6. Summary and Future Perspectives
A plethora of nanomaterial-enabled wearable sensors have been recently developed with high sensitivity and large stretchability, which have shown promising potential in a broad range of applications including health monitoring, activity tracking, and electronic skin. In spite of the exciting progress, there remain many challenges and opportunities associated with materials, sensing performance and integration into wearable systems for practical applications.
In terms of materials, more understanding of nanomaterial properties and development of fabrication and processing methods are in demand to achieve low-cost, high performance, and reliable sensors. For example, only preliminary experiments were performed on biocompatibility of nanomaterials for wearable applications.[94,95,205] More systematic studies on long-term biocompatibility of nanomaterials are in critical need to promote the practical applications of nanomaterial-enabled wearable sensors, especially for healthcare. Graphene has been utilized to develop a variety of wearable sensors. To ensure high performance, more efforts should be devoted to optimizing the large-scale growth with good homogeneousness as well as improving the defect-free transfer onto diverse substrates with high quality and yield.[206] CuNW was explored as a highly promising material due to the relative low cost and high conductivity, however, the poor stability against oxidation and chemical corrosion and the resulting degradation of conductivity over time may hamper the their practical applications for wearable sensors. Research is underway to improve the long-term stability without sacrificing much of the conductivity.[207–211] The distribution and assembly of nanomaterials are crucial to the mechanical and electrical properties of the sensors. Scalable assembly of nanomaterials with controlled density, low defect, good uniformity, and high spatial resolution should be further developed.
