Scientists have
developed a highly sensitive camera system with graphene film that can help map
tiny electric fields in a liquid - an advance that will allow more extensive
and precise imaging of electrical signals in the human heart and brain.
The ability to visually depict the
strength and motion of very faint electrical fields may also aid in the
development of ‘lab-on-a-chip' devices that use very small quantities of fluids
on a microchip-like platform to diagnose disease or aid in drug development.
The set-up could potentially be adapted
for sensing or trapping specific chemicals and for studies of light-based
electronics. “The basic concept was how graphene could be used as a very
general and scalable method for resolving very small changes in the magnitude,
position, and timing pattern of a local electric field, such as the electrical
impulses produced by a single nerve cell,” said Halleh B Balch, a PhD student
at UC Berkeley. “One of the outstanding problems in studying a large network of
cells is understanding how information propagates between them,” she added.
Other techniques developed to measure
electrical signals from small arrays of cells can be difficult to scale up to
larger arrays and in some cases cannot trace individual electrical impulses to
a specific cell.
“This new method does not perturb cells
in any way, which is fundamentally different from existing methods that use
either genetic or chemical modifications of the cell membrane,” said Bianxiao
Cui, from Stanford University. The new platform should more easily permit
single-cell measurements of electrical impulses traveling across networks
containing 100 or more living cells, researchers said.
Researchers first used infrared light to
understand the effects of an electric field on graphene's absorption of
infrared light. In the experiment, they aimed an infrared laser through a prism
to a thin layer called a waveguide. The waveguide was designed to precisely
match graphene's light-absorbing properties. Researchers then fired tiny
electrical pulses in a liquid solution above the graphene layer that very
slightly disrupted the graphene layer's light absorption, allowing some light
to escape in a way that carried a precise signature of the electrical field.
They captured a sequence of images of
this escaping light in thousandths-of-a-second intervals which provided a
direct visualisation of the electrical field's strength and location along the
surface of the graphene. -PTI
Source: DNA-21st-December-2016
