NOMFET: The Organic Transistor That Mimics the Human Synapse
Edis Osmanbasic posted on November 13, 2018 |
An overview of how nanotechnology can be used to develop transistors which mimic the human brain.

Nanotechnology is a great scientific step forward that can change computer technology, diagnosis and the treatment of disease in the 21st Century. The technology requires material manipulation and controlling in nanometer scales the size of one atom. Scientists from the Institute for Electronics Microelectronics and Nanotechnology(CNRS) have already developed a hybrid nano-particle organic transistor known as NOMFET (Nanoparticle Organic Memory Field-Effect Transistor).

Currently, computers require a significant amount of power when processing large volumes of information, while the human brain is able to process the same information while consuming very little power. The NOMFET device mimics human synapse functionalities, such as the ability to strengthen or weaken depending on which activities are required. This is done through variations in the speed and strength of the signals which go from neuron to neuron. Essentially, the synapse is the connection between two neurons which transmit an electrical signal. If the synapse receives high-density incoming signals, it will cause a more intense action potential. Otherwise, the synapse will transmit a weaker action potential.

"Basically, we have demonstrated that electric charges flowing through a mixture of an organic semiconductor and metallic nanoparticles can behave the same way as neurotransmitters through a synaptic connection in the brain," says Dominique Vuillaume, a research director at CNRS.

The NOMFET transistor imitates the synapses function by a simple signal switching thus enabling or disabling the transmission of the signal. It also has additional functions, such as amplifying, modulation, encoding, etc.

Physically, the transistor is made of the molecule pentacene (organic semiconductor) and gold nanoparticles. It is composed of a p + doped bottom-gate covered with silicon oxide (SiO2) approximately 200 nm in size. Both the source and the drain electrodes are made of gold (Au).  Gold nanoparticles are deposited on the inter-electrode gap of 20 nm size, before the pentacene deposition.

NOMFET design(Image courtesy of the author.)
NOMFET design (Image courtesy of the author.)

The new transistor enables a better replication of the human cognitive processes, such as recognition and image processing. The innovation is a good start for a new generation of neuro-inspired computers which operate on the principle of anervous system. This computer could emulate the human brain functions such as sensation, perception, action, interaction.

The additional benefit of using the NOMFET in a neuromorphic circuit is its compact size, replacing a group of several traditional silicon-based transistors required for the same function. This significantly resizes the processor size.

Neurons do not function individually, but rather act through complex but synchronized neural circuits and the network generating sensory perceptions, actions, memories. This is why the integration of more NOMFET in neuronal circuits is required for a complex function which will be the focus of researchers in the next period.

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