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Eric J. Griffith

Bio: Eric J. Griffith is an academic researcher from Delft University of Technology. The author has contributed to research in topics: Virtual reality & Planar array. The author has an hindex of 8, co-authored 13 publications receiving 501 citations. Previous affiliations of Eric J. Griffith include Rensselaer Polytechnic Institute.

Papers
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Journal ArticleDOI
TL;DR: A polynomial-time algorithm for coordinating droplet movement under such hardware limitations is developed and described, and a layout-based system that can be rapidly reconfigured for new biochemical analyses is introduced.
Abstract: This paper describes a computational approach to designing a digital microfluidic system (DMFS) that can be rapidly reconfigured for new biochemical analyses. Such a “lab-on-a-chip” system for biochemical analysis, based on electrowetting or dielectrophoresis, must coordinate the motions of discrete droplets or biological cells using a planar array of electrodes. The authors have earlier introduced a layout-based system and demonstrated its flexibility through simulation, including the system's ability to perform multiple assays simultaneously. Since array-layout design and droplet-routing strategies are closely related in such a DMFS, their goal is to provide designers with algorithms that enable rapid simulation and control of these DMFS devices. In this paper, the effects of variations in the basic array-layout design, droplet-routing control algorithms, and droplet spacing on system performance are characterized. DMFS arrays with hardware limited row-column addressing are considered, and a polynomial-time algorithm for coordinating droplet movement under such hardware limitations is developed. To demonstrate the capabilities of our system, we describe example scenarios, including dilution control and minimalist layouts, in which our system can be successfully applied.

164 citations

Journal ArticleDOI
TL;DR: A general-purpose system that uses simple algorithms and yet is versatile is described that has been able to successfully coordinate hundreds of droplets simultaneously and perform one or more chemical analyses in parallel.
Abstract: In this paper we present an approach to coordinate the motions of droplets in digital microfluidic systems, a new class of lab-on-a-chip systems for biochemical analysis. A digital microfluidic system typically consists of a planar array of cells with electrodes that control the droplets. The primary challenge in using droplet-based systems is that they require the simultaneous coordination of a potentially large number of droplets on the array as the droplets move, mix, and split. In this paper we describe a general-purpose system that uses simple algorithms and yet is versatile. First, we present a semi-automated approach to generate the array layout in terms of components. Next, we discuss simple algorithms to select destination components for the droplets and a decentralized scheme for components to route the droplets on the array. These are then combined into a reconfigurable system that has been simulated in software to perform analyses such as the DNA polymerase chain reaction. The algorithms have ...

77 citations

Patent
07 Jul 2005
TL;DR: In this article, the authors present a method, system, and program product for controlling chemical reactions in a digital microfluidic system that include logically partitioning cells of an array into a plurality of virtual components wherein at least one virtual component is capable of handling droplets of reactants associated with distinct chemical reactions concurrently.
Abstract: The present invention provides, in a first aspect, a method, system, and program product for controlling chemical reactions in a digital microfluidic system that include logically partitioning cells of a digital microfluidic system array into a plurality of virtual components wherein at least one of the virtual components is capable of handling droplets of reactants associated with distinct chemical reactions concurrently. In a second aspect, a respective next cell is determined for each of a plurality of chemical droplets in the digital microfluidic system array, which may include droplets of reactants associated with distinct chemical reactions. In another aspect, a method, system, and program product for controlling chemical reactions in a digital microfluidic system in accordance with the present invention induce a chemical droplet of the plurality of chemical droplets in the digital microfluidic system array to move to the respective next cell determined for the chemical droplet.

76 citations

Journal ArticleDOI
TL;DR: A new method is developed to investigate the entire life cycle of shallow cumuli in large eddy simulations, and the most dominant feature is the pulsating growth that is present throughout the entire lifetime of the cloud, independent of the case and of the large-scale forcings.
Abstract: In this study, a new method is developed to investigate the entire life cycle of shallow cumuli in large eddy simulations. Although trained observers have no problem in distinguishing the different life stages of a cloud, this process proves difficult to automate, because cloud-splitting and cloud-merging events complicate the distinction between a single system divided in several cloudy parts and two independent systems that collided. Because the human perception is well equipped to capture and to make sense of these time-dependent three-dimensional features, a combination of automated constraints and human inspection in a three-dimensional virtual reality environment is used to select clouds that are exemplary in their behavior throughout their entire life span. Three specific cases (ARM, BOMEX, and BOMEX without large-scale forcings) are analyzed in this way, and the considerable number of selected clouds warrants reliable statistics of cloud properties conditioned on the phase in their life cycle. The most dominant feature in this statistical life cycle analysis is the pulsating growth that is present throughout the entire lifetime of the cloud, independent of the case and of the large-scale forcings. The pulses are a self-sustained phenomenon, driven by a balance between buoyancy and horizontal convergence of dry air. The convective inhibition just above the cloud base plays a crucial role as a barrier for the cloud to overcome in its infancy stage, and as a buffer region later on, ensuring a steady supply of buoyancy into the cloud.

59 citations

Proceedings ArticleDOI
27 Oct 2008
TL;DR: By processing the sensor values from the balance board, the Wii Balance Board is able to use it for both discrete and continuous input, which can be used to drive a variety of VR interaction metaphors.
Abstract: We demonstrate the use of the Wii Balance Board™ as a low-cost virtual reality input device. We provide an overview of obtaining and working with the sensor input. By processing the sensor values from the balance board, we are able to use it for both discrete and continuous input, which can be used to drive a variety of VR interaction metaphors. Using continuous input, the balance board is well suited for interactions requiring two simultaneous degrees of freedom and up to three total degrees of freedom, such as navigation or rotation. The discrete input is suitable for control input, such as mode switching or object selection.

53 citations


Cited by
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MonographDOI
01 Jan 2006
TL;DR: This coherent and comprehensive book unifies material from several sources, including robotics, control theory, artificial intelligence, and algorithms, into planning under differential constraints that arise when automating the motions of virtually any mechanical system.
Abstract: Planning algorithms are impacting technical disciplines and industries around the world, including robotics, computer-aided design, manufacturing, computer graphics, aerospace applications, drug design, and protein folding. This coherent and comprehensive book unifies material from several sources, including robotics, control theory, artificial intelligence, and algorithms. The treatment is centered on robot motion planning but integrates material on planning in discrete spaces. A major part of the book is devoted to planning under uncertainty, including decision theory, Markov decision processes, and information spaces, which are the “configuration spaces” of all sensor-based planning problems. The last part of the book delves into planning under differential constraints that arise when automating the motions of virtually any mechanical system. Developed from courses taught by the author, the book is intended for students, engineers, and researchers in robotics, artificial intelligence, and control theory as well as computer graphics, algorithms, and computational biology.

6,340 citations

Journal ArticleDOI
Richard B. Fair1
TL;DR: To understand the opportunities and limitations of EWD microfluidics, this paper looks at the development of lab-on-chip applications in a hierarchical approach.
Abstract: The suitability of electrowetting-on-dielectric (EWD) microfluidics for true lab-on-a-chip applications is discussed. The wide diversity in biomedical applications can be parsed into manageable components and assembled into architecture that requires the advantages of being programmable, reconfigurable, and reusable. This capability opens the possibility of handling all of the protocols that a given laboratory application or a class of applications would require. And, it provides a path toward realizing the true lab-on-a-chip. However, this capability can only be realized with a complete set of elemental fluidic components that support all of the required fluidic operations. Architectural choices are described along with the realization of various biomedical fluidic functions implemented in on-chip electrowetting operations. The current status of this EWD toolkit is discussed. However, the question remains: which applications can be performed on a digital microfluidic platform? And, are there other advantages offered by electrowetting technology, such as the programming of different fluidic functions on a common platform (reconfigurability)? To understand the opportunities and limitations of EWD microfluidics, this paper looks at the development of lab-on-chip applications in a hierarchical approach. Diverse applications in biotechnology, for example, will serve as the basis for the requirements for electrowetting devices. These applications drive a set of biomedical fluidic functions required to perform an application, such as cell lysing, molecular separation, or analysis. In turn, each fluidic function encompasses a set of elemental operations, such as transport, mixing, or dispensing. These elemental operations are performed on an elemental set of components, such as electrode arrays, separation columns, or reservoirs. Examples of the incorporation of these principles in complex biomedical applications are described.

1,094 citations

Journal ArticleDOI
TL;DR: Recent research on chip substrates, surface treatments, PCR reaction volume and speed, architecture, approaches to eliminating cross-contamination and control and measurement of temperature and liquid flow is summarized.
Abstract: The possibility of performing fast and small-volume nucleic acid amplification and analysis on a single chip has attracted great interest. Devices based on this idea, referred to as micro total analysis, microfluidic analysis, or simply ‘Lab on a chip’ systems, have witnessed steady advances over the last several years. Here, we summarize recent research on chip substrates, surface treatments, PCR reaction volume and speed, architecture, approaches to eliminating cross-contamination and control and measurement of temperature and liquid flow. We also discuss product-detection methods, integration of functional components, biological samples used in PCR chips, potential applications and other practical issues related to implementation of lab-on-a-chip technologies.

475 citations

Journal ArticleDOI
TL;DR: A motion sickness measurement index in a virtual reality (VR) environment is developed and the target selection method and button size were found to be significant factors that affect motion sickness in a VR environment.

383 citations