Dartmouth Engineer - The Magazine of Thayer School of EngineeringDartmouth Engineer - The Magazine of Thayer School of Engineering

Q&A with Cell Phone Camera Inventor Eric Fossum

By Anna Fiorentino
June 2013 • Thayer By Degrees: PhD

We sat down to talk with Professor of Engineering Eric Fossum, Faculty Coordinator of Dartmouth’s Ph.D. Innovation Program and inventor of the complementary metal oxide semiconductor (CMOS) active pixel image sensor. Fossum’s technology can be found in over one billion new cameras each year, in almost every cell phone camera, in laptops and cars, and even in X-ray machines. And with more than 180 patents, it’s no surprise that this National Inventors Hall of Fame inductee recently not only became a Charter Fellow for the National Academy of Inventors (NAI), but also was elected shortly after to the National Academy of Engineering.

Congratulations—what an honor to be recognized by these organizations for your CMOS active pixel image sensor.

Thank you! Being elected to the National Academy of Engineering represents my managing to do something substantial over the course of my career and have that be recognized and appreciated by colleagues at the national level. It feels good! And I'm glad to be part of the NAI because I think its goals of elevating the role of invention and technology transfer in academic institutions is important to enhancing the economic growth and prosperity of the nation. Most academic institutions have not formally recognized invention and technology transfer along with the traditional metrics of academic success, such as publications and citations. Thayer, to its credit, seems to be far ahead of the curve.

What led you to invent the CMOS active pixel image sensor at the NASA Jet Propulsion Laboratory in the 1990s?

Eric Fossum
Professor Eric Fossum

Necessity is the mother of invention, as they say. We were tasked with miniaturizing the cameras flying in interplanetary spacecraft. Fortunately, I knew what made the incumbent CCD [charge-coupled device sensors] technology work well and that making an image sensor in CMOS technology would open the door to a “camera-on-a-chip” and other tiny cameras. It was a matter of implementing the positive attributes of CCDs in a baseline CMOS technology.

Can you breakdown CMOS technology?

CMOS technology, developed since 1963, is used in today's mainstream microelectronics, such as microprocessors. Usually each CMOS circuit has two types of complementary transistor structures that lead to low power dissipation and some nice operating properties that make circuit design easier. Building an image sensor in a baseline CMOS process meant we could use existing analog and digital circuits on the same chip as the image sensor and use mainstream microelectronics fabrication techniques—something not true with the older incumbent CCD technology.

What has it been like to watch your technology take off?

Originally, there was widespread doubt and resistance to this technology and overcoming that among technical peers as well as in the commercial business sector was quite a sustained challenge. It started off being very exciting when the first consumer devices became available on store shelves, and seeing “CMOS” on the outside of consumer camera products today is still a thrill. But overall it is a little overwhelming, as the technology has a life of its own. Perhaps more overwhelming is seeing how a ubiquitous camera technology has made all kinds of social impact and launched social debates on security vs. privacy, for example.

What are your current research goals at Dartmouth?

My Ph.D. students are working, with sponsorship by Rambus, Inc., on the “Quantum Image Sensor” (QIS) to try to count every photoelectron generated by light in the image sensor and record its location and time as accurately as we can. Implementing a commercially viable QIS has many challenges, but if we can solve those challenges, then there would be a major paradigm shift in imaging. Still, I can’t help but think of how unlikely it is that lightning will strike twice in my career!

How has this work, combined with teaching, been rewarding for you?

It is a luxury to be able to explore new ideas for image sensors in such a vibrant environment, and I like teaching undergraduates and also sharing my entrepreneurial experiences with the students in our Ph.D. Innovation Program.

Tags: award, faculty, innovation, innovation program, patent, research

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