Genesis of Creativity

James M. Tour*

Departments of Chemistry, Computer Science, and Mechanical Engineering and Materials Science, and the Smalley Institute for Nanoscale Science and Technology,Rice University, 6100 Main Street, Houston, Texas 77005, United States

ACS Nano, Article ASAP

DOI: 10.1021/nn301299x

Publication Date (Web): April 26, 2012

Copyright © 2012 American Chemical Society

As advances in nanoscience and nanotechnology are sought, what will be the source of the inspiration to open the doors for new developments? In my opinion, it most often resides in the ingenuity of students, and among those ingenious students, was there a formative spark or a progressive set of stimuli in their childhoods that gave rise to the most precious asset in scientific advance, namely, creativity? Here, I outline the work of three of my students who have propelled the field of nanotechnology, and then I glimpse into their childhood years to see if there lays the key.

Electromechanical Actuator with Controllable Motion, Fast Response Rate, and High-Frequency Resonance Based on Graphene and Polydiacetylene

Jiajie Liang†, Lu Huang†, Na Li†, Yi Huang†*, Yingpeng Wu†, Shaoli Fang‡, Jiyoung Oh‡, Mikhail Kozlov‡, Yanfeng Ma†, Feifei Li†, Ray Baughman‡, and Yongsheng Chen†*

^† Key Laboratory of Functional Polymer Materials and Centre for Nanoscale Science and Technology, Institute of Polymer Chemistry, College of Chemistry, Nankai University, 300071, Tianjin, China

^‡ Alan G. MacDiarmid NanoTech Institute, University of Texas at Dallas, Richardson, Texas 75083, United States

ACS Nano, Article ASAP

DOI: 10.1021/nn3006812

Publication Date (Web): April 18, 2012

Copyright © 2012 American Chemical Society

Although widely investigated, novel electromechanical actuators with high overall actuation performance are still in urgent need for various practical and scientific applications, such as robots, prosthetic devices, sensor switches, and sonar projectors. In this work, combining the properties of unique environmental perturbations-actuated deformational isomerization of polydiacetylene (PDA) and the outstanding intrinsic features of graphene together for the first time, we design and fabricate an electromechanical bimorph actuator composed of a layer of PDA crystal and a layer of flexible graphene paper through a simple yet versatile solution approach. Under low applied direct current (dc), the graphene–PDA bimorph actuator with strong mechanical strength can generate large actuation motion (curvature is about 0.37 cm^–1 under a current density of 0.74 A/mm²) and produce high actuation stress (more than 160 MPa/g under an applied dc of only 0.29 A/mm²). When applying alternating current (ac), this actuator can display reversible swing behavior with long cycle life under high frequencies even up to 200 Hz; significantly, while the frequency and the value of applied ac and the state of the actuators reach an appropriate value, the graphene–PDA actuator can produce a strong resonance and the swing amplitude will jump to a peak value. Moreover, this stable graphene–PDA actuator also demonstrates rapidly and partially reversible electrochromatic phenomenon when applying an ac. Two mechanisms—the dominant one, electric-induced deformation, and a secondary one, thermal-induced expansion of PDA—are proposed to contribute to these interesting actuation performances of the graphene–PDA actuators. On the basis of these results, a mini-robot with controllable direction of motion based on the graphene–PDA actuator is designed to illustrate the great potential of our discoveries for practical use. Combining the unique actuation mechanism and many outstanding properties of graphene and PDA, this novel kind of graphene–PDA actuator exhibits compelling advantages to traditional electromechanical actuation technology and may provide a new avenue for actuation applications.

Sliding on a Nanotube: Interplay of Friction, Deformations and Structure

1. Hsiang-Chih Chiu^1,*, 
2. Beate Ritz³, 
3. Suenne Kim¹, 
4. Erio Tosatti², 
5. Christian Klinke³, 
6. Elisa Riedo^1,*

Article first published online: 27 APR 2012

DOI: 10.1002/adma.201104712

The frictional properties of individual carbon nanotubes (CNTs) are studied by sliding an atomic force microscopy tip across and along its principle axis. This direction dependent frictional behavior is found to strongly correlate with the presence of structural defects, surface chemistry, and CNT chirality. This study shows that it is experimentally possible to tune the frictional/adhesion properties of a CNT by controlling the CNT structure and surface chemistry, as well as use friction force to predict its structural and chemical properties.

Paper-Based, Capacitive Touch Pads

1. Aaron D. Mazzeo¹, 
2. William B. Kalb¹,
3. Lawrence Chan¹, 
4. Matthew G. Killian¹, 
5. Jean-Francis Bloch², 
6. Brian A. Mazzeo³, 
7. George M. Whitesides^1,4,*

Article first published online: 27 APR 2012

DOI: 10.1002/adma.201200137

Metallized paper is patterned to create touch pads of arrayed buttons that are sensitive to contact with both bare and gloved fingers. The paper-based keypad detects the change in capacitance associated with the touch of a finger to one of its buttons. Mounted on an alarmed cardboard box, the keypad requires the appropriate sequence of touches to disarm the system.

Light Bends by Itself

Ido Kaminer, Rivka Bekenstein, Jonathan Nemirovsky, and Mordechai Segev Physics Department and Solid State Institute, Technion, Haifa 32000, Israel

Phys. Rev. Lett. 108, 163901 (2012)

We present the nondiffracting spatially accelerating solutions of the Maxwell equations. Such beams accelerate in a circular trajectory, thus generalizing the concept of Airy beams to the full domain of the wave equation. For both TE and TM polarizations, the beams exhibit shape-preserving bending which can have subwavelength features, and the Poynting vector of the main lobe displays a turn of more than 90°. We show that these accelerating beams are self-healing, analyze their properties, and find the new class of accelerating breathers: self-bending beams of periodically oscillating shapes. Finally, we emphasize that in their scalar form, these beams are the exact solutions for nondispersive accelerating wave packets of the most common wave equation describing time-harmonic waves. As such, this work has profound implications to many linear wave systems in nature, ranging from acoustic and elastic waves to surface waves in fluids and membranes.

Injectable protein nanofactories

Nature

 

484,

 

290

 

(19 April 2012)

 

doi:10.1038/484290c

Published online

 

18 April 2012

Daniel Anderson and his group at the Massachusetts Institute of Technology in Cambridge created lipid spheres more than 100 nanometres in diameter that contained DNA and all the cellular ingredients and machinery needed to make proteins. By tagging the DNA with a chemical group that prevents it from being transcribed into RNA but can be removed using ultraviolet light, the researchers were able to control activation of RNA and protein production.

High-Efficiency Si/Polymer Hybrid Solar Cells Based on Synergistic Surface Texturing of Si Nanowires on Pyramids

1. Lining He^1,2,3, 
2. Donny Lai^1,3, 
3. Hao Wang¹,
4. Changyun Jiang^2,*, 
5. Rusli^1,3,*

Article first published online: 21 MAR 2012

DOI: 10.1002/smll.20110209

An efficient Si/PEDOT:PSS hybrid solar cell using synergistic surface texturing of Si nanowires (SiNWs) on pyramids is demonstrated. A power conversion efficiency (PCE) of 9.9% is achieved from the cells using the SiNW/pyramid binary structure, which is much higher than similar cells based on planar Si, pyramid-textured Si, and SiNWs. The PCE is the highest reported to-date for hybrid cells based on Si nanostructures and PEDOT

High-Throughput Transfection of Interfering RNA into a 3D Cell-Culture Chip

1. Zhang¹, 
2. Moo-Yeal Lee², 
3. Michael G. Hogg², 
4. Jonathan S. Dordick¹, 
5. Susan T. Sharfstein^3,*

Article first published online: 17 APR 2012

DOI: 10.1002/smll.20110220

1.  Amethod for high-throughput retroviral transfection of genes and interfering RNA into 3D cell-culture microarrays is described. 3D cultures more closely mimic the in vivo cellular milieu, thus providing cellular responses to genetic manipulation more similar to the in vivo situation than 2D cultures. This technique is applied to transfect several “toxic” short-hairpin RNAs (shRNAs) into 3D cell cultures. It is demonstrated that the toxicity is similar to that obtained by conventional (non-high-throughput) retroviral transfection of cells grown in similar 3D culture microarrays.

A Self-healing Conductive Ink

1. Susan A. Odom¹, 
2. Sarut Chayanupatkul²,
3. Benjamin J. Blaiszik², 
4. Ou Zhao¹, 
5. Aaron C. Jackson², 
6. Paul V. Braun², 
7. Nancy R. Sottos²,
8. Scott R. White^3,*, 
9. Jeffrey S. Moore^1,*

Article first published online: 10 APR 2012

DOI: 10.1002/adma.201200196

Electrical conductivity of mechanically damaged silver ink circuits is automatically restored using core–shell microcapsules. Upon mechanical damage to the circuit and microcapsules, silver particles reorganize by dissolution of the polymer binder layer upon release of solvent, hexyl acetate, from microcapsule cores. Conductivity is restored within minutes of damage, and no short-circuiting is revealed during the healing of closely spaced lines.

Dynamic Electrostatic Lithography: Multiscale On-Demand Patterning on Large-Area Curved Surfaces

1. Qiming Wang, 
2. Mukarram Tahir, 
3. Jianfeng Zang, 
4. Xuanhe Zhao^*

Article first published online: 10 APR 2012

DOI: 10.1002/adma.201290084

A new technology is invented, described on page 1947 by X. Zhao and coworkers, for the use of electrical voltages to dynamically generate various patterns on curved surfaces and over large areas, such as the surfaces of gloves. As a result, the texture and smoothness of these surfaces can be varied on demand for a wide variety of applications.