Dutch experimental physicist Eric Mazur. Photo: Eliza Grinnell/Harvard SEAS


Serendipity has played a key role in Professor Eric Mazur’s life, or at least in his career. That’s what the Dutch experimental physicist learned in his laser research and role as Academic Dean of Applied Sciences and Engineering at Harvard University in Cambridge, Mass.

Serendipity led to the invention of a new material that can absorb most visible and infrared light and ignited a teaching revolution that helps students to improve their problem solving skills. It has helped Professor Mazur become a successful founder of several startups and an educational innovator who is changing traditional education around the world.

Black silicon

“It was serendipity,” Professor Mazur said when he and his team discovered black silicon. They had been studying the interaction of ultrashort laser pulses with different materials for years and to spark new interest from his funders, Mazur promised to explore chemical reactions on semiconductor surfaces.

One such surface that his team experimented with was regular “gray” silicon. His graduate student placed a chip of the silicon in a vacuum chamber, filled it with sulfur hexafluoride gas, focused a high-intensity laser beam on the chip, and saw that the smooth surface turned into a black, light-absorbing forest of cones so tiny that 100 of them could fit inside a human hair.

They noticed that the spikes on the new material, which they dubbed “black silicon,” absorbed almost 98 percent of visible light – and even absorbed infrared light – a more potent quality than its source material.

As black silicon is an excellent light absorber, it could be used to absorb light in any application, Dr. Mazur explained. A leading example is solar cells, but “not the type of solar cells for your roof, but for applications where you need to get the maximum conversion of light into power, like a satellite.”

Black silicon is used in optical applications, such as detectors, sensors, and the night-vision cameras that Mazur’s first startup, SiOnyx, produces.

From the lab to Amazon.com

Professor Mazur only began considering commercializing his inventions when Harvard University’s Office of Technology Development asked him if he had any ideas that could be patented.

Harvard helps its researchers ensure their intellectual property is protected and managed, and it shares ownership of the royalties with the inventor and the lab. This prompted Mazur to consider ideas that could have an impact on society, had intellectual value, and needed to be protected. Black silicon fit the bill.

“Universities have two responsibilities: education and the advancement of knowledge,” he said. “I used to think that the currency of the advancement of knowledge was purely publications, and I think that’s certainly the mindset of most European universities. In the US, universities are branching out, not just into publications, but also into patents and they are trying to have an impact on society through intellectual property broadly defined. I think this is very healthy and it more strongly connects the university to society.”

Mazur co-founded SiOnyx in 2006 to commercialize black silicon. The company initially made night-vision cameras for the defense industry and expanded into the consumer market. But moving an idea from the lab to Amazon.com was not easy.

“One is the scientific discovery, the next is the engineering that’s required to turn the discovery into something reproducible and produce them so that they can be fabricated, and then comes the difficulty of raising the money to actually build the product,” he said.

Additionally, a board of directors that consisted mostly of investors without a scientific background who would sometimes steer the company in directions that the founders did not want to go. “For example, they pushed us very hard to get into solar applications, even though we knew that was not going to be an immediate product, and we wasted a lot of time.”

Maintaining control of his company was a valuable lesson Professor Mazur learned and applied in startups he later founded. SiOnyx managed successfully to launch a night-vision camera, but “it was a learning curve and a long and difficult road,” Mazur said. “I can understand why 90 percent of startups never make it and that many ideas die very early on in the commercialization process.”

Nanosurgery

Mazur’s work on ultrashort laser pulses continues to disrupt different fields, and his current research focuses on surgery inside a living cell. Human cells are protected by an outer membrane that is impermeable to most chemicals and materials.

“Otherwise, things would just go into the cell and destroy this very delicate mechanism that supports life,” Mazur said.

For years, researchers have been looking for ways to operate in cells and to get cargo into a cell, like implementing genetic material to remove genes that cause disease. Currently, there are a couple of techniques that could perform this kind of surgery, but not without problems.

Existing techniques, such as electroporation, use high voltage to open the cell’s membrane, but are rough, imprecise, and kill many cells in the process. Professor Mazur and his team showed that laser light can open pores in the membrane without destroying the cell or the cells that surround it, allowing precise surgery within a cell.

The challenge is to target enough cells to make a meaningful difference, but Mazur’s technique could help cure disease in the future.

Peer instruction

Mazur credits his family with developing his transformative style. They never hesitated to tackle any questions in childhood, not even awkward ones like “Why am I? or “What is the universe?”

His grandfather, a civil engineer, would give him things to tinker with, and when he was 10 he built his first transistor radio. “You don’t need to be a scientist, we’re all born curious. It’s sort of a sad fact that education beats it out of us.”

After his physics study in Leiden University, he took his father’s advice and went to Harvard to do a postdoc, where he worked with Nobel laureate physics Nicolaas Bloembergen. At Harvard he started a research group that studied the effects of ultrashort laser pulses on different materials and became a professor at Harvard.

When he started teaching physics to pre-medical students nearly four decades ago, he simply imitated his teachers in education via lecture. “For many years I went on thinking that I was a successful educator,” Mazur said. His students did well on their exams and he received high ratings from them in return.

After a number of years, he read an article by physicist David Hestenes that claimed students did not learn anything in their introductory physics course. Hestenes had tested students to see if they understood the concept of “force” and tested their knowledge with real-life examples. They scored badly, as they did not understand the principles behind the formulas. Mazur decided to give his Harvard students the same test, and to his dismay he found out that the majority did poorly.

“Students were able to solve textbook problems and pass exams, but if I asked some very basic word-based questions, they had no clue what I was asking,” he said.

He tried to explain one of the answers to the test, but after 10 minutes his students still looked puzzled. Mazur knew half of the students had given the right answer and in a moment of despair he asked, “Why don’t you discuss it with each other?”

Chaos broke out in class as 250 students discussed the problem with each other, but to his surprise the students who knew the right answer convinced the rest in just two minutes. He realized that the students who had recently learned the material knew where the difficulties were in understanding, whereas he, who had learned it a long time ago, forgot about the difficulties of a beginning learner. This serendipitous discovery changed the way he would teach forever.

He stopped lecturing and started teaching through questioning. He asks his students to read the textbook or his notes before class and in class he asks conceptual, open-ended questions on a relevant topic. After students commit to an answer, Mazur asks them to find a neighbor with a different perspective to convince the other of their answer.

“You see a lot of students as they’re talking have an ‘aha moment,’” Mazur said. “Once you have that aha moment, you know it for life, not just to pass the exam.” He then wraps up with an explanation and the cycle repeats.

Data from these interactive classes demonstrated that this learning method tripled the students’ gains in knowledge. The model also helps to close the knowledge gap between male and female science students in the US and Nordic European countries, where men tend to perform better than women in sciences, Mazur said. “When I lectured that gap just translated up, men gained, women gained, but the gap persisted. With peer instruction, I was able to double the gains, but the women disproportionately gained and the gap was eliminated at the end of the year.”

“Peer Instruction: A User’s Manual,” the book that Mazur published about his learning method, has inspired instructors all over the world. To Mazur’s surprise, Stanford University was one of the first to revise its introductory physics courses to peer instruction, whereas his own Harvard colleagues followed only later.

“It’s kind of ironic. You’re never a prophet in your own backyard,” Mazur said. “Many Dutch universities, such as the University of Groningen and the University of Amsterdam, have been active with this learning method. There’s been a huge transformation in the past 10 years, moving away from passive lecturing to more engaged learning.”

Read about other Dutch researchers in the United States.