Tech Briefs Magazine - April 2021 - 37

matrix from which the water can easily
evaporate. This is then covered with an
upper layer of aerogel, playing the part of
fur by keeping out the external heat while
allowing the vapor to pass through.
The two-layer material, less than a halfinch thick, can provide cooling of more
than 7 °C for five times longer than the
hydrogel alone - more than eight days
versus less than two. The system could be
used for food packaging to preserve freshness and open up greater distribution
options for farmers to sell their perishable

crops. It could also allow medicines, such
as vaccines, to be kept safely as they are
delivered to remote locations. In addition
to providing cooling, the passive system -
powered purely by heat - can reduce the
variations in temperature that the goods
experience, eliminating spikes that can
accelerate spoilage.
The basic raw materials involved in the
two-layer system are inexpensive - the
aerogel is made of silica (essentially
beach sand), which is cheap and abundant. But the processing equipment for

making the aerogel is large and expensive, so that aspect will require further
development in order to scale up the system for useful applications.
The hydrogel material is composed of
97 percent water that gradually evaporates away. In the experimental setup, it
took 200 hours for a 5-millimeter layer of
hydrogel - covered with 5 millimeters
of aerogel - to lose all its moisture compared to 40 hours for the bare hydrogel.
For more information, contact Abby
Abazorius at abbya@mit.edu; 617-253-2709.

Shape-Shifting Nanomaterial
This invention holds potential for a range of biomedical applications, from controlled-release
drug delivery to tissue engineering.
Emory University, Atlanta, Georgia

hemists have developed a nanomaterial that they can trigger to shapeshift - from flat sheets to tubes and
back to sheets again - in a controllable
fashion. The nanomaterial, which in
sheet form is 10,000 times thinner than
the width of a human hair, is made of

synthetic collagen. Naturally occurring
collagen is the most abundant protein in
humans, making the new material intrinsically biocompatible.
Collagen is the main structural protein in the body's connective tissue such
as cartilage, bones, tendons, ligaments,

and skin. It is also abundant in blood
vessels, the gut, muscles, and in other
parts of the body. Collagen taken from
other mammals, such as pigs, is sometimes used for wound healing and other
medical applications in humans. The
collagen protein is composed of a triple

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Tech Briefs Magazine - April 2021

Table of Contents for the Digital Edition of Tech Briefs Magazine - April 2021