Tech Briefs Magazine - November 2023 - 46

Materials & Coatings
Algae-Powered Devices Inspired by Bioluminescent Waves
The devices do not require any electronics to light up, making them an ideal choice for
building soft robots that explore the deep sea and other dark environments.
University of California San Diego, La Jolla, CA
R
esearchers at the University of California
San Diego have developed soft devices
containing algae that glow in the
dark
Mechanical perturbations
when experiencing mechanical
stress, such as being squished, stretched,
twisted, or bent. The devices do not require
any electronics to light up, making
them an ideal choice for building soft robots
that explore the deep sea and other
dark environments, researchers said.
The researchers took their inspiration
for these devices from the bioluminescent
waves that sometimes occur at San Diego's
beaches during red tide events. Shengqiang
Cai, Professor of Mechanical and
Aerospace Engineering at the UC San Diego
Jacobs School of Engineering and the
study's senior author, was watching the
glowing blue waves with his family one
spring night and was curious to learn more
about what causes this impressive display.
The source of the glow is a type of single-celled
algae called dinoflagellates. But
what fascinated Cai was learning that dinoflagellates
produce light when subjected
to mechanical stress, such as the forces
from the ocean waves. " This was very interesting
to me because my research focuses
on the mechanics of materials -
anything related to how deformation and
stress affect material behavior, " he said.
Cai wanted to harness this natural glow
to develop devices for soft robots that can
be used in the dark without electricity. He
teamed up with Michael Latz, a marine biologist
at UC San Diego's Scripps Institution
of Oceanography, who studies bioluminescence
in dinoflagellates and how it
responds to various water flow conditions.
To make the devices, the researchers
inject a culture solution of the dinoflagellate
Pyrocystis lunula inside a cavity of
a soft,
stretchy,
transparent material.
The material can be any shape - here,
the researchers tested a variety of shapes
including flat
sheets, X-shaped structures,
and small pouches.
When the material is pressed, stretched,
or deformed in any way, it causes the dinoflagellate
solution inside to flow. The mechanical
stress from that flow triggers the
dinoflagellates to glow. A key feature of the
design here is that the inner surface of the
material is lined with small pillars to give it
a rough inner texture. This disturbs the flu46
Visualizing
mechanical perturbations in the dark phase
Undeformed state
Luminescent patterns
Contact stimuli
In the light phase
Charged with light
for photosynthesis
Integrated with dinoflagellate
culture solution
Invisible objects
Soft biohybrid robots
Stiff
Visible objects
Unactivated stateActivated state
Optical signaling by actuations in the dark phase
Bendable actuators
Undeformed
robot
Soft
Actuation
Actuated
leg
Invisible objects
Air flow Deformed state
Contactless stimuli
Illumination by actuations/disturbances in the dark phase
Visible objects
Actuation or
disturbance
Luminescent
robot
" C "
" S "
Actuated legsActuated all legs
Display lettersProgramable patterns
In the light phase, the soft biohybrid robot integrated with dinoflagellate culture solution is
charged with sunlight for photosynthesis to produce oxygen, providing energy for the organism. In
the dark phase, the mechanically induced bioluminescence of the soft biohybrid robot can visualize
mechanical perturbations, illuminate surrounding area, and produce optical signals. (Image: UCSD)
id flow inside the material and makes it
stronger. A stronger flow applies more
stress to the dinoflagellates, which in turn
triggers a brighter glow.
The devices are so sensitive that even a
soft tap is enough to make them glow.
The researchers also made the devices
glow by vibrating them, drawing on their
surfaces, and blowing air on them to
make them bend and sway, which shows
that they could potentially be used to
harvest air flow to produce light. The researchers
also inserted small magnets
inside the devices so that they can be
magnetically steered, glowing as they
move and contort.
The devices can be recharged with light.
The dinoflagellates are photosynthetic,
www.techbriefs.com
meaning they use sunlight to produce food
and energy. Shining light on the devices
during the day gives them the juice they
need to glow during the night.
The researchers are now creating new
glowing materials with the dinoflagellates.
The team is excited about the possibilities
this work could bring to the
fields of marine biology and materials
science. " This work continues to advance
our understanding of bioluminescent
systems from the basic research side
while setting the stage for a variety of applications,
ranging from biological force
sensors to electronics-free robotics and
much more, " said Latz.
For more information, contact Liezel
Labios at llabios@ucsd.edu.
Tech Briefs, November 2023
Programmable patterns

http://www.techbriefs.com

Tech Briefs Magazine - November 2023

Table of Contents for the Digital Edition of Tech Briefs Magazine - November 2023