By Jenny Lu ’14, thurj Staff

Sometimes the theoretical aspects of class may not seem directly applicable to real-world experiences in research, industry, and the workplace. At Harvard’s School of Engineering and Applied Sciences, however, there is no such thing as “lack of application.” Among those spearheading Harvard’s innovation in SEAS coursework is Dr. Anas Chalah, the Director of Undergraduate Labs at the School of Engineering and Applied Sciences at Harvard.

At the ground floor of Pierce Hall, Chalah demonstrated the functionality of the Microfluidics Lab currently in development. The lab offers undergraduates the opportunity to learn how to design and use microfluidic devices through the course Engineering Sciences 123: Introduction to Fluid Mechanics and Transport Processes. Microfluidic devices enable scientists to perform reactions and experiments on a microliter, nanoliter, or even smaller scale. By running fluids through a specially designed maze of channels, researchers can create specific gradients of concentrations and conduct biological experiments in the same way one would conduct an experiment on a more macroscopic level with Erlenmeyers and test tubes. Thus, a microfluidic device can be thought of as a “lab-on-a-chip.”

Such a lab may at first appear commonplace among other science courses, but in reality this hands-on experience is uncommon for undergraduates. Standard microfluidic devices are often expensive and unaffordable for an entire class of students. The solution is to create effective microfluidic devices that are cost-effective to produce and easy to create.

Joe Childs, a teacher at the Cambridge Rindge & Latin School, used transparencies, the see-through pieces of acetate often used in school for projecting information with overhead projectors, to create microfluidic devices. By photocopying a pattern onto the transparency many times, the ink forms channels for the fluids to travel through separately. Through the Research Experience for Teachers outreach program with Harvard, this process was perfected with graduate student Keith Brown in the lab of Bob M. Westervelt, Mallinckrodt Professor of Applied Physics at SEAS and Professor of Physics, and now with Chalah. [1]

At the Microfluidics Lab, the simple technique with transparencies is expanded upon even further by creating a sandwich between two surfaces. One surface is created using the polymer polydimethylsiloxane (PDMS), also known as silicone. Channels are imprinted into the PDMS surface by pouring liquid PDMS over a positive mold and letting the polymer solidify. The positive mold is created by using a laser cutter on a transparency-thick sticker-like material. This grooved PDMS surface is placed on top of a second solid, flat surface, creating channels through which fluid can travel as if in a microfluidic device. This method improves the design of the microfluidic device by reducing air bubbles in the PDMS and by creating sharper and more defined channels. Currently, Chalah is interested in incorporating photolithography into the microfluidics lab. By placing a transparency on a photosensitive plate and exposing the plate to light, a positive mold is created on the plate. In this way, students are able to connect the technique of soft lithography, which goes into making the channels in the PDMS, with the concepts behind photolithography.

Real-world applications of microfluidics are abundant. An obvious example of the utility of microfluidics is in drug testing: using such a microfluidic device, one can easily create a network of channels that can generate a mix of drug concentrations. Each of those drug concentrations can be tested on eight different cell lines incorporated into in the same microfluidic device. “You can have eight experiments at one time at a micro level,” Chalah explains. “That’s the beauty of this high throughput experiment!”

Undergraduate labs like the microfluidics lab offer students the opportunity to engage in a diverse array of lab setting and learn a variety of techniques otherwise only found in research labs. “What we did is bring [microfluidics] to the teaching lab level,” Chalah notes. “Most students don’t have the luxury to go to a lab to do this….We owe it to our students to teach them.”

Beyond the Microfluidics Lab, other labs for undergraduates are being developed for courses in SEAS that connect the classroom to the real world. Chalah showed the newly created water engineering lab, which is used by students in Environmental Sciences 164: Soil and Environmental Chemistry and Environmental Sciences 165: Water Engineering. In Water Engineering, a lab course, students are given samples of raw pond water collected from Fresh Pond, a source for the Cambridge tap water system. Their task is to perform experiments on the water sample as a typical water treatment plant would perform large-scale for the water in Cambridge. Inside the lab are a variety of filters and even an ozone treatment device, which just arrived. “Everything here is new,” remarks Chalah. “Students are wowed when we show them how these instruments work.”

After each experiment, students are also asked to take measurements regarding nearly all aspects on the quality of the water. On the other side of the filters is an array of handheld meters with probes that measure everything from specific ion concentration to carbon dioxide concentration. Moreover, these handhelds, equipped with wireless capabilities and a screen to generate real-time plots, are useful because they “are what you would use out on the field,” as Chalah notes. The labs done in these newly-developed SEAS classes are prepared with the aim to introduce students to real-world experiences as research scientists.

Ultimately, the microfluidics lab and the water engineering lab are exemplary examples of the hands-on experiences that undergraduates are able to obtain from the coursework through SEAS. Moreover, these labs allow students to tangibly work with and explore the scientific and engineering concepts behind the textbook. Yet, Chalah notes that the creation of such undergraduate lab coursework is really “brand new.” Methods are frequently revised to make the labs run more smoothly, effectively, and cost-efficiently. As Chalah describes it, “This is Harvard. We are constantly improving.”

  1. [1] “Microfluidics Lab provides new core facility for undergraduate teaching.” Harvard SEAS Press Release. 20 Jan 2011.

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