Multiphysics Brings Vaccines
to the Developing World
COMSOL Multiphysics provides resources to deliver vaccines to areas of the world
with limited electricity.
In many areas of the developing world, there’s limited access to electricity, and many places have never had any type of power infrastructure. This presents a challenge for aid workers and
doctors. In the recent past, vaccines that needed to be stored
at cold, relatively constant temperatures couldn’t be taken into
the remote areas where they were needed most. As part of the
Global Good program at Intellectual Venture Labs (IVL), a
team of innovators invented a thermos-like container called
the Passive Vaccine Storage Device (PVSD) that uses high-performance insulation to completely change the way vaccines are
stored in areas with little or no electricity.
Meeting strict safety requirements
If not kept within the necessary temperature range at all
times, vaccines can spoil and become unusable. Global Good’s
researchers were tasked with following the parameters dictated by the World Health Organization. To be delivered safely,
the vaccines are required to stay within a narrow window of 0
to 10 C.
The first prototype that the researchers designed was based
on a cryogenic dewar, a device that relies on vacuum and
multi-layer insulation technology to store extremely cold liquids. Dewars that can normally hold liquid nitrogen or liquid
oxygen for extended periods of time were only able to hold ice
for a few days before it melted.
Global Good’s researchers used experimentation along
with thermal and vacuum system modeling with COMSOL
Multiphysics in order to identify materials and designs that
would allow the PVSD to maintain high vacuum levels at
high temperatures. Like a cryogenic dewar, the PVSD relies
on multi-layer insulation within a vacuum space to minimize
heat transfer. The high-quality vacuum virtually eliminates
convective and gas conduction heat transfer, while the
multi-layer insulation cuts down on radiative heat transfer.
The multi-layer insulation, made of reflective, extremely thin
sheets of aluminum and a low-conductivity spacer, is similar
to materials used in spacecraft.
Simulating vaccine storage in
Researchers for Intellectual Ventures’ Global Good program
used an environmental chamber to recreate conditions similar
to the climate in Sub-Saharan Africa in order to rigorously
test and understand the performance of their prototypes.
However, building a quality prototype of a vacuum dewar
is an involved effort. To explore different design directions
more efficiently before building prototypes, the team turned
to COMSOL Multiphysics and its Heat Transfer Module and
Molecular Flow Module, among
others. Their challenges includ-
ed optimizing the internal ge-
ometry for maximum cold stor-
age time, maintaining higher
vacuum capacity and managing
outgassing in the vacuum space.
The minimization of outgassing
is critical, as even moderate
amounts of residual outgassing
within the vacuum space over
the life of the PVSD can cause
the vacuum to lose its integrity,
increasing heat transfer into the
The geometry of the device is
optimized to maximize vaccine
hold time and to be as accessible
as possible for health workers in
the field. As a first line of defense
against the elements, the outside
of the device consists of a metal
enclosure padded with protective rubber bumpers, while the
inner part of the PVSD consists
of a smaller shell connected
at the very top to the outside
with a cantilever neck. Because
of this design, conductive heat
transfer can only happen at the
connection point. In addition, a
composite neck maintains the vacuum space so that there is no
gas permeation from ambient air.
Improving storage device design for future generations
As a result of the experimental and theoretical work that went
into the PVSD, the device is capable of making a significant impact on the vaccine cold chain in the developing world, allowing
vaccines to travel into more remote regions and to be stored for
longer periods of time without the need for power. Down the
road, Intellectual Ventures will improve their storage device designs to keep vaccines cold for extended periods with even more
efficiency. The team will continue working to create ground-breaking tools with the ability to save lives around the world.
( Top): Thermal simulation of the
PVSD shortly after loading; the
process of melting ice blocks is
modeled using the phase change
feature in COMSOL Multiphysics.
(Bottom): The PVSD uses similar
temperature control storage
methods to a cryogenic dewar.
With a single batch of ice, it can
store vaccines for extended peri-
ods of time. Image: COMSOL