Klavs Flemming Jensen (born August 5, 1952) is a chemical engineer who is now the Warren K. Lewis Professor at the Massachusetts Institute of Technology (MIT).

In 2002, Jensen was chosen to be a member of the National Academy of Engineering for important work in chemical reaction engineering at different scales. His research has helped improve processes for making materials used in microelectronics and developing microreactor technology.

From 2007 to July 2015, Jensen led the Department of Chemical Engineering at MIT.

Education and career

Jensen studied chemical engineering at the Technical University of Denmark, where he earned a Master of Science degree in 1976, and at the University of Wisconsin–Madison, where he received a Doctor of Philosophy degree in 1980. His PhD advisor was W. Harmon Ray. In 1980, Jensen began working as an assistant professor of chemical engineering and materials science at the University of Minnesota. He was promoted to associate professor in 1984 and to full professor in 1988. In 1989, he moved to the Massachusetts Institute of Technology.

At MIT, Professor Jensen held several positions, including the Joseph R. Mares Career Development Chair in Chemical Engineering from 1989 to 1994, the Lammot du Pont Professor of Chemical Engineering from 1996 to 2007, and the Warren K. Lewis Professor of Chemical Engineering from 2007 to the present. Klavs served as Head of the MIT Department of Chemical Engineering from 2007 to 2015. In 2015, Professor Jensen became the founding chair of the scientific journal Reaction Chemistry and Engineering, published by the Royal Society of Chemistry. The journal focuses on connecting chemistry and chemical engineering.

Research

Jensen's work focuses on methods to mix and separate chemicals for making medicines step by step, ways to automate chemical processes, and tools to study and control living cells. He is considered one of the first scientists to develop flow chemistry.

Jensen, Armon Sharei, and Robert S. Langer started a company called SQZ Biotech. Along with Andrea Adamo, they created the cell squeezing method in 2012. This method gently presses cells to let molecules enter them. It is a fast, safe system that uses tiny channels to deliver materials into cells without using harmful substances or electricity.

Jensen, Timothy F. Jamison, Allan Myerson, and others designed a mini factory the size of a refrigerator to make drugs ready for use in medical treatments. The mini factory can produce thousands of drug doses in about two hours. This system helps address sudden public health needs, supports medicine production in developing countries, and makes drugs with short shelf lives easier to create. In 2016, Chemical & Engineering News listed the mini factory as one of the most important chemistry research advances.

Cell Squeeze is the name for a method that changes the shape of a cell by passing it through a narrow opening. This process temporarily breaks the cell’s outer layer, allowing materials to enter the cell. It is an alternative to methods that use electricity or special proteins, and it works like a tool that gently presses cells without breaking them completely.

The pressure change that disrupts the cell is created by moving cells through a narrow channel in a tiny device. The device has channels carved into a flat piece of material. As cells move through the channel, the space becomes smaller. The cell’s flexible outer layer stretches and becomes thinner, letting it pass through. The cell’s width decreases by about 30 to 80 percent, and the sudden shape change creates small holes in the outer layer without harming the cell.

When the cell’s outer layer is temporarily broken, molecules nearby can enter the cell through the holes. As the cell returns to its normal shape, the holes close. This method can deliver almost any type of molecule into any kind of cell. It can process about one million cells each second. Compared to electrical or chemical methods, this mechanical approach causes fewer changes in how genes are expressed, which is helpful for studies that need to control gene activity.

Like other methods that let materials enter cells, this technique can deliver substances such as proteins, siRNA, or carbon nanotubes into cells. It has been tested on more than 20 types of cells, including stem cells and immune cells. Early uses included delivering:
– Anti-HIV siRNA to block HIV infection in CD4+ T cells.
– Whole proteins that help immune cells recognize and respond to diseases, supporting vaccine development.

The process was first created in 2013 by Armon Sharei and Andrea Adamo in the lab of Langer and Jensen at the Massachusetts Institute of Technology. In 2014, Sharei started SQZBiotech to show how the technology works. That same year, SQZBiotech won the $100,000 grand prize in a startup competition run by MassChallenge.

Boeing and the Center for the Advancement of Science in Space (CASIS) gave SQZBiotech the CASIS-Boeing Prize for Technology in Space to support using Cell Squeeze on the International Space Station (ISS).

Honours

Jensen received a Guggenheim Fellowship in 1987. In 2004, he was chosen as an Elected Fellow of the Royal Society of Chemistry. In 2007, he became an Elected Fellow of the American Association for the Advancement of Science. He joined the National Academy of Engineering in 2002 and the American Academy of Arts and Sciences in 2008. In May 2017, he was elected to the National Academy of Sciences for his "distinguished and continuing achievements in original research."

In 2008, Jensen was named one of the "100 Chemical Engineers of the Modern Era" by the American Institute of Chemical Engineers' Centennial Celebration Committee. In March 2012, he became the first person to receive the IUPAC-ThalesNano Prize in Flow Chemistry. In 2016, he was listed in Foreign Policy magazine's ranking of leading global thinkers alongside Timothy F. Jamison and Allan Myerson. That same year, he received the AIChE Founders Award for Outstanding Contributions to the Field of Chemical Engineering. Jensen has also been honored with the National Science Foundation Presidential Young Investigator Award.

Selected works

Klavs Jensen has written many articles in scientific journals about important progress in flow chemistry, microfluidics, chemical vapor deposition, and chemical engineering. These include but are not limited to:

• Bashir O Dabbousi, Javier Rodriguez-Viejo, Frederic V Mikulec, Jason R Heine, Hedi Mattoussi, Raymond Ober, Klavs F Jensen, Moungi G Bawendi "CdSe ZnS core− shell quantum dots: synthesis and characterization of a size series of highly luminescent nanocrystallites," Journal of Physical Chemistry B, Volume 46, Issue 101, Pages 9463–9475 (1997).

• Jamil El-Ali, Peter K Sorger, Klavs F Jensen "Cells on Chips," Nature, Volume 442, Issue 7101, Page 403 (2006).

• Klavs F Jensen "Microreaction engineering – is small better?," Chemical Engineering Science, Volume 56, Issue 2, Pages 293–303 (2001).

• Jinwook Lee, Vikram C Sundar, Jason R Heine, Moungi G Bawendi, Klavs F Jensen "Full color emission from II–VI semiconductor quantum dot–polymer composites," Advanced Materials, Volume 12, Issue 15, Pages 1102–1105 (2000).

• Axel Gunther, Klavs F Jensen "Multiphase microfluidics: from flow characteristics to chemical and materials synthesis," Lab on a Chip, Volume 6, Issue 12, Pages 1487–1503 (2006).

• Harry Moffat, Klavs F Jensen "Complex flow phenomena in MOCVD reactors: I. Horizontal reactors," Journal of Crystal Growth, Volume 77, Issues 1–3, Pages 108–119 (1986).

• Lisi Xie, Qing Zhao, Klavs F. Jensen, Heather J. Kulik "Direct Observation of Early-Stage Quantum Dot Growth Mechanisms with High-Temperature Ab Initio Molecular Dynamics," The Journal of Physical Chemistry C, Volume 120, Issue 4, Pages 2472–2483 (2016).