What are FET, GFET, BioFET, and FEB? Here’s the Difference


It’s hard enough to understand what transistors are, much less all the variations of transistors, such as Field Effect Transistor (FET), Graphene Field Effect Transistor (GFET), Biological Field Effect Transistor (BioFET), and Field Effect Biosensing (FEB).

Transistors are the building blocks of modern electronics. Fundamentally, they amplify small electrical signals and enable switching between “on” and “off” states, for applications such as computing, transmitting cell phone signals, and converting AC to DC voltage.

FET: Taking It to the Next Level

Most transistors are FETs which use electric fields to regulate whether the device is “on” or “off.” Essentially, when current is flowing through the device, it is “on.” When there is no current, it’s “off.” These electric fields are controlled by applying voltage through a gate, usually made of a conducting metal like gold or copper, and the surface of the transistor is typically made of silicon. Current flows from the source to the drain. An easy way to picture an FET device is to imagine your kitchen sink. Water (current) comes out of the faucet (source) and leaves through the drain (drain), and your faucet handle (gate) controls whether the water (current) is on or off. The energy it takes to move the faucet handle is the applied voltage.

Field Effect Transistor (FET)
Field Effect Transistor (FET)

GFET: The Proof is in the Graphene

Over the last several decades, there have been many design changes to FETs as researchers seek to use them for chemical and biochemical sensing. One obstacle in using a typical FET for these purposes is that silicon is unstable in air and water, making it a poor performer when placed in the conditions needed for chemical and biological testing. The GFET gets around this challenge.

A GFET has one simple design change that distinguishes it from an FET: The silicon material in a typical FET is replaced with graphene, a semiconducting nanomaterial. Unlike silicon, graphene is stable in air and water, taking the capabilities of transistors to a new dimension, one where the transistor can interact with, and therefore decode the natural environment around it.

Graphene Field Effect Transistor (GFET)

BioFET: Making it Biological

When an FET interacts with biomolecules, it’s called a Biological Field Effect Transistor (BioFET). The difference between a BioFET and a typical FET is that instead of “on” or “off” being controlled by applying voltage through a gate, it’s controlled by the binding of biomolecules. When two biomolecules bind, the change in charge distribution on the transistor surface changes the current flow through the device, which is measured by the system. Essentially, the biomolecular interaction becomes the gate!

Biological Field Effect Transistor (BioFET)

FEB: Bringing It All Together

Nanomedical Diagnostics combines the best of these two types of transistors, GFET and BioFET, into a proprietary electrical technology called Field Effect Biosensing (FEB). With FEB, graphene biosensors are used to measure biomolecular interactions. Graphene is considered a “super material,” with high electrical conductivity and surface area that makes it extremely sensitive to even the smallest of electrical changes. Hence it has an exceptional application in detecting biomolecular interactions, which currently depend on less sensitive optical techniques such as Surface Plasmon Resonance (SPR), Bio-layer Interferometry (BLI) and Mesoscale Thermophoresis (MST). FEB presents a unique orthogonal option that can provide answers when optical methods fail.

Field Effect Bio Sensing (FEB)

The Definitions

What is a transistor?
A device that amplifies small electrical signals and enables switching between “on” and “off” states.

What is FET (Field Effect Transistor)?
An FET is a device consisting of a source, drain, and gate, through which current flows. An electric field regulates the current flow, and changes in the electric field are induced by applying voltage via the gate.

What is BioFET (Biological Field Effect Transistor)?
A BioFET is an FET where changes in the electric field are induced by the binding of biomolecules rather than the application of voltage. Biomolecular interactions become the gate.

What is GFET (Graphene Field Effect Transistor)?
A GFET is an FET where graphene is used in place of silicon.

Venn Diagram of Field Effect Transistor (FET), Graphene Field Effect Transistor (GFET), Biological Field Effect Transistor (BioFET), and Field Effect Biosensing (FEB)

What is FEB (Field Effect Biosensing)?
FEB is essentially the combination of a BioFET and a GFET. A BioFET made with graphene instead of silicon.

What is Agile R100?
Developed by Nanomedical Diagnostics, Agile R100 is an FEB system specifically designed to characterize small molecule and protein interactions for drug discovery.