Figure 11.

Skin-like microfluidic/electronic device that is waterproof, (A) schematic depiction of the major layers of a typical device [147], (B) geometry of microfluidic channels [147], (C) optical micrograph of the colorimetric reagent and microfluidic intake and outflow ports [147], (D) a flow-driven color shift is produced by a dye made up of blue and red water-soluble particles that dissolve at different speeds. The total volume of collected perspiration is calculated by counting the number of turns of filled tubes [147], (E) NFC coil for wireless evaluations of skin temperature [147], (F) sweat gathering in aquatic environments without contamination is supported by small outlet geometries and constituent polymer materials that are hydrophobic and largely impermeable to water and water vapor. Underwater functioning of the electronics, containing the NFC coil, integrated circuit chip, and indicator LED, is supported by dip-coating an encapsulation of the same material [147].