Hardware
setup:
The setup consists of a microcontroller (such as an Arduino), an
overhanging projector camera, a UV flashlight weakened with UV filters, a
3D printed stand for the flashlight, a plastic container with metal sheets hot
glued on the sides, a tablet computer, and a servo motor with a metal tip
attached to the tablet for pressing record.
The tablet is connected to t
he
camera as well as the Arduino,
used to control the recording state
and to run/modify
the Arduino
program
. The Arduino uses
transistors to control a 9V DC
electric current through the
testing
aquarium using
the 2 metal plates
on the sides,
as well as
the UV
light’s
on/off state
and strength. It
also controls a servo motor
attached to the side of the tablet
with an aluminum foil tip and an
alligator clip such that it can
interact with the tablet’s
touchscreen and control the
camera’s recording state.
Above is a rough diagram of the wiring
with the Arduino, with an extra LED as a
sign of an electric shock being administered (not necessary).
Note that there should
be a 9V voltage source (like a battery)
in between the cyan
and black wires
connecting the transistor to the electrodes on the aquarium, and
the servo motor for turning recording on/off is not shown.
The
angled UV light holder, aquarium, and the
servo motor holder for
tapping record on tablet
were
modeled and 3D printed, althoug
h they can
be substituted with any other similarly structured hardware.
Determining the UV Strength:
The UV light must be strong enough for the planarians to sense but weak
enough to not cause a physical reaction. For this, we exposed the
planarians to
the UV light
periodically, each time with decreasing strength
(controlled either by attaching 50% UV filters or using the Arduino’s PWM
mechanism with the transistor) until the planarians no longer react to the
UV light.