Development of a robust closed loop pressure control system for droplet generation

IF 4.1 3区工程技术 Q2 ENGINEERING, ELECTRICAL & ELECTRONIC

Sensors and Actuators A-physical Pub Date : 2025-04-22 DOI:10.1016/j.sna.2025.116596

Suleman A. Naz , Van Thanh Huynh , Egan H. Doeven , Scott Adams , Abbas Z. Kouzani , Rosanne M. Guijt

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引用次数: 0

Abstract

In droplet microfluidics, the precision of droplet length is essential for assay consistency. Pneumatic control is commonly utilized to regulate fluid flow and droplet generation, but the absence of feedback in open-loop systems makes these systems vulnerable to disturbances and restricts dynamic pressure regulation. To minimize variability and optimize resilience to perturbations, a closed-loop control strategy was implemented with the help of a proportional valve regulating the pressure in a sealed container. Using system identification, a mathematical model for the pneumatic system was developed to form the basis for a closed-loop Proportional-Integral (PI) controller. Compared to conventional methods, that derive mathematical models using physical laws, system identification is used to simplify complex models and design an effective robust controller while considering experimental uncertainties. The effectiveness of the closed-loop feedback system was evaluated for dynamic pressure changes and disturbance rejection. This resulted in a significant reduction of the coefficient of variation (CV) from 9.32 % (best-case scenario) during open loop control to < 3 % during closed loop control. Additionally, the stability of container pressures over a 30-minute period demonstrated a 25-fold improvement compared to open loop, alongside 1.6-fold enhancement in stability in droplet length.

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一种用于液滴生成的鲁棒闭环压力控制系统的开发

在液滴微流体中，液滴长度的精度对测定一致性至关重要。气动控制通常用于调节流体流动和液滴的产生，但是在开环系统中缺乏反馈使得这些系统容易受到干扰并限制了动态压力调节。为了最小化可变性和优化对扰动的恢复能力，采用了一种闭环控制策略，利用比例阀调节密封容器中的压力。利用系统辨识，建立了气动系统的数学模型，为闭环比例积分（PI）控制器的设计奠定了基础。与传统的利用物理定律推导数学模型的方法相比，系统辨识可以简化复杂的模型，并在考虑实验不确定性的情况下设计有效的鲁棒控制器。评价了闭环反馈系统在动态压力变化和抗扰方面的有效性。这导致变异系数（CV）从开环控制期间的9.32 %（最佳情况）显著降低到闭环控制期间的<； 3 %。此外，与开环相比，30分钟内容器压力的稳定性提高了25倍，液滴长度的稳定性提高了1.6倍。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Sensors and Actuators A-physical 工程技术-工程：电子与电气

CiteScore

8.10

自引率

6.50%

发文量

630

审稿时长

49 days

期刊介绍： Sensors and Actuators A: Physical brings together multidisciplinary interests in one journal entirely devoted to disseminating information on all aspects of research and development of solid-state devices for transducing physical signals. Sensors and Actuators A: Physical regularly publishes original papers, letters to the Editors and from time to time invited review articles within the following device areas: • Fundamentals and Physics, such as: classification of effects, physical effects, measurement theory, modelling of sensors, measurement standards, measurement errors, units and constants, time and frequency measurement. Modeling papers should bring new modeling techniques to the field and be supported by experimental results. • Materials and their Processing, such as: piezoelectric materials, polymers, metal oxides, III-V and II-VI semiconductors, thick and thin films, optical glass fibres, amorphous, polycrystalline and monocrystalline silicon. • Optoelectronic sensors, such as: photovoltaic diodes, photoconductors, photodiodes, phototransistors, positron-sensitive photodetectors, optoisolators, photodiode arrays, charge-coupled devices, light-emitting diodes, injection lasers and liquid-crystal displays. • Mechanical sensors, such as: metallic, thin-film and semiconductor strain gauges, diffused silicon pressure sensors, silicon accelerometers, solid-state displacement transducers, piezo junction devices, piezoelectric field-effect transducers (PiFETs), tunnel-diode strain sensors, surface acoustic wave devices, silicon micromechanical switches, solid-state flow meters and electronic flow controllers. Etc...