| 1. |
- Aldaeus, Fredrik, et al.
(författare)
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Multi-step dielectrophoresis for separation of particles
- 2006
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1131:1-2, s. 261-266
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Tidskriftsartikel (refereegranskat)abstract
- A new concept for separation of particles based on repetitive dielectrophoretic trapping and release in a flow system is proposed. Calculations using the finite element method have been performed to envision the particle behavior and the separation effectiveness of the proposed method. As a model system, polystyrene beads in deionized water and a micro-flow channel with arrays of interdigited electrodes have been used. Results show that the resolution increases as a direct function of the number of trap-and-release steps, and that a difference in size will have a larger influence on the separation than a difference in other dielectrophoretic properties. About 200 trap-and-release steps would be required to separate particles with a size difference of 0.2%. The enhanced separation power of dielectrophoresis with multiple steps could be of great importance, not only for fractionation of particles with small differences in size, but also for measuring changes in surface conductivity, or for separations based on combinations of difference in size and dielectric properties.
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| 2. |
- Aldaeus, Fredrik, et al.
(författare)
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Superpositioned dielectrophoresis for enhanced trapping efficiency
- 2005
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Ingår i: Electrophoresis. - : Wiley. - 0173-0835 .- 1522-2683. ; 26:22, s. 4252-4259
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Tidskriftsartikel (refereegranskat)abstract
- One of the major applications for dielectrophoresis is selective trapping and fractionation of particles. If the surrounding medium is of low conductivity, the trapping force is high, but if the conductivity increases, the attraction decreases and may even become negative. However, high-conductivity media are essential when working with biological material such as living cells. In this paper, some basic calculations have been performed, and a model has been developed which employs both positive and negative dielectrophoresis in a channel with interdigitated electrodes. The finite element method was utilized to predict the trajectories of Escherichia coli bacteria in the superpositioned electrical fields. It is shown that a drastic improvement of trapping efficiency can be obtained in this way, when a high conductivity medium is employed.
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| 3. |
- Do-Quang, Minh, et al.
(författare)
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Modelling the influence of wetting properties on the solid liquid impact
- 2008
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Ingår i: PROCEEDINGS OF THE 6TH INTERNATIONAL CONFERENCE ON NANOCHANNELS, MICROCHANNELS, AND MINICHANNELS, PTS A AND B. - NEW YORK : AMER SOC MECHANICAL ENGINEERS. - 9780791848340 ; , s. 1915-1917
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Konferensbidrag (refereegranskat)abstract
- The impact of a solid object on a free liquid surface is quite complex. This problem has challenged researchers for centuries and remains of interest today. Recently Duez et al. [1] published experimental results on the splash when a solid sphere enters a liquid Surprisingly, a small change in the surface chemistry of the object can turn a big splash into an inconspicuous disappearance and vice versa. We study this problem by solving the Navier-Stokes together with the Cahn-Hilliard equations, [2, 3], which allows us to simulate the motion of a free air-water surface in detail, in the presence of surface tension and dynamic wetting. Quantitative computational modeling of dynamic wetting is difficult in itself, but here the use of this tool allows us to study in detail how the wetting properties determine whether a splash appears or not. Our simulated results are compared with the experiments of Duez et al.
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| 4. |
- Huettenrauch, Helge, et al.
(författare)
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Investigating spatial relationships in human-robot interaction
- 2006
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Ingår i: IEEE/RSJ International Conference on Intelligent Robots and Systems. - NEW YORK, NY : IEEE. - 9781424402588 ; , s. 5052-5059, s. 5052-5059
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Konferensbidrag (refereegranskat)abstract
- Co-presence and embodied interaction are two fundamental characteristics of the command and control situation for service robots. This paper presents a study of spatial distances and orientation of a robot with respect to a human user in an experimental setting. Relevant concepts of spatiality from social interaction studies are introduced and related to Human-Robot Interaction (HRI). A Wizard-of-Oz study quantifies the observed spatial distances and spatial formations encountered. However, it is claimed that a simplistic parameterization and measurement of spatial interaction misses the dynamic character and might be counterproductive in the design of socially appropriate robots.
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| 5. |
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| 6. |
- Hüttenrauch, Helge, et al.
(författare)
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Involving users in the design of a mobile office robot
- 2004
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Ingår i: IEEE transactions on systems, man and cybernetics. Part C, Applications and reviews. - : IEEE. - 1094-6977 .- 1558-2442. ; 34:2, s. 113-124
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes the experiences from the iterative design of a fetch-and-carry-robot, to be used by motion-impaired people in an office environment. A user-centered approach was chosen, involving several steps of information elicitation to inform the design. We describe the main elements of the design process, the communication and interaction components of the final prototype system, and an evaluation of the system in the form of a longitudinal study. Results from this study confirmed that continuous testing with users is extremely important in the design process for service robots. The trials have also revealed that interaction design for robots should not focus only on the individual user, but that other members in the environment can be seen "secondary users" or "bystanders" who tend to relate to the robot actively in various ways. We conclude that these social and collaborative issues should be studied in future research.
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| 7. |
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| 8. |
- Hüttenrauch, Helge, et al.
(författare)
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To help or not to help a service robot - Bystander intervention as a resource in human-robot collaboration
- 2006
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Ingår i: Interaction Studies. - : John Benjamins Publishing Company. - 1572-0373 .- 1572-0381. ; 7:3, s. 455-477
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Tidskriftsartikel (refereegranskat)abstract
- A mobile service robot performing a task for its user(s) might not be able to accomplish its mission without help from other people present in the shared environment. In previous research, collaborative control has been studied as an interactive mode of operation with a robot, compensating for its limitations in autonomy. However, few studies of robots requesting assistance by detecting potential collaborators, directing its attention to them, addressing them, and finally obtaining help from them, have previously been performed in real-world use contexts. This study focuses on a fetch-and-carry robot, Cero, which has been designed to operate in an office environment as an aid for motion-impaired users. During its missions, the robot sometimes needs help with loading or unloading an object. The main question for the study was: under what conditions are people willing to help when requested to do so by the robot? We were particularly interested in bystanders, i.e. people who happened to be in the environment but who did not have any official business with the robot (they neither knew anything about the robot, nor did they have access rights to the robot or its functions). To answer these questions and to provide a better understanding of human-robot help-seeking situations, we conducted an experimental study in which subjects who had not encountered our service robot before were requested to assist it with a task. The results of the study confirm that bystanders can to some degree be expected to help in robot missions, but that their willingness to help the robot depends on the situation and state of occupation that people are in when requested to interact with and assist the robot.
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| 9. |
- Hüttenrauch, Helge, et al.
(författare)
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What's in the gap? : Interaction Transitions that make the HRI work
- 2006
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Ingår i: Proceedings of the 15th IEEE international symposium on robot and human interactive communication. - New York : IEEE. ; , s. 123-128
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents an in-depth analysis from a Human Robot Interaction (HRI) study on spatial positioning and interaction episode transitions. Subjects showed a living room to a robot to teach it new places and objects. This joint task was analyzed with respect to organizing strategies for interaction episodes. Noticing the importance of transitions between interaction episodes, small adaptive movements in posturewere observed. This finding needs to be incorporated into HRI modules that plan and execute robots’ spatial behavior in interaction, e.g., through dynamic adaptation of spatial formations and distances depending on interaction episode.
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| 10. |
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