David Beebe

Associate Professor, Department of Biomedical Engineering, University of Wisconsin at Madison

Born in 1963 at the tail end of the baby boom, I was raised in a small Wisconsin town near the Mississippi river. My family was involved in agriculture (cash crop farming and farm equipment sales and repair). So I'm one of a continually shrinking percentage of people “raised on a farm.” Currently, I live in Monona, Wisconsin (just across the lake from Madison) with my partner, Jane and our two children, Wilson and Mara. My free time is occupied with the kids soccer games, remodelling a 60 year old house and training for athletic events (mainly 10K road races and triatholons).

I began my graduate training at the University of Wisconsin-Madison in 1989. After receiving my PhD in Electrical Engineering, I accepted a faculty position as an Assistant Professor at Louisiana Tech University. This was then followed by a 4 year period as an Assistant Professor at the University of Illinois at Urbana-Champaign until 2000 when I returned to the University of Wisconsin-Madison as an Associate Professor. Now I am combining the role of Associate Professor with that of a “student” whilst studying Cell Biology with the aid of an NIH re-training grant.

In order to describe a summary of my research, it is important to understand that one of the main motivations for pursuing a PhD and an academic career was a short attention span. That is, I felt that an academic position is one of the few jobs that would allow me to change topics every 5–10 years without changing jobs! My PhD research focused on traditional silicon MEMS fabrication of a flexible force sensing skin for rehabilitation applications. This was back in the days of “one device, one PhD,” and thus, I spent the majority of my graduate school days in a “bunny suit” “pushing wafers.” With degree in hand, I headed for my first academic position at Louisiana Tech University where I immediately began to pursue microfluidic interests while continuing research in tactile sensors and displays. It was at Louisiana Tech that we began to “play” with the use of micro technology and embryology and published a little known paper that demonstrated the use of micropolysilicon “branding irons” to label individual embryos—a rather silly idea in hindsight, but it did get us starting learning about embryology. Simultaneously, we were exploring DNA manipulations in electrical fields within microchannels, but soon discovered Bob Austin at Princeton was well ahead of us in that area of research. But it quickly became apparent that the merging of microfludics and embryology held great promise. Upon moving to UIUC about a year later, we linked up with Matt Wheeler, an embryologist, and began to explore the use of microfluidics in assisted reproduction in earnest which lead to the founding of a company, Vitae, LLC, dedicated to commercializing the technology.

At UIUC, our research expanded into a variety of microfluidic related areas via intellectually rich collaborations. Juan Santiago (now a professor at Stanford) joined the lab as a post doc and made important contributions to the development of chaotic advection based micro mixers and micro particle imaging velocimetry in collaboration with Ron Adrian and Hassan Aref. In parallel, we set about to develop a completely organic approach to micro system creation with synthetic chemist Jeff Moore. Through the hard work of graduate students working across the boundaries of microfluidics and polymer chemistry we created a platform based on liquid phase photopolymerization that we called microfluidic tectonics. Funding from DARPA allowed us to extend this technology to create systems for bioagent detection. Over the past 5 years we have focused on understanding the basic physics of microfluidics and leveraging that knowledge to advantage to address issues such as pumping, mixing, sample concentration and autonomous operation. By scaling stimuli responsive hydrogel structures, actuation times that are in the order of hours at the mm scale are reduced to seconds at the microscale, making autonomous operation and decision making in all organic systems practical.

More recently, we have begun to address the issues related to the long term culture of cells in controlled microenvironments. If microfluidics is to play an important role in basic cell biology research, an improved understanding of the interactions between diffusion-limited microenvironments and cell behavior will be needed. As with previous uses of microfluidics, understanding the physics of the scale will be critical to applying microfluidics to the study of cell growth and behavior. The interplay of constrained (from a diffusion perspective) environments and cell behavior is quite intriguing. We are currently studying this interplay using a variety of model systems including insect cells, mammalian embryos, mammary epithetial cells and human embryonic stem cells. Our studies are currently focused at a very basic level as we try to gain an understanding of the relationship between microenvironment parameters and cell behavior. In the future, we hope to use this understanding to develop systems to, for example, guide the differentiation of stem cells down clinically relevant paths.

While the complete impact of microfluidics is yet to be determined, it is now clear that at a minimum, microfluidics will find use in niche applications where the unique properties of the scale provide competitive advantages or new functionality over existing technologies. I'm particularly hopeful that the synthesis of methods and techniques developed in microfluidics, tissue engineering and MEMS will help us complete our understanding of cell structure/function relationships in the coming years. In a personal effort to help complete the technology/cell biology bridge, I will be returning to school this fall to study cell biology via an NIH re-training grant. Hopefully, I will re-emerge 5 years from now with a new and useful perspective on the biology/technology interface.

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