• Unusual Format Electronics -- Large Area, Flexible and Stretchable
• Microfluidics and Liquid Crystals for Photonics
• Unconventional Techniques for Nanofabrication
• Microstructural Acoustics and Picosecond Ultrasonics

Unusual Format Electronics -- Large Area, Flexible and Stretchable:

The field of large area, flexible and stretchable electronics is interesting partly because it has the potential to enable useful devices - flexible paperlike displays, woven electrotextiles, low cost identification tags, etc - that might be difficult to achieve with established silicon technologies. In addition, many of the materials and processing approaches developed for this area are important for a variety of emerging carbon-based nanoelectronic systems that might have roles in future high density memories or processors. This project focuses on fundamental and applied aspects related to the active organic and inorganic materials and the lithographic methods that are used to pattern circuits out of them. The work involves materials ranging from small molecule semiconductors, to polymeric electroluminescent materials, to single wall carbon nanotubes, to organic self-assembled monolayers to micro/nanostructures of single crystal inorganics. Patterning these materials into active electronic components allows their chemistry, mechanics and other basic properties to be correlated to device performance.

Recent papers:

H.C. Ko, M.P. Stoykovich, J. Song, V. Malyarchuk, W.M. Choi, C.-J. Yu, J.B. Geddes, J. Xiao, S. Wang, Y. Huang and J.A. Rogers, “A Hemispherical Electronic Eye Camera Based on Compressible Silicon Optoelectronics,” Nature 454, 748-753 (2008).

Q. Cao, H.-S. Kim, N. Pimparkar, J.P. Kulkarni, C. Wang, M. Shim, K. Roy, M.A. Alam and J.A. Rogers, “Medium-Scale Carbon Nanotube Thin-Film Integrated Circuits on Flexible Plastic Substrates,” Nature 454, 495-500 (2008).

M.J. Schultz, X. Zhang, S. Unarunotai, D.-Y. Khang, Q. Cao, C. Wang, C. Lei, S. MacLaren, J.A.N.T. Soares, I. Petrov, J.S. Moore and J.A. Rogers, “Synthesis of Linked Carbon Monolayers: Films, Balloons, Tubes, and Pleated Sheets,” Proceedings of the National Academy of Sciences USA 105(21), 7353-7358 (2008).

C. Kocabas, H.-S. Kim, T. Banks, J.A. Rogers, A.A. Pesetski, J.E. Baumgardner, S. V. Krishnaswamy and H. Zhang, “Radio Frequency Analog Electronics Based on Carbon Nanotube Transistors,” Proceedings of the National Academy of Sciences USA 105(5), 1405-1409 (2008).

D.-H. Kim, J.-H. Ahn, W.-M. Choi, H.-S. Kim, T.-H. Kim, J. Song, Y.Y. Huang, L. Zhuangjian, L. Chun and J.A. Rogers, “ Stretchable and Foldable Silicon Integrated Circuits,” Science 320, 507-511 (2008).

Microfluidics, Liquid Crystals and Plasmonics for Photonics and Sensors

This project seeks to exploit pumped microfluidics, plasmonic structures and liquid crystals for new classes of tunable photonic and sensing devices. It includes basic study and development of (i) means to fabricate microfluidic networks and plasmonic structures, (ii) phenomena, such as electrowetting, that can be used to pump the fluids, (iii) theoretical undersanding of these systems, and (iv) practical use ind devices. With proper designs, the motion of the fluids can be coupled to the optical properties of basic photonic elements such as planar waveguides and optical fiber. In another approach, it is possible to construct directly these and other elements (e.g. microlenses) out of fluidic structures whose shapes can be dynamically adjusted. These types of technologies have capabilities that can complement those of conventional systems. A closely related effort attempts to understand fundamental issues and practical considerations that define upper limits for the operating speed of liquid crystal based modulators and switches, and the fundamental aspects of anchoring and alignment in these systems. It includes a component that focuses on inventing unusual means to use liquid crystals for tunable fiber and integrated optical devices. Separate efforts seek to exploit plasmonic behaviors in metal nanostructures, for their use in sensing devices.

Recent papers:

M.E. Stewart, C.R. Anderton, L.B. Thompson, J. Maria, S.K. Gray, J.A. Rogers and R.G. Nuzzo, “Nanostructured Plasmonic Sensors,” Chemical Reviews 108, 494-521 (2008).

B.R. Acharya, C. Madsen, L. Moller, K.W. Baldwin, R.A. MacHarrie, C.C. Huang, R. Pindak and J.A. Rogers, "In-Line Liquid Crystal Microcell Polarimeters With Applications in 40 Gb/s Systems", Applied Optics, 42(27), 5407-5412 (2003).

J. Yao, M.E. Stewart, J. Maria, T.-W. Lee, S.K. Gray, J.A. Rogers and R.G. Nuzzo, “Seeing Molecules by Eye: Surface Plasmon Resonance Imaging at Visible Wavelengths with High Spatial Resolution and Submonolayer Sensitivity,” Angewandte Chemie International Edition 47, 5013-5017 (2008).

M.E. Stewart, N.H. Mack, V. Malyarchuk, J.A.N.T. Soares, T.-W. Lee, S.K. Gray, R.G. Nuzzo and J.A. Rogers, “Quantitative Multispectral Biosensing and 1D Imaging Using Quasi-3D Plasmonic Crystals,” Proceedings of the National Academy of Science USA, 103(46), 17143–17148 (2006).

V. Malyarchuk, F. Hua, N.H. Mack, V.T. Velasquez, J.O. White, R.G. Nuzzo and J.A. Rogers, “High Performance Plasmonic Crystal Sensor Formed by Soft Nanoimprint Lithography,” Optics Express 13(15), 5669-5675 (2005).

R. Lin and J.A. Rogers, “Molecular-Scale Soft Imprint Lithography for Alignment Layers in Liquid Crystal Devices,” Nano Letters 7(6), 1613-1621 (2007).

P. Mach, C. Kerbage, M. Dolinski, K.W. Baldwin, R.S. Windeler, B.J. Eggleton, J.A. Rogers, "Tunable Microfluidic Optical Fiber", Applied Physics Letters, 80(23), 4294-4296 (2002).

Unconventional Techniques for Nanofabrication

New tools for fabricating structures with micron and nanometer dimensions are critical to the progress of nanoscience and nanotechnology. This project seeks to develop soft lithographic and fluidic methods for nanofabrication, and to use them for building structures that are needed for basic and applied studies. Our recent efforts focus on methods for building 2D and 3D nanophotonic systems and for constructing organic transistors and diodes that have nanometer or molecular scale dimensions.

Recent papers:

J. Zaumseil, M.A. Meitl, J.W.P. Hsu, B. Acharya, K.W. Baldwin, Y.-L. Loo and J.A. Rogers, “Three-dimensional and Multilayer Nanostructures Formed by Nanotransfer Printing”, Nano Letters, 3(9), 1223-1227 (2003).

J.-U. Park, M. Hardy, S.J. Kang, K. Barton, K. Adair, D.K. Mukhopadhyay, C.Y. Lee, M.S. Strano, J.G. Georgiadis, P.M. Ferreira and J.A. Rogers, “High-Resolution Electrohydrodynamic Jet Printing,” Nature Materials 6, 782-789 (2007).

S. Jeon, J.-U. Park, R. Cirelli, S. Yang, C.E. Heitzman, P.V. Braun, P.J.A. Kenis, and J.A. Rogers, “Fabricating Complex Three Dimensional Nanostructures With High Resolution Conformable Phase Masks”, Proc. Nat. Acad. Sci. USA, 101(34), 12428-12433 (2004).

D. Shir, H. Liao, S. Jeon, D. Xiao, H.T. Johnson, G.R. Bogart, K.H.A. Bogart and J.A. Rogers, “Three-Dimensional Nanostructures Formed by Single Step, Two-Photon Exposures through Elastomeric Penrose Quasicrystal Phase Masks,” Nano Letters 8(8), 2236-2244 (2008).

S.J. Kang, C. Kocabas, H.-S. Kim, Q. Cao, M.A. Meitl, D.-Y. Khang and J.A. Rogers, ”Printed Multilayer Superstructures of Aligned Single-Walled Carbon Nanotubes for Electronic Applications,” Nano Letters 7(11), 3343-3348 (2007).

Microstructural Acoustics and Picosecond Ultrasonics:

Picosecond pulsed lasers provide a convenient source of acoustic waves with frequencies in the GHz range and with wavelengths between one and several hundred microns. This project seeks to develop and use these laser-based tools to study the high frequency acoustic responses of structures with characteristic dimensions that are similar to the acoustic wavelengths: thin films and membranes, multilayer stacks, microfluidic networks, etc. Analysis of these measurements yields intrinsic mechanical and thermal properties on micron length scales. These methods can also be used for basic studies of phononic bandgaps and other interesting acoustic phenomena in micro and nanofabricated structures.

Recent papers:

J.A. Rogers, G.R. Bogart and R.E. Miller, “Quantitative Non-Contact Spatial Mapping of Stress and Flexural Rigidity in Thin Membranes Using a Picosecond Transient Grating Photoacoustic Technique”, Journal of the Acoustical Society of America, 109(2), 547-553 (2001).

J.A. Rogers, “Impulsive Stimulated Thermal Scattering”, McGraw-Hill 2002 Yearbook of Science and Technology, (McGraw-Hill, 2002).

L. Dhar and J.A. Rogers, “High Frequency Phononic Crystals Characterized With a Picosecond Transient Grating Photoacoustic Technique”, Applied Physics Letters, 77(9), 1402-1404 (2000).

J.A. Rogers, A.A. Maznev, M.J. Banet and K.A. Nelson, “Optical Generation and Characterization of Acoustic Waves in Thin Films: Fundamentals and Applications”, Annual Reviews of Materials Science, 30, 117-157 (2000).