for rapid prototyping of paper fluidics. Fabrication of electrodes for digital
microfluidic devices in a classic clean room would be significantly more expen-
sive. Another example is a combination of paper with hydrogels, where
hydrogels are used for liquid storage and upon application of external stimulus
release liquid into paper [ 79 ]. Sugars were applied to paper for programmable
time-delays, that can be used for sequential reagent delivery [ 80 ].Fig. 7.3 Example of an assay based on 3D origami immunodevice. (a) The filter tab was folded
above the test pad; (b) the blood sample was added into each paper microzone on the folded
filter tab with the aid of Folder-I; (c) the filter tab was removed and one waste tab was folded
below the test pad; (d) the washing buffer was added into each immunozone on the test pad to
wash the immunozones with the aid of the used Folder-I; (e) the used waste tab was removed
and a solution of AgNPs-luminol/Ab2 was added into each immunozone on the test pad; (f) the
remaining waste tab was folded below the reversed test pad and the device was washed again
with the aid of Folder-II; (g) the used waste tab was removed and the reagent tab was folded
above the test pad; (h) the hydrogen peroxide solution was added into the reagent cell to trigger
the CL reactions with the aid of a new Folder-I. Reproduced from [ 72 ] with permission of from
Royal Society of Chemistry
7 Paper Microfluidics 175