Medical Design Briefs - February 2025 - 20

n Efficient Wearable Energy Harvester
Researchers have developed a
three-dimensional stretchable
piezoelectric energy harvester
that can harvest electrical energy
using body movements. The device
is to be used as a wearable
energy harvester as it can be attached
to the skin or clothes.
Energy harvesters are of two
types based on whether they work
n Gel-Based Nanogenerators for Wearables
Researchers have developed
a gel polymer-based triboelectric
nanogenerator
on
the triboelectric effect or piezoelectric effect. This device is
based on the piezoelectric effect, which produces electricity
from physical activities such as elastic skin or joint movements.
The device is based on the lead zirconate titanate (PZT),
which has a high piezoelectric efficiency. PZT has excellent
piezoelectric performance but is hard and brittle, making it difficult
to use it as a stretchable device. However, the researchers
designed PZT into a three-dimensional structure that is insensitive
to deformation, ensuring high energy efficiency and
stretchability at the same time.
They also introduced a new curvature-specific coupling electrode
design to divide the electrodes into different sections so
that the electrical energy of the device is not canceled out. This
led to an energy efficiency that is 280 times higher than that of
conventional stretching piezoelectric energy harvesters. (Image
credit: DGIST/ACS Nano)
For more information, visit www.medicaldesignbriefs.com/
roundup/0225/energy-harvester.
n Sensors Charge Biological Cells
A team has developed
new biosensors with which
the
ratio
the
of NADPH to
NADP+ can be measured
in living cells in real time
for
first
time. The
team's observations provide
new insights into the evolution of the most important protective
function of cells, cellular detoxification. NADP is involved
in many reactions in the cell in which electrons are
transferred between different substances.
For the new sensors, the scientists used genetic engineering
methods to modify a previously developed fluorescent molecule,
which contains parts of a luminescent jellyfish protein, in
such a way that it specifically recognizes NADPH and NADP+.
Among other things, they discovered that the " NADP charge "
is very robust and is recharged particularly efficiently by cellular
metabolism when required.
They also observed NADP charge cycles, i.e., oscillations of the
cell battery during cell division, and an influence of photosynthesis
and the availability of oxygen on the NADP battery. Another
important finding was that the detoxification of reactive
oxygen species - e.g., hydrogen peroxide - takes place primarily
via the glutathione present in the cells (a tripeptide that
is present in the cell in comparatively high concentrations),
regardless of whether in yeast, plant, or mammalian cells. (Image
credit: University of Münster)
For more information, visit www.medicaldesignbriefs.com/
roundup/0225/NADP-sensors.
20
n 3D Printing Shape-Changing Materials
Researchers have helped
create a new 3D printing approach
for shape-changing materials
that are likened to muscles,
opening the door for
improved applications in robotics
as well as biomedical and
energy devices.
The liquid crystalline elastomer
(LCE) structures can
crawl, fold, and snap directly
after printing. The lightly cross-linked polymer networks
change shape significantly upon exposure to certain stimuli,
like heat.
The researchers varied the strength of the magnetic field
and studied how it and other factors, such as the thickness of
each printed layer, affected molecular alignment. This enabled
them to print complicated liquid crystalline elastomer shapes
that change in specific ways when heated. Aligning the molecules
is the key to unlocking the LCEs' full potential and enabling
their use in advanced, functional applications. (Image
credit: David Roach/Oregon State University)
For more information, visit www.medicaldesignbriefs.com/
roundup/0225/shape-changing.
www.medicaldesignbriefs.com
Medical Design Briefs, February 2025
(TENG) that generates electrical
signals from body movement
to power electronics like
LEDs and functions as a
self-powered touch panel for
user identification. The device
can stretch up to 375 percent
of its original size and
withstand rigorous mechanical
deformations, making it suitable for wearable applications.
TENGs that convert mechanical energy such as body movement
to electrical energy offer a solution to power wearable
devices without relying on batteries.
To fabricate the device, the researchers poured a gel mixture
of polyethylene oxide (PEO) and lithium bis(trifluoromethanesulfonyl)imide
(LiTFSI) into an ecoflex mold. The gel is
spread evenly and then covered with another ecoflex layer. A
copper wire is attached to the gel for electrical connection, and
the entire assembly is cured at 70 °C for 12 hours, allowing the
gel to bond strongly with the ecoflex layers.
The result is a durable, flexible, and semitransparent device
that generates electrical signals when tapped or stretched, delivering
a peak power of 0.36 W/m² at a load of 15 MΩ. In tests,
the device stretched up to 375 percent of its original size without
damage and could withstand two months of bending, twisting,
folding, and stretching without any signs of delamination
or loss of electrical performance. (Image credit: Chemical Engineering
Journal/Dongguk University)
For more information, visit www.medicaldesignbriefs.com/
roundup/0225/nanogenerators.
http://www.medicaldesignbriefs.com/roundup/0225/energy-harvester http://www.medicaldesignbriefs.com/roundup/0225/nanogenerators http://www.medicaldesignbriefs.com/roundup/0225/shape-changing http://www.medicaldesignbriefs.com/roundup/0225/NADP-sensors http://www.medicaldesignbriefs.com
Medical Design Briefs - February 2025

Table of Contents for the Digital Edition of Medical Design Briefs - February 2025
