A team of scientists at the University of California, Santa Barbara, have developed an atomically thin, 2D, ultrasensitive semiconductor material for biosensing uses that, they say, could expand the boundaries of biosensing technology in many fields, from healthcare to forensic industries.

Concept art of a molybdenum disulfide field-effect transistor-based biosensor demonstrated by UCSB researchers with ability to detect ultra-low (femtomolar) concentrations with high sensitivity that is 74-fold higher than that of graphene FET biosensors. (Credit: Peter Allen)

Based on molybdenum disulfide or molybdenite, the dry lubricant material surpasses graphene’s high sensitivity, offers better scalability, and lends itself to high-volume manufacturing, they said.

Their invention may lead to a new generation of ultrasensitive and low-cost biosensors that could eventually allow single-molecule detection. The key, they explain, is the material’s band gap, which determines its electrical conductivity.

Semiconductor materials have a small but non-zero band gap and can be switched between conductive and insulated states controllably. The larger the band gap, the better its ability to switch states and to insulate leakage current in an insulated state. Molybdenite’s wide band gap allows current to travel, but prevents leakage resulting in more sensitive and accurate readings.

While graphene had attracted interest as a biosensor due to its 2D nature that allows excellent electrostatic control of the transistor channel by the gate, and high surface-to-volume ratio, the sensitivity of a graphene field-effect transistor (FET) biosensor is limited by its zero band gap. Electrons travel freely across a graphene FET, so it can’t be turned off, leading to a higher potential for inaccuracies.

Single or few-layer molybdenite has a uniform band gap, which increases the sensitivity of the biosensor. And, 2D molybdenite is relatively simple to manufacture, they said, which could lead to low-cost mass production.