Graphene e-tattoos for unobstructive ambulatory electrodermal activity sensing on the palm enabled by heterogeneous serpentine ribbons

Electrodermal activity (EDA) is a popular index of mental stress. Current EDA sensors are either obstructive when placed on the palm or have low signal fidelity when placed elsewhere. This paper presents a sub-micron-thin, imperceptible graphene e-tattoo (GET) for unobstructed EDA sensing on the palm, addressing the challenge of robust electrical connection between ultrathin devices and rigid circuit boards for ambulatory use. A heterogeneous serpentine ribbon (HSPR) design, involving a GET serpentine partially overlapping with a gold serpentine without adhesive, achieves a fifty-fold strain reduction compared to straight ribbons. The combination of HSPR, a soft interlayer, and a novel EDA event selection policy allows for successful ambulatory EDA monitoring in free-living conditions, validated against gold-standard methods.

Hongwoo Jang, Kaan Sel, Eunbin Kim, Sangjun Kim, Xiangxing Yang, Seungmin Kang, Kyoung-Ho Ha, Rebecca Wang, Yifan Rao, Roozbeh Jafari, Nanshu Lu