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2016


A New Perspective and Extension of the Gaussian Filter
A New Perspective and Extension of the Gaussian Filter

Wüthrich, M., Trimpe, S., Garcia Cifuentes, C., Kappler, D., Schaal, S.

The International Journal of Robotics Research, 35(14):1731-1749, December 2016 (article)

Abstract
The Gaussian Filter (GF) is one of the most widely used filtering algorithms; instances are the Extended Kalman Filter, the Unscented Kalman Filter and the Divided Difference Filter. The GF represents the belief of the current state by a Gaussian distribution, whose mean is an affine function of the measurement. We show that this representation can be too restrictive to accurately capture the dependences in systems with nonlinear observation models, and we investigate how the GF can be generalized to alleviate this problem. To this end, we view the GF as the solution to a constrained optimization problem. From this new perspective, the GF is seen as a special case of a much broader class of filters, obtained by relaxing the constraint on the form of the approximate posterior. On this basis, we outline some conditions which potential generalizations have to satisfy in order to maintain the computational efficiency of the GF. We propose one concrete generalization which corresponds to the standard GF using a pseudo measurement instead of the actual measurement. Extending an existing GF implementation in this manner is trivial. Nevertheless, we show that this small change can have a major impact on the estimation accuracy.

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PDF DOI Project Page [BibTex]

2016


PDF DOI Project Page [BibTex]


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Predictive and Self Triggering for Event-based State Estimation

Trimpe, S.

In Proceedings of the 55th IEEE Conference on Decision and Control (CDC), pages: 3098-3105, Las Vegas, NV, USA, December 2016 (inproceedings)

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arXiv PDF DOI Project Page [BibTex]

arXiv PDF DOI Project Page [BibTex]


Robust Gaussian Filtering using a Pseudo Measurement
Robust Gaussian Filtering using a Pseudo Measurement

Wüthrich, M., Garcia Cifuentes, C., Trimpe, S., Meier, F., Bohg, J., Issac, J., Schaal, S.

In Proceedings of the American Control Conference (ACC), Boston, MA, USA, July 2016 (inproceedings)

Abstract
Most widely-used state estimation algorithms, such as the Extended Kalman Filter and the Unscented Kalman Filter, belong to the family of Gaussian Filters (GF). Unfortunately, GFs fail if the measurement process is modelled by a fat-tailed distribution. This is a severe limitation, because thin-tailed measurement models, such as the analytically-convenient and therefore widely-used Gaussian distribution, are sensitive to outliers. In this paper, we show that mapping the measurements into a specific feature space enables any existing GF algorithm to work with fat-tailed measurement models. We find a feature function which is optimal under certain conditions. Simulation results show that the proposed method allows for robust filtering in both linear and nonlinear systems with measurements contaminated by fat-tailed noise.

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Web link (url) DOI Project Page [BibTex]

Web link (url) DOI Project Page [BibTex]


Automatic LQR Tuning Based on Gaussian Process Global Optimization
Automatic LQR Tuning Based on Gaussian Process Global Optimization

Marco, A., Hennig, P., Bohg, J., Schaal, S., Trimpe, S.

In Proceedings of the IEEE International Conference on Robotics and Automation (ICRA), pages: 270-277, IEEE, IEEE International Conference on Robotics and Automation, May 2016 (inproceedings)

Abstract
This paper proposes an automatic controller tuning framework based on linear optimal control combined with Bayesian optimization. With this framework, an initial set of controller gains is automatically improved according to a pre-defined performance objective evaluated from experimental data. The underlying Bayesian optimization algorithm is Entropy Search, which represents the latent objective as a Gaussian process and constructs an explicit belief over the location of the objective minimum. This is used to maximize the information gain from each experimental evaluation. Thus, this framework shall yield improved controllers with fewer evaluations compared to alternative approaches. A seven-degree- of-freedom robot arm balancing an inverted pole is used as the experimental demonstrator. Results of a two- and four- dimensional tuning problems highlight the method’s potential for automatic controller tuning on robotic platforms.

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Video - Automatic LQR Tuning Based on Gaussian Process Global Optimization - ICRA 2016 Video - Automatic Controller Tuning on a Two-legged Robot PDF DOI Project Page [BibTex]

Video - Automatic LQR Tuning Based on Gaussian Process Global Optimization - ICRA 2016 Video - Automatic Controller Tuning on a Two-legged Robot PDF DOI Project Page [BibTex]


Depth-based Object Tracking Using a Robust Gaussian Filter
Depth-based Object Tracking Using a Robust Gaussian Filter

Issac, J., Wüthrich, M., Garcia Cifuentes, C., Bohg, J., Trimpe, S., Schaal, S.

In Proceedings of the IEEE International Conference on Robotics and Automation (ICRA) 2016, IEEE, IEEE International Conference on Robotics and Automation, May 2016 (inproceedings)

Abstract
We consider the problem of model-based 3D- tracking of objects given dense depth images as input. Two difficulties preclude the application of a standard Gaussian filter to this problem. First of all, depth sensors are characterized by fat-tailed measurement noise. To address this issue, we show how a recently published robustification method for Gaussian filters can be applied to the problem at hand. Thereby, we avoid using heuristic outlier detection methods that simply reject measurements if they do not match the model. Secondly, the computational cost of the standard Gaussian filter is prohibitive due to the high-dimensional measurement, i.e. the depth image. To address this problem, we propose an approximation to reduce the computational complexity of the filter. In quantitative experiments on real data we show how our method clearly outperforms the standard Gaussian filter. Furthermore, we compare its performance to a particle-filter-based tracking method, and observe comparable computational efficiency and improved accuracy and smoothness of the estimates.

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Video Bayesian Object Tracking Library Bayesian Filtering Framework Object Tracking Dataset link (url) DOI Project Page [BibTex]

Video Bayesian Object Tracking Library Bayesian Filtering Framework Object Tracking Dataset link (url) DOI Project Page [BibTex]


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Communication Rate Analysis for Event-based State Estimation

(Best student paper finalist)

Ebner, S., Trimpe, S.

In Proceedings of the 13th International Workshop on Discrete Event Systems, May 2016 (inproceedings)

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PDF DOI [BibTex]

PDF DOI [BibTex]


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Self-diffusiophoresis of chemically active colloids

Popescu, M. N., Uspal, W. E., Dietrich, S.

The European Physical Journal Special Topics, 225(11-12):2189-2206, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Perpetual superhydrophobicity

Giacomello, A., Schimmele, L., Dietrich, S., Tasinkevych, M.

Soft Matter, 12, pages: 8927-8934, Royal Society of Chemistry, Cambridge, UK, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Molecular dynamics simulation of a binary mixture near the lower critical point

Pousaneh, F., Edholm, O., Maciolek, A.

The Journal of Chemical Physics, 145(1), American Institute of Physics, Woodbury, N.Y., 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Effective Interaction between Active Colloids and Fluid Interfaces Induced by Marangoni Flows

Dom\’\inguez, A., Malgaretti, P., Popescu, M. N., Dietrich, S.

Physical Review Letters, 116, American Physical Society, Woodbury, N.Y., 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Dynamics of Novel Photoactive AgCl Microstars and Their Environmental Applications

Simmchen, J., Baeza, A., Miguel-Lopez, A., Stanton, M. M., Vallet-Regi, M., Ruiz-Molina, D., Sánchez, S.

ChemNanoMat, 3(1):65-71, Wiley, Weinheim, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Wetting hysteresis induced by nanodefects

Giacomello, A., Schimmele, L., Dietrich, S.

Proceedings of the National Academy of Sciences of the United States of America, 113(3):E262-E271, National Academy of Sciences, Washington, D.C., 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Three-phase contact line and line tension of electrolyte solutions in contact with charged substrates

Ibagon, I., Bier, M., Dietrich, S.

Journal of Physics: Condensed Matter, 28(24), IOP Publishing, Bristol, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Smart biosensors for multiplexed and fully integrated point-of-care diagnostics

Romeo, A., Leung, T. S., Sanchez, S.

Lab on a Chip, 16(11):1957-1961, Royal Society of Chemistry, Cambridge, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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The sequential activation of the mitotic microtubule assembly pathways favors bipolar spindle formation

Cavazza, T., Malgaretti, P., Vernos, I.

Molecular Biology of the Cell, 27(19):2935-2945, American Society for Cell Biology, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Entropically induced asymmetric passage times of charged tracers across corrugated channels

Malgaretti, P., Pagonabarraga, I., Rubi, J. M.

The Journal of Chemical Physics, 144(3), American Institute of Physics, Woodbury, N.Y., 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Topographical pathways guide chemical microswimmers

Simmchen, J., Katuri, J., Uspal, W., Popescu, M. N., Tasinkevych, M., Sanchez, S.

Nature Communications, 7, Nature Publishing Group, London, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Fluctuational electrodynamics for nonlinear media

Soo, H., Krüger, M.

EPL, 115(4), EDP Science, Les-Ulis, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Poisson-Boltzmann study of the effective electrostatic interaction between colloids at an electrolyte interface

Majee, A., Bier, M., Dietrich, S.

The Journal of Chemical Physics, 145(6), American Institute of Physics, Woodbury, N.Y., 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Bubble-Free Propulsion of Ultrasmall Tubular Nanojets Powered by Biocatalytic Reactions

Ma, X., Hortelao, A. C., Miquel-Lopez, A., Sanchez, S.

Journal of the American Chemical Society, 138(42):13782-13785, American Chemical Society, Washington, DC, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Wetting and orientation of catalytic Janus colloids at the surface of water

Wang, X., In, M., Blanc, C., Malgaretti, P., Nobilia, M., Stocco, A.

Faraday Discussions, 191, pages: 305-324, Royal Society of Chemistry, London, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Collective dynamics of chemically active particles trapped at a fluid interface

Dom\’\inguez, A., Malgaretti, P., Popescu, M. N., Dietrich, S.

Soft Matter, 12(40):8398-8406, Royal Society of Chemistry, Cambridge, UK, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Guiding Catalytically Active Particles with Chemically Patterned Surfaces

Uspal, W. E., Popescu, M. N., Dietrich, S., Tasinkevych, M.

Physical Review Letters, 117(4), American Physical Society, Woodbury, N.Y., 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Structure and dynamics of binary liquid mixtures near their continuous demixing transitions

Roy, S., Höfling, F., Dietrich, S.

The Journal of Chemical Physics, 145(4), American Institute of Physics, Woodbury, N.Y., 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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A dynamic DFT approach to generalized diffusion equations in a system with long-ranged and hydrodynamic interactions

Bleibel, J., Dominguez, A., Oettel, M.

Journal of Physics: Condensed Matter, 28(24), IOP Publishing, Bristol, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Rectification and Non-Gaussian Diffusion in Heterogeneous Media

Malgaretti, P., Pagonabarraga, I., Rubi, J. M.

Entropy, 18(11), Molecular Diversity Preservation International, Basel, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Lateral critical Casimir force in two\textendashdimensional inhomogeneous Ising strip. Exact results

Nowakowski, P., Napiorkowski, M.

The Journal of Chemical Physics, 144(21), 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Tailoring three-dimensional architectures by rolled-up nanotechnology for mimicking microvasculatures

Arayanarakool, R., Meyer, A. K., Helbig, L., Sanchez, S., Schmidt, O. G.

Lab on a Chip, 15(14):2981-2989, Royal Society of Chemistry, Cambridge, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Flexible sensors for biomedical technology

Vilela, D., Romeo, A., Sanchez, S.

Lab on a Chip, 16(3):402-408, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Mechanical stability of bipolar spindle assembly

Malgaretti, P., Muhuri, S.

EPL, 115(2), EDP Science, Les-Ulis, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Reversed Janus micro/nanomotors with internal chemical engine

Ma, X., Jang, S., Popescu, M. N., Uspal, W. E., Miguel-López, A., Hahn, K., Kim, D., Sanchez, S.

ACS Nano, 10(9):8751-8759, American Chemical Society, Washington, DC, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Driven colloidal fluids: construction of dynamical density functional theories from exactly solvable limits

Scacchi, A., Krüger, M., Brader, J. M.

Journal of Physics: Condensed Matter, 28(24), IOP Publishing, Bristol, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Flight of a heavy particle nonlinearly coupled to a quantum bath

Maghrebi, M. F., Krüger, M., Kardar, M.

Physical Review B, 93(1), American Physical Society, Woodbury, NY, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Critical Casimir forces between defects in the 2D Ising model

Nowakowski, P., Maciolek, A., Dietrich, S.

Journal of Physics A: Mathematical and Theoretical, 49(48), IOP Pub., Bristol, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Miniaturized soft bio-hybrid robotics: a step forward into healthcare applications

Patino, T., Mestre, R., Sanchez, S.

Lab on a Chip, 16(19):3626-3630, Royal Society of Chemistry, Cambridge, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Characterizing anomalous diffusion in crowded polymer solutions and gels over five decades in time with variable-lengthscale fluorescence correlation spectroscopy

Banks, Daniel S, Tressler, Charmaine, Peters, Robert D, Höfling, Felix, Fradin, Cécile

Soft Matter, 12(18):4190-4203, Royal Society of Chemistry, Cambridge, UK, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Slip Length Enhancement in Nanofluidic Flow using Nanotextured Superhydrophobic Surfaces

Heverhagen, Jonas, Tasinkevych, M., Rahman, A., Black, C.T., Checco, A.

Advanced Materials Interfaces, 3(17), Wiley-VCH, Weinheim, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Event-based Sampling for Reducing Communication Load in Realtime Human Motion Analysis by Wireless Inertial Sensor Networks

Laidig, D., Trimpe, S., Seel, T.

Current Directions in Biomedical Engineering, 2(1):711-714, De Gruyter, 2016 (article)

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PDF DOI [BibTex]

PDF DOI [BibTex]


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Active colloids at fluid interfaces

Malgaretti, P., Popescu, M. N., Dietrich, S.

Soft Matter, 12(17):4007-4023, Royal Society of Chemistry, Cambridge, UK, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Critical adsorption and critical Casimir forces in the canonical ensemble

Gross, M., Vasilyev, O., Gambassi, A., Dietrich, S.

Physical Review E, 94(2), American Physical Society, Melville, NY, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Critical Casimir interactions between Janus particles

Labbe-Laurent, M., Dietrich, S.

Soft Matter, 12(31):6621-6648, Royal Society of Chemistry, Cambridge, UK, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Motion Control of Urea-Powerde Biocompatible Hollow Microcapsule

Ma, X., Wang, X., Hahn, K., Sanchez, S.

ACS Nano, 10(3):3597-3605, American Chemical Society, Washington, DC, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Enzyme Catalysis To Power Micro/Nanomachines

Ma, X., Hortelao, A. C., Patino, T., Sanchez, S.

ACS Nano, 10(10):9111-9122, American Chemical Society, Washington, DC, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Microfluidic fuel cells for energy generation

Safdar, M., Jänis, J., Sanchez, S.

Lab on a Chip, 16(15):2754-2758, Royal Society of Chemistry, Cambridge, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Reusable and Long-Lasting Active Microcleaners for Heterogeneous Water Remediation

Parmar, J., Vilela, D., Pellicer, E., Esque-de-los Ojos, D., Sort, J., Sanchez, S.

Advanced Functional Materials, 26(23):4152-4161, Wiley-VCH Verlag GmbH, Weinheim, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Self-Assembly of Micromachining Systems Powered by Janus Micromotors

Maggi, C., Simmchen, J., Saglimbeni, F., Katuri, J., Dipalo, M., De Angelis, F., Sanchez, S., Di Leonardo, R.

Small, 12(4):446-451, Wiley, Weinheim, Germany, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Graphene-Based Microrobots for Toxic Heavy Metal Removal and Recovery from Water

Vilela, D., Parmar, J., Zeng, Y., Zhao, Y., Sanchez, S.

Nano Letters, 16(4):2860-2866, American Chemical Society, Washington, DC, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Colloidal Particles in Thin Nematic Wetting Films

Jeridi, H., Tasinkevych, M., Othman, T., Blanc, C.

Langmuir, 32(35):9097-9107, American Chemical Society, Columbus, OH, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Anisotropic particles near surfaces: Propulsion force and friction

Müller, B., Krüger, M.

Physical Review A, 93, American Physical Society, New York, NY, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Tubular microjets: Fabrication, factors affecting the motion and mechanism of propulsion

Parmar, J., Vilela, D., Sanchez, S.

The European Physical Journal Special Topics, 225(11):2255-2267, Springer, Berlin, 2016 (article)

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DOI [BibTex]

DOI [BibTex]