Synaptic transistor mimics brain to make robots more intelligent

The flexible device from Penn State works like neurons in the brain to send signals to some cells and inhibit others in order to enhance and weaken the devices' memories.

Led by Cunjiang Yu, Dorothy Quiggle Career Development Associate Professor of Engineering Science and Mechanics and associate professor of biomedical engineering and of materials science and engineering, the team designed the synaptic transistor to be integrated in robots or wearables and use artificial intelligence to optimise functions. The team’s findings are published in Nature Electronics.

"Mirroring the human brain, robots and wearable devices using the synaptic transistor can use its artificial neurons to 'learn' and adapt their behaviours," Yu said in a statement. "For example, if we burn our hand on a stove, it hurts, and we know to avoid touching it next time. The same results will be possible for devices that use the synaptic transistor, as the artificial intelligence is able to 'learn' and adapt to its environment."

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According to Yu, the artificial neurons in the device were designed to perform like neurons in the ventral tegmental area, a small section of the human brain located in the uppermost part of the brain stem. Neurons process and transmit information by releasing neurotransmitters at their synapses, which are normally located at the neural cell ends. Excitatory neurotransmitters trigger the activity of other neurons and are associated with enhancing memories, while inhibitory neurotransmitters reduce the activity of other neurons and are associated with weakening memories.

"Unlike all other areas of the brain, neurons in the ventral tegmental area are capable of releasing both excitatory and inhibitory neurotransmitters at the same time," Yu said. "By designing the synaptic transistor to operate with both synaptic behaviours simultaneously, fewer transistors are needed compared to conventional integrated electronics technology, which simplifies the system architecture and allows the device to conserve energy."

To model soft, flexible biological tissues, the researchers used stretchable bilayer semiconductor materials to fabricate the device, allowing it to stretch and twist while in use. Conventional transistors, in contrast, are rigid and will break when deformed.

"The transistor is mechanically deformable and functionally reconfigurable, yet still retains its functions when stretched extensively," Yu said. "It can attach to a robot or wearable device to serve as their outermost skin."