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Cover Image

Rarest Flower: This picture is a false-color scanning electron microscopy image of a collapsed carbon nanotube (CNT) pillar. The pillar is fabricated using chemical vapor deposition process on a substrate that has been pre-coated with a thin-film iron catalyst. Here, the catalyst layer is patterned with a periodic array of five-pointed stars. Subsequent to the growth process, this pillar is subjected to oxygen plasma treatment and capillography process. The role of oxygen plasma treatment is twofold: to functionalize each CNT with oxygenated groups and to etch the outer portion of the pillar. The capillography process is performed to collapse CNT pillars radially inward.

Generally, the etching process of CNT pillars by oxygen plasma treatment occurs isotropically in both lateral and vertical directions. However, the presence of CNT entanglement at the tip of the pillar creates a directional variation in the etching process. Thus, the mid-section of the CNT pillar is typically etched faster than the tip. The mid-section of the CNT pillar is further collapsed when it is subjected to capillography process. The flower-like shape is then formed due to the mismatch in diameter of the mid-section and the tip of the CNT pillar.

A combination of oxygen plasma treatment and capillography process is utilized to reduce the size and to improve the CNT packing density of CNT pillars subsequent to the growth process. Such modification is deemed necessary whenever the CNT pillars are used as scaffolds for composite microneedles. These microneedles have been envisioned for use in a rapid self-administered and painless drug delivery system, replacing the commonly used hypodermic needles.

The Caltech Division of Engineering and Applied Science consists of seven departments and supports close to 90 faculty who are working at the edges of fundamental science to invent the technologies of the future.


Message From The Chair

Ares Rosakis

Snap Shots

French Republic's Order of Academic Palms
Decreasing the Energy Bill of California Homeowners
The Art of Data
Engineers Without Borders

Alumni Profile

James E. Hall

Progress Report

Untangling Turbulence

EAS Feature

Medical Engineering
A Moral Obligation

Progress Report

Move Bits not Watts
Algorithms for Sustainable Data Centers

Alumni Profile

Clive Smith
Using Mathematics to Reinvent the Stethoscope

Research Note

Therapeutic Bubbles

Campus Resource

Asking the Tough Questions
Caltech Center for Teaching, Learning, and Outreach


Trity Pourbahrami


Vicki Chiu


Leona Kershaw

Copy Editor

Sara Arnold

Contributing Writers

Jeff Mortimer
Vicki Chiu

Image Credits

Cover: Adrianus Indrat Aria (advisor: Morteza Gharib)
p. 2: Robert Whittlesey, MS Aero '09, PhD Aero '13 (advisor: John O. Dabiri)
pp. 3, 11, 15, 16, 18, 19, 21, 22, 23, 24, 26, 27, 28, 32, 35, 40, 43: Vicki Chiu p. 4: French Republic: Bill Youngblood; Esha Wang: Janet Wang
p. 5: Interactive Game of Life: Alan Menezes; Mushkin, Exoskeleton: Russell Smith; bottom right: courtesy of Engineers Without Borders, University of Colorado-Boulder Chapter
pp. 6, 8: Courtesy of Jim Hall
p. 9: Trity Pourbahrami
p. 10: Hanabusa Itcho
p. 12: Caltech/JPL/Art Center Data Visualization Summer Internship Program and McKeon Research Group
p. 17: Courtesy of Gharib Group
pp. 20, 25, 30, and inside front cover: Lance Hayashida
p. 31: Wenbin Du, reproduced with permission from Royal Society of Chemistry from Lab on a Chip, 2010
pp. 36–39: Courtesy of Clive Smith
p. 37: Laennec stethoscope: Science Museum/Science & Society Picture Library
Inside back cover: © AC Martin 2013