A High-Throughput Microfluidic Magnetic Separation (µFMS) Platform for Water Quality Monitoring

Abstract

The long-term aim of this work is to develop a biosensing system that rapidly detects bacterial targets of interest, such as Escherichia coli, in drinking and recreational water quality monitoring. For these applications, a standard sample size is 100 mL, which is quite large for magnetic separation microfluidic analysis platforms that typically function with <20 µL/s throughput. Here, we report the use of 1.5-µm-diameter magnetic microdisc to selectively tag target bacteria, and a high-throughput microfluidic device that can potentially isolate the magnetically tagged bacteria from 100 mL water samples in less than 15 min. Simulations and experiments show~90% capture efficiencies of magnetic particles at flow rates up to 120 µL/s. Also, the platform enables the magnetic microdiscs/bacteria conjugates to be directly imaged, providing a path for quantitative assay.From the large-volume samples experiments with IONs, the magnetic separation microfluidic device was capable of processing > 50 mL samples (Figure 7). The 50 mL sample (IONs concentration of 100 µg/mL) was filtered in~7 min at a flow rate of 120 µL/s and the estimated capture efficiency was 70.0 ± 2.3%. Similarly, the 100 mL sample (IONs concentration 12.5 µg/mL, 100 mL) was filtered in Micromachines 2020, 11, 16 9 of 13 15 min at a flow rate of 120 µL/s and the estimated capture efficiency was 72.2 ± 2.0%. Figure 7 show 100 mL sample experiment images of the solutions before filtering (A), after filtering (B), the µFMS device with all captured IONs (C), and the VSM data to estimate capture efficiency for 100 mL sample (D).

Computer simulation of submicron fluid flows in microfluidic chips and their applications in food analysis

“…Although the magnetic drive is an effective operation technique to manipulate magnetic particles in microfluidics, its typical small capacity is the main limitation for the magnetic separation microfluidic chip (Castillo‐Torres et al., 2019). For example, in a microfluidic chip that magnetically captures E. coli , a relatively low flow rate of usually less than 20 μL/s could completely perform the capture in a short time.…”

“…For improving the separation efficiency, Castillo‐Torres et al. (2019) developed a high‐throughput microfluidic magnetic separation platform to isolate the magnetically tagged bacteria. COMSOL was used to simulate the capture efficiency of different nanoparticles at various flow rates in the microfluidic chip, and the results were similar to the experiment.…”

“…Microfluidic chips have a growing trend in the development of biochemical analysis and detection and have been deeply studied as a potential POC (point of care) diagnostic system in clinical microbiology. With many advantages, such as low sample consumption, being able to perform complex high‐throughput tasks in microfluidic channels including sampling (Zhao et al., 2021), dilution (Weibull et al., 2013), reagent addition (Song et al., 2006), reaction (Parisi et al., 2013), separation (Castillo‐Torres et al., 2019), and detection (Gao et al., 2014), and increase of the speed of sample analysis by hundreds of times (Fukushima et al., 2007), the detection efficiency can be significantly improved. In recent decades, with the development of microfluidic technology and as a novel and powerful fluid manipulation technology combined with traditional detection methods, microfluidics has shown great potential in the detection and analysis of food contaminants (Guo et al., 2020).…”

Magnetic Polymers for Magnetophoretic Separation in Microfluidic Devices

“…Nevertheless, challenges remain regarding the complexity of microfabrication of magnetic micro-sources and their integration with polymer-based microfluidic systems. Film-based approaches, in which magnetic elements are integrated through standard microfabrication techniques such as sputtering [22][23][24], electroplating [25][26][27][28][29], thermal deposition [30,31], or thermo-magnetic patterning [32,33], led to unrivalled control over the reproducibility, shape, and microstructuration. However, these approaches suffer from poor adhesion with polymer substrates, the difficulty of achieving large aspect ratio microstructures, and the need for expensive and tedious fabrication processes.…”

Enhanced Microfluidic Sample Homogeneity and Improved Antibody-Based Assay Kinetics Due to Magnetic Mixing

“…Point-of-care (PoC) devices utilize lab-on-chip technologies to deliver testing results at the PoC in a fast turnaround time. Recent examples of lab-on-chip (bio)chemical processes are antibody (AB)-based testing such as the SARS-CoV-2 tests, 2 bacteria detection, 3 cancer cell isolation, 4 biomarker detection for the identification of different diseases, 5 with broad applications in water quality measurements, 6 cancer diagnostics, 7 drug administration, 8 and more, that could translate into a PoC device.…”