Towards autonomous lab-on-a-chip devices for cell phone biosensing

MIP-on-a-chip: Artificial receptors on microfluidic platforms for biomedical applications

Lab-on-a-chip (LOC) as an alternative biosensing approach concerning cost efficiency, parallelization, ergonomics, diagnostic speed, and sensitivity integrates the techniques of various laboratory operations such as biochemical analysis, chemical synthesis, or DNA sequencing, etc. on miniaturized microfluidic single chips. Meanwhile, LOC tools based on molecularly imprinted biosensing approach permit their applications in various fields such as medical diagnostics, pharmaceuticals, etc., which are user-, and eco-friendly sensing platforms for not only alternative to the commercial competitor but also on-site detection like point-of-care measurements. In this review, we focused our attention on compiling recent pioneer studies that utilized those intriguing methodologies, the microfluidic Lab-on-a-chip and molecularly imprinting approach, and their biomedical applications.

Application of smartphone-based spectroscopy to biosample analysis: A review

The emergence of the smartphones has brought extensive changes to our lifestyles, from communicating with one another, to shopping and enjoyment of entertainment, and from studying to functioning at the workplace (and in the field). At the same time, this portable device has also provided new possibilities in scientific research and applications. Based on the growing awareness of good health management, researchers have coupled health monitoring to smartphone sensing technologies. Along the way, there have been developed a variety of smartphone-based optical detection platforms for analyzing biological samples, including standalone smartphone units and integrated smartphone sensing systems. In this review, we outline the applications of smartphone-based optical sensors for biosamples. These applications focus mainly on three aspects: Microscopic imaging sensing, colorimetric sensing and luminescence sensing. We also discuss briefly some limitations of the current state of smartphone-based spectroscopy and present prospects of the future applicability of smartphone sensors.

Towards practical sample preparation in point-of-care testing: user-friendly microfluidic devices

Microfluidic technologies offer a number of advantages for sample preparation in point-of-care testing (POCT), but the requirement for complicated external pumping systems limits their wide use. To facilitate sample preparation in POCT, various methods have been developed to operate microfluidic devices without complicated external pumping systems. In this review, we introduce an overview of user-friendly microfluidic devices for practical sample preparation in POCT, including self- and hand-operated microfluidic devices. Self-operated microfluidic devices exploit capillary force, vacuum-driven pressure, or gas-generating chemical reactions to apply pressure into microchannels, and hand-operated microfluidic devices utilize human power sources using simple equipment, including a syringe, pipette, or simply by using finger actuation. Furthermore, this review provides future perspectives to realize user-friendly integrated microfluidic circuits for wider applications with the integration of simple microfluidic valves.

Autonomous lab-on-a-chip generic architecture for disposables with integrated actuation

The integration of actuators within disposable lab-on-a-chip devices is a demanding goal that requires reliable mechanisms, systematic fabrication procedures and marginal costs compatible with single-use devices. In this work an affordable 3D printed prototype that offers a compact and modular configuration to integrate actuation in autonomous lab-on-a-chip devices is demonstrated. The proposed concept can handle multiple step preparation protocols, such as the enzyme-linked immunosorbent assay (ELISA) configuration, by integrating reagents, volume metering capabilities with performance comparable to pipettes (e.g. 2.68% error for 5 μL volume), arbitrary dilution ratio support, effective mixing and active control of the sample injection. The chosen architecture is a manifold served by multiple injectors ending in unidirectional valves, which exchange a null dead volume when idle, thus isolating reagents until they are used. Functionalization is modularly provided by a plug-in element, which together with the selection of reagents can easily repurpose the platform to diverse targets, and this work demonstrates the systematic fabrication of 6 injectors/device at a development cost of USD$ 0.55/device. The concept was tested with a commercial ELISA kit for tumor necrosis factor (TNF), a marker for infectious, inflammatory and autoimmune disorders, and its performance satisfactorily compared with the classical microplate implementation.

A Hybrid Lab-on-a-Chip Injector System for Autonomous Carbofuran Screening

Securing food safety standards is crucial to protect the population from health-threatening food contaminants. In the case of pesticide residues, reference procedures typically find less than 1% of tested samples being contaminated, thus indicating the necessity for new tools able to support smart and affordable prescreening. Here, we introduce a hybrid paper-lab-on-a-chip platform, which integrates on-demand injectors to perform multiple step protocols in a single disposable device. Simultaneous detection of enzymatic color response in sample and reference cells, using a regular smartphone, enabled semiquantitative detection of carbofuran, a neurotoxic and EU-banned carbamate pesticide, in a wide concentration range. The resulting evaluation procedure is generic and allows the rejection of spurious measurements based on their dynamic responses, and was effectively applied for the binary detection of carbofuran in apple extracts.

Lighting Up Biosensors: Now and the Decade To Come

Optical biosensors are defined as portable optical devices that use biorecognition molecules to interrogate a sample for the presence of a target. The capabilities of optical biosensors have expanded rapidly with advances in miniature optical components and molecular engineering. Biosensors to meet the needs in health and environmental monitoring and food safety have become commercially available, with many more in the pipeline. We review the innovative approaches to overcoming existing hurdles to practical biosensor designs and explore potential areas for future breakthroughs in optical biosensor technology.

The end user sensor tree: An end-user friendly sensor database

Detailed knowledge regarding sensor based technologies for the detection of food contamination often remains concealed within scientific journals or divided between numerous commercial kits which prevents optimal connectivity between companies and end-users. To overcome this barrier The End user Sensor Tree (TEST) has been developed. TEST is a comprehensive, interactive platform including over 900 sensor based methods, retrieved from the scientific literature and commercial market, for aquatic-toxins, mycotoxins, pesticides and microorganism detection. Key analytical parameters are recorded in excel files while a novel classification system is used which provides, tailor-made, experts' feedback using an online decision tree and database introduced here. Additionally, a critical comparison of reviewed sensors is presented alongside a global perspective on research pioneers and commercially available products. The lack of commercial uptake of the academically popular electrochemical and nanomaterial based sensors, as well as multiplexing platforms became very apparent and reasons for this anomaly are discussed.

Smartphone-based apparatus for measuring upconversion luminescence lifetimes

Luminescence lifetime detection plays an important role in time-resolved detection and research. However, the traditional instruments always require expensive detectors such as time-correlated single photon counter or streak camera. Herein, a low-cost and miniaturized apparatus for measuring upconversion luminescence lifetimes was developed by using a smartphone equipped with a 980 nm CW laser and a motor. When the motor was driving the sample circling at a high linear velocity, the excited sample would emit a luminescence arc, which could be photographed by the phone camera. The rotating rate could be measured by a tuner APP and then used for transferring arc length to delay times. By analyzing the grayscale distribution of the luminescence arc, the luminescence decay curve was obtained, which was then used for exponential fit and calculating lifetimes. The images captured by different smartphones revealed similar lifetime values, suggesting a wide universality of this method. The whole system was not only remarkably cheaper but also more miniaturized than traditional instruments for measuring luminescence lifetimes, indicating the promising applications in point of care testing for time-resolved luminescence detection for bioanalysis and disease diagnosis.

Highly integrated autonomous lab-on-a-chip device for on-line and in situ determination of environmental chemical parameters

The successful integration of sample pretreatment stages, sensors, actuators and electronics in microfluidic devices enables the attainment of complete micro total analysis systems, also known as lab-on-a-chip devices. In this work, we present a novel monolithic autonomous microanalyzer that integrates microfluidics, electronics, a highly sensitive photometric detection system and a sample pretreatment stage consisting on an embedded microcolumn, all in the same device, for on-line determination of relevant environmental parameters. The microcolumn can be filled/emptied with any resin or powder substrate whenever required, paving the way for its application to several analytical processes: separation, pre-concentration or ionic-exchange. To promote its autonomous operation, avoiding issues caused by bubbles in photometric detection systems, an efficient monolithic bubble removal structure was also integrated. To demonstrate its feasibility, the microanalyzer was successfully used to determine nitrate and nitrite in continuous flow conditions, providing real time and continuous information.

Label-Free and High-Throughput Detection of Biomolecular Interactions Using a Flatbed Scanner Biosensor

Fluorescence based microarray detection systems provide sensitive measurements; however, variation of probe immobilization and poor repeatability negatively affect the final readout, and thus quantification capability of these systems. Here, we demonstrate a label-free and high-throughput optical biosensor that can be utilized for calibration of fluorescence microarrays. The sensor employs a commercial flatbed scanner, and we demonstrate transformation of this low cost (∼100 USD) system into an Interferometric Reflectance Imaging Sensor through hardware and software modifications. Using this sensor, we report detection of DNA hybridization and DNA directed antibody immobilization on label-free microarrays with a noise floor of ∼30 pg/mm², and a scan speed of 5 s (50 s for 10 frames averaged) for a 2 mm × 2 mm area. This novel system may be used as a standalone label-free sensor especially in low-resource settings, as well as for quality control and calibration of microarrays in existing fluorescence-based DNA and protein detection platforms.

Advanced bioanalytics for precision medicine

Precision medicine is a new paradigm that combines diagnostic, imaging, and analytical tools to produce accurate diagnoses and therapeutic interventions tailored to the individual patient. This approach stands in contrast to the traditional "one size fits all" concept, according to which researchers develop disease treatments and preventions for an "average" patient without considering individual differences. The "one size fits all" concept has led to many ineffective or inappropriate treatments, especially for pathologies such as Alzheimer's disease and cancer. Now, precision medicine is receiving massive funding in many countries, thanks to its social and economic potential in terms of improved disease prevention, diagnosis, and therapy. Bioanalytical chemistry is critical to precision medicine. This is because identifying an appropriate tailored therapy requires researchers to collect and analyze information on each patient's specific molecular biomarkers (e.g., proteins, nucleic acids, and metabolites). In other words, precision diagnostics is not possible without precise bioanalytical chemistry. This Trend article highlights some of the most recent advances, including massive analysis of multilayer omics, and new imaging technique applications suitable for implementing precision medicine. Graphical abstract Precision medicine combines bioanalytical chemistry, molecular diagnostics, and imaging tools for performing accurate diagnoses and selecting optimal therapies for each patient.

Towards Multiplex Molecular Diagnosis-A Review of Microfluidic Genomics Technologies

Highly sensitive and specific pathogen diagnosis is essential for correct and timely treatment of infectious diseases, especially virulent strains, in people. Point-of-care pathogen diagnosis can be a tremendous help in managing disease outbreaks as well as in routine healthcare settings. Infectious pathogens can be identified with high specificity using molecular methods. A plethora of microfluidic innovations in recent years have now made it increasingly feasible to develop portable, robust, accurate, and sensitive genomic diagnostic devices for deployment at the point of care. However, improving processing time, multiplexed detection, sensitivity and limit of detection, specificity, and ease of deployment in resource-limited settings are ongoing challenges. This review outlines recent techniques in microfluidic genomic diagnosis and devices with a focus on integrating them into a lab on a chip that will lead towards the development of multiplexed point-of-care devices of high sensitivity and specificity.

Point-of-care testing: applications of 3D printing

Point-of-care testing (POCT) devices fulfil a critical need in the modern healthcare ecosystem, enabling the decentralized delivery of imperative clinical strategies in both developed and developing worlds. To achieve diagnostic utility and clinical impact, POCT technologies are immensely dependent on effective translation from academic laboratories out to real-world deployment. However, the current research and development pipeline is highly bottlenecked owing to multiple restraints in material, cost, and complexity of conventionally available fabrication techniques. Recently, 3D printing technology has emerged as a revolutionary, industry-compatible method enabling cost-effective, facile, and rapid manufacturing of objects. This has allowed iterative design-build-test cycles of various things, from microfluidic chips to smartphone interfaces, that are geared towards point-of-care applications. In this review, we focus on highlighting recent works that exploit 3D printing in developing POCT devices, underscoring its utility in all analytical steps. Moreover, we also discuss key advantages of adopting 3D printing in the device development pipeline and identify promising opportunities in 3D printing technology that can benefit global health applications.

3D printed microfluidic mixer for point-of-care diagnosis of anemia

3D printing has been an emerging fabrication tool in prototyping and manufacturing. We demonstrated a 3D microfluidic simulation guided computer design and 3D printer prototyping for quick turnaround development of microfluidic 3D mixers, which allows fast self-mixing of reagents with blood through capillary force. Combined with smartphone, the point-of-care diagnosis of anemia from finger-prick blood has been successfully implemented and showed consistent results with clinical measurements. Capable of 3D fabrication flexibility and smartphone compatibility, this work presents a novel diagnostic strategy for advancing personalized medicine and mobile healthcare.

Integrating printed microfluidics with silicon photomultipliers for miniaturised and highly sensitive ATP bioluminescence detection

Bioluminescence has been widely used for important biosensing applications such as the measurement of adenosine triphosphate (ATP), the energy unit in biological systems and an indicator of vital processes. The current technology for detection is mainly based on large equipment such as readers and imaging systems, which require intensive and time-consuming procedures. A miniaturised bioluminescence sensing system, which would allow sensitive and continuous monitoring of ATP, with an integrated and low-cost disposable microfluidic chamber for handling of biological samples, is highly desirable. Here, we report the design, fabrication and testing of 3D printed microfluidics chips coupled with silicon photomultipliers (SiPMs) for high sensitive real-time ATP detection. The 3D microfluidic chip reduces reactant consumption and facilitates solution delivery close to the SiPM to increase the detection efficiency. Our system detects ATP with a limit of detection (LoD) of 8nM and an analytical dynamic range between 15nM and 1µM, showing a stability error of 3%, and a reproducibility error below of 20%. We demonstrate the dynamic monitoring of ATP in a continuous-flow system exhibiting a fast response time, ~4s, and a full recovery to the baseline level within 17s. Moreover, the SiPM-based bioluminescence sensing system shows a similar analytical dynamic range for ATP detection to that of a full-size PerkinElmer laboratory luminescence reader.

3D printed auto-mixing chip enables rapid smartphone diagnosis of anemia

Clinical diagnosis requiring central facilities and site visits can be burdensome for patients in resource-limited or rural areas. Therefore, development of a low-cost test that utilizes smartphone data collection and transmission would beneficially enable disease self-management and point-of-care (POC) diagnosis. In this paper, we introduce a low-cost iPOC^3D diagnostic strategy which integrates 3D design and printing of microfluidic POC device with smartphone-based disease diagnosis in one process as a stand-alone system, offering strong adaptability for establishing diagnostic capacity in resource-limited areas and low-income countries. We employ smartphone output (AutoCAD 360 app) and readout (color-scale analytical app written in-house) functionalities for rapid 3D printing of microfluidic auto-mixers and colorimetric detection of blood hemoglobin levels. The auto-mixing of reagents with blood via capillary force has been demonstrated in 1 second without the requirement of external pumps. We employed this iPOC^3D system for point-of-care diagnosis of anemia using a training set of patients (n_anemia = 16 and n_healthy = 6), which showed consistent measurements of blood hemoglobin levels (a.u.c. = 0.97) and comparable diagnostic sensitivity and specificity, compared with standard clinical hematology analyzer. Capable of 3D fabrication flexibility and smartphone compatibility, this work presents a novel diagnostic strategy for advancing personalized medicine and mobile healthcare.

A portable smart phone-based plasmonic nanosensor readout platform that measures transmitted light intensities of nanosubstrates using an ambient light sensor

Plasmonic nanosensors may be used as tools for diagnostic testing in the field of medicine. However, quantification of plasmonic nanosensors often requires complex and bulky readout instruments. Here, we report the development of a portable smart phone-based plasmonic nanosensor readout platform (PNRP) for accurate quantification of plasmonic nanosensors. This device operates by transmitting excitation light from a LED through a nanosubstrate and measuring the intensity of the transmitted light using the ambient light sensor of a smart phone. The device is a cylinder with a diameter of 14 mm, a length of 38 mm, and a gross weight of 3.5 g. We demonstrated the utility of this smart phone-based PNRP by measuring two well-established plasmonic nanosensors with this system. In the first experiment, the device measured the morphology changes of triangular silver nanoprisms (AgNPRs) in an immunoassay for the detection of carcinoembryonic antigen (CEA). In the second experiment, the device measured the aggregation of gold nanoparticles (AuNPs) in an aptamer-based assay for the detection of adenosine triphosphate (ATP). The results from the smart phone-based PNRP were consistent with those from commercial spectrophotometers, demonstrating that the smart phone-based PNRP enables accurate quantification of plasmonic nanosensors.