Xiangfeng Duan Receives 2022 Herbert Newby McCoy Award

Professor Xiangfeng Duan receives the prestigious 2022 McCoy Award, which recognizes the researchers in the department who have made the greatest contribution of the year to the science of chemistry and biochemistry

By Penny Jennings

This article was originally published by UCLA Chemistry

This year two faculty members received the 2022 Chemistry & Biochemistry Herbert Newby McCoy Award for their important research projects. Duan and Professor Juli Feigon (read about her research here) were recognized at our annual departmental awards ceremony on May 13, 2022. 

The Duan group and their UCLA collaborators developed a unique design of ultrathin films for highly flexible yet mechanically robust bioelectronic membranes that could pave the way for diagnostic on-skin sensors that fit precisely over the body’s contours and conform to its movements.  

These breakthrough advancements define the critical intellectual underpinning for a new generation of electronic membranes that may actively adapt into different form factors and readily merge with irregular objects or dynamic living organisms, while retaining sufficient electronic performance for sensing, signal amplification, processing and communication. It could open up exciting opportunities for diverse emerging applications, including wearable health monitoring devices, human-machine interfaces, robotic technologies, artificial intelligence; cellular-scale bioelectronics that accurately monitor electrophysiological signals at the organism or cell level. Such capabilities could greatly benefit future healthcare.

Artistic representation of a skin transistor made from van der Waals thin films. (Image credit: Yan et al./UCLA)

In February 2022, the prestigious journal Science published a paper describing the research and, in March 2022, the research was featured in the UCLA Samueli School of Engineering News.

“Conceptually, the membrane is like a much-thinner version of kitchen cling film, with excellent semiconducting electronic functionality and unusual stretchability that naturally adapts to soft biological tissues with highly conformal interfaces,” Duan said. “It could open up a diverse range of powerful sensing and signaling applications. For example, wearable health-monitoring devices built with this material can accurately track electrophysiological signals at the organism level or down to the level of individual cells.”

The layered patchwork design of van der Waals thin films enables the membrane to stretch and flex over irregular geometries. (Image credit: Yan et al./UCLA)

The development of flexible and stretchable electronic materials that adapt to irregular, soft biological substrates such as human skin is central for bioelectronic systems actively monitoring dynamic events in living organisms, diagnosing and treating human diseases for personalized medicine and telehealth. A robust bioelectronic system requires intimate interaction with biological structures to perform specific operations, such as biological signal recording, amplification, extraction, and delivering electrical or chemical stimulations, which is difficult to achieve with conventional electronic materials. Although hard inorganic materials may be made flexible in an ultrathin membrane format, they are hardly stretchable and cannot form conformal interfaces with irregular geometries with non-zero Gaussian curvatures due to fundamental topological limitations. Organic or composite semiconductor thin films may be made stretchable and conformal, but are usually of insufficient performance or limited stability in typical wet biological environments. To enable seamless semi-bio hybrids requires the development of new semiconductor materials with an unusual combination of high electronic performance, material stability, mechanical robustness at ultrathin thicknesses, exceptional flexibility, stretchability, adaptability and permeability.

Inspired by the universal van der Waals (VDW) interactions in biological assemblies, Duan and his team exploited the VDW interactions to assemble colloidal 2D nanosheets into a unique design of VDW thin films (VDWTFs) with an excellent mechanical match with soft biological tissues and a unique set of combined merits beyond the reach of existing materials: (1) within the VDWTFs, the dangling-bond-free 2D nanosheets are staggered with respect to each other to establish broad-area plane-to-plane vdW contacts with minimum interfacial trapping states to ensure excellent charge transport across the inter-sheet grain boundaries; (2) the bond-free VDW interactions between the 2D nanosheets greatly reduces the Young’s modulus and offers a natural mechanical match with soft biological assemblies that are typically characterized by vdW interactions; (3) when deformed, the bonding-free broad-area vdW interfaces allows 2D nanosheets to slide or rotate against each other to accommodate the local tension or compression without breaking the broad-area vdW interfaces and the conductive pathways, which is essential for achieving unusual stretchability and structural integrity in the ultrathin freestanding format; (4) with the unusual stretchability to accommodate local strains/deformations and overcome the topological limitations, the VDWTFs exhibit exceptional malleability and adaptability to irregular and dynamically changing surface topographies, in a way that is impossible with traditional thin-film materials; and (5) the VDWTFs feature percolating networks of nanoscale channels (dictated by nanosheet thickness: ~3 nm) winding around the staggered nanosheets for gas/nutrient permeation/exchange, which is critical for the breathability of bioelectronics.

Their recent studies have clearly demonstrated that freestanding VDWTFs feature a greatly reduced Young’s modulus of 47.3 MPa (~3 orders of magnitude smaller than that of bulk MoS2) and an exceptional stretchability of up to 60%; they can readily adapt to microscopic topographies and form high conformal interfaces. The resulting VWTFTs can seamlessly merge with soft, dynamically changing biological substrates to form low-voltage skin gate transistors with sufficient frequency response (>100 KHz) for on-skin amplification of electrophysiological signals, including electrocardiography (ECG) and electroencephalography (EEG) signals.

Together, the unique design of the VDWTFs promises an entirely new materials platform for highly flexible and stretchable electronics beyond the limit of traditional materials to satisfy the unusual demands of next- generation technologies. The resulting VDWTFs feature a unique combination of high electronic performance, material stability, mechanical robustness, exceptional flexibility, stretchability, adaptability and breathability. 

About the Herbert Newby McCoy Award

The Herbert Newby McCoy Award was established in 1964 by Mrs. Ethel Terry McCoy, also a chemist, in honor of her husband who was an American chemist who taught at the University of Chicago and the University of Utah and was the vice-president of Lindsay Light & Chemical Company. Each year the award is given to the researcher(s) in the department who made the greatest contribution of the year to the science of chemistry and biochemistry. The selection of the winner(s) is made by the full professors of the department and the Chancellor. Nobel Laureate Donald Cram was the recipient of the first McCoy Award in 1965.

  • 2022  Xiangfeng Duan, Juli Feigon
  • 2020-21 Ellen Sletten
  • 2019-20 Ohyun Kwon
  • 2018-19 Jose Rodriguez & Hosea Nelson
  • 2017-18 Hosea Nelson, Elena Grintsevich
  • 2016   Anastassia Alexandrova, Ankur Gholkar, Patrick Harran
  • 2015   Anne Hong-Hermesdorf, Kendall Houk, Neil Garg 
  • 2014   Jeffrey Zink
  • 2013   Janette Kropat, Heather Maynard, Thi Nguyen
  • 2012   Maher El-Kady, Jorge Torres
  • 2011   Xiangfeng Duan, Neil Garg 
  • 2010   Carla Koehler, Beth Marbois, Benjamin Schwartz
  • 2009   Juli Feigon, Mike Jung, Kenneth Stabe, Shiho Tanaka, Todd Yeates
  • 2008   Timothy Deming, Saeed Khan, Thomas Mason
  • 2007   Richard Kaner, Max Kopelevich, Sarah Tolbert
  • 2006   David Eisenberg, Rebecca Nelson, Michael Sawaya, Eric Scerri, Omar Yaghi
  • 2005   Dmitri Kudryashov, Emil Reisler, Michael Sawaya, M. Jane Strouse, Todd Yeates
  • 2004   Sabeeha Merchant
  • 2003   Alex Evilevitch, William Gelbart, Charles Knobler, Laurence Lavelle
  • 2002   Andrea Liu
  • 2001   Fred Wudl
  • 2000   J. Fraser Stoddart
  • 1999   Miguel Garcia Garcia-Garibay, Yves Rubin
  • 1998   James Bowie
  • 1997   Rafael Levine
  • 1996   Joan Valentine
  • 1995   Robin Garrell, James Heath, David Myles, Todd Yeates
  • 1994   Ken Houk, X. Zhang
  • 1993   Emily Carter, Juli Feigon, M. Jane Strouse, H. Xie
  • 1992   Peter Felker, Richard Kaner, Flint Smith
  • 1991   Michael Jung, David Sigman
  • 1990   Steven Clarke, François Diederich, R.L. Whetten, M. Anderson, B. Mattes
  • 1989   Charles Knobler, R.S. Williams
  • 1988   William Gelbart, Z. Xue
  • 1987   Douglas Rees, M. Miller
  • 1986   Charles West, F. Jensen
  • 1985   Jeffrey Zink, T. Smith
  • 1984   Malcom Nicol
  • 1983   Orville Chapman, W.D. Harris
  • 1982   Richard Dickerson, David Eisenberg
  • 1981   Eric Heller
  • 1980   Charles Knobler
  • 1979   Charles Strouse
  • 1978   John McTague
  • 1977   Christopher Foote
  • 1976   Paul Boyer
  • 1975   Donald Cram
  • 1974   Howard Reiss
  • 1973   Verne Schumaker
  • 1972   M. Fredrick Hawthorne
  • 1971   Daniel Kivelson
  • 1970   D.A. Harris, R.B. Gillespie
  • 1969   M.A. El-Sayed
  • 1968   Frank Anet
  • 1967   Daniel Atkinson
  • 1966   Saul Winstein
  • 1965   Donald Cram

Penny Jennings, UCLA Department of Chemistry & Biochemistry, penny@chem.ucla.edu.