This document describes the development of a device capable of applying a polymer blend via blow spinning laparoscopically. The current method requires open surgery. The researchers designed a 5mm diameter, 20-30cm long device that can withstand pressures of 15mmHg and successfully deliver PLGA/PEG polymer nanofibers during testing. Future work includes animal studies and a trigger mechanism to control polymer release. The global market for laparoscopic devices is growing, indicating potential for this technology.

1. Laparoscopic Blow Spinning Device for Sutures
Darren D’Souza, Greg Laslo, Carmen Rinard, William Swygert, Stamatia Vafeas
Clinical Mentor: Dr. Anthony Sandler, Center for Surgical Care, Children’s National Medical Center
Faculty Mentor: Dr. Peter Kofinas, Fischell Department of Bioengineering, University of Maryland
Current methods for suturing wounds during surgery are laborious and prone to
complications. Dr. Kofinas’ lab has developed a polymer solution composed of
PLGA and PEG dissolved in acetone that can be applied via blow spinning to
yield nanofibers. Blow spinning is done using CO2 gas which helps to create a
shear force leading to the formation of nanofibers. The nanofibers have adhesive
properties, and can therefore be used to complement sutures and seal internal
anastomosis. In animal testing, blow spinning the polymer blend allows repaired
anastomoses to withstand higher burst pressures compared to current methods.
With the current device developed by researchers at Children’s National Medical
Center, the polymer blend can only be applied through open surgery. There are
several drawbacks to open surgery including the risk of hospital acquired
bacterial infections and longer recovery times. Our objective was to develop a
device capable of blow spinning this polymer laparoscopically.
Motivation Approach
Design Specifications
● Device must be 5mm in (outer) diameter in order to be compatible with
SILS ports used during laparoscopic procedures (Figure 1)
● 20-30cm in length (typical length required for laparoscopic devices to
reach the abdomen)
● Must be operable under pressures exceeding 15mmHg (the pressure
that the abdomen is insufflated to during laparoscopic surgery)
Figure 1. SILS port for
laparoscopic surgery
Our original prototype consisted of a plastic pipette tip, a 20cm plastic tube,
and plastic tubing connected with electrical tape. The plastic tubing connects
to the CO2 tank and the polymer was delivered via a syringe and needle to the
tip of the device.
Figure 4. Original prototype with enlarged depiction (Fig. 4a) of needle tip
where polymer was delivered.
Figure 2. Insufflated abdomen
during laparoscopic procedure
Device Design
Results
Prototype Testing
After testing our device in both at atmospheric pressure and in a pressurized
environment of about 8-10 mmHg (using a glove bag), we were able to
successfully produce nanofibers. Testing was done using a polymer blend of
10% PLGA and 5% PEG (weight by volume) dissolved in acetone and 40 psi of
CO2. The device was fit through a 5 mm trocar to ensure compatibility with
laparoscopic ports. The syringe used to deliver the polymer was connected to a
syringe pump, and flow rates of 50 mL/min to 125 ml/min were able to
successfully yield nanofibers.
Future Work
Aknowledgements and References
In addition to our mentors, Dr. Sandler and Dr. Kofinas, we would like to
thank John Daristotle, Gary Seibel, and Justin Opfermann for their guidance
and for helping to make this project possible.
Eliton S., et al.“Solution Blowspinning: A New Method to Produce Micro- and Nanofibers
from Polymer Solutions,” Journal of Applied Polymer Science 113 (2008): (4). Accessed
December 10, 2015. doi: 10.1002/app.30275.
● Developing a spring-loaded trigger to be able to control the
release of the polymer from the inner tube.
● Animal studies to further validate that our device is able to
successfully deliver the polymer blend via blow spinning.
Market Research
Laparoscopic surgery, also known as minimally invasive surgery, is a surgical
technique in which the operation is performed through small incisions. Currently,
there are about 7-8 million laparoscopic surgeries performed annually throughout
the world The estimated global market for laparoscopic devices is on the rise, and
is expected to hit 8.5 billion dollars by 2018. Suturing wounds is a critical step to
any operation and some procedures, like anastomoses, would be more efficiently
completed with the development of this technology. With 40% of the surgical
sealant market comprising synthetic materials a laparoscopic blow spinning device
would be a welcome addition to a surgeon's tool kit.
Figure 3. Blow spinning fluid
model. The inner tube is where the
polymer flows while the outer tube
is where CO2 flows (represented by
streamlines). The shear stress from
the needle helps with fiber
formation.
Figure 5. SolidWorks sketch representing tip of our device as viewed from cross
sectional view . The Inner tube delivers the polymer while the surrounding tube is
filled with CO2 gas. The protrusion of the inner tube is necessary to yield proper
fibers. All dimensions are in millimeters.
Figure 6. Images of manufactured device, including the entire device fitted into a
5mm diameter trocar in blue (Fig 6a.), close up of the T-luer lock connector with
syringe pump attached (Fig 6b.), and close up of the tip of our device (Fig 6c.).
Figure 7. Fibers produced from our device on various surfaces including a
petri dish (Fig 7a.) and a latex glove (Fig. 7b.).
A B
A
CB
A B
Figure 8. Velocity profile of CO2 gas using COMSOL Multiphysics 4.1
software. The results demonstrate that the flow of CO2 increases within a
smaller chamber to assist in fiber development.
We were concerned that the sharp 90° would affect the flow rate of CO2 gas
and possibly lead to turbulent flow, which may disrupt the formation of the
nanofibers. Modeling of the velocity profile for the CO2 gas demonstrates that
the flow remains laminar as expected.