Ultrasensitive Field‐Effect Biosensors Enabled by the Unique Electronic Properties of Graphene

Abstract

This review provides a critical overview of current developments on nanoelectronic biochemical sensors based on graphene. Composed of a single layer of conjugated carbon atoms, graphene has outstanding high carrier mobility and low intrinsic electrical noise, but a chemically inert surface. Surface functionalization is therefore crucial to unravel graphene sensitivity and selectivity for the detection of targeted analytes. To achieve optimal performance of graphene transistors for biochemical sensing, the tuning of the graphene surface properties via surface functionalization and passivation is highlighted, as well as the tuning of its electrical operation by utilizing multifrequency ambipolar configuration and a high frequency measurement scheme to overcome the Debye screening to achieve low noise and highly sensitive detection. Potential applications and prospectives of ultrasensitive graphene electronic biochemical sensors ranging from environmental monitoring and food safety, healthcare and medical diagnosis, to life science research, are presented as well.

Graphene-Based Biosensor for Early Detection of Iron Deficiency

“…Next, a blocking buffer comprising a wash step with 0.05% Tween-20 was applied to remove unbound biomolecules from the graphene surface as much as possible, before incubating the functionalized channel with ETA to block the remaining unreacted N -hydroxy succinimidyl (NHS) ester linkers on the channel surface. Specificity of the biosensor was also assured by means of a previously tested method of additional biosensor passivation performed with ethanolamine and Tween-20 [39,40]. This last functionalization step yielded an average Vdirac of 240 ± 40 mV (Figure 2, blue line).…”

Detection of an IL-6 Biomarker Using a GFET Platform Developed with a Facile Organic Solvent-Free Aptamer Immobilization Approach

“…Gate leakage has been a very common phenomenon in liquid-gated GFETs and is primarily caused by the electrochemical redox reaction at the graphene/liquid interface resulting in an increased current flow which negatively impacts the sensing performances of the sensor. Though passivation of the exposed electrodes can reduce the leakage current, carbon clusters and photoresist residues during the wet transfer of CVD-graphene can act as a source of carbon leading to redox current during the device operation [ 24 , 25 ]. Among the three gate materials tested, Ag/AgCl resulted in the lowest gate leakage.…”

Graphene field-effect transistors as bioanalytical sensors: design, operation and performance

“…which depends on the width W and length L of the graphene, μ the mobility of charge carriers and C g the gate capacitance. 148 Transconductances for holes and electrons are not necessarily the same, in which case the transfer curve is asymmetrical. Transfer curves can be obtained using any of the three gate electrode configurations described in section 2.2 and illustrated in Fig.…”