Pratt Fellow Levy Develops Tools for Better Disease and Chemical Detection

levy.jpgAs a Pratt Undergraduate Research Fellow in the laboratory of J.A. Jones Distinguished Professor of Electrical and Computer Engineering Nan Marie Jokerst, Melissa Levy is a member of a team designing a hand-held “lab on a chip” capable of detecting the parasite responsible for malaria in a single drop of blood, among other applications. Such a malaria detector would have particular advantages in the developing world countries where people are most at risk for the mosquito-borne illness. In those settings, a lack of electricity and medical expertise often limits testing.

The integrated optical sensor under development includes a laser and waveguides that channel the laser light to several sensors. It is that combination of sensors that can determine a variety of qualities, including the presence of malaria or of a pollutant chemical in a water droplet, Levy said.

Levy’s focus is the design and fabrication of another component of the chip, which she calls surface relief optical gratings. The gratings, a series of ridges that sit between the laser and the waveguides, are meant to tighten the wavelengths of light able to pass through to the waveguides and on to the sensors while maintaining the same output power.

“The idea is that the optical properties of a drop of liquid–— a blood or water sample, for example–— will change based on the other substances it contains and you will detect a small shift in wavelength,” Levy explained. “The grating takes the output of light from the laser and narrows the spectrum,” ultimately increasing the resolution of the optical sensor, by making any shift in wavelength easier to see.

To design the grating, Levy takes into account the characteristics of the laser and other features of the chip to precisely calculate the spacing required–— on the order of 500 nanometers. She then fabricates the gratings on glass slides, which will ultimately be replaced with silicon, in the new Shared Materials Instrumentation Facility (SMiF) clean room in the Fitzpatrick Center, making her one of the first to take advantage of the facility’s enhanced capabilities.

“The biggest difference with SMiF is that there is more of everything,” Levy said. “It is a much higher quality clean room, enabling more accurate and reliable fabrication." The additional space and equipment are also beneficial changes, she added.

In principle, the gratings Levy is building could be used in optical chips designed to detect any biological or chemical agent. “The grating could be included in the overall sensor, regardless of application,” she said.

Finding Photonics

Levy said her interest in optics and photonics began in high school, but she hadn’t yet decided on engineering. She took Engineering 10 once at Duke to help her decide whether or not the discipline was really for her, and if so, which area she would focus on. After going through units on biomedical engineering, civil and environmental engineering and mechanical engineering, she was nearly ready to drop out when the course turned to electrical and computer engineering, rekindling her earlier interest in optics and introducing her to new interests in photonics and circuits.

Now a senior, Levy is a double major in electrical engineering and mathematics and a physics minor. “My favorite time is when all of my classes overlap,” she said. “That’s fun.” Levy cites the ease with which engineering students at Duke can double major and the close ties between the engineering school and the rest of the campus as major factors in her decision to enroll at Duke.

In addition to her work in the Pratt Fellows program, Levy has been a frequent teaching assistant in the ECE department. She has also been an active participant in Innoworks, a program designed to increase enthusiasm for learning science and engineering in disadvantaged youth, a crew leader for a community service based pre-orientation program called Project BUILD and religious vice president of the student board of Duke Hillel.

As for life after Duke, she is weighing her options between graduate school and an engineering or optics-related job. Either way, she intends to find a way to continue teaching, an activity she said has “taught her a lot.”