Digitized microfluidic platform combined with colorimetric 

method and loop-mediated isothermal amplification (LAMP) 

technology for on-site visual diagnosis of various diseases

Research Background and Abstract

With the global prevalence of infectious diseases, nucleic acid detection techniques such as 

Polymerase Chain Reaction (PCR) and Loop-mediated Isothermal Amplification (LAMP) have 

played a crucial role in the rapid diagnosis of various illnesses. Typically, samples need to be 

transported through a cold chain to well-equipped hospitals or testing centers for analysis. 

The conventional testing process heavily relies on skilled professionals for manual operations, 

leading to a time-consuming procedure from sample collection to result generation. This 

hinders the ability to meet the demand for rapid on-site diagnostics, especially in resource-

limited areas. Moreover, sample transportation not only adds to the overall cost but may also

 result in sample degradation and false-negative outcomes if storage and transportation 

conditions are inadequate. Therefore, the development of a fast, simple, and cost-effective 

on-site testing platform is of significant importance.

Research Content Overview

Recently, a joint research effort involving Professor Leibo's team from the Beijing Normal University-

Hong Kong Baptist University United International College, Digifluidic, and collaborative partners 

from Jinan University and Hong Kong Baptist University has resulted in the development of a visual

detection platform based on Digital Microfluidics (DMF) technology and Loop-mediated Isothermal

Amplification (LAMP) colorimetric reaction. This platform comprises multiple reaction units that can 

simultaneously detect multiple target genes in various samples, significantly improving detection 

efficiency.

Furthermore, leveraging the powerful droplet manipulation capability of DMF, the platform achieves 

automated endpoint detection, thereby avoiding contamination issues caused by manual operations 

in traditional endpoint detection methods. The research also enhances the color development of 

small reaction droplets (5 μl) by applying high-concentration dry dyes for LAMP colorimetric 

detection. This improvement enables the reaction results to be visually interpreted under ambient 

light without the need for specific light source conditions.

Fig 1. Schematic of the diagnosis of shrimp diseases by colorimetric DMF-LAMP method. (a) Sample preparation. 

(b) On-chip operation and LAMP reaction. (c) The side view of the DMF chip and the block diagram of the control 

system. (d) The structure of neutral red and color transition that caused by positive LAMP amplification.

(e) Timeline of the whole process from sample to the result.

The platform was applied for the detection of aquatic diseases and was able to rapidly and 

accurately detect three common pathogens in shrimp: Enterocytozoon hepatopenaei (EHP), 

Infectious Hypodermal and Hematopoietic Necrosis Virus (IHHNV), and White Spot Syndrome 

Virus (WSSV), with a detection limit of 101 copies/μl of DNA. In this study, the team also 

evaluated the specificity and real sample detection capability of the DMF-LAMP method.

The specificity experiments demonstrated that the method showed no non-specific amplification 

in cross-reaction tests with common pathogens found in water and aquatic products, such as 

Escherichia coli, Staphylococcus aureus, Salmonella enterica, Early Mortality Syndrome (EMS), 

and Shrimp Hemocyte Iridescent Virus (SHIV). It exhibited good specificity in these tests.

In the real sample detection experiment, 58 shrimp samples were tested using both the DMF-

LAMP method and a commercial qPCR kit. The results showed a high degree of agreement 

between the DMF-LAMP method and the commercial qPCR method, with Kappa values ranging 

from 0.91 to 1, demonstrating the reliability and accuracy of the DMF-LAMP method in practical 

applications.

Overall, the platform's DMF-LAMP method proved to be a reliable, rapid, and accurate tool for 

on-site detection of shrimp pathogens, offering potential benefits for the aquaculture industry 

and disease control in aquatic organisms.

Fig 2. DMF chip design and fabrication. ITO glass was coated with a hydrophobic surface used as the top plate. 

PCB substrate with hydrophobic coating was used as the bottom plate. The bottom plate was loaded with LAMP 

reagents and air-dried before chip assembly. The two plates sandwiched a 0.6 mm spacer for droplet transportation 

and LAMP reaction.

The team also proposed an RGB-based image processing method, utilizing smartphones to capture 

result images under various outdoor lighting conditions. Through RGB analysis, they developed a 

straightforward interpretation approach. In the future, this method holds the potential to create a 

custom smartphone app, enabling rapid and automated analysis of a large number of results.

Fig 3. RBG-based image processing analysis. (a) LAMP reactions containing NR were performed on a DMF chip 

and the images were captured with a smartphone. The ROI was manually selected and the average RGB of the 

ROI was measured in ImageJ. (b) A comparison of the average RGB values of negative (n = 120) and positive 

reactions (n = 120) based on the images captured under the laboratory LED lighting. (c) The RGB differences 

calculated from the negative and positive reactions. (d) The graph plotted the R/G ratios against the B/G ratios 

of negative (N-) and positive (P-) results under different lighting conditions. LED: Indoor LED lighting, N-OBL: 

Outdoor bright lighting, OML: Outdoor moderate lighting, N-ODL: Outdoor dim lighting.

Title: A digital microfluidic platform coupled with colorimetric loop-mediated isothermal 

amplification for on-site visual diagnosis of multiple diseases.

The above-mentioned research was published in the journal "Lab on a Chip" by the Royal Society 

of Chemistry in the United Kingdom.

Future Prospects

The DMF-LAMP platform established in this study has a wide range of potential applications in clinical, 

biomedical, food safety, and environmental fields. It offers advantages such as low cost, ease of operation, 

and high detection efficiency. In the future, there are plans to further integrate sample processing steps, 

such as nucleic acid extraction, into the platform to achieve an integrated detection process of "sample 

in - result out."

Paper Information

A digital microfluidic platform coupled with colorimetric loopmediated isothermal amplification 

for on-site visual diagnosis of multiple diseases

Mei Xie, a,c Tianlan Chen, b Zongwei Cai, c Bo Leia* and Cheng Dong b,d**

https://doi.org/10.1039/D2LC01156E

Author Profile

Mei Xie, Ph.D. Candidate Beijing Normal University - Hong Kong Baptist University  United International College The first author of this paper specializes in the application  of digital microfluidics technology in the detection of  agricultural product quality and food safety.

Bo Lei    Professor Beijing Normal University - Hong Kong Baptist University  United International College The corresponding author of this paper is currently a  professor and doctoral supervisor in the School of Science  and Technology,UIC. Director of the Key Laboratory of  Agricultural Product Quality and Food Safety in Zhuhai City,  Head of the UIC Food Safety Testing Center, and Deputy  Director of the Zhuhai City Food Safety Expert Committee.

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