Finger-powered agglutination lab chip with CMOS image sensing for rapid point-of-care diagnosis applications

Rapid parallel blood typing on centrifugal microfluidic platform by microcolumn gel immunoassay

Microcolumn gel immunoassay (MGIA) has the ability to meet the requirements of clinical diagnosis due to its reliable sensitivity and accuracy. However, traditional MGIA exhibits limitations including inadequate portability, low throughput, and extended analysis time. To address these challenges, we combined MGIA with microfluidic technology, demonstrating a centrifugal microfluidic-based microcolumn gel immunoassay (μMGIA) platform for blood typing of clinical samples. Experimental results indicate that the μMGIA platform can simultaneously detect six blood group antigens in five clinical blood samples within 2 min. Notably, it offers comprehensive detection of ABO blood group antigens and Rh blood group antigens with 100 % accuracy, outperforming the traditional slide method. The integration of microfluidic technology with MGIA circumvents the constraints of traditional methods, providing a new avenue for blood typing and immunoanalysis of clinical samples.

Current advances in Hepatitis C diagnostics

Nearly 60 million people worldwide are infected with Hepatitis C Virus (HCV), a bloodborne pathogen which leads to liver cirrhosis and increases the risk of hepatocellular carcinoma. Those with limited access to healthcare resources, such as injection drug users and people in low- and middle-income countries, carry the highest burden. The current diagnostic algorithm for HCV is slow and costly, leading to a significant barrier in diagnosis and treatment for those most at risk from HCV. There remains no available vaccine for HCV, and infection is often asymptomatic until significant cirrhosis has occurred, which makes screening incredibly important to prevent liver damage and transmission. Recent investigation has sought to address these issues through improvements in various aspects of the diagnostic procedure, using methods such as isothermal amplification techniques for viral RNA amplification, the use of viral protein as an analyte, and the incorporation of streamlined, self-contained testing systems to reduce administrative skill requirements. This review provides a comprehensive overview of current commercial standards and novel improvements in HCV diagnostics, as well as a framework for future integration of these improvements to develop a one-step diagnostic that meets the needs of those most affected.

Microfluidics-Based Blood Typing Devices: An In-Depth Overview

Identification of correct blood types holds paramount importance in understanding the pathophysiological parameters of patients, therapeutic interventions, and blood transfusion. Considering the wide applications of blood typing, the requirement of centralized laboratory facilities is not well suited on many occasions. In this context, there has been a significant development of such blood typing devices on different microfluidic platforms. The advantages of these microfluidic devices offer easy, rapid test protocols, which could potentially be adapted in resource-limited settings and thereby can truly lead to the decentralization of testing facilities. The advantages of pump-free liquid transport (i.e., low power consumption) and biodegradability of paper substrates (e.g., reduction in medical wastes) make it a more preferred platform in comparison to other microfluidic devices. However, these devices are often coupled with some inherent challenges, which limit their potential to be used on a mass commercial scale. In this context, our Review offers a succinct summary of the recent development, especially to understand the importance of underlying facets for long-term sustainability. Our Review also delineates the role of integration with digital technologies to minimize errors in interpreting the readouts.

Advancements in the research of finger-actuated POCT chips

Microfluidic point-of-care testing (POCT) chips are used to enable the mixing and reaction of small sample volumes, facilitating target molecule detection. Traditional methods for actuating POCT chips rely on external pumps or power supplies, which are complex and non-portable. The development of finger-actuated chips has reduced operational difficulty and improved portability, promoting the development of POCT chips. This paper reviews the significance, developments, and potential applications of finger-actuated POCT chips. Three methods for controlling the flow accuracy of finger-actuated chips are summarized: direct push, indirect control, and sample injection control method, along with their respective advantages and disadvantages. Meanwhile, a comprehensive analysis of multi-fluid driving modes is provided, categorizing them into single-push multi-driving and multi-push multi-driving modes. Furthermore, recent research breakthroughs in finger-actuated chips are thoroughly summarized, and their structures, driving, and detection methods are discussed. Finally, this paper discusses the driving performance of finger-actuated chips, the suitability of detection scenarios, and the compatibility with existing detection technologies. It also provides prospects for the future development and application of finger-actuated POCT chips.

Open Hardware for Microfluidics: Exploiting Raspberry Pi Singleboard Computer and Camera Systems for Customisable Laboratory Instrumentation

The integration of Raspberry Pi miniature computer systems with microfluidics has revolutionised the development of low-cost and customizable analytical systems in life science laboratories. This review explores the applications of Raspberry Pi in microfluidics, with a focus on imaging, including microscopy and automated image capture. By leveraging the low cost, flexibility and accessibility of Raspberry Pi components, high-resolution imaging and analysis have been achieved in direct mammalian and bacterial cellular imaging and a plethora of image-based biochemical and molecular assays, from immunoassays, through microbial growth, to nucleic acid methods such as real-time-qPCR. The control of image capture permitted by Raspberry Pi hardware can also be combined with onboard image analysis. Open-source hardware offers an opportunity to develop complex laboratory instrumentation systems at a fraction of the cost of commercial equipment and, importantly, offers an opportunity for complete customisation to meet the users' needs. However, these benefits come with a trade-off: challenges remain for those wishing to incorporate open-source hardware equipment in their own work, including requirements for construction and operator skill, the need for good documentation and the availability of rapid prototyping such as 3D printing plus other components. These advances in open-source hardware have the potential to improve the efficiency, accessibility, and cost-effectiveness of microfluidic-based experiments and applications.

Merging microfluidics with luminescence immunoassays for urgent point-of-care diagnostics of COVID-19

The Coronavirus disease 2019 (COVID-19) outbreak has urged the establishment of a global-wide rapid diagnostic system. Current widely-used tests for COVID-19 include nucleic acid assays, immunoassays, and radiological imaging. Immunoassays play an irreplaceable role in rapidly diagnosing COVID-19 and monitoring the patients for the assessment of their severity, risks of the immune storm, and prediction of treatment outcomes. Despite of the enormous needs for immunoassays, the widespread use of traditional immunoassay platforms is still limited by high cost and low automation, which are currently not suitable for point-of-care tests (POCTs). Microfluidic chips with the features of low consumption, high throughput, and integration, provide the potential to enable immunoassays for POCTs, especially in remote areas. Meanwhile, luminescence detection can be merged with immunoassays on microfluidic platforms for their good performance in quantification, sensitivity, and specificity. This review introduces both homogenous and heterogenous luminescence immunoassays with various microfluidic platforms. We also summarize the strengths and weaknesses of the categorized methods, highlighting their recent typical progress. Additionally, different microfluidic platforms are described for comparison. The latest advances in combining luminescence immunoassays with microfluidic platforms for POCTs of COVID-19 are further explained with antigens, antibodies, and related cytokines. Finally, challenges and future perspectives were discussed.

A self-contained acoustofluidic platform for biomarker detection

Self-contained microfluidic platforms with on-chip integration of flow control units, microreactors, (bio)sensors, etc. are ideal systems for point-of-care (POC) testing. However, current approaches such as micropumps and microvalves, increase the cost and the control system, and it is rather difficult to integrate into a single chip. Herein, we demonstrated a versatile acoustofluidic platform actuated by a Lamb wave resonator (LWR) array, in which pumping, mixing, fluidic switching, and particle trapping are all achieved on a single chip. The high-speed microscale acoustic streaming triggered by the LWR in the confined microchannel can be utilized to realize a flow resistor and switch. Variable unidirectional pumping was realized by regulating the relative position of the LWR in various custom-designed microfluidic structures and adoption of different geometric parameters for the microchannel. In addition, to realize quantitative biomarker detection, the on-chip flow resistor, micropump, micromixer and particle trapper were also integrated with a CMOS photo sensor and electronic driver circuit, resulting in an automated handheld microfluidic system with no moving parts. Finally, the acoustofluidic platform was tested for prostate-specific antigen (PSA) sensing, which demonstrates the biocompatibility and applied potency of this proposed self-contained system in POC biomedical applications.

Pushbutton-activated microfluidic cartridge as a user-friendly sample preparation tool for diagnostics

Microfluidic technologies have several advantages in sample preparation for diagnostics but suffer from the need for an external operation system that hampers user-friendliness. To overcome this limitation in microfluidic technologies, a number of user-friendly methods utilizing capillary force, degassed poly(dimethylsiloxane), pushbutton-driven pressure, a syringe, or a pipette have been reported. Among these methods, the pushbutton-driven, pressure-based method has a great potential to be widely used as a user-friendly sample preparation tool for point-of-care testing or portable diagnostics. In this Perspective, we focus on the pushbutton-activated microfluidic technologies toward a user-friendly sample preparation tool. The working principle and recent advances in pushbutton-activated microfluidic technologies are briefly reviewed, and future perspectives for wide application are discussed in terms of integration with the signal analysis system, user-dependent variation, and universal and facile use.

Stretch-driven microfluidic chip for nucleic acid detection

Molecular diagnosis is an essential means to detect pathogens. The portable nucleic acid detection chip has excellent prospects in places where medical resources are scarce, and it is also of research interest in the field of microfluidic chips. Here, the article developed a new type of microfluidic chip for nucleic acid detection where stretching acts as the driving force. The sample entered the chip by applying capillary force. The strain valve was opened under the action of tensile force, and the spring pump generated the power to drive the fluid to flow to the detection chamber in a specific direction. The detection of coronavirus disease 2019 (COVID-19) was realized on the chip. The RT-LAMP amplification system was adopted to observe the liquid color in the detection chamber to decide whether the sample tested positive or negative qualitatively.

Human Body-Related Disease Diagnosis Systems Using CMOS Image Sensors: A Systematic Review

According to the Center for Disease Control and Prevention (CDC), the average human life expectancy is 78.8 years. Specifically, 3.2 million deaths are reported yearly due to heart disease, cancer, Alzheimer’s disease, diabetes, and COVID-19. Diagnosing the disease is mandatory in the current way of living to avoid unfortunate deaths and maintain average life expectancy. CMOS image sensor (CIS) became a prominent technology in assisting the monitoring and clinical diagnosis devices to treat diseases in the medical domain. To address the significance of CMOS image ‘sensors’ usage in disease diagnosis systems, this paper focuses on the CIS incorporated disease diagnosis systems related to vital organs of the human body like the heart, lungs, brain, eyes, intestines, bones, skin, blood, and bacteria cells causing diseases. This literature survey’s main objective is to evaluate the ‘systems’ capabilities and highlight the most potent ones with advantages, disadvantages, and accuracy, that are used in disease diagnosis. This systematic review used PRISMA workflow for study selection methodology, and the parameter-based evaluation is performed on disease diagnosis systems related to the human body’s organs. The corresponding CIS models used in systems are mapped organ-wise, and the data collected over the last decade are tabulated.