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Various approaches have been proposed for point-of-care diagnostics, and in particular, optical detection is preferred because it is relatively simple and fast. At the same time, field-effect transistor (FET)-based biosensors have attracted great attention because they can provide highly sensitive and label-free detection. In this work, we present highly sensitive, epidermal skin-type point-of-care devices with system-level integration of flexible MoS2 FET biosensors, read-out circuits, and light-emitting diode (LEDs) that enable real-time detection of prostate cancer antigens (PSA). Regardless of the physical forms or mechanical stress conditions, our proposed high-performance MoS2 biosensors can detect a PSA concentration of 1 pg·mL–1 without specific surface treatment for anti-PSA immobilization on the MoS2 surface on which we characterize and confirm physisorption of anti-PSA using Kelvin probe force microscopy (KPFM) and tapping-mode atomic force microscopy (tm-AFM). Furthermore, current modulation induced by the binding process was stably maintained for longer than 2–3 min. The results indicate that flexible MoS2-based FET biosensors have great potential for point-of-care diagnostics for prostate cancer as well as other biomarkers.

Multilayer MoS2 is a promising active material for sensing, energy harvesting, and optoelectronic devices owing to its intriguing tunable electronic band structure. However, its optoelectronic applications have been limited due to its indirect band gap nature. In this study, we fabricated a new type of phototransistor using multilayer MoS2 crystal hybridized with p-type organic semiconducting rubrene patches. Owing to the outstanding photophysical properties of rubrene, the device characteristics such as charge mobility and photoresponsivity were considerably enhanced to an extent depending on the thickness of the rubrene patches. The enhanced photoresponsive conductance was analyzed in terms of the charge transfer doping effect, validated by the results of the nanoscale laser confocal microscope photoluminescence (PL) and time-resolved PL measurements.