purcc 2012 - University of the Pacific

Bioengineering Senior Projects
Project Alpha: Co-Current Device for
Synthesis of Spider Silk
Tyler Chuang, Brandon Hill
Faculty Mentors: Shelly Gulati, Craig Vierra
Spider silk is a material that is has proven to
have many applications in fields of Surgery, and
Bioengineering. It has been shown to be bioinert,
allowing for use in physiological
environments, as well as having unique and
valuable mechanical characteristics allowing
new uses in engineering and surgery as devices
such as sutures or implants. Unfortunately there
are no feasible ways to farm natural silk, making
artificial synthesis of the material a very
important research topic. Artificial silk synthesis
involves expressing silk in bacteria and then
purifying it. This purified silk must be
concentrated in order to yield fiber. The silk is
dehydrated, then dissolved it in a volatile
solvent, creating a concentrated dope. Modern
spinning involves pushing silk dope through a
simple needle, allowing the shear forces of the
needle to form the silk. This traps pockets of
solvent in the fiber, weakening the fiber’s
mechanical properties. Utilizing microfluidics, a
novel approach has been developed which
involves the co-current of the silk dope with a
buffer, allowing diffusion of the solvent present
in the dope into the buffer, while also allowing
the shear forces of the buffer to form the silk,
thus allowing for a stronger silk fiber. This cocurrent
device allows the flow of a buffer to
surround the silk dope, allowing them both to be
present in the state of laminar flow. This forces
the substances to interact just through the mode
of diffusion, thus allowing the removal of
solvent pockets, and thereby improving the
mechanical properties.
Ankle Healing Aid
Isha Srivastava, Grace Ramos
Faculty Mentors: Shelly Gulati, Simon Tang,
Mark Van Ness
About 25,000 people per day in the United States
alone suffer from an ankle sprain. Ankle injuries
mayoccur during sports as well as everyday
activities when an unnatural twisting action
befalls on the ankle bone. Sprains can be
categorized into various types and grades,
depending on the anatomical location and
severity of the injury. We have designed a
pressurized ankle brace in order to assist the
healing process for ankle sprain injuries that
require multiple adjustments. Our ankle brace
design provides comfort to the patient during
recovery and also can be worn after recovery to
prevent re-injury. The addition of pressure
surrounding the ankle serves the need to have
multiple adjustments. When the ankle first
heals, it requires a stiff support to heal the ankle
back in place but as the healing process
continues it requires less pressure and adjusted
torque to the ankle to provide comfort as well as
more natural motion of the joint. The pressure is
administered using a detachable hand pump and
the air enters pockets encased within the ankle
brace. A small, digital pressure gauge will be
affixed on to the ankle brace to ensure proper
amount of pressure. Success of the ankle brace
will be determined by testing the ankle brace on
a control group—people who have never had an
ankle injury and an experimental group—people
who have sustained an ankle injury.
The Puzzle of Getting up From a Seat
Eileen Thai, Nestor Decierdo, Matthew Ebia
Faculty Mentors: Shelly Gulati, Simon Tang
Millions of people in the United States have
difficulty rising from a chair. To address this
issue various companies have developed seat
assists and lifting cushions to help people
transition from a seated position to a standing
position and vice versa. Current assist devices
are only capable of moving the user in one plane
of motion - up and down. Attaching a swiveling
base will provide an axis of rotation so the user
can move to the right or left while seated. No
seat assist or lifting cushion on the market has
this feature. We have re-engineered the current
design of the UpEasy Seat Assist, a portable
lifting cushion. By adding a swiveling base, our
assist device will have an additional axis of
rotation for a larger range of motion. The overall
design of the seat was reshaped to be smaller and
circular so that it can be used in a larger variety
of chairs. A biomechanical analysis of the joints
during the interval from sitting to standing was
also carried out. It was determined that the
reaction forces experienced by the hip, knee, and
ankle joints were lessened when the seat assist
was used. The rise times from a seated position
to a standing position will be measured with and
without the seat on a test group to determine the
advantage of using the seat assist device and a
questionnaire will be distributed to all
participants to assess the device’s ease of use.
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