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THE HINDU Magazine DELHI SCIENCE & TECHNOLOGY
Sunday, March 3, 2019 19

Hotspot: The scientists came across the
fossils in northeast India. GAURAV SRIVASTAVA
Asia’s oldest

bamboo fossil

AATHIRA PERINCHERY

Northeast India, a bamboo hotspot,
has thrown up several bamboo fossils.
Robust: The device One of them at around 28 million years
has high mechanical old, is the oldest Asian bamboo fossil
durability and ever unearthed.
chemical stability, Scientists from institutes including
say Bhanu Bhusan Lucknow’s Birbal Sahni Institute of
Khatua (left) and Palaeosciences came across the fossils
Sumanta Kumar on their digs in northeast India. At
Karan. Assam’s Makum Coalfield, they came
across three culm (bamboo stem)
INNOVATION fossils, one almost a metre long. At the
CCCCCCCCCCCCCCCCCCCC Download Indian Library App Subansiri Formation of Doimara in
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#70929
Arunachal Pradesh, the team also came
Multipurpose piezoelectric across two bamboo leaf fossils.
The team compared these culm and
leaf fossils to extant bamboo species at
the bamboo garden in China’s
nanogenerator fabricated Xishuangbanna Tropical Botanical
Garden and samples at the Botanical
Survey of India (Kolkata). The leaf
fossils belong to two different
bamboos, Bambusium doimaraense
The piezoelectric nanogenerator has high energy conversion efficiency and B. arunachalense (named after
where they were unearthed from),
approximately 10 million years old
R. PRASAD alignment of the PVDF chain. “This 1,80,000 cycles — and chemical (dating to the age of the sandstone
causes the PVDF to change its phase stability for up to 10 weeks, making it deposits, in the late Miocene­Pliocene).
or the first time a piezoelectric from alpha to predominantly (over suitable for various applications The culm fossils have been named
nanogenerator that is capable 93%) beta, which is highly including e­health care monitoring. new species too: Bambusiculmus
of generating electrical energy piezoelectric,” says Prof. Khatua. “The When made into a thin film and tirapensis and Bambusiculmus
Ffrom diverse sources — nanogenerator is also completely placed on the wrist, the device was makumensis. These are around 28
mechanical, acoustic and wind — has organic and biocompatible and so can able to convert the biomechanical million years old and date to the late
been developed. The device, fabricated be used for both in vitro and in vivo energy to electrical energy (0.15 volt). Oligocene period. According to the
by a team led by researchers from the applications.” The proportion of beta Same when it was placed on the throat c scientists who published their work in
Indian Institute of Technology (IIT) phase in PVDF and hence the output and the person was speaking (0.5 volt), The innovative the Review of Palaeobotany and
Kharagpur, has remarkable energy voltage and current increased with gargling (1.6 volt) or swallowing (0.29 device is Palynology, the culm fossils are the
conversion efficiency of 62%, high increasing amount of vitamin B2 added volt). When pressed by the heel, the earliest evidence of bamboos in Asia
output current (over 12 microampere), to it reaching a peak at 5 weight device produced about 58 volts, and capable of (so far, bamboo fossils from Asia date
voltage (about 61.5 volt) and power percentage, according to Sumanta about 79 volts when placed under a generating back only to the Neogene).
density (over 9 mW per cubic cm). The Kumar Karan from IIT Kharagpur and running car. It could convert the electrical These fossil finds raise two
high voltage of nanogenerator can be first author of the paper. To fabricate pressure applied by water falling from energy from important points, according to lead
used to light up about 100 the nanogenerator, the researchers a tap into electricity. When placed on diverse author Gaurav Srivastava (Birbal Sahni
commercially available microwatt made two thin films made by mixing speakers, the device was able to sources — Institute). “The earliest bamboos in
LEDs. vitamin B2 and PVDF and spin coating harvest sound energy. Similarly, when Asia probably originated in eastern
the solution. The films with electrodes placed on the lid of a table fan it could mechanical, Gondwana, which comprises India
Vitamin B2 adds stability attached and separated by nylon net convert wind pressure into acoustic and too,” he says. “Independent molecular
The team led by Bhanu Bhusan Khatua are then taped together. The device electricity.“We want to use this device wind. studies also suggest this. This is not
from the Materials Science Centre, IIT was found to have good flexibility and to convert heartbeat to power a pace surprising because northeast is a
Kharagpur, used vitamin B2 to stabilise durability. maker by using a rechargeable battery. centre of diversity for bamboos, as is
the beta phase of the piezoelectric We are also trying to explore large­ nearby southern China.”
polymer PVDF (polyvinylidene High sensitivity scale application by placing the device Secondly, based on vegetation
difluoride) and thereby enhance the “The device was found to be highly on dancing floor, entrances to high reconstruction and climate prediction
piezoelectric performance. The results sensitive to even very small external throughput passages and storing the studies, ancient bamboos probably
were published in Nano Energy. force such as touching, bending and electrical energy in capacitors to run evolved during a warm and humid
About 80% of PVDF is in alpha air­flow,” says Sandip Maiti, co­author small devices,” says Prof. Khatua. period, he adds. “However, they seem
phase, which is not piezoelectric in of the paper. It also showed high “We are highly optimistic of to have adapted over the years and
nature. When vitamin B2 is added, it mechanical durability — no change in commercialising the technology in the modern bamboos are found in both
binds to PVDF and causes a change in output performance was seen for about near future.” warm and cold climates now,” he says.