CMOS compatible, low power, high-sensitivity Zn/Al layered double hydroxides humidity micro-sensor

Layered Double Hydroxides (LDHs) are a class of ionic lamellar compounds [1] whose general formula is [M2+1-x M3+x(OH)2]x+(Ax/nn-) o m H2O, where M2+ stands for a divalent metal, M3+ for a trivalent one and A for the intercalated anion. Their lattice structure is composed by the alternate stacking of brucite-shaped layers (divalent metal ions octahedrally coordinated by hydroxide groups) intercalated with anionic species, like carbonates, nitrates, sulfates, silicates, hydroxide ions and more complex molecules of negative charge. Typical metals which can be used for fabricating LDH structures are Ca, Mg, Zn, Ni for the bivalent cation and Fe, Al, Cr, Mn for the trivalent one. We have successfully used an hydrothermal method for growing LDH nanoplatelets, composed by Zinc and Aluminum as cations on a glass substrate.