ZnO Nanowire Application in Chemoresistive Sensing: A Review

Abstract

This article provides an overview of the recent development of ZnO nanowires (NWs) for chemoresistive sensing. Working mechanisms of chemoresistive sensors are unified for gas, ultraviolet (UV) and bio sensor types: single nanowire and nanowire junction sensors are described, giving the overview for a simple sensor manufacture by multiple nanowire junctions. ZnO NW surface functionalization is discussed, and how this effects the sensing is explained. Further, novel approaches for sensing, using ZnO NW functionalization with other materials such as metal nanoparticles or heterojunctions, are explained, and limiting factors and possible improvements are discussed. The review concludes with the insights and recommendations for the future improvement of the ZnO NW chemoresistive sensing.

Migration Energy Barriers for the Surface and Bulk of Self-Assembly ZnO Nanorods

“…SA-ZnO nanorods (ZNRs) frequently generate many point defects during the growth process and exhibit high levels of unintentional n-type conductivity [ 12 , 13 ], with oxygen vacancies and zinc interstitials being the major composition of native point defects. ZNRs have large surface-to-volume ratio and that provide correlative optical analyses on the surface and bulk parts of ZNRs after post-annealing treatment [ 14 , 15 , 16 ].…”

The Room-Temperature Chemiresistive Properties of Potassium Titanate Whiskers versus Organic Vapors

“…These sensors are known to be robust under a long-term operation with rather high response, which is matured from an advanced receptor function due to existence of number of surface adsorption sites and a transduction function that is based on nano-dimensionality of characteristic percolation contacts at the polycrystalline samples. However, these sensors should be activated by quite high temperatures, up to 400 °C [ 6 , 7 ], or by UV radiation [ 8 , 9 ], to allow for electron exchange between local states in the semiconductor gap and conductance band, as well as surface reactions. However, many applications, like mobile gas-analytical units [ 10 ], need sensors to operate just at a room temperature.…”

Piezophototronic Effect Modulated Multilevel Current Amplification from Highly Transparent and Flexible Device Based on Zinc Oxide Thin Film

“…The ZnO thin film experiences tensile (compressive) strain when a tensile (compressive) strain is applied to the bottom of the PET. The fundamental processes behind the observed experimental results are related to strain‐induced polarization charges, which in turn can effectively modulate the oxygen absorption/desorption process, resulting in tunable optoelectronic performance . In fact, multilevel photo current amplification with UV illumination in ZnO‐based device has been demonstrated due to oxygen absorption/desorption process by Russo et al For better understanding, the band diagram of the device under the thermal equilibrium condition is presented in Figure d …”

“…So far, ZnO has been effectively applied in UV optoelectronics where performance was modulated by mixing with impurities and/or an applied electric field . However, few studies have attempted to tune the optoelectronic properties of ZnO thin film by utilizing the piezoelectric effect for next‐generation devices . A sophisticated device which combines high transmittance and flexibility has significant potential due to its multifunctionality and smart applications but has yet to be demonstrated.…”