We tested a range from 0 to 5 mg/mL of BSA, and as low as
0.08 mg/mL of sample could be detected by naked eye. The paper strips used for test are prepared
in the same way as the tree-shaped
device in Section 2.2. A standard curve could be made by image
software Quantity One according to the intensities of color in the
pictures by a camera (Fig. 4). Similar results could be obtained with
a camera cell phone.