The NanoRobotics Lab's research program is focused on developing new methods to design, manufacture, and control novel and high impact micro/nano-robotic systems in three thrust areas: miniature mobile robots, bio-inspired fibrillar adhesives, and micro/nano-manipulation systems. Our group has had the below significant impacts in these three areas. The first two areas are our major current focus areas.

Impact Area 1: Miniaturization of Mobile RobotsOur approach to realize miniature mobile robots with variety of locomotion capabilities involves developing a biologically inspired design methodology. Adapting the 'just good-enough', robust, efficient, and sub-optimal solutions of nature to miniature robots, we introduced new miniature robots with water surface, climbing, flying, and swimming locomotion capabilities, being inspired by lizards, insects, and bacteria. As example unique bio-inspired locomotion principles at the small scale, we proposed two new bio-inspired legged locomotion mechanisms on water surface. A new insect robot inspired by water striders used the repulsive surface tension forces on its hydrophobic supporting feet to lift its body weight while propelling and steering itself by a sculling motion of its two side legs. This robot enabled low power locomotion at shallow waters. We proposed a new quadruped robot inspired by basilisk lizards, which uses hydrodynamic drag forces on its directionally compliant feet to lift and propel its body on water by high-frequency rotation of its legs in an optimal elliptic trajectory. Stable control of this highly dynamic legged robot has been a great challenge for which we have proposed and implemented successful solutions.

To miniaturize mobile robots down to micron scale sizes, the most critical bottleneck is the lack of on-board micron scale actuators and power sources. We proposed two methods to solve this challenge. At first, I used external magnetic actuation to crawl magnetic micro-robots in 2-D. By proposing an asymmetric rotational rocking based new stick-slip locomotion method, we steered single or teams of magnetic micro-robots on a wide range of surfaces in air and liquids. These micro-robots can manipulate micro-parts in 2-D using contact and a newly characterized non-contact method in liquids. Our team also showed the controlled assembly and disassembly of multiple magnetic micro-robots towards reconfigurable micro-robotic systems for the first time. This magnetic micro-robot system received the Best Paper Award in IROS'09. Next, as a new approach in the robotics community (based on the approach demonstrated by a biologist, Howard Berg, at Harvard in 2004), we proposed to attach motile biological microorganisms to synthetic swimming micro-robot bodies to propel them in liquids using the chemical energy inside the cell body or the environment. We attached S. marcescens bacteria to polymer micro-objects, and experimentally demonstrated their stochastic navigation, on/off propulsion control using an external chemical stimulus, and chemotactic passive steering, and we have been proposing stochastic dynamic models to understand and design single and swarm of such inherently stochastic and complex micro-robotic systems. I have recently received a grant from NSF Cyberphysical Systems (CPS) program to conduct research on this challenging project.

Impact Area 2: Gecko-Inspired Repeatable Adhesives Advanced new materials are crucial for building new miniature robots with improved and robust performance. Exploring bio-inspired repeatable adhesives as power efficient, robust and compact gripping nanomaterials for new miniature climbing robots, Dr. Sitti's team at UC Berkeley showed evidences for the van der Waals forces dominated dry adhesion principle of gecko foot-hairs in PNAS in 2002 (472 journal paper citations in ISI Web of Science), which initiated a new bio-inspired fibrillar adhesives research field. At the NanoRobotics Lab, we have focused on design, analysis, fabrication, and applications of elastomer micro-fibrillar adhesives inspired by these biological foot-hairs. For the first time, our NanoRobotics Lab team had below achievements: (1) Created two new processes to fabricate vertical and angled polymer micro/nano-fibers with and without spatulated tip endings. These methods are scalable up, high yield, and cost-effective, and resulted in 5 filed patents; (2) Demonstrated enhanced adhesion and shear of mushroom shaped micro-fibers as good as geckos on smooth surfaces; (3) Showed the significance of the backing layer thickness of single-level elastomer fiber arrays; (4) Demonstrated controlled adhesion and directional friction of angled fiber stems with angled spatulated tips as good as biological foot-hairs; (5) Manufactured hierarchical elastomer fiber adhesives with enhanced adhesion on single-asperity rough surfaces; (6) Proposed mechanical loading based adhesion switching mechanisms of micro/nano-fiber structures for pick-and-place manipulation of fragile macro and micro-objects; (7) Applied the fabricated new fibrillar adhesives to miniature robots: (a) non-invasive anchoring of capsule robots inside the gastrointestinal tract for therapeutic applications, which was funded by the 21st Century Frontier Program in Korea and nominated for the World Technology Award in 2009; (b) palm-size climbing robots called Waalbots, which was funded by NASA and Boeing and enabled us to receive the Best Biomimetics Paper Award in RoBio'04. Finally, Dr. Sitti founded nanoGriptech LLC to commercialize these fibrillar adhesives for sports, consumer products, medical, defense, product design, and robotics applications. The start-up company is currently exploring high volume manufacturing of micro/nano-fiber adhesives for commercial applications.

Impact Area 3: Tip-Based Precision Micro/Nano-Manipulation Systems Since Dr. Sitti's PhD research in Japan, our group has proposed new tip-based micro/nano-manipulation methods and systems. We developed micro/nano-mechanics models and teleoperated and automated control methods for atomic force microscope based contact manipulation systems in 2-D, which was published as a book in 2011 in collaboration with Prof. Stephane Regnier. We proposed a new fiber drawing method using glass micropipettes to deposit suspended polymer fibers down to 17 nm diameters on surfaces. We drew multi-layer fiber networks to create new aligned tissue scaffolds, which enabled basic tissue cell growth studies with controlled geometric boundary conditions. These two studies constituted the core of Dr. Sitti's NSF CAREER award research program. Finally, in a recent DARPA project, we have been working on a new tip-based nanowire growth method with a few nanometers precision using near field emission. Our role in this project is automated high-speed precision control of the nanowire growth system using single- and multiple-tips. Finally, Dr. Sitti received the SPIE Nanoengineering Pioneer Award in 2011 due to his contributions on the nanomanipulation field.

Above achievements were conducted by our NanoRobotics Lab team, which has involved 28 PhD (17 graduated), 34 MSc (29 graduated), and 54 undergraduate student members since 2003. Former graduate students have continued in academia, including assistant professors at UIUC, Virginia Tech and Texas Tech and several as postdoctoral fellows at MIT and Harvard, and in industry, including companies such as BostonDynamics, Apple, Intel, and Arete Associates. We have published peer-reviewed 96 journal articles (with total ~2,000 journal paper citations in ISI Web of Science and ~4,500 paper citations in scholar.google.com) and 114 peer-reviewed conference papers. Dr. Sitti presented our research findings in 100 invited presentations in universities and conferences.