A Low-Cost Microfluidic-Based Detection Device for Rapid Identification and Quantification of Biomarkers-Based on a Smartphone

Abstract

The sensitive and rapid detection of microsamples is crucial for early diagnosis of diseases. The short response times and low sample volume requirements of microfluidic chips have shown great potential in early diagnosis, but there are still shortcomings such as complex preparation processes and high costs. We developed a low-cost smartphone-based fluorescence detection device (Smartphone-BFDD) without precision equipment for rapid identification and quantification of biomarkers on glass capillary. The device combines microfluidic technology with RGB image analysis, effectively reducing the sample volume to 20 μL and detection time to only 30 min. For the sensitivity of the device, we constructed a standard sandwich immunoassay (antibody-antigen-antibody) in a glass capillary using the N-protein of SARS-CoV-2 as a biological model, realizing a low limit of detection (LOD, 40 ng mL^-1). This device provides potential applications for different biomarkers and offers wide use for rapid biochemical analysis in biomedical research.

Keywords: RGB; biomarkers; fluorescence; glass capillary; smartphone.

Figure 1

(a) Photograph of the smartphone-based fluorescence detection device (Smartphone-BFDD). (b) Schematic illustration of the Smartphone-BFDD.

Figure 2

RGB image analysis: (a) Correspondence between RGB image and wavelength. (b) Schematic of RGB image analysis.

Figure 3

Effects of smartphone camera parameters on SNR: (a) Blue channel. (b) Green channel. (c) Red channel.

Figure 4

Fluorescence quantitative test of BSA-FITC: (a) Fluorescence images of BSA-FITC. (b) Fitting relationship between the mean fluorescence intensity and concentration of BSA-FITC in the range of 0–22.375 μg mL⁻¹. The red line is the fitting relationship between BSA-FITC concentration and mean fluorescence intensity. (c) Fitting linear relationship between the mean fluorescence intensity and concentration of BSA-FITC in the range of 1.4–7.16 μg mL⁻¹.

Figure 5

Schematic of glass capillary fluorescence immunoassay.

Figure 6

Fluorescence quantitative test of N-protein: (a) Fluorescence images of N-protein. (b) Fitting relationship between the mean fluorescence intensity and concentration of N-protein in the range of 0–400 ng mL⁻¹. (c) Fitting linear relationship between the mean fluorescence intensity and concentration of N-protein in the range of 0–120 ng mL⁻¹.