Senior Design 2014

Senior Design Projects Spring 2014

Nanofiber Manufacturing Device for Stem Cell Studies

Advisors – Dr. Nitin Agrawal, Dr. Jennifer G. Barrett
Team – Alaa Alhussein, Alex Baker, Anuraag Ravikumar, Katrina Nguyen
Website – http://bioeng-proj.vse.gmu.edu/492-f13-team1/

Abstract –

The purpose of this senior design project is to engineer a robust method of consistently reproducing biodegradable and biocompatible nanofiber scaffolds that mimic the microenvironment of the extracellular matrix of tendons. Our objective was to develop a nanofabrication device that manufactures scalable and parallel aligned nanofiber scaffolds, which can be further used as a platform to cultivate stem cells that will differentiate into tendon.

Our device consists of an electrospinning apparatus including a rotating, surface-patterned mandrel and mobile spinneret. The mandrel is connected to the grounded lead of a high voltage DC power supply, and its rotation driven by a DC motor. A microcontroller controlled the rotation speed of the motor and the x-y movement of the syringe. The syringe expelled a polymeric solution (consisting of PLGA and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP)) onto the mandrel. The positive lead of the DC power supply charged the polymeric solution through its connection to a conductive needle tip causing a jet of fibers to eject from the syringe and onto the mandrel to produce 8”x6” sheets of nanofibers.

The concentration of PLGA, the flow rate of the polymeric solution, and the rotation speed of the mandrel dictated the ideal parameters for making successful scaffolds. After examining our samples under scanning electron microscopy (SEM) and liquid intrusion tests the scaffolds showed adequate nanofibers’ alignment, scaffold porosity, nanofibers’ diameter (200-600nm). Our results confirmed that our device was able to create nanofiber scaffolds with necessary properties to successfully seed and differentiate stem cells.


Lab-in-a-Box: Portable Incubator and Image Processing Program for Conducting Bacterial Growth Experiments

Advisor – Dr. Caitlin Laurence
Team – Emily Eastlake, Katie McDonald
Website – http://bioeng-proj.vse.gmu.edu/492-f13-team2/

Abstract –

At the pre-college level, studies have shown that students’ perceptions of STEM fields become increasingly negative as students age. One way to address this problem is to introduce hands-on, interdisciplinary learning modules into the classroom to promote student engagement, success, and retention in STEM fields. The Center for Outreach in Mathematics Professional Learning and Educational Technology (COMPLETE center) at George Mason University holds professional development workshops to help local high-school math teachers learn how to facilitate engaging interdisciplinary lessons in their classrooms.

During one COMPLETE center workshop, teachers culture bacteria in a lab incubator, measure the growth of the colony’s area versus time, and perform statistics and regression on the resulting data points. Unfortunately, teachers cannot bring this lesson back to their classrooms because they have no realistic mechanism for culturing bacteria in a high school setting. Additionally, the current method of measuring bacterial colony area, which involves tracing the edge of the colony onto a transparency, is inefficient and can be inaccurate.

Our research project consisted of building a simple, low-cost, easy-to-use incubator out of readily available materials that can be used to culture bacteria in a high school setting. In addition, we wrote an image processing algorithm to calculate the area of bacterial colony growth (in mm2) from a smartphone image of the petri dish. Initial results suggest our box will provide teachers with an inexpensive means for culturing bacteria in a high-school setting. In addition, our image-processing program should improve upon the existing tracing method for measuring colony area, potentially eliminating the need to manually measure the area of bacterial colonies.


Contactless Pulse Transit Time Measurement and its Potential Application in Measuring Blood Pressure

Advisor – Dr. Vasiliki Ikonomidou
Team – Martin Cissel, Misha Vaidya, Nhien Tran
Website – http://bioeng-proj.vse.gmu.edu/492-f13-team3/

Abstract –

Blood pressure cuffs are currently the standard device for measuring blood pressure at home or by a physician. However, many patients often develop pain and discomfort due to the inflation of the cuff. In addition, repeated re-inflation by the automatic cuff can even lead to the injury of the applied areas. Contactless blood pressure monitoring introduces a new way of measuring blood pressure without the requirement of any equipment contacting the body. The objective of our project was to develop a contactless device using a camera to detect a change in blood pressure. We collected waveforms using an RGB camera from subjects’ two regions of interest, the forehead and the palm, before and after an exercise; these wave signals closely compared to cardiovascular pulses. We then measured the difference in the time intervals of these signals, also known as pulse transit time (PTT) and used this calculated difference to derive the change in blood pressure. After testing a few subjects, PTT changed between pre and post exercise, and an inverse relationship between our derived PTT and blood pressure recorded from a cuff was observed. Future plans include carrying out our testing procedures on a larger population and support the results found in our preliminary data.

UNAR: User Navigated Autonomous Robot

Advisors – Samantha Watkins, Anthony Nunez
Team – Liban Hassan, Ahsanul Haque, and Shezeen Rehmani
Website – http://bioeng-proj.vse.gmu.edu/492-f13-team4/

Abstract –

Autonomous systems have become an important asset for domestic and commercial use, and research continues to enhance functionality and increase return on investment for users. According to the CDC, nearly 37.4 million adults have a physical disability. While the majority of these people are being assisted through services such as a home nurse or an assistive animal, the cost of maintaining these services are high. Autonomous robots have an advantage over these services because of low maintenance cost of owning robots and high efficiency in carrying out simple tasks.

Our task for this project was to design an assistive device that target customers with disabilities limiting them from carrying excessive weights. The proposed solution we implemented was an autonomous robot on wheels with indoor and outdoor capabilities, able to follow a user, avoid obstacles, and carry the user’s belongings. Our design was equipped with a Polulu IR beacon trans-receiver, with a matching homing transmitter carried by the user. The robot also has ultrasonic sensors attached to the front of the chassis for obstacle avoidance. The robot will also feature a compartment for the user to place their belongings.

We have tested obstacle avoidance along with the beacon transceiver using subsumption logic flow for information processing by the ATmega2560 microcontroller. The entire system is fully autonomous and self-contained. Our design was successful in carrying a specific load for the user, while avoiding obstacles and maintaining reasonable proximity.


Self-Guided Pedicle Screw System

Advisors – Dr. Mahesh B. Shenai, Dr. Siddhartha Sikdar
Team – Von Botteicher, German Borda, Susheela Meyyappan
Website – http://bioeng-proj.vse.gmu.edu/492-f13-team5/

Abstract –

Creating a pilot hole through the pedicle for pedicle screws is a high risk aspect of spinal fixation surgery. A breach of the pedicle cortical wall risks damage to the spinal cord, spinal nerves, and surrounding tissue. Low frequency A-mode ultrasound can penetrate cancellous bone and therefore be used to detect the cortical wall during pilot hole formation. Our objective was to demonstrate proof of concept of using ultrasound for a guided pedicle screw placement system and develop an algorithm that uses ultrasound to provide surgeons with real-time feedback during spinal fixation surgery. We used 2.5MHz A-mode ultrasound on bone phantoms to look for the cancellous-cortical bone interface. In a large air-filled pedicle model, we tested our algorithm with three ultrasound transducers.