Darren J. Lipomi, Ph.D.
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My name is Darren Lipomi. I am a scientist interested in the overlap between three areas: micro- and nanofabrication and processing, soft electronics, and chemical synthesis. I am interested in fundamental and applied studies that relate molecular and nanoscale structure to function, and in devices that incorporate new physical effects to solve real-world problems. What motivates me is the potential of new materials and new forms of old materials to produce, store, and save energy, and to improve human well-being.
I earned my Ph.D. from the Department of Chemistry and Chemical Biology at Harvard University in June, 2010. I worked in the laboratory of Professor George M. Whitesides in the areas of materials chemistry; nanofabrication, including soft lithography and nanoskiving; materials for optics and electronics; chemical synthesis; and organic photovoltaics. My current position is as a US Intelligence Community Postdoctoral Fellow at Stanford University, department of Chemical Engineering, in the Laboratory of Professor Zhenan Bao, where my work focuses on organic materials for mechanically compliant photovoltaic cells and electronic skin.
I am an author on twenty-two publications (including fifteen first-author and three cover articles). Competitive fellowships supported my research at every stage of my education: undergraduate (Beckman Scholars Program); graduate (ACS Division of Organic Chemistry Fellowship); and postdoctoral (US Intelligence Community Fellowship). I served for a year as the chair of the Graduate Student & Postdoc Council in my department at Harvard, and I have a certificate ("mini MBA") from the Stanford University Graduate School of Business. My research has been covered by around one hundred news organizations and sci-tech websites, including CNN, Nature, Popular Science (twice), Wired (twice), Physics World, CNET, PCWorld, and Gizmodo. Two funded grants for which I wrote the scientific content generated a total of $570,000 for my graduate and postdoctoral laboratories. I am a member of the American Institute of Chemical Engineers (AIChE), the Materials Research Society (MRS), and the American Chemical Society (ACS).
Applications of Stretchable, Transparent Conductors: Solar Cells & "E-Skin"
Since arriving at Stanford, my research has focused on a number of different materials and approaches to generate stretchable, transparent electrodes. Materials that do not fail under significant tensile strain are potentially useful for applications that require reversible stretchability, extreme flexibility, and one-time bonding to non-planar surfaces other than cones and cylinders. I invented a stretchable plastic solar cell bearing a wavy microstructure (rendered elastic by mechanical buckling), that could be integrated into fabrics, moving parts of the body or machines, or bonded to the exteriors of cars or architectural elements without wrinkling (below). Another area I am developing is the use of carbon-based nanomaterials as stretchable electrodes in transparent elastic touch sensors ("e-skin").
Unconventional Micro- and Nanofabrication for Electronic & Optical Applications
My Ph.D. work characterized and developed several extensions of a technique called "nanoskiving"—a simple and inexpensive method of nanofabrication, originally invented by a former colleague, Qiaobing Xu, in 2004. Nanoskiving requires three steps: i) chemical synthesis and/or deposition of a metallic, semiconducting, ceramic, or polymeric thin film onto an epoxy substrate (which may be topographically patterned); ii) embedding this film in epoxy, to form an epoxy block, with the film as an inclusion; and, the key step, iii) sectioning the epoxy block into slabs with an ultramicrotome. These epoxy slabs, which can be 30 nm – 10 μm thick, contain nanostructures whose lateral dimensions are equal to the thicknesses of the embedded thin films, and thus can be as thin as 10 nm. When combined with soft lithographic molding and other processes, nanoskiving can produce patterns of structures that can be transferred to almost any substrate, and that would be difficult or impossible to generate by other procedures. Optical applications of structures produced by this method include surface plasmon resonators, plasmonic waveguides, and frequency-selective surfaces. Electronic applications include nanoelectrodes for electrochemistry, chemoresistive nanowires, and heterostructures of organic semiconductors that exhibit a photovoltaic effect.
In addition to nanoskiving, I also helped develop Indentation Lithography (nanoscratch lithography using a commercial, diamond-tipped indenter) and Topographically Encoded Microlithography (TEMIL), a technique of shadow evaporation that enables the fabrication of silicon microelectronic devices using a single step of photolithography and a series of angle-dependent physical vapor depositions. In a book chapter, "Green Nanofabrication", my co-authors and I explored the idea that nanofabrication itself could be a target for the reduction of waste by exploiting unconventional patterning and processing techniques.
Asymmetric Synthesis and Green Reaction Methodology
In my undergraduate work, I synthesized, for the first time, two antifungal compounds, basiliskamides A and B, pictured below. (See publications.)
I also developed a three-component reaction using solid, recyclable Bronsted acid catalysts to generate homoallylic amines from an aldehyde, carbamate, and chiral allyl- and crotylsilanes. The reaction proceeded at room temperature in acetonitrile, and could even be run in a single-pass reaction column.
News
May 3, 2012. I learned that I was the top applicant for the faculty search for Advanced Energy Technologies in the Jacobs School of Engineering at the University of California, San Diego! I will be starting a new faculty position in the Department of NanoEngineering on July 1st!
April 4, 2012. Congratulations to Kaltenbrunner et al. for achieving highly efficient and lightweight stretchable organic solar cells, as published in Nature Communications! The authors used a similar approach to what I described in "Stretchable Organic Solar Cells" in Advanced Materials. To read my argument for why mechanical compliance is a necessity for many future applications of photovoltaics, see my article in Energy & Environmental Science, "Stretchable, Elastic Materials and Devices for Solar Energy Conversion".
March, 2012. Due to strong sales, there will be a Second Edition of Nanotechnology for the Energy Challenge, of which I contributed Chapter 10 on "Green Nanofabrication"(available at fine bookstores everywhere)!
February, 2012. Congratulations to first author Phil Kim for getting the cover artwork for our paper in Nano Letters.
January 30, 2012. I was interviewed on the Big Picture Science radio show on our stretchable, transparent conductors for applications in solar energy conversion and electronic skin. Thanks to Molly Bentley for producing the segment!
December, 2011. Chemical Engineering Progress, published by the American Institute of Chemical Engineers (AIChE), ran a story (p. 6, subscription required) in the Update section on our transparent, stretchable, nanotube-based conductors for solar cells and electronic skin: the key result of our paper in Nature Nanotechnology. Thanks to Michelle Bryner for doing the write-up!
October 25, 2011. The results presented in our paper in Nature Nanotechnology have been covered by more than forty organizations (and counting), including Popular Science, Wired, CNET, PCWorld, and Gizmodo.
October 24, 2011. Our Nature Nanotechnology paper was the top story in today's Stanford Report. Thanks to Lou Bergeron and Steve Fyffe for doing a great press release and video!
October 23, 2011. Our paper "Skin-Like Pressure and Strain Sensors Based on Transparent Elastic Films of Carbon Nanotubes" appeared online today in Nature Nanotechnology. Details to follow.
September 5, 2011. My review in Angewandte Chemie, International Edition (English) and Angewandte Chemie (German) on the combination of chemical synthesis and self-assembly with top-down methods of nanofabrication ("Nanoskiving") was in print today.
September 2, 2011. I learned I won the grand prize (an iPad 2!) at the UW Chemical Engineering Distinguished Young Scientist Seminar Series. There were ninety applicants. Of those ninety, eight were selected for on-site, mock interviews.
August, 2011. My article "Stretchable, elastic materials and devices for solar energy conversion" was one of the top-ten most accessed articles in Energy & Environmental Science.
July 25, 2011. I gave the Distinguished Young Scientist Seminar Series at the University of Washington, Seattle, Department of Chemical Engineering on July 25th. Many thanks to all involved in putting the seminar series together. Seattle and UW are great places.
April 15, 2011. Stretchable Organic Solar Cells was selected for a full page frontispiece in Advanced Materials.
April 7, 2011. Philseok Kim's paper received a write-up in Nature. Nanotechnology: Painting and shaping pillars.
March 8, 2011. Short write-up in this week's Nature. "Solar cells take a stretch."
February 28, 2011. CNN aired a story on our electronic skin, and included my contribution on stretchable organic solar cells.
February 25, 2011. Stretchable solar cells featured on Optics and Photonics News.
February 22, 2011. Our work on stretchable organic solar cells was featured in Stanford News here.
September 22, 2010. Our paper "Survey of Materials for Nanoskiving and Influence of the Cutting Process on the Nanostructures Produced" by Darren J. Lipomi, Ramses V. Martinez, Robert M. Rioux, Ludovico Cademartiri, William F. Reus, and George M. Whitesides is featured on the current cover of ACS Applied Materials & Interfaces.
September 20, 2010. Nanotechnology for the Energy Challenge received nice reviews from these publications:
August 31, 2010. Topographically Encoded Microlithography (TEMIL) was featured in Materials Views on Wiley's website.
July 2010. "Fabrication and Replication of Single- or Multicomponent Nanostructures by Replica Molding and Mechanical Sectioning" was featured in the Perspective by Benjamin Wiley, Dong Qin, and Younan Xia and the Editorial by Paul Weiss in the July issue of ACS Nano.
July 2010. Our paper "Fabrication and Replication of Single- or Multicomponent Nanostructures by Replica Molding and Mechanical Sectioning" was featured on the cover of ACS Nano in July 2010.
March 2010. Nanotechnology for the Energy Challenge is now available at fine bookstores everywhere. Chapter 10 - "Green Nanofabrication: Unconventional Approaches for the Conservative Use of Energy" - was written by me, Emily Weiss and George Whitesides.
November 2009. My essay Plastic Solar Cells: Science, Expectations, and Challenges won the $2,500 grand prize in the University Science Writing Competition on ScientificBlogging.com.
