Photoenhanced Two-Dimensional Field Effect Transistor Sensors for Ultrasensitive Linker-Free Dye Molecules Detection

Although organic dyes, due to their unique color properties, are widely applied in food, environmental, biological research, and processing industries, improper use of dye molecules can cause food poisoning and environmental pollution. A linker-free field-effect transistor (FET) sensing platform for ultrasensitive detection of dye molecules was presented here, which is small in size, has low power consumption, and has low noise. Through electrostatic interactions dye molecules could be spontaneously adsorbed on the surface of the channel material MoS₂. The doping effect coming from the dye molecules would directly modulate the Fermi level of the MoS₂, resulting in a change in the transport performance of the FET sensors. Based on this influence correlation, a standard curve for dye molecules can be established based on the FET sensors with a detection limit reaching below 10^-9 M. Then, by application of an optimized laser, the photoinduced carriers from the dye molecules could further contribute to the sensitivity of the FET sensor, which will enhance the detection limit for crystal violet, malachite green, and rhodamine 6G molecules to be as low as 10^-11 M, 10^-12 M, and 10^-10 M, respectively. Moreover, by the application of a 635 nm light, three dye molecules could be marked out in an unknown sample, as their light absorption and contributions to the performance of the devices are different. Such a linker-free FET platform thus offers the dual capabilities of high sensitivity and specific analyte recognition.