AlN based microgenerators for powering implantable sensor devices

Abstract

In this work we report on microstructures made of AlN for the use as piezoelectric microgenerators in energy harvesting applications. Experimental results on the mechanical and piezoelectrical properties of sputtered AlN thin films deposited on Si(001) substrates as well as results on vibrometry of fabricated microcantilevers are presented. It is shown that due to the constant d33 piezo coefficients of > 5 pm/V, AlN films are well suited for the integration in cantilever structures for powering of low-consumption sensor networks

AlN-based piezoelectric bimorph microgenerator utilizing low-level non-resonant excitation

“…Offering some promising properties, they also provide a good capability for EH in medical applications. In agreement with literature values, nanocrystalline thin films of AlN show an excellent mechanical stability, proven by laser Doppler vibrometry measurements (LDV) of the resonant mode frequencies of AlN/Al microcantilevers of known dimensions and layer thicknesses (Young's modulus E≈310 GPa, acoustic wave velocity (E/ρ) 1/2 ≈10 4 m/s, biaxial modulus ≈420 GPa), [9]. Process advantages can be found in the low temperature deposition by dc-pulsed magnetron sputtering at 300°C.…”

“…Out of d 33 =δ/U the piezoelectric modulus could be directly determined from the measurements to d 33 >5 pm/V. For more information see [9].…”

“…Especially piezoelectric thin films offer new design possibilities for biocompatible, mechanical-electrical converters. Different authors outline the desirable *stefan.hampl@tu-ilmenau.de; phone +49 3677 69-3421; fax +49 3677 69-1840; www.macronano.de generator output power in the order of tens of µW for continuous and 1µW for intermittent operated wireless sensor systems ( [4], [6], [7], [9]). In this work we report on the excitation spectrum of human eye movements along with mechanical and piezoelectric properties of aluminum nitride (AlN) thin films, deduced design considerations, modeling, simulation and microfabrication of piezoelectric harvester structures for an intraocular IOP-sensor.…”

Dynamic characterization of thin aluminum nitride microstructures

“…Also, from variations in the membrane surface deflection as a function of applied hydrostatic pressure during the bulge test, the Young's modulus and the residual stress in AlN films were derived to be E ~ 336 GPa and σ ~ 0.41 GPa, respectively, in good agreement with the values obtained by wafer curvature measurements (E ~ 342 GPa and σ ~ 0.31 GPa) and the analysis of oscillating cantilevers (E ~ 310 GPa) [9]. Additionally, these experiments reveal extreme flexibility and robustness of 200 nm thick AlN membranes showing no degradation after multiple bulge cycling with the pressures up to 1.0 bar.…”

Low-Temperature Grown High-Quality Piezoelectric AlN Film for Sensor Applications

“…The detail of the fabrication process is given in reference [8]. The out-ofplane displacement of the cantilever has been measured using Laser Doppler Vibrometry (LDV) (Polytec MSA-500) with a resolution better than 1 pm.…”