FIG. 10.

Paper-based devices used for quantification of hydrogen peroxide. (a) By measuring the needed time for the sample to flow in the z-direction, this device can quantify the concentration of hydrogen peroxide. (b) The concentration of hydrogen peroxide can be quantified using this analog device by counting the number of bars that become colored. (c) 3D representation of the digital device. To conduct the test, the sample should be pipetted on the top; then, the device is inverted to make the detection layer visible. Seven bright green layers indicate the end of the assay. (d) Analog device assay procedure diagram. After putting the sample at the top, it wicks into the device. The number of colored bars indicates the test result.¹³⁴ Reproduced with permission from Lewis et al., Angew. Chem. Int. Ed. 51(51), 12707–12710 (2012). Copyright 2012 John Wiley & Sons, Inc.