Microsized Electrochemical Energy Storage Devices and Their Fabrication Techniques For Portable Applications

Over the last decade, Lab-on-chip (LOC) technology has been thriving to support the ever-increasing demand of high-throughput, fast, accurate, and reliable analysis in an extensive variety of miniaturized systems for medical, chemical, and biological applications. Furthermore, portable electronics and consumer devices such as cell phones, tablets, smart watches, point-of-care devices, wireless sensor nodes, radio frequency identification, and other gadgets have witnessed a tremendous demand worldwide. These fast-paced technologies have an intimate correlation with the booming research activity in micro-supercapacitors (MSCs) and microbatteries (MBs); two energy storage devices which have claimed the lion's share in powering LOC components and other portable devices. In this review, MSCs and MBs are presented with highlights on their main components, structure, and types, as well as their state-of-the-art performance capabilities. The recent efforts in fabrication strategies, mainly those compatible with device fabrication techniques, stating the advantages and limitations of each are also reviewed. The paper also emphasizes the need for a benchmarking standard upon which performance is compared, as scholarly work shows a discrepancy in the use of different performance metrics to describe the electrochemical performance of such devices.