According to foreign media reports, scientists from UC Berkeley demonstrated another use of graphene, that is, using it as the basis of an advanced sensor to image electrical signals from living cells and tissues. It is reported that the team's "graphene camera" is used to record the electrical activity of the beating heart, and when it comes to the brain, it can also open up new perception.
Graphene is a two-dimensional carbon sheet, which can measure the thickness of a single atom, and its incredible list of properties has captured the imagination of scientists from a wide range of research fields. These characteristics include remarkable thickness, high thermal and electrical conductivity and its position as the strongest man-made material.
Scientists at the University of California, Berkeley, in cooperation with chemists at Stanford University, explored the possibility of how this material will lead to a new advanced medical sensor. It is understood that this work is based on previous research. Previous research shows that the electric field can affect the way a piece of graphene reflects or absorbs light. The team explored this by placing about 1 square centimeter of graphene on the heart of a beating chicken embryo.
"When cells contract, they emit an action potential, which in turn generates a small electric field outside the cell," explained Halleh Balch, the author of this study. "Because the absorption of graphene under the cell is changed, we will see that the amount of light reflected from that position of graphene in a large area has changed."
but this technology needs some adjustment. At first, because the electric field generated by beating cardiac myocytes is too small, the reflectivity of graphene is not enough to have a significant impact. To this end, the team added a thin waveguide below it to amplify it. The waveguide works with the input laser. Before leaving the device, the laser will reflect graphene about 1 times through the prism.
"One way of thinking is that when light passes through this small cavity, the more times it is reflected from graphene, the more light effects will be produced by the reaction of graphene, which makes us very, very sensitive to electric fields and microvolts," Balch said.
The research team can use this "graphene camera" to study myocardial cells to measure myocardial cells only 1 microns wide in real time and produce optical images of the weak electric field generated by their beating. Although electrodes and chemical dyes can be used to measure the electrical activity of cells, they can only be carried out at a specific location, while thin sheets can measure the voltage of the whole tissue area. The team envisions combining these sensing technologies by recording the electrical signals of cells and simultaneously imaging the stained tissues.
Allister mcGuire from Stanford University, the first author of the study, said: "You can easily image the whole area of a sample, which is especially useful in the study of neural networks involving various cell types. If you have a fluorescently labeled cellular system, then you may only target specific types of neurons. Our system allows you to capture the electrical activity of all neurons and their supporting cells with very high integrity, which may really affect the way people conduct these network-level studies. "
this kind of sensor called "graphene camera" or coupled waveguide amplified graphene electric field (CAGE) can be used to test candidate drugs on myocardium before clinical trials. This is proved by injecting the chicken embryo with drugs that inhibit muscle protein to stop the heart beating and at the same time let the team observe that it has no effect on the electric field.
In addition, the device may open up new possibilities for directly sensing the brain. Now, although it can only be done in hundreds of places, electrode arrays can be used to study the electrical activity of brain cells. Strong graphene sheets can be placed on the surface to obtain a wider image of continuous electrical activity.
"One thing that surprises me about this project is that electric fields mediate chemical interactions and biophysical interactions-they mediate various processes in nature-but we have never measured them. We measure current and we measure voltage. And the ability to actually image the electric field allows you to see a form that you rarely saw before, "Balch said.
related research reports have been published in Nano Letters.