A new RT-LAMP-on-a-Chip Instrument for SARS-CoV-2 diagnostics

This work describes the development of a Point-of-Care (POC) Lab-on-a-Chip (LOC) instrument for diagnosis of SARS-CoV-2 by Reverse-Transcription Loop-mediated isothermal amplification (RT-LAMP). The hardware is based on a Raspberry Pi computer ($35), a video camera, an Arduino Nano microcontroller, a printed circuit board as a heater and a 3D printed housing. The chips were manufactured in polymethyl methacrylate (PMMA) using a CO2 laser cutting machine and sealed with a PCR optic plastic film. The chip temperature is precisely controlled by a proportional-integral-derivative (PID) algorithm. During the RT-LAMP amplifications the chip was maintained at ~ (65.0 +/- 0.1) ?C for 25 minutes and 5 minutes cooling down, totaling a 30 minutes of re-action .The software interpretation occurs in less than a second. The chip design has four 25 mu L chambers, two for clinical samples and two for positive and negative control-samples. The RT-LAMP master mix solution added in the chip chambers contains the pH indicator Phenol Red, that is pink (for pH ~ 8.0) before amplification and becomes yellow (pH ~ 6.0) if the genetic material is amplified. The RT-LAMP SARS-CoV-2 diagnostic was made by color image recognition using the OpenCV machine vision software library. The software was programmed to automatically distinguish the HSV color parameter distribution in each one of the four chip chambers. The in-strument was successfully tested for SARS-CoV-2 diagnosis, in 22 clinic samples, 11 positives and 11 negatives, achieving an assertiveness of 86% when compared to the results obtained by RT-LAMP standard reactions performed in conventional PCR equipment.

Automated summary

This work presents the development of a portable Lab-on-a-Chip (LOC) instrument for Point-of-Care (POC) diagnosis of SARS-CoV-2 using Reverse-Transcription Loop-mediated isothermal amplification (RT-LAMP). The instrument utilizes a Raspberry Pi computer, a video camera, an Arduino Nano microcontroller, a printed circuit board as a heater, and a 3D printed housing. The chips are made of polymethyl methacrylate (PMMA) and are sealed with a PCR optic plastic film. The chip temperature is precisely controlled using a PID algorithm. The diagnostic process involves color image recognition and achieves an accuracy of 86% when compared to the results obtained by conventional PCR equipment.