Nanomesh-patterning on multilayer MoS2 field-effect transistors for ultra-sensitive detection of cortisol

Absence of functional groups on the basal plane of molybdenum disulfide (MoS2) significantly hinders the performance of MoS2 field-effect transistor-based biosensor (bio-FET). We present a novel method for creating nano-scale holes on a MoS2 channel using block copolymer lithography, where the edge areas on the nanoholes were used to form covalent linkage between the capture molecules of cortisol aptamer and the MoS2 channel. The comparative analysis of Raman and XPS spectra well supported the formation of the nanoholes on MoS2 together with the concomitant increase in the edge area. The performance of the nanomesh bio-FET was studied by comparing its detection behavior for cortisol with that of a bio-FET manufactured with pristine MoS2. The nanomesh MoS2 bio-FET detected cortisol 109 times as low as that by the pristine MoS2 bio-FET. The selectivity of the nanomesh bio-FET was validated by detection experiments with other steroid hormones and antigens. Additionally, clinical applicability was demonstrated by performing experiments in artificial saliva and human serum.