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. 2020 Dec 4;184(2):323–333.e9. doi: 10.1016/j.cell.2020.12.001

Figure 4.

Figure 4

Harnessing the mobile phone camera as a portable plate reader

(A) Schematic of mobile phone-based microscope for fluorescence detection showing illumination and image collection components (left). Picture of assembled device used for data collection and sample image taken by the mobile phone camera after running a Cas13a assay (right). See also Figures S3A–S3C.

(B) Results from the Cas13a assay run on the mobile device with two different dilutions of genomic SARS-CoV-2 viral RNA isolated from infected Vero CCL-81 cells (500 and 200 copies/μL) and RNP alone, using three combined crRNAs (crRNA 2, crRNA 4, and crRNA 21). y axis is the fluorescent signal of each sample normalized by the first time point. The error bars indicate the root-mean-square error (RMSE) of simple linear regression to individual curves. See also Figures S3D and S3E.

(C) Slope of the curve over 30 min of measurement on the device from Figure 4B was calculated by simple linear regression and is shown as slope ± 95% confidence interval.

(D) Detection accuracy of the Cas13a assay is characterized in the mobile device using genomic SARS-CoV-2 viral RNA. For each target dilutions, the slope at three different times—10, 20, and 30 min of measurement time on the device—were compared to the slope of the no target RNA RNP alone controls, and the detection accuracy was determined at the 95% confidence level. The number of replicates for each concentration is 8 (500 copies/μL), 7 (200 copies/μL), 9 (100 copies/μL), and 11 (50 copies/μL). See also Figures S4A–S4C.

(E) Results from a Cas13a assay run on mobile device with two different nasal swab samples, confirmed positive for SARS-CoV-2 using RT-qPCR, and the RNP alone control, all using the crRNA combination of crRNA 2, crRNA 4, and crRNA 21. The error bars indicate the RMSE of simple linear regression to individual curves. See also Figure S3F.

(F) Slope of the curve over 30 min from Figure 4E was calculated by simple linear regression and is shown as slope ± 95% confidence interval.

(G) Detection accuracy of Cas13a assay for 5 nasal swab samples, confirmed positive by RT-qPCR. Detection accuracy was evaluated at four different time points: 5, 10, 20, and 30 min of measurement time on the device.