Piezoelectricity and Biocompatibility of Flexible Sc_xAl_(1–x)N Thin Films for Compliant MEMS Transducers

Abstract

There is huge research activity in the development of flexible and biocompatible piezoelectric materials for next-generation compliant micro electro-mechanical systems (MEMS) transducers to be exploited in wearable devices and implants. This work reports for the first time on the development of flexible Sc x Al(1–x)N films deposited by sputtering technique onto polyimide substrates, assessing their piezoelectricity and biocompatibility. Flexible Sc x Al(1–x)N films have been analyzed in terms of morphological, structural, and piezoelectric properties. Sc x Al(1–x)N layer exhibits a good surface roughness of 4.40 nm and moderate piezoelectricity with an extracted effective piezoelectric coefficient (d 33 eff) value of 1.87 ± 0.06 pm/V, in good agreement with the diffraction pattern analysis results. Cell viability assay, performed to study the interaction of the Sc x Al(1–x)N films with human cell lines, shows that this material does not have significant effects on tested cells. Furthermore, the Sc x Al(1–x)N layer, integrated onto a flexible device and analyzed by bending/unbending measurements, shows a peak-to-peak open-circuit voltage (V OC) of 0.32 V and a short-circuit current (I SC) of 0.27 μA, with a generated power of 19.28 nW under optimal resistive load, thus demonstrating the potential of flexible Sc x Al(1–x)N films as active layers for next-generation wearable/implantable piezoelectrics.

Effect of Doping in Aluminium Nitride (AlN) Nanomaterials: A Review

“…Luciana Algieri et al in his article reported different techniques inorder to understand and verify the influence of doped flexible ScxAl(1-x) N films. They analysed surface morphology performance by atomic force microscopy, structural properties by scanning electron microscopy, diffraction pattern analysis by X-Ray Diffractometry, scandium concentration analysis by X-ray Energy Dispersive Spectroscopy, piezo electric property analysis by Piezo response Force microscopy, Bending/unbending measurements by linear micro-actuator and control board managed by ARDUINO, voltage measurement by oscilloscope and finally cyclotoxicity determination by Cell viability assay (22).In 2021 Kristina Bespalova et al investigated the effect of Sc in Scandium-alloyed aluminum nitride (AlScN). They prepared sample by sputter deposition, morphology analysis by scanning electron microscopy, analysis of formation of new phase-X-ray diffraction (XRD) analysis, crystal quality analysis by Diffractogram indexing, X-ray rocking curves (XRCs) were measured, Electron-transparent lamellas were prepared using Focused Ion Beam Scanning Electron Microscopy(SEM), selected area electron diffraction (SAED), and energy-dispersive X-ray spectroscopy (EDX) mapping were used to acquire more accurate information on the metal/piezoelectric interface (23).…”

Piezoelectric MEMS—evolution from sensing technology to diversified applications in the 5G/Internet of Things (IoT) era

“…physical and physiological signs) and in-situ disease treatment [258][259][260]. Furthermore, with the unique capability for energy harvesting, piezoelectric devices can obtain more diverse functionalities in wearable and implantable applications, such as energy harvesting, self-powered monitoring, and self-powered stimulation [261][262][263][264][265][266][267][268][269][270][271]. Therefore, in this section, the recent developments of piezoelectric devices toward wearable and implantable applications are discussed.…”

Hybrid Approach Control of Micro-Positioning Stage with a Piezoelectric Actuator

“…They need compact devices or a small footprint for particular operations [1][2][3][4]. Their high integrative power [5,6], low heat [7,8], and low noise levels [9,10] can provide relatively large efforts, high reliability, and biocompatibility [11][12][13][14]. Because of these benefits, the piezoelectric actuator has been widely used in a variety of industries, including space exploration [15,16], active shutters, pulsed jets [17][18][19], vibration control [20][21][22][23][24], optical path control [25][26][27][28], micro-motorization of instruments [29,30], valves and pumps for implants [31][32][33][34][35][36], magnetic resonance imaging (MRI) [37,38], microsurgery [39][40][41][42], and other micro-displacement techniques [43][44][45][46]…”