Houston, September 10, 2005
Seemz Kachru
PTI
NRI (non-resident Indian) professor at Ohio
University has just completed a new comprehensive
study of human hair on the nanometer level,
which may help all on their bad hair days.
Special equipment enabled Bharat Bhushan and
his colleagues to get an unprecedented close-up
look at a rogue's gallery of bad hair days --
from chemically overprocessed locks to curls
kinked up by humidity. They used the techniques
they developed to test a new high-tech hair
conditioner.
"Ultimately, the same techniques could
be used to improve lipstick, nail polish and
other beauty products," claimed Bhushan,
the Howard D Winbigler Professor of mechanical
engineering at Ohio State. His specialty is
nanotribology -- the measurement of very small
things, such as the friction between moving
parts in microelectronics.
"At first, hair seemed like an unlikely
study subject," he said. Then he was invited
to give a lecture to scientists at Procter &
Gamble Co. "We realised that beauty care
was an emerging area for us and we should dive
in," Bhushan said.
He consulted for the company until P&G
became an industrial partner in his laboratory,
supplying him with samples of healthy and damaged
hair.
The Ohio State engineers examined hairs under
an atomic force microscope (AFM), a tool that
let them scratch the surface of hairs and probe
inside the hair shaft with a very tiny needle.
They published their results in the journal
Ultramicroscopy.
They also examined healthy and damaged hairs
under an electron microscope and an AFM, and
simulated everyday wear and tear by rubbing
hairs together and against polyurethane film
to simulate skin.
"We didn't know what we were looking for,"
Bhushan said. "People know a lot about
hair, but nobody has used an AFM to really study
the structure of hair." Under the electron
microscope, individual hairs looked like tree
trunks, wrapped in layers of cuticle that resembled
bark. In healthy hair, the cuticle edges lay
flat against the hair shaft, but as hair gets
damaged from chemical treatments or wear and
tear, the cuticle edges begin to peel away from
the shaft, he said.
The researchers simulated what happens when
damaged hair is exposed to humidity; the hairs
plump up, and the cuticles stick out even further,
leading to frizz. More frizz meant more friction
-- a fact confirmed by the AFM as researchers
dragged a tiny needle across the surface.
Conditioner tends to stick to the cuticle edges,
and can make the hair sticky on the nanometer
scale. The researchers determined that by poking
the hair shaft with the needle, and measuring
the force required to pull it away.
They also probed inside hairs to measure the
hardness of different layers of the shaft. Hair
has a very complex structure, Bhushan said,
and these first ultra-precise measurements of
interior structure could one day lead to new
products that treat hair from the inside.
"In the future, AFM techniques could also
be used to develop wear-resistant nail polishes
and lipsticks," Bhushan said.
