Figure 4
Biodegradability of the nanopaper memory device. (a) Time series of photographs for the nanopaper memory on the nanopaper substrate, polyethylene terephthalate (PET) substrate and Si substrate after burying in the natural soil. The test soil was collected in September at 34:49:30 north latitude and 135:31:28 east longitude. The soil (4 l in total amount) was kept in a plastic bag to minimize the variation of the water concentration of the soil all through the biodegradation test. The humidity in the plastic bag was controlled to be ca. 90%. (b) Time evolution of residual area ratio (%) of nanopaper memory devices on nanopaper substrate (red), PET substrate (yellow) and Si substrate (purple). A significant decrease in the residual area ratio was obtained only for the nanopaper substrate, whereas the other substrates fully remained.
