Closed-loop feedback control for microfluidic systems through automated capacitive fluid height sensing

AbstractPrecise fluid height sensing in open-channel microfluidics has long been a desirable feature for a wide range of applications. However, performing accurate measurements of the fluid level in small-scale reservoirs (<1mL) has proven to be an elusive goal, especially if direct fluid-sensor contact needs to be avoided. In particular, gravity-driven systems used in several microfluidic applications to establish pressure gradients and impose flow remain open-loop and largely unmonitored due to these sensing limitations. Here we present an optimized self-shielded coplanar capacitive sensor design and automated control system to provide submillimeter fluid-height resolution (~250 μm) and control of small-scale open reservoirs without the need for direct fluid contact. Results from testing and validation of our optimized sensor and system also suggest that accurate fluid height information can be used to robustly characterize, calibrate and dynamically control a range of microfluidic systems with complex pumping mechanisms, even in cell culture conditions. Capacitive sensing technology provides a scalable and cost-effective way to enable continuous monitoring and closed-loop feedback control of fluid volumes in small-scale gravity-dominated wells in a variety of microfluidic applications.

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Closed-loop feedback control for microfluidic systems through automated capacitive fluid height sensing

Lab on a Chip ◽

10.1039/c7lc01223c ◽

2018 ◽

Vol 18 (6) ◽

pp. 902-914 ◽

Cited By ~ 7

Author(s):

L. R. Soenksen ◽

T. Kassis ◽

M. Noh ◽

L. G. Griffith ◽

D. L. Trumper

Keyword(s):

Feedback Control ◽

Open Channel ◽

Closed Loop ◽

Microfluidic Systems ◽

Wide Range ◽

Desirable Feature ◽

Loop Feedback ◽

Closed Loop Feedback

Precise fluid height sensing in open-channel microfluidics has long been a desirable feature for a wide range of applications.

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Closed-Loop Feedback Control Algorithms for Flow Control Over NACA 0015 Airfoil

Volume 6: Fluids and Thermal Systems; Advances for Process Industries, Parts A and B ◽

10.1115/imece2011-65050 ◽

2011 ◽

Author(s):

Sohaib Obeid ◽

Rataheshwar Jha ◽

Goodarz Ahmadi

Keyword(s):

Feedback Control ◽

Closed Loop ◽

Moving Average ◽

Leading Edge ◽

Open Loop ◽

Synthetic Jet ◽

Identification Technique ◽

Loop Feedback ◽

Closed Loop Feedback ◽

Naca 0015

This study investigates control algorithm for closed-loop feedback control system design aimed at reduction of turbulent flow separation over a NACA 0015 airfoil equipped with leading-edge synthetic jet actuators (SJAs). The algorithm employs system identification technique based on Nonlinear Auto Regressive Moving Average with eXogenous inputs (NARMAX) method to model nonlinear dynamics of the flow and design controller for single-input singleoutput systems. The resulting closed loop response tracks the desired pressure value and significant improvement in the transient response over the open-loop system at high angles of attack is realized.

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Closed-Loop Feedback Control of Flow Over a Flapped Airfoil at High Angles of Attack Using Identified NARMAX Model

Volume 1: Symposia, Parts A and B ◽

10.1115/fedsm2012-72350 ◽

2012 ◽

Cited By ~ 1

Author(s):

Sohaib Obeid ◽

Ratneshwar Jha ◽

Goodarz Ahmadi

Keyword(s):

Feedback Control ◽

Closed Loop ◽

Active Flow Control ◽

Leading Edge ◽

Open Loop ◽

Synthetic Jet ◽

Trailing Edge ◽

Loop Feedback ◽

Closed Loop Feedback ◽

High Angles Of Attack

This study investigates closed-loop feedback control system design aimed at reduction of turbulent flow separation over a NACA 0015 airfoil having 30% integral type trailing edge flap and equipped with leading-edge and trailing edge synthetic jet actuators (SJAs). The multiple-input single-output controller employs system identification techniques based on Nonlinear Auto Regressive Moving Average with eXogenous inputs (NARMAX) method to model nonlinear dynamics of the flow. RANS FLUENT simulations for 2-D airfoil are used besides an analytical modeling for the set of synthetic actuators. The resulting closed loop response using NARMAX tracks the desired pressure value and significant improvement in the transient response over the open-loop system at high angles of attack is realized. Improvements in aerodynamic efficiency and maximum lift values through active flow control would lead to better performance characteristics of airplanes.

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Closed-Loop Feedback Control in Intelligent Wells: Application to a Heterogeneous, Thin Oil-Rim Reservoir in the North Sea

SPE Reservoir Evaluation & Engineering ◽

10.2118/159550-pa ◽

2015 ◽

Vol 18 (01) ◽

pp. 69-83 ◽

Cited By ~ 10

Author(s):

F.A.. A. Dilib ◽

M.D.. D. Jackson ◽

A. Mojaddam Zadeh ◽

R.. Aasheim ◽

K.. Årland ◽

...

Keyword(s):

Feedback Control ◽

Closed Loop ◽

Control Strategies ◽

Open Loop ◽

Loop Control ◽

Loop Feedback ◽

Closed Loop Feedback ◽

Intelligent Wells ◽

Oil Rim ◽

Direct Feedback

Summary Important challenges remain in the development of optimized control strategies for intelligent wells, particularly with respect to incorporating the impact of reservoir uncertainty. Most optimization methods are model-based and are effective only if the model or ensemble of models used in the optimization captures all possible reservoir behaviors at the individual-well and -completion level. This is rarely the case. Moreover, reservoir models are rarely predictive at the spatial and temporal scales required to identify control actions. We evaluate the benefit of the use of closed-loop control strategies, on the basis of direct feedback between reservoir monitoring and inflow-valve settings, within a geologically heterogeneous, thin oil-rim reservoir. This approach does not omit model predictions completely; rather, model predictions are used to optimize a number of adjustable parameters within a general direct feedback relationship between measured data and inflow-control settings. A high-resolution sector model is used to capture reservoir heterogeneity, which incorporates a locally refined horizontal grid in the oil zone, to accurately represent the horizontal-well geometry and fluid contacts, and capture water and gas flow. Two inflow-control strategies are tested. The first is an open-loop approach, using fixed inflow-control devices to balance the pressure drawdown along the well, sized before installation. The second is a closed-loop, feedback-control strategy, using variable inflow-control valves that can be controlled from the surface in response to multiphase-flow data obtained downhole. The closed-loop strategy is optimized with a base-case model, and then tested against unexpected reservoir behavior by adjusting a number of uncertain parameters in the model but not reoptimizing. We find that closed-loop feedback control yields positive gains in net-present value (NPV) for the majority of reservoir behaviors investigated, and higher gains than the open-loop strategy. Closed-loop control also can yield positive gains in NPV even when the reservoir does not behave as expected, and in tested scenarios returned a near optimal NPV. However, inflow control can be risky, because unpredicted reservoir behavior also leads to negative returns. Moreover, assessing the benefits of inflow control over an arbitrarily fixed well life can be misleading, because observed gains depend on when the calculation is made.

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Closed-loop feedback control of microfluidic cell manipulation via deep-learning integrated sensor networks

Lab on a Chip ◽

10.1039/d1lc00076d ◽

2021 ◽

Author(s):

Ningquan Wang ◽

Ruxiu Liu ◽

Norh Asmare ◽

Chia-Heng Chu ◽

Ozgun Civelekoglu ◽

...

Keyword(s):

Deep Learning ◽

Sensor Networks ◽

Feedback Control ◽

Closed Loop ◽

Microfluidic System ◽

Cell Manipulation ◽

Integrated Sensor ◽

Loop Feedback ◽

Closed Loop Feedback ◽

On Chip

An adaptive microfluidic system changing its operational state in real-time based on cell measurements through an on-chip electrical sensor network.

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Stability analysis in machining process by using adaptive closed-loop feedback control system in turning process

Journal of Vibration and Control ◽

10.1177/1077546320952613 ◽

2020 ◽

pp. 107754632095261

Author(s):

Kashfull Orra ◽

Sounak K Choudhury

Keyword(s):

Control System ◽

Feedback Control ◽

Closed Loop ◽

Machining Process ◽

Feedback Control System ◽

Turning Process ◽

Tool Vibration ◽

Loop Feedback ◽

Closed Loop Feedback ◽

The Stability

The study presents model-based mechanism of nonlinear cutting tool vibration in turning process and the strategy of improving cutting process stability by suppressing machine tool vibration. The approach used is based on the closed-loop feedback control system with the help of electro–magneto–rheological damper. A machine tool vibration signal generated by an accelerometer is fed back to the coil of a damper after suitable amplification. The damper, attached under the tool holder, generates counter forces to suppress the vibration after being excited by the signal in terms of current. The study also discusses the use of transfer function approach for the development of a mathematical model and adaptively controlling the process dynamics of the turning process. The purpose of developing such mechanism is to stabilize the machining process with respect to the dynamic uncut chip thickness responsible for the type-II regenerative effect. The state-space model used in this study successfully checked the adequacy of the model through controllability and observability matrices. The eigenvalue and eigenvector have confirmed the stability of the system more accurately. The characteristic of the stability lobe chart is discussed for the present model-based mechanism.

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III–V Epitaxy, Monitoring and Closed-Loop Feedback Control of Spectroscopic Ellipsometry of

Encyclopedia of Materials: Science and Technology ◽

10.1016/b0-08-043152-6/00497-6 ◽

2001 ◽

pp. 2799-2807 ◽

Cited By ~ 1

Author(s):

D.E. Aspnes

Keyword(s):

Feedback Control ◽

Spectroscopic Ellipsometry ◽

Closed Loop ◽

Loop Feedback ◽

Closed Loop Feedback

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Feedback and Mapping Control of Natural Gas Engines

4th International Pipeline Conference, Parts A and B ◽

10.1115/ipc2002-27397 ◽

2002 ◽

Author(s):

Greg Sorge

Keyword(s):

Natural Gas ◽

Control Systems ◽

Closed Loop ◽

Open Loop ◽

Natural Gas Engines ◽

Feedback Type ◽

History Of ◽

Loop Feedback ◽

Closed Loop Feedback ◽

The 19Th Century

Automatic controls have been used on all types of machinery since the first complicated machines became popular in the 19th century. Controls are used to maintain pressures, temperatures, operating speeds, flows and many other operating parameters. Natural gas engines have used a variety of controls for various purposes since the first natural gas engines were produced. This paper will discuss the history of mechanical controls used on natural gas engines and the introduction and application of electronic controls. The paper will discuss open loop (mapping) and closed loop (feedback) type controls and common applications of each. Mechanical control systems such as governors, fuel regulators, fuel mixing valves, thermostats, and turbocharger wastegates will be discussed and classified as open or closed loop controls. Electronic control systems such as governors, air/fuel ratio controls, detonation controls, and turbocharger controls will also be discussed and classified. This paper will also discuss state of the art controls which perform numerous functions to get desired performance, and can be communicated with remotely.

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