (TENG) has multiple working modes and high structural adaptability, which is a potential solution for multi-parameter sensing and miniaturizing of traditional interactive electronic devices. Herein, a self-powered hybrid coder (SHC) based on TENG is reported to encode two action parameters of touch and press, which can be used as a smart interface for human-machine interaction. The top-down hollow structure of the SHC, not only constructs a compositing mode to generate stable touch and press signals but also builds a hybrid coding platform for generating action codes in synergy mode. When a finger touches or presses the SHC, Morse code and Gray code can be transmitted for text information or remote control of electric devices. This self-powered coder is of reference value for designing an alternative human-machine interface and having the potential to contribute to the next generation of highly integrated portable smart electronics.

Wash-free operation of smartphone-integrated optical immunosensor using retroreflective microparticles

Herein, we introduce a smartphone-integrated immunosensor based on non-spectroscopic optical detection. Sedimentation of the retroreflector and gentle inversion of the microfluidic chip was chosen as biosensing principles to ensure minimal human involvement. To realize this, wash-free immunosensing was implemented on a polymeric microfluidic chip device fabricated for light signal penetration in retroreflection signal acquisition. Applying a transparent chip and passive modulation of retroreflectors enabled the minimization of human error during sensing. In addition, a retroreflection-detectable optical gadget was constructed for integration with the commercial smartphone. The gadget had an optical chamber that induced retroreflection by integration with a smartphone. When the micro-sized reflector, named the retroreflective Janus microparticle, reacted on the sensing surface, the incident light was retroreflected towards the image sensor and quantified by a smartphone-installed Android application package. The developed application package features include time-lapse image capture performed by manipulating LED flash and camera modules, and quantification of retroreflected signal counts by image processing of time-lapse images. With this platform, the user could independently commence optical signal processing without a complicated optical setup and running software on a PC, and sensitive and reproducible immunosensing results could be obtained. The applicability test for creatine kinase-myocardial band detection from the buffer to serum was conducted and presented a calibration curve of 0-1000 ng/mL within 1 h. With the developed system, we believe that the applicability of the platform in bioanalytical detection can be expanded.

A smartphone-based visual biosensor for CRISPR-Cas powered SARS-CoV-2 diagnostics

The pandemic of coronavirus disease 2019 (COVID-19) resulted from novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a worldwide concern. It is imperative to develop rapid, sensitive, and specific biosensing methods. Herein, we developed a CRISPR-Cas12a powered visual biosensor with a smartphone readout for ultrasensitive and selective detection of SARS-CoV-2. Simply, the SARS-CoV-2 derived nucleic acids triggered CRISPR-Cas12a based indiscriminate degradation of a single-stranded DNA that was supposed to link two gold nanoparticles, inducing the dis-aggregation of gold nanoparticles and thus generating observable color changes. This change can be readily distinguished by naked eyes as well as a smartphone with a Color Picker App. The proposed biosensor was successfully applied to detect SARS-CoV-2 gene in synthetic vectors, transcribed RNA and SARS-CoV-2 pseudoviruses. It rendered “single copy resolution” as evidenced by the 1 copy/μL limit of detection of pseudoviruses with no cross-reactivity. When the developed biosensor was challenged with SARS-CoV-2 clinical bio-samples, it provided 100% agreement (both positive and negative) with qPCR results. The sample-to-result time was roughly 90 min. Our work provides a novel and robust technology for ultrasensitive detection of SARS-CoV-2 that could be used clinically.

Design and implementation of low-cost portable potentiostat based on wechat

The potentiostat is critical in the development of electrochemical systems; however, its cumbersome detection and high cost considerably limit its large-scale application. To provide an affordable alternative to developing countries and resource-constrained areas, this study designs an electrochemical detection system based on smartphones, which uses Bluetooth Low Energy to convert open-source potentiostat data based on PSoC-5LP. The WeChat application on the smartphone provides an interface for entering experimental parameters and visualizing the results in real time. The smartphone-based electro-chemical detection system has a simple design and reduces the size (10?3?0.3 cm) and the cost of the hardware ($ 18). The system performs the most commonly used cyclic voltammetry for electrochemical detection, with results that are comparable to those obtained using a commercial potentiostat and an error rate of 1.3 %. In the classical teaching experiment of electrochemical determination of ascorbic acid in orange juice samples, the measured value of the system is 0.367 ? 0.012 mg/mL, compared with the standard reference value of 0.37 mg/ mL, which is obviously a convincing value. Therefore, this system is a low-cost, reliable alternative to a potentiostat for research, education, or product integration development.

CRISPR-Cas based virus detection: Recent advances and perspectives

Viral infections are one of the most intimidating threats to human beings. One convincing example is the coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2. Rapid, sensitive, specific and field-deployable identification of causal viruses is critical for disease surveillance, control and treatment. The shortcomings of current methods create an impending need for developing novel biosensing platforms. CRISPR-Cas systems, especially CRISPR-Cas12a and CRISPR-Cas13a, characterized by their sensitivity, specificity, high base resolution and programmability upon nucleic acid recognition, have been repurposed for molecular diagnostics, surging a new path forward in biosensing. They, as the core of some robust diagnostic tools, are revolutionizing the way that virus can be detected. This review focuses on recent advances in virus detection with CRISPR-Cas systems especially CRISPR-Cas12a/Cas13a. We started with a short introduction to CRISPR-Cas systems and the properties of Cas12a and Cas13a effectors, and continued with reviewing the current advances of virus detection utilizing CRISPR-Cas systems. The significance and advantages of such methods were then discussed. Finally, the challenges and perspectives were proposed. We tried to provide readers with a concise profile of emerging and fast-expanding CRISPR-Cas based biosensing technology, and highlighted its potential applications in a range of scenarios with regard to virus detection.

Recent Advancements in the Technologies Detecting Food Spoiling Agents

To match the current life-style, there is a huge demand and market for the processed food whose manufacturing requires multiple steps. The mounting demand increases the pressure on the producers and the regulatory bodies to provide sensitive, facile, and cost-effective methods to safeguard consumers' health. In the multistep process of food processing, there are several chances that the food-spoiling microbes or contaminants could enter the supply chain. In this contest, there is a dire necessity to comprehend, implement, and monitor the levels of contaminants by utilizing various available methods, such as single-cell droplet microfluidic system, DNA biosensor, nanobiosensor, smartphone-based biosensor, aptasensor, and DNA microarray-based methods. The current review focuses on the advancements in these methods for the detection of food-borne contaminants and pathogens.

Nano-functionalized paper-based IoT enabled devices for point-of-care testing: a review

Over the last few years, the microfluidics phenomenon coupled with the Internet of Things (IoT) using innovative nano-functional materials has been recognized as a sustainable and economical tool for point-of-care testing (POCT) of various pathogens influencing human health. The sensors based on these phenomena aim to be designed for cost-effectiveness, make it handy, environment-friendly, and get an accurate, easy, and rapid response. Considering the burgeoning importance of analytical devices in the healthcare domain, this review paper is based on the gist of sensing aspects of the microfabricated paper-based analytical devices (μPADs). The article discusses the various used design methodologies and fabrication approaches and elucidates the recently reported surface modification strategies, detection mechanisms viz., colorimetric, electrochemical, fluorescence, electrochemiluminescence, etc. In a nutshell, this article summarizes the state-of-the-art research work carried out over the nano functionalized paper-based analytical devices and associated challenges/solutions in the point of care testing domain.

A plug, print & play inkjet printing and impedance-based biosensing technology operating through a smartphone for clinical diagnostics

Simplicity is one of the key feature for the spread of any successful technological product. Here, a method for rapid and low-cost fabrication of electrochemical biosensors is presented. This "plug, print & play" method involves inkjet-printing even in an office-like environment, without the need of highly specialized expertise or equipment, guaranteeing an ultra-fast idea to (scaled) prototype production time. The printed biosensors can be connected to a smartphone through its audio input for their impedance readout, demonstrating the validity of the system for point-of-care biosensing. Proper electrodes layout guarantees high sensitivity and is validated by finite element simulations. The introduction of a passivation method (wax printing) allowed to complete the devices fabrication process, increasing their sensitivity. Indeed, the wax allowed reducing the interference related to the parasitic currents flowing through the permeable coating of the employed substrates, which was used for the chemical sintering, thus avoiding the common thermal treatment after printing. As a case study, we used the devices to develop an electrochemical aptamer-based sensor for the rapid detection of neutrophil gelatinase-associated lipocalin (NGAL) in urine - a clinically important marker of acute kidney injury. The aptasensor platform is capable of detecting clinically relevant concentrations of NGAL with a simple and rapid smartphone readout. The developed technology may be extended in the future to continuous monitoring, taking advantage of its flexibility to integrate it in tubes, or to other diagnostic applications where cost/efficiency and rapidity of the research, development and implementation of point of care devices is a must.

The Importance of Citizen Scientists in the Move Towards Sustainable Diets and a Sustainable Food System

To enhance sustainability, the food system requires significant shifts in the production, processing and supply of food. Ideally, a sustainable food system should operate, not only to protect the biosphere, but also to provide nutritious, high-quality food, and to support social values, an equitable economy, and human and animal health. It should also be governed responsibly within a supportive policy environment. Implementing these shifts is a task of immense scale; but citizen participation/engagement has the potential to help make sustainability a reality through distributed learning, dynamic sensing, and knowledge generation. Technological advancements in sensing and data processing have enabled new forms of citizen participation in research. When food system research is embedded within society it can help us to understand which changes towards sustainability work and which do not. Indeed, citizen engagement in food systems research has the potential to help bring citizens on side, supporting the growth of a food culture of resilience and of sustainable practises (including dietary change). This commentary provides examples of how existing research and alternative food production systems and agroecological practises may provide possible frameworks for citizen participation in food system studies. We highlight potential future food and citizen science approaches. Widening citizen participation and encouraging the involvement of other food system actors, including those in local, national and international governance, is essential to capture the full potential of citizen science in enabling transition to a sustainable food system. For the research community citizen science offers engagement and empowerment of wider communities with science; collecting and analysing data; and creating viable solutions to food system and diet issues.

A Smartphone-Enabled Portable Digital Light Processing 3D Printer

3D printing has emerged as an enabling approach in a variety of different fields. However, the bulk volume of printing systems limits the expansion of their applications. In this study, a portable 3D Digital Light Processing (DLP) printer is built based on a smartphone-powered projector and a custom-written smartphone-operated app. Constructs with detailed surface architectures, porous features, or hollow structures, as well as sophisticated tissue analogs, are successfully printed using this platform, by utilizing commercial resins as well as a range of hydrogel-based inks, including poly(ethylene glycol)-diacrylate, gelatin methacryloyl, or allylated gelatin. Moreover, due to the portability of the unique DLP printer, medical implants can be fabricated for point-of-care usage, and cell-laden tissues can be produced in situ, achieving a new milestone for mobile-health technologies. Additionally, the all-in-one printing system described herein enables the integration of the 3D scanning smartphone app to obtain object-derived 3D digital models for subsequent printing. Along with further developments, this portable, modular, and easy-to-use smartphone-enabled DLP printer is anticipated to secure exciting opportunities for applications in resource-limited and point-of-care settings not only in biomedicine but also for home and educational purposes.

Smartphone-based competitive immunoassay for quantitative on-site detection of meat adulteration

Rapid, sensitive, and portable analytical methods for on-site inspection of food fraud are now an urgent requirement to ensure food quality and satisfy the ethnic considerations of consumers. Hence, for the first time, a colorimetric smartphone-based immunoassay was developed for the on-site detection of pork adulteration in meat. In detail, the immunoassay was based on a competitive strategy in which immobilized standard porcine IgG competed with the target porcine IgG extracted in a single step from meat samples. The parameters involved in each step of the immunoassay conception and the digital colorimetric detection were carefully investigated and optimized. Using polystyrene microplates as ready-to-use stable and portable immunoplatforms, TMB as chromogenic substrate, smartphone as signal readout, and Image J software for image processing; the developed immunoassay was able to detect as low as 0.01% of pork in meat mixtures in a total assay time of 30 min. The selectivity of the immunoassay was evaluated for different meat species, and it was shown to selectively respond only to pork. Furthermore, excellent stability of the prepared immunological platform was demonstrated under extreme temperature conditions (50 °C), which confirms its high portability potential for in situ quantification of pork, while being relatively cost effective and non-laborious. The developed method also provides great precision (RSD < 6%) and accuracy (relative error< 6%). Given the universal use of smartphones as portable and affordable devices, such format of immunoassay could be a promising approach for rapid and sensitive real-time monitoring of food fraud.

How 3D printing can boost advances in analytical and bioanalytical chemistry

3D printing fabrication methods have received lately an enormous attention by the scientific community. Laboratories and research groups working on analytical chemistry applications, among others, have advantageously adopted 3D printing to fabricate a wide range of tools, from common laboratory hardware to fluidic systems, sample treatment platforms, sensing structures, and complete fully functional analytical devices. This technology is becoming more affordable over time and therefore preferred over the commonly used fabrication processes like hot embossing, soft lithography, injection molding and micromilling. However, to better exploit 3D printing fabrication methods, it is important to fully understand their benefits and limitations which are also directly associated to the properties of the materials used for printing. Costs, printing resolution, chemical and biological compatibility of the materials, design complexity, robustness of the printed object, and integration with commercially available systems represent important aspects to be weighted in relation to the intended task. In this review, a useful introductory summary of the most commonly used 3D printing systems and mechanisms is provided before the description of the most recent trends of the use of 3D printing for analytical and bioanalytical chemistry. Concluding remarks will be also given together with a brief discussion of possible future directions.

Photoluminescent Nanoparticles for Chemical and Biological Analysis and Imaging

Research related to the development and application of luminescent nanoparticles (LNPs) for chemical and biological analysis and imaging is flourishing. Novel materials and new applications continue to be reported after two decades of research. This review provides a comprehensive and heuristic overview of this field. It is targeted to both newcomers and experts who are interested in a critical assessment of LNP materials, their properties, strengths and weaknesses, and prospective applications. Numerous LNP materials are cataloged by fundamental descriptions of their chemical identities and physical morphology, quantitative photoluminescence (PL) properties, PL mechanisms, and surface chemistry. These materials include various semiconductor quantum dots, carbon nanotubes, graphene derivatives, carbon dots, nanodiamonds, luminescent metal nanoclusters, lanthanide-doped upconversion nanoparticles and downshifting nanoparticles, triplet-triplet annihilation nanoparticles, persistent-luminescence nanoparticles, conjugated polymer nanoparticles and semiconducting polymer dots, multi-nanoparticle assemblies, and doped and labeled nanoparticles, including but not limited to those based on polymers and silica. As an exercise in the critical assessment of LNP properties, these materials are ranked by several application-related functional criteria. Additional sections highlight recent examples of advances in chemical and biological analysis, point-of-care diagnostics, and cellular, tissue, and in vivo imaging and theranostics. These examples are drawn from the recent literature and organized by both LNP material and the particular properties that are leveraged to an advantage. Finally, a perspective on what comes next for the field is offered.

User experience analysis of AbC-19 Rapid Test via lateral flow immunoassays for self-administrated SARS-CoV-2 antibody testing

Lateral flow immunoassays are low cost, rapid and highly efficacious point-of-care devices, which have been used for SARS-CoV-2 antibody testing by professionals. However, there is a lack of understanding about how self-administered tests are used by the general public for mass testing in different environmental settings. The purpose of this study was to assess the user experience (UX) (including usability) of a self-testing kit to identify COVID-19 antibodies used by a representative sample of the public in their cars, which included 1544 participants in Northern Ireland. The results based on 5-point Likert ratings from a post-test questionnaire achieved an average UX score of 96.03% [95% confidence interval (CI) 95.05–97.01%], suggesting a good degree of user experience. The results of the Wilcoxon rank sum tests suggest that UX scores were independent of the user’s age and education level although the confidence in this conclusion could be strengthened by including more participants aged younger than 18 and those with only primary or secondary education. The agreement between the test result as interpreted by the participant and the researcher was 95.85% [95% CI 94.85–96.85%], Kappa score 0.75 [95% CI 0.69–0.81] (indicating substantial agreement). Text analysis via the latent Dirichlet allocation model for the free text responses in the survey suggest that the user experience could be improved for blood-sample collection, by modifying the method of sample transfer to the test device and giving clearer instructions on how to interpret the test results. The overall findings provide an insight into the opportunities for improving the design of SARS-CoV-2 antibody testing kits to be used by the general public and therefore inform protocols for future user experience studies of point-of-care tests.

A smartphone-integrated optosensing platform based on red-emission carbon dots for real-time detection of pyrethroids

This report described the development of an optosensing platform based on red-emission carbon dots (RCDs) integrated with a smartphone application that, together, can detect pyrethroids in real time. Based on the high stability and selectivity of molecular imprinting technology, RCDs-based optosensing imprinted polymers was obtained by using a one-pot inverse microemulsion surface imprinting method. Lambda-cyhalothrin (LC), which is a pyrethroid pesticide, can interact with the widely distributed -NH₂ groups on the surface of the RCD-based optosensing nanomaterials to achieve fixed-point adsorption. The quantitative detection of pyrethroids in a wide concentration range (1-120 μg/L) could be achieved, and the limit of detection (LOD) was 0.89 μg/L. Furthermore, a portable UV light box combined with a smartphone was used to convert the change in fluorescence of the RCDs-based optosensing nanomaterials into specific values upon adding pyrethroids, and the LOD by using smartphone was 6.66 μg/L. The developed platform has numerous advantages, including low cost, simple operation, high sensitivity, and good specificity, among others, and it achieves on-site visualization and rapid detection.

Smartphone-Enabled Personalized Diagnostics: Current Status and Future Prospects

Smartphones are becoming increasingly versatile thanks to the wide variety of sensor and actuator systems packed in them. Mobile devices today go well beyond their original purpose as communication devices, and this enables important new applications, ranging from augmented reality to the Internet of Things. Personalized diagnostics is one of the areas where mobile devices can have the greatest impact. Hitherto, the camera and communication abilities of these devices have been barely exploited for point of care (POC) purposes. This short review covers the recent evolution of mobile devices in the area of POC diagnostics and puts forward some ideas that may facilitate the development of more advanced applications and devices in the area of personalized diagnostics. With this purpose, the potential exploitation of wireless power and actuation of sensors and biosensors using near field communication (NFC), the use of the screen as a light source for actuation and spectroscopic analysis, using the haptic module to enhance mass transport in micro volumes, and the use of magnetic sensors are discussed.

Ratiometric Fluorescent Lateral Flow Immunoassay for Point-of-Care Testing of Acute Myocardial Infarction

We report the development of a highly sensitive ratiometric fluorescent lateral flow immunoassay (RFLFIA) strip for rapid and accurate detection of acute myocardial infarction biomarker, namely heart-type fatty acid binding protein (H-FABP). The RFLFIA strip works in terms of ratiometric change of fluorescence signal, arising from blending of fluorescence emitted by two composite nanostructures conjugated to capture and probe antibodies and inner filter effect of gold nanoparticles. In conjunction with using custom smartphone-based analytical device and tonality analysis, quantitative detection of H-FABP was achieved with a low limit of detection at 0.21 ng mL^-1 . The RFLFIA strip can generate a visually distinguishable green-to-red color change around the threshold concentration of H-FABP (6.2 ng mL^-1 ), thus allowing the semi-quantitative diagnosis by the naked eye.