Detection of harmful gases is important to ensure human and environmental health. Industrial waste gases such as CO, NO₂, H₂S, and NH₃ are of typical focus among researchers over the years. Chemiresistive sensors are suitable for detecting these harmful gases. One suitable candidate material for this sensor is the conducting polymer, which offers the advantage of room-temperature operation. This review focuses on the overall development of conducting polymer as chemiresistive sensing materials. Effects of different parameters influencing sensor performance such as response, gas concentration, response time, and recovery time of conducting polymers are explored. Different conducting polymers are compared and their affinities to specific gases are determined. An understanding of pure conducting polymers assists further exploration of these polymers in composite form. A comprehensive understanding based on an overview of literature will facilitate researchers in selecting appropriate conducting polymers for different gas sensing applications and is expected to encourage further progress in this area.

An inexpensive single-step carbon-assisted thermal evaporation method for the growth of SnO₂-core/ZnO-shell nanostructures is described, and the ethanol sensing properties are presented. The structure and phases of the grown nanostructures are investigated by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. XRD analysis indicates that the core-shell nanostructures have good crystallinity. At a lower growth duration of 15 min, only SnO₂ nanowires with a rectangular cross-section are observed, while the ZnO shell is observed when the growth time is increased to 30 min. Core-shell hierarchical nanostructures are present for a growth time exceeding 60 min. The growth mechanism for SnO₂-core/ZnO-shell nanowires and hierarchical nanostructures are also discussed. The sensitivity of the synthesized SnO₂-core/ZnO-shell nanostructures towards ethanol sensing is investigated. Results show that the SnO₂-core/ZnO-shell nanostructures deposited at 90 min exhibit enhanced sensitivity to ethanol. The sensitivity of SnO₂-core/ZnO-shell nanostructures towards 20 ppm ethanol gas at 400 °C is about ~5-times that of SnO₂ nanowires. This improvement in ethanol gas response is attributed to high active sensing sites and the synergistic effect of the encapsulation of SnO₂ by ZnO nanostructures.

Electrochemical migration (ECM) is one of the serious failure modes encountered in electronic devices due to the electrochemical reactions triggered by the presence of moisture and bias voltage, leading to the growth of dendrites and short circuits. The classical ECM mechanism consists of four consecutive stages: (i) electrolyte formation, (ii) anodic dissolution, (iii) ion transport, and (iv) dendrite growth. ECM is a delicate process that involves a combination of a good number of factors, such as the electrode properties, climatic conditions, contaminants, electric field, additives, etc. We intend to provide a comprehensive review of the complex effects that these factors have on each stage of ECM and provide insights into the recent developments in ECM research. Previous findings, current debates and recent discoveries are covered in this article. This review paper also provides a review of recent strategies for ameliorating ECM failures in electronics.