A group of eye conditions that cause damage to the optic nerve, leading to blindness, Glaucoma is the second-most common cause of blindness in the United States and worldwide. In many cases, damage to the optic nerve is a result of high intraocular pressure (IOP) caused by a buildup of fluid within the anterior chamber of the eye – between the colored part and the outer cornea. This pressure builds and pinches the optic nerve, progressively diminishing sight at the edge of vision until complete blindness occurs. Treatments for glaucoma attempt to lower intraocular pressure to a normal level.
Though drug and surgical treatments for high intraocular pressure exist, there are problems associated with each. "The problem with pharmacological solutions such as pills and eye drops is compliance," Johanna explains. "You have to use a lot of pills or eye drops during the day, which a lot of patients do not like."
Surgical implants, which have been around since the 1960s, present their own problems, says Ken. "Most current devices are of a tube and plate design, with an implanted tube draining onto a plate somewhere outside of the eye. Pressure is maintained by promoting tissue growth on the plate, but the tissue growth cannot be controlled. After 1 to 2 years, the flow is blocked, pressure builds again, and the device has to be replaced." Tissue growth has plagued implanted glaucoma treatments for years.
The Stevens team sought an innovative design that would allow fluid to drain from the eye at a particular rate, without relying on growing tissue to mitigate the flow. Their solution is a Microelectromechanical systems (MEMS) microchannel – a long serpentine canal a mere 100 microns wide, that winds along a plate. Fluid from the eye flows through a channel about the width of a human hair. The width and length of the channel effectively regulates drainage through friction, leaving a healthy pressure in the eye.
"Rather than having a huge outflow that we have to restrict, we regulate the flow from beginning to end so that the amount to come out is exactly the amount we want," David explains. "It's a consistent design. Unlike current treatments, it won't change how it operates over time."
"This is the first Senior Design project which truly demonstrates the MEMS technology," says Professor Yang, who has 15 years of extensive experience in MEMS technology. "David was one of the students enrolled in the Introduction to BioMEMS course that I taught, from which he came up with an initial MEMS-based microvalve idea that led to his summer project in 2010 under the Stevens Scholars Program. The research concept was eventually developed toward the current Senior Design project. It is important to note that this project is the first undergraduate student project that fully utilizes ourMicro Device Laboratory
(MDL) facilities! The team has made great strides in demonstrating the MEMS microchannel-based Intra Ocular Pressure regulator."
The team is comprised of a diverse group of students, all Mechanical Engineers, but each with a different specialty: some in math, others in physics, and others in nanotechnology. The variety of experience helped the team to deliver a truly innovative product, David says. "We were able to apply our strengths to the project, whether in modeling or in testing."
For David, this project represents a stepping stone in his nanotechnology future. He will graduate with both Bachelor's and Master's of Engineering Degrees, and plans to pursue his Ph.D. in nanotechnology at University of California, Berkeley. He attributes his success to Stevens strong program, which allows undergraduates to pursue their Master's degrees simultaneously. "Doing the master's program allowed me to focus on nanotechnology, and gave me direction as to what to pursue for a doctoral degree."