Paper provides a useful matrix for small electrochemical devices.
It provides a thin, mechanically stabilized film of water or other
fluids that deliver analytes to the surface of the electrodes. The
fact that the cellulose matrix is mechanically rigid, and that the
electrodes are in physical contact with the paper slab containing
the analytes inhibits convective movement of the solutions after
the complete wetting of the paper channel with fluids, and thus
increases the accuracy of time-dependent measurements (chronoamperometry
and chronopotentiometry). The continuous
capillary wicking of fluids along the paper channel and across the
electrode that is easily accomplished by introducing a cellulose
blotting paper that acts as a sink provides an excellent platform
for the measurements required for convection and hydrodynamic
conditions (anodic stripping voltammetry, hydrodynamic
amperometry and voltammetry).