Double-layers of lithium doped ZnO (LZO) and aluminum doped ZnO (AZO) are grown on r-cut sapphire (r-Al(2)O(3)) crystal substrates by pulsed-laser deposition. The epitaxial double-layers are a-axis lattice oriented to the substrate. The LZO/AZO/r-Al(2)O(3) samples have high optical transmission in the visible range and a bandgap energy of E(g) = 3.28 eV according to the absorption edge of ZnO. The AZO bottom layers are electrically conductive (resistivity at room temperature rho similar to 10(-3) Omega cm) and LZO top layers are highly resistive (rho >= 10(5) Omega cm). Acoustic shear mode resonances in r-Al(2)O(3) are excited by employing electric fields to the piezoelectric LZO layer(frequency interval 1.5-3 GHz). For biological applications, Madin-Darby canine kidney cells are cultivated on Platinum coated LZO/AZO/r-Al(2)O(3) samples. Osmotic pressure applied to the cells increases or reduces the cell volume depending on the osmolarity of the medium. (C) 2009 Elsevier B.V. All rights reserved.