Digital printing of selective and reversible ion optodes on fabrics: toward smart clothes for epidermal chemical sensing.

While wearable chemical sensors often rely on electrochemical techniques, optical chemical sensors coupled with a smartphone or a miniaturized camera represent an attractive approach to the monitoring of sweat composition. In this paper, we modify real sports fabrics such as polyester-spandex fabrics with rational combinations of sensing chemicals including a pH indicator, an ion exchanger, and an ionophore one-step inkjet printing. Highly selective and fully reversible pH optodes as well as Na- and K-selective optodes are obtained only when the most hydrophobic sensing chemicals are used (, sodium ionophore VIII sodium ionophore VI).