Review-Flexible and Stretchable Electrochemical Sensing Systems: Materials, Energy Sources, and Integrations

This review details the key progress made on flexible and stretchable electrochemical sensing systems, along with their relevant challenges and opportunities for the future. Stepping forward from traditional rigid electrodes, recent advancements in non-rigid electrochemical sensors offer new and exciting opportunities for various applications, such as biomedical, fitness, or environmental monitoring. The key factors in developing such devices are the materials and integrated systems needed to retain mechanical compliance while maintaining electrochemical functions. This requires a devotion to judiciously engineer both the underlying substrates and electrode materials. However, the realization of compliant electrochemical sensing devices still faces many obstacles. The requirements and potential strategies to enable flexible and stretchable electrodes are further discussed in this review. In addition to such sensing units, which mainly consist of electrodes and functionalized transducers, integrated systems also require miniaturized viable and mechanically compliant energy sources, as well as low-power electronics for controlling the device and wirelessly communicating with users. Such advancements, alongside other attractive functionalities such as self-healing and transparent properties, are also discussed. The innovative flexible and stretchable sensing systems will extend a variety of non-invasive, minimally invasive, wearable, and implantable applications to patients. Examples of compliant sensing systems and relevant challenges are included alongside perspectives of this emerging technology. (C) 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.