Figure 4 | Scientific Reports

Figure 4

From: Using intrinsic properties of quantum dots to provide additional security when uniquely identifying devices

Figure 4

Measuring the non-linear response of a quantum dot-based tag using a smartphone’s camera and flash. (a) A smartphone image of a tag comprising a QR Code (black and white outer) surrounding a blank region in the centre that is coated with colloidal quantum dots (CQDs) in a polymer. (b) and (c) false-colour images showing the exponent extracted from a power fit on the emission-excitation curved measured across the area of a ‘fake’ tag (b) and a ‘real’ tag (c). The exponent in the centre of the QD region is lower degree than the surroundings. (d) For a series of ‘real’ (R1-5, containing CQDs in the centre region) and ‘fake’ (F1-3, no CQDs) tags, the difference in linearity is plotted, with whiskers on the boxes spanning two standard deviations.

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