Characterizing and Optimizing Piezoelectric Response of ZnO Nanowire/PMMA Composite-Based Sensor

Abstract

Due to the outstanding coupling between piezoelectric and semiconducting properties of zinc oxide nanowires, ZnO NW-based structures have been demonstrating promising potential with respect to their applicability in piezoelectric, piezotronic and piezo-phototronic devices. Particularly considering their biocompatibility and biosafety for applications regarding implantable medical detection, this paper proposed a new concept of piezoelectric composite, i.e., one consisting of vertically aligned ZnO NW arrays and an insulating polymer matrix. First, the finite element method (FEM) was employed to drive optimization strategies through adjustment of the key parameters such as Young’s modules and the dielectric constant of the dielectric constituents, together with the density and dimension of nanowire (NW) itself. Second, to investigate the functionality of each individual layer of composite, different designed structures were fabricated and characterized in terms of electrical and piezoelectric properties. Next, experimental and simulation tests were performed, indicating that the decreasing thickness of the top poly(methyl methacrylate) layer (PMMA) can substantially enhance the piezoelectric sensitivity of the ZnO NW composite. Besides the further benefit of no polarization being needed, our material has a comparable charge coefficient (d33) with respect to other lead-free alternatives (e.g., BaTiO3), confirming the high sensing abilities of the developed structure based on vertically aligned ZnO NW arrays. Finally, a time-varying model combining piezoelectricity and electric circuit modules was investigated in detail, giving rise to an estimation of the d33 coefficient for ZnO NWs. Based on this study, the developed material is revealed to be highly promising in medical applications, particularly regarding the FFR technique, where coronary pressure can be measured through a piezoelectric sensor.

Electromechanical conversion efficiency of GaN NWs: critical influence of the NW stiffness, the Schottky nano-contact and the surface charge effects

“…Thanks to their large surface-to-volume ratio, high crystalline quality and nanometer scale dimensions, semiconductor nanowires (NWs) offer unique advantages for a wide range of applications. [1][2][3][4][5] In particular, NWs presenting piezoelectric properties appear as promising active nanostructures for a new generation of piezoelectric sensors [6][7][8][9][10] and harvesters. [11][12][13][14][15] Especially, the sub-100 nm-wide NWs present the particularity to exhibit novel properties, non-existing or non-significant at micrometric scales that can lead to a strong modulation/modification of their characteristics.…”

Facile In Situ Synthesis of ZnO Flower-like Hierarchical Nanostructures by the Microwave Irradiation Method for Multifunctional Textile Coatings

“…Optoelectronic applications of ZnO nanoparticles (ZnO NPs) are based on their emissions, one in the ultraviolet UV domain, centered at approximately 380 nm and the other in the visible region in the range of 450-765 nm, and in the wide band gap of 3.37 eV with a high exciton binding energy of 60 meV, which allows excitonic transitions at room temperature [12]. Zinc oxide is considered very suitable for the production of a large variety of sensor and transducers since it is relatively bio-safe and a biocompatible material [13]. The specific optical and photochemical properties of ZnO are also used in a large variety of biomedical applications, such as antitumoral, antibacterial, antifungal, antioxidant, anti-inflammatory, and wound healing agents, including novel vectors in the fields of bio-imaging and drug delivery [14].…”

“…The type and the concentration of the defects generated in a ZnO material depend greatly on the preparation method and directly impact their optical, catalytic, and biological properties [7,16]. As a result, over the past several years, different synthetic methods for obtaining nanostructured ZnO have been proposed, such as (i) chemical vapor condensation, arc discharge, hydrogen plasma-metal reaction, and laser pyrolysis in the vapor phase; (ii) microemulsion, direct precipitation [15], hydrothermal synthesis, sol-gel processing [7,13,17], sonochemical [17], and microbial processes taking place in the liquid phase; and (iii) ball milling carried out in the solid phase. However, the classic methods to prepare ZnO nanomaterials involve the use toxic chemicals, intensive energy consumption, and, in the case of functional materials, time consuming multi step processes.…”

Piezo‐Semiconductor Coupled Model for the Simulation of Zinc Oxide 1–3 Piezo‐Composite

“…It can be seen that with the addition of the dielectric polymer layer on top of both the ZnO NW and the laterally embedding polymer, the voltage increases with the polymer width as for the case of the polymer matrix only (see Section 3.3.2 with Figure S3a,b, Supporting Information). For the same mechanical reasons, [ 40 ] the wider the polymer submitted to the compressive load, the higher the average stress in the NW and so the higher the generated piezo voltage.…”