Microfluidic Point-of-Care (POC) Devices in Early Diagnosis: A Review of Opportunities and Challenges

Abstract

The early diagnosis of infectious diseases is critical because it can greatly increase recovery rates and prevent the spread of diseases such as COVID-19; however, in many areas with insufficient medical facilities, the timely detection of diseases is challenging. Conventional medical testing methods require specialized laboratory equipment and well-trained operators, limiting the applicability of these tests. Microfluidic point-of-care (POC) equipment can rapidly detect diseases at low cost. This technology could be used to detect diseases in underdeveloped areas to reduce the effects of disease and improve quality of life in these areas. This review details microfluidic POC equipment and its applications. First, the concept of microfluidic POC devices is discussed. We then describe applications of microfluidic POC devices for infectious diseases, cardiovascular diseases, tumors (cancer), and chronic diseases, and discuss the future incorporation of microfluidic POC devices into applications such as wearable devices and telemedicine. Finally, the review concludes by analyzing the present state of the microfluidic field, and suggestions are made. This review is intended to call attention to the status of disease treatment in underdeveloped areas and to encourage the researchers of microfluidics to develop standards for these devices.

Keywords: COVID-19; POC (point-of-care); medical testing; microfluidic; telemedicine; wearable devices.

Figure 1

Single-molecule enzyme-linked immunosorbent assays (digital ELISA) based on singulation of enzyme labels. (A) Capturing and labeling individual protein molecules on microbeads using standard ELISA reagents. (B) Microspheres are loaded into a reaction chamber array for the separation and detection of individual molecules. (C) Scanning electron microscope image of the microspheres after placement in the reaction chamber array. Reprinted with permission from [29]. Copyright 2010 Springer Nature.

Figure 2

Schematic of multiplexed digital ELISA process. Reprinted with permission from [33]. Copyright 2013 Royal Society of Chemistry.

Figure 3

Measurement of electrolytes in tears by a paper-based integrated microfluidic system and data acquisition with a smartphone. (A) Paper-based microfluidic device impregnated with fluorescent probe. (B) Samples were collected and diluted using capillary tubes. (C) The schematic diagram of the portable readout device. (D) The use of the portable readout device in combination with a smartphone to capture the image of the fluorescent probes. (E) Photograph of the interlayer groove used to place the paper-based microfluidic device. (F) Screenshots of smartphone applications that capture the measured images. Reprinted with permission from [62]. Copyright 2017 Royal Society of Chemistry.

Figure 4

The classifications of handheld microfluidic centrifuge. (A) Handheld microfluidic centrifuge made with 3D printing technology. (B) PDMS handheld microfluidic centrifuge. (C) Plastic handheld microfluidic centrifuge. Reprinted with permission from [81]. Copyright 2017 Springer Nature.

Figure 5

Structure and operation of FICA-μPADs. (A) Decomposition of a FICA-μPAD. (B) Blood samples from a finger puncture were placed into a capillary tube and centrifuged. (C–E) ELISA generates signals using a portable inter-reader. (F) Base image of the FICA-μPad, highlighting immune response areas, washing channels, and vascularization vessels. Reprinted with permission from [82]. Copyright 2020 Elsevier.

Figure 6

The production of 3D-Fuge. (A) Physical picture of a 3D-Fuge. (B) Printing of a 3D-Fuge. Reprinted with permission from [84]. Copyright 2019 Public Library of Science.

Figure 7

Paper-based microfluidic platform with wireless communication for telemedicine. Reprinted with permission from [127]. Copyright 2016 AIP Publishing.

Figure 8

Schematic of 3D μPAD with three detection zone for multiple immunoassays of H-FABP, cTnI, and copeptin. Reprinted with permission from [146]. Copyright 2020 Elsevier.

Figure 9

The process of the microfluidic chemical analyzer for analyzing diabetes and hyperlipidemia. (A) The process has four steps. First, the serum sample is mixed with a reagent. Second, the mixed solution is injected at the entrance of the microfluidic chip. Third, the detector is used for detection and analysis. Finally, the mobile phone is used to read the data. (B) Schematic of a microfluidic chip for multi-index analysis. (C) A microfluidic chemical analyzer assisted by a smartphone was used to analyze the color changes of two reagents in the chip reaction chamber. Reprinted with permission from [190]. Copyright 2019 Elsevier.