Serotonin is a stress biomarker and is one of the major neurotransmitters, and its concentration in the body is related to psychological functions such as mental illness. In particular, this biomarker is used to indicate depression caused by the increased stress of modern society. Therefore, detection and monitoring technologies are important for tracing concentration changes. In this study, we developed a serotonin antibodyconjugated graphene micropatterned field-effect transistor (SAb-GMFET)-based portable device for on-site or self-diagnosis of serotonin. The SAb-GMFET consisted of a graphene micropatterned channel, SAb for selective detection, and electrodes to supply the voltage. The SAb was immobilized by forming an amide bond with a diamine linker. SAb-GFMET showed high performance of limit of detection of 10 pM within 10 s and exhibited excellent selective detection among the interfering materials. For on-site and self-diagnosis applications, a portable device was developed with a sim chip, and the SAb-GMFET was connected to a printed circuit board using wire bonding. The portable SAb-GMFET showed a similar performance to that of the SAb-GMFET. Therefore, this portable platform can be utilized for point-of-care tests.

Keywords: Serotonin, Portable biosensor, Graphene, Field-effect transistor, Neurotransmitters