Breakthrough application of moisture-trapping film to reduce heat stress
in personal protective suits
New composite film brings down the heat index or `felt air temperature'
by about 40%

Date:
March 25, 2022
Source:
National University of Singapore
Summary:
Researchers have developed a novel super-hygroscopic material that
enhances sweat evaporation within a personal protective suit,
to create a cooling effect for better thermal comfort for users
such as healthcare workers and other frontline officers. With this
innovation, users will feel 40% cooler and their risk of getting
heat stroke is lowered significantly.



FULL STORY ==========================================================================
A team of researchers from the National University of Singapore (NUS)
has developed a novel super-hygroscopic material that enhances sweat evaporation within a personal protective suit, to create a cooling effect
for better thermal comfort for users such as healthcare workers and other frontline officers. This invention was validated through laboratory tests conducted in collaboration with researchers from HTX (Home Team Science & Technology Agency) in Singapore.


==========================================================================
The new desiccant film, which is biocompatible and non-toxic, has fast absorption rate, high absorption capacity and excellent mechanical
properties.

This means that the material is very robust and durable for practical applications such as for protective suits worn by healthcare workers. It
is also affordable, light-weight, easy to fabricate and reusable.

"Under room temperature of about 35deg C, a healthcare worker who dons a protective suit for one hour typically experiences a heat index of about
64 deg C. This causes discomfort and prolong thermal strain can result in
heat stroke and even death. Our novel composite moisture-trapping film
achieves a cooling effect within the protective suit via evaporative
cooling -- by increasing sweat evaporation from the skin," explained
research team leader Assistant Professor Tan Swee Ching, who is from the Department of Materials Science and Engineering under the NUS College
of Design and Engineering.

Attaching a piece of novel composite film in a protective suit -- for
example at the back of the suit -- could bring down the heat index by
about 40%, remarkably lowering the likelihood of heat stroke.

This invention was published in the scientific journal Small on 20
February 2022.

This research breakthrough demonstrates the positive outcome of leveraging
the complementary strengths of NUS and HTX to create tangible benefits
for the Home Team and the wider community. By combining the NUS team's scientific knowledge of advanced hydrogel materials and HTX's deep understanding of the Home Team's needs and engineering capabilities,
the joint research team was able to customise and optimise the novel moisture-trapping material for practical applications to enhance the performance and productivity of frontline officers.



========================================================================== Cooling down by increasing sweat evaporation Medical protective suits
have excellent anti-bacterial and water-proof properties. However, this
high level of protection stops the venting of water vapour produced by evaporated sweat and impedes heat loss from the body. This is why users
such as healthcare workers who need to don protective suits for long
hours, especially in tropical environments, often report of occupational
heat strain.

Thermal management solutions such as air-cooling garments with electrical
fans or ingestion of ice slurry are impractical due to limitations such
as bulkiness, heavy weight, and limited effectiveness. While advanced
textiles and coatings are promising solutions, they are difficult to
fabricate and production costs are high.

The NUS team came up with a practical strategy to overcome the current challenges by leveraging the principle of evaporative cooling. Their
solution involves using a super-hygroscopic composite film to control
the humidity level in the micro-environment in the protective suit. When
the moisture-trapping composite film absorbs water vapour within the
protective suit, the humidity level drops. This in turn speeds up sweat evaporation from the skin. As a result, more heat is dissipated from
the human body through sweating, providing thermal comfort for users
such as healthcare workers.

To examine the effectiveness of their solution, the NUS team conducted
tests in collaboration with researchers from HTX, using a 20-zone 'Newton' manikin within a climatic chamber. This is an important experimental
milestone in assessing the feasibility of applying the composite film
to the scale of full body clothing.



==========================================================================
With the composite film, relative humidity (RH) under moderate sweating condition dropped by about 40% -- from 91% to 48.2% after one hour
of sweating and to 53.2% after two hours of sweating. The team also
found that within the first hour of sweating, the heat index or 'felt
air temperature' dropped significantly from 64.6 deg C to 40 deg C at
air temperature of 35 deg C. At this level, while users still feel hot,
the likelihood of getting heat stroke, heat cramps and heat exhaustion
is remarkably reduced.

"These experiments show that our moisture-trapping film effectively
reduces the RH inside the protective suit, hence bringing the heat
index down significantly and improving the thermal comfort for users,"
Asst Prof Tan explained.

In another laboratory experiment, the research team also showed that
body temperature (or skin temperature) could be significantly reduced
by 1.5 deg C through evaporative cooling. This further proves that the composite film can potentially help users -- such as healthcare workers, soldiers or firefighters -- relieve thermal stress, especially during
strenuous activities.

Regeneration of the NUS team's composite film is also more energy
efficient, as it requires a lower temperature to release the trapped
moisture. At 50 deg C, the composite film releases 80% of its water
contents after 10 minutes and this reaches 95% after 40 minutes. Most hygroscopic materials regenerate at a temperature of more than 100 deg C,
over a duration of more than an hour.

"From the findings of various studies in this project, we are hopeful
that the moisture-trapping film can be embedded to Personal Protective Equipment (PPE) and/or Personal Protective Clothing (PPC) of the Home
Team officers, to enhance thermal comfort and improve performance of
the frontline officers," said Ying Meng Fai, Director, Human Factors & Simulation Centre of Expertise, at HTX.

Refinements and commercialisation Encouraged by the results of their
latest study, the NUS team is now working to improve their hygroscopic
material so that it can absorb more and faster. The team is also planning
to apply their cooling strategy to other types of protective apparel
such as those for firefighters.

In addition, Asst Prof Tan and his team are looking for opportunities
to commercialise this technology.


========================================================================== Story Source: Materials provided by
National_University_of_Singapore. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Jiachen Yang, Xueping Zhang, J. Justin Koh, Rensheng Deng, Saravana
Kumarasamy, Yuan Xing Xu, Hao Qu, Songlin Zhang, Yaoxin Zhang, Swee
Ching Tan. Reversible Hydration Composite Films for Evaporative
Perspiration Control and Heat Stress Management. Small, 2022;
2107636 DOI: 10.1002/ smll.202107636 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220325122703.htm

--- up 3 weeks, 4 days, 10 hours, 50 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)