Freely suspended layer-by-layer nanomembranes: Testing micromechanical properties

Freely suspended nanocomposite layer-by-layer (LbL) nanomembranes composed of a central layer of gold nanoparticles sandwiched between polyelectrolyte multilayers are fabricated via spin-assisted LbL assembly. The diameter of the circular membranes is varied from 150 to 600 mu m and the thickness is kept within the range of 25-70 nm. The micro- and nanomechanical properties of these membranes are studied using a combination of resonance-frequency and bulging tests, and point-load nanodeflection experiments. Our results suggest that these freely suspended nanomembranes, with a Young's modulus of 5-10 GPa are very robust and can sustain multiple significant deformations. They are very sensitive to minor variations in pressure, surpassing ordinary semiconductor and metal membranes by three to four orders of magnitude and therefore have potential applications as pressure and acoustic microsensors.