Black phosphorus is an ultra-thin material that changes electrical resistance in response to differing wavelengths of light. It is an inherently defective material in nature and the least reactive form of phosphorus with no significant commercial uses. However, through precision engineering, the Functional Materials and Microsystems Research Group at RMIT University (Melbourne, Australia) were creative in using this defective material to develop a novel and useful chip that imitates some mechanisms of the brain. Thus, this chip can store and delete information in a similar way that our neurons do.
How do neurons help us learn?
The synapse is a structure that transmits the information between neurons. When two or more neurons are repetitively given electrical impulses, it impacts the strength of the synaptic transmission. This mechanism known as synaptic plasticity plays a key role in binding neurons together to create a memory. The connections between neurons can either be strengthened (long-term potentiation) or weakened (long-term depression), depending on the activity between the neurons. These cellular mechanisms are considered as major contributors to the way we learn and forget things.
How does the new chip mimic this learning process?
The new chip made from black phosphorus works in a similar way. The light is used to generate photocurrents on the chip. By switching between different light wavelengths, these photocurrents can reverse direction from positive to negative and vice versa. This is then equivalent to the binding and breaking of neural connections in the brain, a mechanism involved in the processes of learning and forgetting. This technology is very similar to optogenetics wherein light-induced changes can either stimulate or inhibit neuronal activity, inducing modifications of the synaptic plasticity in neural circuits. The researchers explain: “We’re able to simulate the brain’s neural approach simply by shining different colors onto our chip.”
The researchers at RMIT University commented that “this technology creates tremendous opportunities for researchers to better understand the brain and how it’s affected by disorders that disrupt neural connections, like Alzheimer’s disease and dementia.” They further demonstrated that this chip can perform logic operations such as information processing. The success of this research has, therefore, brought us a step closer to artificial intelligence and creating a brain-on-a-chip, that will in future be able to learn from environmental input, just as we do.
Queensland Brain Institute. The Brain. Learning and Memory. How are memories formed? July 23, 2019. Available from: https://qbi.uq.edu.au/brain-basics/memory/how-are-memories-formed
Ahmed T, Kuriakose S, Abbas S, Spencer MJS, Rahman A, Tahir M, et al. Multifunctional optoelectronics via harnessing defects in layered black phosphorus. Advanced Functional Materials, 2019. July 16, 2019. DOI: 10.1002/adfm.201901991