An Indian Institute of Technology, Kharagpur alumnus says that bottom-up manufacturing may hold the key to designing tiny medical devices that have the capability of testing multiple molecules like viruses and cancer markers.
"Diagnostic chips can be made more useful by
assembling, at predetermined locations on the chip, large numbers of nanowires
pre-treated off chip. Using this new bottom-up method, our group has
demonstrated that thousands of single wires can be successfully aligned and
anchored to form tiny diving board resonator arrays," Nature
Nanotechnology quoted Rustom B. Bhiladvala, who is currently an assistant
professor at the Pennsylvania State University, as saying.
The researchers point out that, though the traditional
top-down process, which begins with silicon and carves nanoresonator devices
from the material, works well and produces many devices that are nearly
identical, it has several limitations. They says that the addition of chemical
probes or other changes in the existing materials have to be done after the
devices are fabricated on the chips.
In contrast, the research team says that the bottom-up
method, though not producing identical devices, is more flexible.
The researchers say that in bottom-up fabrication,
nanowires are manufactured off chips by using any inorganic or organic material
that will produce nanowires.
They say that with the bottom-up approach, researchers
can attach probe molecules to the wires off chip, using a variety of chemicals.
According to them, researchers can also attach each
group of nanowires and their probes to the chips in the numbers and at the
"We can achieve high device integration yields,
but the devices are not as uniform as top-down manufactured devices. However,
we can access materials that are not easy to integrate into the devices with
top-down methods. We can also integrate wires treated off-chip with entirely different
probe molecules that are attached to the wires using condition optimised for
that molecule," says Theresa S. Mayer, professor of electrical
fabrication is an entirely new nanomanufacturing approach and we need to create
devices that have properties that match what we can now make using top-down
fabrication. Our vision is to make large arrays of nano size devices with
multiple probes for multiple targets by placing different groups of
functionalised nanowires sequentially on chips," says Mayer.