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2009


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Full phase and amplitude control in computer-generated holography

Fratz, M., Fischer, P., Giel, D. M.

OPTICS LETTERS, 34(23):3659-3661, 2009 (article)

Abstract
We report what we believe to be the first realization of a computer-generated complex-valued hologram recorded in a single film of photoactive polymer. Complex-valued holograms give rise to a diffracted optical field with control over its amplitude and phase. The holograms are generated by a one-step direct laser writing process in which a spatial light modulator (SLM) is imaged onto a polymer film. Temporal modulation of the SLM during exposure controls both the strength of the induced birefringence and the orientation of the fast axis. We demonstrate that complex holograms can be used to impart arbitrary amplitude and phase profiles onto a beam and thereby open new possibilities in the control of optical beams. (C) 2009 Optical Society of America

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2009


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Digital polarization holograms with defined magnitude and orientation of each pixel’s birefringence

Fratz, M., Giel, D. M., Fischer, P.

OPTICS LETTERS, 34(8):1270-1272, 2009 (article)

Abstract
A new form of digital polarization holography is demonstrated that permits both the amplitude and the phase of a diffracted beam to be independently controlled. This permits two independent intensity images to be stored in the same hologram. To fabricate the holograms, a birefringence with defined retardance and orientation of the fast axis is recorded into a photopolymer film. The holograms are selectively read out by choosing the polarization state of the read beam. Polarization holograms of this kind increase the data density in holographic data storage and allow higher quality diffractive optical elements to be written. (C) 2009 Optical Society of America

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Controlled Propulsion of Artificial Magnetic Nanostructured Propellers

Ghosh, A., Fischer, P.

NANO LETTERS, 9(6):2243-2245, 2009, Featured highlight ‘Nanotechnology: The helix that delivers’ Nature 459, 13 (2009). (article)

Abstract
For biomedical applications, such as targeted drug delivery and microsurgery, it is essential to develop a system of swimmers that can be propelled wirelessly in fluidic environments with good control. Here, we report the construction and operation of chiral colloidal propellers that can be navigated in water with micrometer-level precision using homogeneous magnetic fields. The propellers are made via nanostructured surfaces and can be produced in large numbers. The nanopropellers can carry chemicals, push loads, and act as local probes in rheological measurements.

Featured highlight ‘Nanotechnology: The helix that delivers’ Nature 459, 13 (2009).

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Video - Nanospropellers DOI [BibTex]

Video - Nanospropellers DOI [BibTex]


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Absolute Asymmetric Reduction Based on the Relative Orientation of Achiral Reactants

Kuhn, A., Fischer, P.

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 48(37):6857-6860, 2009 (article)

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DOI [BibTex]

DOI [BibTex]


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Magnetic mobile micro-robots

Pawashe, C., Floyd, S., Sitti, M.

7eme Journees Nationales de la Recherche en Robotique, 2009 (article)

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Gecko-Inspired Directional and Controllable Adhesion

Murphy, M. P., Aksak, B., Sitti, M.

Small, 5(2):170-175, WILEY-VCH Verlag, 2009 (article)

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Project Page [BibTex]

Project Page [BibTex]


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Multiple magnetic microrobot control using electrostatic anchoring

Pawashe, C., Floyd, S., Sitti, M.

Applied Physics Letters, 94(16):164108, AIP, 2009 (article)

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Characterization of bacterial actuation of micro-objects

Behkam, B., Sitti, M.

In Robotics and Automation, 2009. ICRA’09. IEEE International Conference on, pages: 1022-1027, 2009 (inproceedings)

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Wet self-cleaning of biologically inspired elastomer mushroom shaped microfibrillar adhesives

Kim, S., Cheung, E., Sitti, M.

Langmuir, 25(13):7196-7199, ACS Publications, 2009 (article)

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Compliant footpad design analysis for a bio-inspired quadruped amphibious robot

Park, H. S., Sitti, M.

In Intelligent Robots and Systems, 2009. IROS 2009. IEEE/RSJ International Conference on, pages: 645-651, 2009 (inproceedings)

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A novel artificial hair receptor based on aligned PVDF micro/nano fibers

Weiting, Liu, Bilsay, Sumer, Cesare, Stefanini, Arianna, Menciassi, Fei, Li, Dajing, Chen, Paolo, Dario, Metin, Sitti, Xin, Fu

In Robotics and Biomimetics, 2008. ROBIO 2008. IEEE International Conference on, pages: 49-54, 2009 (inproceedings)

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Robot ceiling climbers harness new tricks

Marks, Paul

New Scientist, 202(2705):18-19, Reed Business Information, 2009 (article)

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Waalbot: Agile climbing with synthetic fibrillar dry adhesives

Murphy, M. P., Sitti, M.

In Robotics and Automation, 2009. ICRA’09. IEEE International Conference on, pages: 1599-1600, 2009 (inproceedings)

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Biologically-Inspired Patterned and Coated Adhesives for Medical Devices

Glass, P, Chung, H, Lee, C, Tworkoski, E, Washburn, NR, Sitti, M

Journal of Medical Devices, 3(2):027537, American Society of Mechanical Engineers, 2009 (article)

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Modeling and experimental characterization of an untethered magnetic micro-robot

Pawashe, C., Floyd, S., Sitti, M.

The International Journal of Robotics Research, 28(8):1077-1094, Sage Publications, 2009 (article)

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Towards automated nanoassembly with the atomic force microscope: A versatile drift compensation procedure

Krohs, F., Onal, C., Sitti, M., Fatikow, S.

Journal of Dynamic Systems, Measurement, and Control, 131(6):061106, American Society of Mechanical Engineers, 2009 (article)

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Enhanced adhesion by gecko-inspired hierarchical fibrillar adhesives

Murphy, M. P., Kim, S., Sitti, M.

ACS applied materials \& interfaces, 1(4):849-855, American Chemical Society, 2009 (article)

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Project Page [BibTex]

Project Page [BibTex]


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Miniature devices: Voyage of the microrobots

Sitti, M.

Nature, 458(7242):1121-1122, Nature Publishing Group, 2009 (article)

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Piezoelectric ultrasonic resonant micromotor with a volume of less than 1 mm 3 for use in medical microbots

Watson, B., Friend, J., Yeo, L., Sitti, M.

In Robotics and Automation, 2009. ICRA’09. IEEE International Conference on, pages: 2225-2230, 2009 (inproceedings)

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Dynamic modeling and analysis of pitch motion of a basilisk lizard inspired quadruped robot running on water

Park, H. S., Floyd, S., Sitti, M.

In Robotics and Automation, 2009. ICRA’09. IEEE International Conference on, pages: 2655-2660, 2009 (inproceedings)

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Dry spinning based spinneret based tunable engineered parameters (STEP) technique for controlled and aligned deposition of polymeric nanofibers

Nain, A. S., Sitti, M., Jacobson, A., Kowalewski, T., Amon, C.

Macromolecular rapid communications, 30(16):1406-1412, WILEY-VCH Verlag, 2009 (article)

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Two-dimensional contact and noncontact micromanipulation in liquid using an untethered mobile magnetic microrobot

Floyd, S., Pawashe, C., Sitti, M.

IEEE Transactions on Robotics, 25(6):1332-1342, IEEE, 2009 (article)

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A scaled bilateral control system for experimental one-dimensional teleoperated nanomanipulation

Onal, C. D., Sitti, M.

The International Journal of Robotics Research, 28(4):484-497, Sage Publications, 2009 (article)

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A Swallowable Tethered Capsule Endoscope for Diagnosing Barrett’s Esophagus

Glass, P., Sitti, M., Pennathur, A., Appasamy, R.

Gastrointestinal Endoscopy, 69(5):AB106, Mosby, 2009 (article)

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Project Page [BibTex]

Project Page [BibTex]


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A miniature ceiling walking robot with flat tacky elastomeric footpads

Unver, O., Sitti, M.

In Robotics and Automation, 2009. ICRA’09. IEEE International Conference on, pages: 2276-2281, 2009 (inproceedings)

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Adhesion of biologically inspired polymer microfibers on soft surfaces

Cheung, E., Sitti, M.

Langmuir, 25(12):6613-6616, ACS Publications, 2009 (article)

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Dangling chain elastomers as repeatable fibrillar adhesives

Sitti, M., Cusick, B., Aksak, B., Nese, A., Lee, H., Dong, H., Kowalewski, T., Matyjaszewski, K.

ACS applied materials \& interfaces, 1(10):2277-2287, American Chemical Society, 2009 (article)

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Reversible dry micro-fibrillar adhesives with thermally controllable adhesion

Kim, S., Sitti, M., Xie, T., Xiao, X.

Soft Matter, 5(19):3689-3693, Royal Society of Chemistry, 2009 (article)

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Project Page [BibTex]

Project Page [BibTex]


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Biologically Inspired Polymer Microfibrillar Arrays for Mask Sealing

Cheung, E., Aksak, B., Sitti, M.

CARNEGIE-MELLON UNIV PITTSBURGH PA, 2009 (techreport)

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Tankbot: A miniature, peeling based climber on rough and smooth surfaces

Unver, O., Sitti, M.

In Robotics and Automation, 2009. ICRA’09. IEEE International Conference on, pages: 2282-2287, 2009 (inproceedings)

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Automated 2-D nanoparticle manipulation with an atomic force microscope

Onal, C. D., Ozcan, O., Sitti, M.

In Robotics and Automation, 2009. ICRA’09. IEEE International Conference on, pages: 1814-1819, 2009 (inproceedings)

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Enhanced reversible adhesion of dopamine methacrylamide-coated elastomer microfibrillar structures under wet conditions

Glass, P., Chung, H., Washburn, N. R., Sitti, M.

Langmuir, 25(12):6607-6612, ACS Publications, 2009 (article)

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Project Page [BibTex]

Project Page [BibTex]


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Microparticle manipulation using multiple untethered magnetic micro-robots on an electrostatic surface

Floyd, S., Pawashe, C., Sitti, M.

In Intelligent Robots and Systems, 2009. IROS 2009. IEEE/RSJ International Conference on, pages: 528-533, 2009 (inproceedings)

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Chiral molecules split light: Reflection and refraction in a chiral liquid

Ghosh, A., Fischer, P.

PHYSICAL REVIEW LETTERS, 97(17), 2006, Featured highlight ‘Fundamental optical physics: Refraction’ Nature Photonics, Nov. 2006. (article)

Abstract
A light beam changes direction as it enters a liquid at an angle from another medium, such as air. Should the liquid contain molecules that lack mirror symmetry, then it has been predicted by Fresnel that the light beam will not only change direction, but will actually split into two separate beams with a small difference in the respective angles of refraction. Here we report the observation of this phenomenon. We also demonstrate that the angle of reflection does not equal the angle of incidence in a chiral medium. Unlike conventional optical rotation, which depends on the path-length through the sample, the reported reflection and refraction phenomena arise within a few wavelengths at the interface and thereby suggest a new approach to polarimetry that can be used in microfluidic volumes.

Featured highlight ‘Fundamental optical physics: Refraction’ Nature Photonics, Nov. 2006.

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DOI [BibTex]

DOI [BibTex]


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Direct chiral discrimination in NMR spectroscopy

Buckingham, A., Fischer, P.

CHEMICAL PHYSICS, 324(1):111-116, 2006 (article)

Abstract
Conventional nuclear magnetic resonance spectroscopy is unable to distinguish between the two mirror-image forms (enantiomers) of a chiral molecule. This is because the NMR spectrum is determined by the chemical shifts and spin-spin coupling constants which - in the absence of a chiral solvent - are identical for the two enantiomers. We discuss how chirality may nevertheless be directly detected in liquid-state NMR spectroscopy: In a chiral molecule, the rotating nuclear magnetic moment induces an electric dipole moment in the direction perpendicular to itself and to the permanent magnetic field of the spectrometer. We present computations of the precessing electric polarization following a pi/2 pulse. Our estimates indicate that the electric polarization should be detectable in favourable cases. We also predict that application of an electrostatic field induces a chirally sensitive magnetization oscillating in the direction of the permanent magnetic field. We show that the electric-field-perturbed chemical shift tensor, the nuclear magnetic shielding polarizability, underlies these chiral NMR effects. (c) 2005 Elsevier B.V. All rights reserved.

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DOI [BibTex]

DOI [BibTex]


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An ultrasonic standing-wave-actuated nano-positioning walking robot: piezoelectric-metal composite beam modeling

Son, K. J., Kartik, V., Wickert, J. A., Sitti, M.

Journal of vibration and control, 12(12):1293-1309, Sage Publications, 2006 (article)

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NONLINEAR OPTICAL PROPERTIES OF CHIRAL LIQUIDS Electric-dipolar pseudoscalars in nonlinear optics

Fischer, P., Champagne, B.

In NON-LINEAR OPTICAL PROPERTIES OF MATTER: FROM MOLECULES TO CONDENSED PHASES, 1, pages: 359-381, Challenges and Advances in Computational Chemistry and Physics, 2006 (incollection)

Abstract
We give all overview of linear and nonlinear optical processes that can be specific to chiral molecules in isotropic media. Specifically, we discuss the pseudoscalars that underlie nonlinear optical activity and chiral frequency conversion processes in fluids. We show that nonlinear optical techniques open entirely new ways of exploring chirality: Sum-frequency-generation (SFG) at second-order and BioCARS at fourth-order arise in the electric-dipole approximation and do not require circularly polarized light to detect chiral molecules in solution. Here the frequency conversion in itself is a measure of chirality. This is in contrast to natural optical activity phenomena which are based on the interference of radiation from induced oscillating electric and magnetic dipoles, and which are observed as a differential response to right and left circularly polarized light. We give examples from our SFG experiments in optically active solutions and show how the application of an additional static electric field to sum-frequency generation allows the absolute configuration of the chiral solute to be determined via all electric-dipolar process. Results from ab initio calculations of the SFG pseudoscalar are presented for a number of chiral molecules

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Ring-resonator-based frequency-domain optical activity measurements of a chiral liquid

Vollmer, F., Fischer, P.

OPTICS LETTERS, 31(4):453-455, 2006 (article)

Abstract
Chiral liquids rotate the plane of polarization of linearly polarized light and are therefore optically active. Here we show that optical rotation can be observed in the frequency domain. A chiral liquid introduced in a fiber-loop ring resonator that supports left and right circularly polarized modes gives rise to relative frequency shifts that are a direct measure of the liquid's circular birefringence and hence of its optical activity. The effect is in principle not diminished if the circumference of the ring is reduced. The technique is similarly applicable to refractive index and linear birefringence measurements. (c) 2006 Optical Society of America.

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DOI [BibTex]


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Sign of the refractive index in a gain medium with negative permittivity and permeability

Chen, Y., Fischer, P., Wise, F.

JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS, 23(1):45-50, 2006 (article)

Abstract
We show how the sign of the refractive index in any medium may be derived using a rigorous analysis based on Einstein causality. In particular, we consider left-handed materials, i.e., media that have negative permittivities and permeabilities at the frequency of interest. We find that the consideration of gain in such media can give rise to a positive refractive index. (c) 2006 Optical Society of America.

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DOI [BibTex]

DOI [BibTex]


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IEEE TRANSACTIONS ON ROBOTICS

VOLZ, RICHARD A, TARN, TJ, MACIEJEWSKI, ANTHONY A, LEE, SUKHAN, BICCHI, ANTONIO, DE LUCA, ALESSANDRO, LUH, PETER B, TAYLOR, RUSSELL H, BEKEY, GEORGE A, ARAI, HIROHIKO, others

2006 (article)

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Design methodology for biomimetic propulsion of miniature swimming robots

Behkam, B., Sitti, M.

Trans.-ASME Journal of Dynamic Systems Measurement and Control, 128(1):36, ASME, 2006 (article)

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Project Page [BibTex]


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Augmented reality user interface for an atomic force microscope-based nanorobotic system

Vogl, W., Ma, B. K., Sitti, M.

IEEE transactions on nanotechnology, 5(4):397-406, IEEE, 2006 (article)

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Friction enhancement via micro-patterned wet elastomer adhesives on small intestinal surfaces

Kwon, J., Cheung, E., Park, S., Sitti, M.

Biomedical Materials, 1(4):216, IOP Publishing, 2006 (article)

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Miniature endoscopic capsule robot using biomimetic micro-patterned adhesives

Karagozler, M. E., Cheung, E., Kwon, J., Sitti, M.

In Biomedical Robotics and Biomechatronics, 2006. BioRob 2006. The First IEEE/RAS-EMBS International Conference on, pages: 105-111, 2006 (inproceedings)

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Compliant and low-cost humidity nanosensors using nanoporous polymer membranes

Yang, B., Aksak, B., Lin, Q., Sitti, M.

Sensors and Actuators B: Chemical, 114(1):254-262, Elsevier, 2006 (article)

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Task-based and stable telenanomanipulation in a nanoscale virtual environment

Kim, S., Sitti, M.

IEEE Transactions on automation science and engineering, 3(3):240-247, IEEE, 2006 (article)

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Drawing suspended polymer micro-/nanofibers using glass micropipettes

Nain, A. S., Wong, J. C., Amon, C., Sitti, M.

Applied Physics Letters, 89(18):183105, AIP, 2006 (article)

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Toward micro wall-climbing robots using biomimetic fibrillar adhesives

Greuter, M., Shah, G., Caprari, G., Tâche, F., Siegwart, R., Sitti, M.

In Proceedings of the 3rd International Symposium on Autonomous Minirobots for Research and Edutainment (AMiRE 2005), pages: 39-46, 2006 (inproceedings)

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